- Email: [email protected]
Leukotrienes in orthodontic tooth movement
Leukotknes
in orthodontic
Abbas H. Mohammed,
tooth movement
BDS, MS,* Dimltris N. Tatakis, DDS,** and Rosemary Dzlak, PhD**
United’ Arab Emirates and Buffalo, N.Y.
Prostagiandins (PGs) and leukotrienes (LTs) are products of arachidonic acid conversion. PGs have an established role in mediating orthodontic tooth movement. The role of LTs in modulating or mediating orthodontic tooth movement was investigated in this study. One hundred thirty-two Sprague-Dawley rats were used; the animals weighed 300 to 400 gm with equal numbers of male and female rats. They were divided into five main groups of 24 animals each and a sham,group of 12 animals. An orthodontic appliance was placed and activated on all the animals except the sham group; in this group the appliances were not active. Each main group was given one of the following treatments daily: distilled water, 5% gum arabic solution, PG.synthesis inhibitor indomethacin, LT synthesis inhibitor AA881, and a combination of both drugs. Each group was divided into six subgmups of four animals; the animals were killed at either 1, 3, 5, 7, 10, or 14, days, and tooth movement measured. The three sham subgroups received distilled water and were killed at 1, 7, or 10 days. The first maxillary molar (the moved tooth) and surrounding tissues were removed from all animals in the sham group and the subgroups killed at 1, 7, and 10 days in the gum arabic solution group and the LT synthesis inhibitor group. Prostaglandin E, (PGE,) and leukotriene B, (LTB,) were extracted, measured with radioimmunoassay @IA), and standardized per milligram of protein in the sample. A significant inhibition of tooth movement occurred beginning on day 7 in the indomethacin, AA861, and combination groups; there was no significant difference among these groups. The leukoitriene inhibitor AA861 caused a significant LTB, inhibition and a significant increase in PGE, production. These findings suggest that LTs might have a role in mediating orthodontic tooth movement. (AM J ORTHOD DENTOFAC ORTHOP 1989;95:231-7.)
A
lthough the exact mechanism for conversion of orthodontic force into cellular response is not understood, gn:at advances recently have been achieved in discovering $e role some factors such as cyclic adenosine monophosphate (CAMP),” calcium,4 collagenase,5 and prostaglandins (PGs)~-~may play in mediating tooth movement in response to orthodontic force. Although the involvement of PGs in mediating orthodontic tooth movement is well established,” the exact role of PGs and other factors is not very clear. PGs are products of the conversion of arachidonic acid through the cyclooxygenase pathway. Leukotrienes (LTs) are compounds, closely related to PGs, that are produced by the conversion of arachidonic acid via the lipoxygenase pathway. In the orthodontic movement of teeth, it is reasonable to expect a perturbation of the levels of LTs in addition to PGs. Many studies have shown that challenges to tissues by various stimuli will cause the release of both the cyclooxygenase and lipoxygenase jproducts.“-‘4 There is an interaction between the cyclooxygenase and lipoxygenase pathways Supported in part by NIDR Grant DE07034. *Ministry of Health, Abu-Dhabi, United Arab Emirates. **Department of Oral Biology, State University of New York at Buffalo.
and modulation of one pathway will usually be reflected in the modulation of the other.“,13,‘5,16 Recent data show that LTs are produced by bone tissuei and that inhibition of LT synthesis combined with mechanical stress blocks bone resorption and enhances bone formation.18~1g Therefore the modulation or mediation of orthodontic tooth movement by LTs in addition to PGs is not unlikely. The purpose of this study was to investigate the potential role of LTs and their interaction with PGs in mediating orthodontic tooth movement in the rat using the selective 5’lipoxygenase inhibitor AA861 ?’ MATERIALS AND METHODS
AA861, 2,3,5-trimethyl-6-( 12-hydroxy-S’lO-dodecadiynyl)-1,6benzoquinone was a generous gift from Dr. Masao Mishikawa, Takeda Chemical Industries, Osaka, Japan. This drug has been shown to be a selective inhibitor of the lipoxygenase pathway of arachidonic acid conversion. 14,20-22 Orthodontic
tooth movement
The experimental animals used in this study were 132 Sprague-Dawley rats of approximately the same age, weighing 300 to 400 gm. They were divided into 231
232
Mohammed,
Tatakis,
and
Am. J. Or&d.
Dziak
Dent&c. Orthop. March 1989
Table I. Tooth movement measurement in millimeters for the different groups
Distilled water group
Appliance usage
5% gum arabic group
5 mglkg body weight indomethacin group
20 mglkg body weight AA861 group
Indomethacinl AA861 combined group
(days)
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
1 3 5 7 10 14
0.203 0.203 0.240 0.288 0.375 0.474
0.0239 0.0146 0.0316 0.0225 0.0122 0.0646
0.203 0.248 0.240 0.315 0.374 0.438
0.0144 0.0118 0.0178 0.0178 0.0063 0.0225
0.198 0.205 0.221 0.247 0.257 0.302
O.Oi 18 0.0122 0.0125 0.0777 0.0155 0.0262
0.203 0.242 0.247 0.255 0.270 0.330
0.0110 0.0050 0.0155 0.0122 0.0285 0.0426
0.202 0.245 0.244 0.250 0.286 0.326
0.0166 0.0168 0.0147 0.0177 0.0449 0.0440
Table II. Prostaglandin E, production in different groups compared by Tukey-HSD Procedure Group Sham Gum arabic AA861
Number
control
8 8 8
PGEJmg protein Mean + SD (pg) 19.05 24.80 68.96
+ 27.44 2 26.60 -t- 54.41
Statistical signz$cance NS NS p < 0.05
five groups of 24 animals in addition to a sham group of 12 animals. Each group was further divided into subgroups of four animals each. These subgroups had an equal number of male and female animals. After anesthetizing with ketamine (44 mg/kg body weight) and xylazine (2 mg / kg / body weight), an orthodontic appliance described in detail in pi,;vious studies’ was placed on all animals including the sham groups in which the appliances were not activated. The’ appliance delivered a 60 gm mesial tipping force to the maxillary first molar. During the experiment .the animals were fed ground rat chow and water ad libitum. A 1Zhour light/dark cycle was maintained and. the 24 animals in each main group were given one of the following daily treatments starting after the appliances were placed: Group A-The leukotriene synthesis inhibitor AA861 (20 mg/kg body weight) in 5% gum arabic solution Group B -Brostaglandin synthesis inhibitor indomethacin (5 mg/kg body weight) suspended in distilled water Group C-Gum arabic control, 5% solution Group D-Distilled water control Group E-Combination of both drugsindomethacin and AA861 The sham group received a 5% gum arabic solution.
All drugs were administered orally with a 10 ml hypodermic syringe fitted with a special needle. In each group of 24 rats, one subgroup of four rats were killed with an ether overdose at either 1, 3, 5, 7, 10, or 14 days. Each rat was decapitated and tooth movement was determined by measuring the space created between the first and second maxillary molars with a calibrated thickness gauge. Meashrsment of leukotriene and prostaglandln levels at site of tooth movement
The maxillae of the animals that received.the leukotriene inhibitor and gum arabic solution and were killed at 1, 7, and 10 days were dissected free with curved scissors. The tissues were immersed immediately in liquid N, and maintained in a - 70” C freezing condition for further preparation. In general the time lapse between animal death and freezing of the maxillae was less than 30 seconds. The three sham subgroups that were sacrificed at 1, 7, and 10 days were subjected to the same procedure of dissection and freezing the maxillae. These time periods were chosen to represent the early and late phases of the tooth movement cycle. The procedure used in this experiment to prepare the tissue for extraction of leukotrienes and prostagiandins has been used in previous studies.5,23The roots of the first molar and tissue adjacent to them were removed from the excised maxillae with a straight handpiece and separating disk. The tissues remained frozen throughout this period and were handled consistently. These procedures were designed to minimize any degradation of the arachidonic acid metabolites. Each sample was homogenized in 3 ml of distilled water while bathing the test tube containing the sample in 5% methanol at - 20” C to avoid heat generation. One milliliter of the tissue homogenate was used for the extraction of either the leukotrienes or prostaglandins; 0.5 ml of the tissue homogenate was used for
Volume 95 Number
Leukotrienes
3
in orthodontic
tooth movement
233
Table III. Student’s t test comparison of
leukotriene B, production between control and AA86 1 groups * c;roup ‘1. Gum arabic AA861 *The
inhibition
9 8
control
was significant
at p < 0.001,
33.40 16.92
t 15.12 ” 8.60
df 15
protein measurement by means of the spectrophotometric method of Lowry and associates.25 LTB, and PGE, were extracted,25.26 measured with a commercially available radioimmunoassay,” and standardized per milligram of protein in the tissue sample. The differences among groups were assessed statistically by analysis of variance, Tukey-HSD, and Student’s t test. RESULTS
During the course of the experiment, the animals tolerated the appliance well and no side effects were observed from the administration of the different drugs. Tooth movement measurement
The measurements for all the groups are presented in Table I. In the control groups (the 5% gum arabic solution group and the distilled water group), the appliance produced a characteristic tooth movement cycle with three different phases (Fig. 1). A rapid tooth movement occurred on the first day caused by the compression of the tissues surrounding the, teeth. A second phase of 4 to 5 days’ duration followed; there was no tooth movement during this phase because of formation of the hyalinization zone. Finally the late tooth movement phase occurred during the period from day 7 to the end of the experiment when the animals were killed. A general one-factor ANOVA test showed a significant difference in tooth movement (p < 0.001) between the groups because of the effect of three factors: (1) type of treatment, (2) period (days) that the appliance was left on the teeth, and (3) the interaction between days and treatment. There was no significant difference in tooth movement between the two control groups at the 0.05 significance level using the Tukey-HSD procedure. in the three experimental groups (the indomethacin group, the AA861 group, and the combined indometh*Du Pont NEN Medical
Products,
North Billerica,
Mass
Time
(Days)
Fig. 1. Tooth movement cycle for gum arabic control group showing the three characteristic phases: (1) compression early phase (day l), (2) delayed hyaiinization period (days 4 and 5), and (3) late rapid tooth movement (day 5 to the end of the experimental period).
acin and AA861 group), tooth movement was inhibited compared to the two control groups (Table I). The Tukey-HSD procedure showed that the difference in tooth movement among each of the three experimental groups and each of the.two control groups was significant at the p < 0.05 level. There was no significant difference between any pair of the experimental groups (Table I) at the 0.05 level. Superimposition of the different tooth movement cycles during the experimental period showed that the indomethacin treatment group had the least tooth movement (Fig. 2). However, there was no significant difference between the indomethacin and the other groups at the day 3 and day 5 time points at the 0.05 significance level. On day 7, all three experimental groups showed significant reduction in tooth movement when compared with controls. The tooth movement in the three experimental groups produced cycles that were very similar from day 5 to the end of the experimental period. The differences among the experimental groups were not statistically significant. Prostaglandln
production
The measurements in picograms of PGEJmg protein for the sham, the gum arabic control, and the leukotriene synthesis inhibitor groups are presented in Table II. Prostaglandin levels were not detectable in some samples most likely because of the size of tissue sample. In some subgroups this resulted in an insufficient number of observations to perform a comparison of the different subgroups at each of the time points. However, within each treatment group, there appeared
234
Mohammed, 0.5 -
Conlrol lndomethacin AA861
.----. - - . .._ -...
04
AA86lelndomelh
- ----.
-
Am. J. Orthod.
Tatakis, and Dziak
Dentofac. Orthop. March 1989
Student’s t test comparison between the gum arabic and AA861 treated groups was performed. This showed that leukotriene B, production was significantly reduced (p < 0.001) as a result of the application of the AA861 drug (Table III). DISCUSSION
23456789
IO
II
12
13
14
lime IDays)
Fig. 2. Superimposition of tooth movement cycles for different groups. The three experimental groups differ significantly from the gum arabic control group in tooth movement during the late tooth movement phase; there were no significant differences among the groups. The points are the mean values from Table I.
to be no differences in prostaglandin levels as a function of time of treatment. Therefore a pooled mean for all the observations was calculated for each group. The leukotriene synthesis inhibitor group showed the highest prostaglandin production as compared with the gum arabic control and sham groups. An analysis of variance showed a signficant (0.01 < p < 0.05) difference among the groups that was caused by the type of treatment. The Tukey-HSD procedure was used to determine which pair(s) had a significant difference. The leukotriene synthesis inhibitor caused a significant prostaglandin production compared with the sham group (p < 0.05) (Table II). Leukotriene B, (LTB,) measurements
In this experiment we were unable to obtain a measurable level for the leukotriene B, in the sham group. Low basal levels and inadequate tissue sample size might account for these undetectable amounts. A mesurable reading for the leukotriene B, was obtained in the gum arabic control and in the leukotriene synthesis inhibitor groups. However, the number in some subgroups was not high enough (for example, two observations) to perform a comparison among the different subgroups. Therefore pooled means for the gum arabic control and for the leukotriene inhibition groups were calculated. Leukotriene B, production in tissue adjacent to orthodontically moved maxillarty first molars was reduced because of the administration of the leukotriene synthesis inhibitor AA861 as compared with the 5% gum arabic (control) treatment.
In agreement with previous studies,23,27the orthodontic appliance produced a characteristic three-phase tooth movement cycle in 14 days (Fig. 1). These three phases were most evident in the control groups. It is theoretically possible that the recorded measurements of movements of the first molar in the experimental groups presented herein are not accurate indications of the in situ movements. In this model movement of the first molar is measured against the second. It is possible that the drugs themselves modify mesial migration of the second molar. Since the stability of the second molar was not tested under the various experimental conditions, the data for the treated animals do have the potential to be quantitatively different from those actually recorded. However, the prostaglandin synthesis inhibitor indomethacin did cause a significant reduction (p < 0.05) in tooth movement in this study. These results are in agreement with the previously reported effect of indomethacin in orthodontic tooth movement using other model systems.4’9 This finding supports the validity of our model for testing the effect of other drugs on tooth movement. The leukotriene synthesis inhibitor AA861 caused a significant inhibition of leukotriene production in tissues adjacent to the moved teeth, as would be expected for this drug. A well-known observation in the literature is that inhibition of one pathway of arachidonic acid conversion will shunt the effect into an increase in the conversion via the other pathway. Inhibition of the lipoxygenase pathway has been reported to potentiate the cyclooxygenase pathway conversion of arachidonic acid and increase prostaglandin production.‘3,‘5,28”’ The leukotriene inhibition group in this experiment had a significant increase in prostaglandin production compared with the gum arabic control group in accordance with the results observed in the other systems referenced previously. However, in spite of the increased prostaglandin level and the established role of prostaglandin in mediating orthodontic tooth movement,416-‘0 a selective inhibition of leukotriene synthesis caused a significant reduction in tooth movement in this experiment . There are several potential mechanisms through which leukotriene might affect tooth movement. Lipoxygenase products have been implicated in the
Volume 95 Number 3
mediation of an inflammatory response. 32-34Inflammation has been suggested as an important factor in initiating the bone remodeling response incidental to orthodontic tooth movement. “~~3~~Therefore leukotriene inhibition might result in a weaker bone remodeling response via inhibition of an inflammatory response. Collagenase has been postulated to be an important enzyme in mediating tooth movement.’ Macrophages or monocytes induce some cells such as fibroblasts3’ and chondrocytes” to synthesize collagenase. Leukotriene product(s) seems to be obligatory for these cells to synthesize collagenase since leukotriene inhibition has been reported to induce inhibition of collagenase production.3” A similar conclusion may be drawn regarding the synthesis/ secretion of collagenase by fibroblast-like cells, which are the pioneer cells in the invasion of the hyalinized zone,36’39and osteoblast cells, which have been reported to be involved in collagenase production in bone.40 Therefore inhibition of collagenase synthesis by the leukotriene synthesis inhibitor might lead to a delay in resolution of the hyalinized zone and bone matrix, which ultimately leads to a delay in tooth movement. However, collagenase is only one among several factors reported to be involved in initiating the bone remodeling response incidental to orthodontic force application. Moreover the action of collagenase is mediated by prostaglandins,4’ which are not inhibited by the leukotriene synthesis inhibitor, but on the contrary appear to be increased. These considerations indicate that the reduction of tooth movement in the leukotriene synthesis inhibitor group was probably not caused by collagenase inhibition alone. Leukotriene-facilitated calcium movement also is present in the neutrophil during the expression of chemotactic activity. It was found that leukotriene products, especially LTB, and 5hydroxyeicosatetraenoic acid (ZGHETEI), cause both an intracellular redistribution of calcium and an increase in the plasma membrane permeability to calcium uptake.42 Lipoxygenase pathway products also mediate the action of plateletactivating factor by induction of increased calcium uptake43 by platelets. Since inhibition of calcium uptake has been reported to induce inhibition of bone resorption” and reduced tooth moveml:nt,4 inhibition of LT synthesis might influence tooth movement via inhibition of bone cell calcium movement. This suggestion is in agreement with previous observations,‘8.‘9 which reported that the inhibition of leukotriene combined with mechanical stress blocke’d the bone resorptive effect in pressure areas.
Leukotrienes
in orthodontic
tooth movement
235
In the group in which both the prostaglandin synthesis inhibitor indomethacin and the leukotriene synthesis inhibitor AA861 were given together, a significant reduction in tooth movement occurred. However, there was no additive effect in the reduction in tooth movement compared with the groups in which AA861 and indomethacin were given separately. This lack of additivity could be attributed to many possible causes: 1. The administration of the two drugs together could have resulted in an interaction that led to interference with their proper actions and ended in reduced effect. 2. The doses administered may have been too low to express the full effect of the drugs, especially with an increased availability of arachidonic acid. 3. The leukotrienes and prostaglandins might mediate different steps in a cascade of events that results in initiation of the signal for the bone remodeling response incidental to orthodontic tooth movement. Prostaglandins may increase the cell membrane permeability to calcium and leukotrienes may be important as an intracellular calcium mobilizer with both of these effects interrelated. Inhibition of either effect can interfere with the whole cascade of events. This interference can make the effect of another disturbance occurring further down the pathway nondetectable. CONCLUSIONS 1. A significant reduction in tooth movement occurred in the indomethacin group as compared with the control groups. 2. AA861, the specific S’lipoxygenase inhibitor, inhibited leukotriene production in tissue adjacent to orthodontically treated teeth and caused an increase in prostaglandin production. 3. Inhibition of leukotriene synthesis resulted in a significant inhibition of tooth movement. These results suggest that leukotriene production is important in the mediation of orthodontic tooth movement. A solid knowledge of the biochemical mediators of orthodontic tooth movement and their mechanisms of action should provide a rationale for better and faster orthodontic treatment. Our studies suggest that leukotrienes in addition to prostaglandins might have future clinical applications that could result in enhanced tooth movement. Moreover clinical use of leukotriene inhibitors for the control of allergic and inflammatory conditions may soon become more common as research
Am. J. Orthod.
236 Mohammed, Tatakis, and Dziak continues on the synthesis of such specific drugs as AA861. Our results suggest that the use of these drugs should be a factor considered by the orthodontist in evaluating the success of the tooth movement protocol.
19. 20.
REFERENCES
1. Davidovich Z, Shanfeld JL. Cyclic AMP level in alveolar bone of orthodontically treated cats. Arch Oral Biol 1975;20:567-74. 2. Tell GPE, CuatrecasasP, VanWyk JJ, Hintz RL. Somatomedin: inhibition of adenylate cyclase activity in subcellular membranes of various tissues. Science 1973;180:312-5. 3. Shanfeld J, Jones J, Laster L, Davidovich S. Biochemical aspects of orthodontic tooth movement: l-cyclic nucleotide and prostaglandin concentrations in tissue surrounding orthodontically treated teeth in vivo. AM J ORTHOD DENTOFAC ORTHOP 1986;
21.
22.
90:139-48.
4. Yamasaki K. The role of cyclic AMP, calcium, and prostaglandins in induction of osteoclastic bone resorption associated with experimental tooth movement. J Dent Res 1983;62:877-81. 5. King GJ, Collier J. A bone resorptive agent extracted from orthodontically treated tissues of the rat. Angle Orthod 1986;56: 299308. 6. Yamasaki K, Miura F, Suda T. Prostaglandin as a mediator of bone resorption induced by experimental tooth movement in rats. J Dent Res 1980;59: 1635-42. 7. Yamasaki K, Shibata Y, Fukuhora T. The effect of prostaglandiis on experimental tooth movement in monkeys. J Dent Res 1982;61:1444-6. 8. Yarnasaki K, Shibata Y, Imai S, Tani Y, Shibasaki Y, Fukuhora T. Clinical application of prostaglandin E,(PGE,) upon orthodontic tooth movement. AM J ORTHOD 1984;85:508-18. 9. Chumbley AB, Tuncay OC. The effect of indomethacin (an aspirin-like drug) on the rate of orthodontic tooth movement. AM J ORTHOD
1986;89:312-4.
10. Mostofa YA, Weaks-Dybuig M, Osdoby P. Orchestration of tooth movement. AM J ORTHOD 1983;83:245-50. Il. Engineer DM, Piper PG, Strais P. Interaction between the release of SRA-A and of prostaglandins. Br 3 Pharmacol 1972;57: 460- 1. 12. Liebig R, Bemauer W, Peskar BA. Prostaglandin, slow-reacting substance, and histamine release from anaphylactic guinea-pig hearts, and its pharmacological modification. Naunyn Schrniedebergs Arch Pharmacol 1975;289:65-76. 13. Bach MK, Brashler JR, Smith HW, Fitzpatric FA, Sun FF, McGuire JC. 6,9 Depoxy-6,9-(phenylimino)- 6,8-prostaglandin II, (U-60-257). A new inhibition of leukotriene C and D synthesis in in vitro studies. Prostaglandin 1982;23:759-70. 14. Schulz R, Seeger W. Release of leukotrienes into the perfusate of calcium-ionophore stimulated rabbit lung. Biochem Pharmacol 1986;35:183-93. 15. Ham EA, Egan RW, Soderman DD, Gale PH, Kuehl FA. Peroxidase-dependent deactivation of prostacyclin synthatase. J Biol Chem 1979;254:2191-4. 16. Walker JL. The regulatory function of prostaglandins in the release of histamine and SRS-A from passively sensitized human lung tissues. Adv Biosci 1972;9:235-40. 17. Offenbacher S, Dole BM, Van Dyke TE. Endotoxin mediated leukotriene release from bone culture. J Dent Res 1986(Abstract 1643);65:351. 18. Collins JL, Daniel JW, Cederquist R, Simmelink JW, Enlow
23. 24.
Dent&c. Orthop. March 1989
DH. Stimulation of bone development by mechanical stressand inhibition of leukotriene biosynthesis. J Dent Res 1987(Abstract 1771);66:328. Collins JL, Daniel JW, Cederquist R, Enlow DH. The role of leukotrienes in force induced bone development. J Dent Res 1987(Abstract 1772);66:328. Yoshiioto T, Yokoyama C, Ochi K, et al. 2,3,5-Tiimethyl-6(12-hydroxy-5,10-dodecadiynyl)l,4-b (AA861), a selective inhibitor of 5-lipoxygenase reaction and the biosynthesis of slowreacting substance of anaphylaxis. Biochim Biophys Acta 1982;713:470-3. Uzumaki H, Yamamoto S, Kato R. Effects of lipoxygenase and cyclooxygenase inhibitors on the induction of omithine decarboxylase by 12-O tetradecanoyl phorbol-13-acetate and isoproterenol in mouse tissue in vivo. Carcinogenesis 1986;7:289-94. Nakadate T, Yamamoto S, Aizu E, Kato R. Inhibition of 12.0tetradecanoylphorbol-13-acetate induced increase in vascular permeability in mouse skin by lipoxygenase inhibitors. Jpn J Pharmacol 1985;36:161-8. King GJ, Fischlschweiger W. The effect of force magnitude on extractable bone resorptive activity and cemental cratering in orthodontic tooth movement. J Dent Res 1982;61:775-9. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ. Protein measurement with the folin phenol reagent. J Biol Chem 1951; 1931265-76.
Jaffe BM, Behrman HR. Prostaglandins E, A, F. In: Jaffe BM, Behrman HR. eds. Methods of hormone radioimmunoassay. New York: Academic Press, 1978;19. 26. Jakschik BA, Harper T, Murphy RC. Methods in enzymology. In: Lands WEM, Smith WL, eds. Prostaglandin and arachidonate metabolites. Vol 6. New York: Academic Press, 1982:30-7. 27. Goldie RS, King GJ. Root resorption and tooth movement in orthodontically treated, calcium deficient, and lactating rats. AM 25.
J ORTHOD
1984;85:424-30.
28. Raisz LG, Martin TJ. Prostaglandin in bone and mineral metabolism. In: Peck WA, ed. Bone and mineral research annual II. Amsterdam: Excerpta, 1983:286-310. 29. Yue DK, Moehman S, Handelsman DJ, Delbridge L, Reeve T, Turtle JR. The effects of cycle-oxygenase and lipoxygenase inhibition on the collagen abnormalities of diabetic rats. Diabetes 1985;34:74-8. 30. Canonico PL, Judd MA, Koike K, Valdenergro CA, MacLeod RM. Arachidonates stimulates prolactin release in vitro: a role for the fatty acid and its metabolites as intracellular regulator(s) in mamatotrophs. Endocrinology 1985a;l lb:218-25. 3 1. Sullivan MH, Cooke BA. Effects of calmodulin and lipoxygenase inhibitors on LH (lutropin)- and LHRH (luliberin)-agoniststimulated steroidogenesis in rat Leydig cells. Biochem J 1985;232:55-9. 32. Samuelsson B. Leukotrienes: mediators of immediate hypersensitivity reactions and inflammation. Science 1983;220:568-75. 33. Samuelsson B. Leukotrienes and related compounds. Adv Prostaglandin Thromboxane Leukotriene Res 1985;15: 1-9. 34. Ford-Hutchinson A, Letts G. Biological actions of leukotrienes, state of the art lecture. Hypertension 1986;8(Suppl 11):l l-49. 35. Reitan K. Biomechanical principles and reactions. In: Graber TM, Swain BF, eds. Orthodontics: current principles and techniques. St. Louis: The CV Mosby Company, 1985:101-92. 36. Rygh P, Bowling K, Houlandsdal L, Williams W. Activation of the vascular system: a main mediator of periodontal fiber remodeling in orthodontic tooth movement. AM J ORTHOD 1986; 89:453-68.
Volume 95 Number 3 37. Dayer JM, K&ne SM, Russell RGG, Robinson DR. Production of collagenase and prostaglandms by isolated adherent rheumatoid synovial cells. Proc Nat1 Acad Sci USA 1976;73:945-9. 38. Nolan JC, Pickett WC. Studies on the effects of cycle-oxygenase and lipoxygenase inhibitors on the macrophage stimulated synthesis of collagenase by rabbit chondrocytes. Agents Actions 1985:17:73-6. 39. Rygh P. Elimination of hyalinized tissue associated with orthodontic tooth movement. Stand J Dent Res 1947b;82:57-73. 40. Sakamota S. Sakamoto M. Biochemical and immunohistochemical studies on collagenase in resorbing bone in tissue culture. J Periodont Res 1982;17:523-6. 41. Dowsett M, Eastmen AR, Easty DM, Easty GC, Powles TJ, Neville AM. Prostaglandin mediation of collagenase-induced bone resorprion. Nature 1976;263:72-4. 42. Naccache PH, Sha’afi RI, Bongeat P, Goetzl EJ. Mono and
Leukotrienes in orthodontic tooth movement 237
43.
44.
dihydroxyeicosatetraenoic acids alter calcium homeostasis in rabbit neutrophils. J Clin Invest 1981;67:1584-7. Lee TC, Malin LB, Synder F. Stimulation of calcium uptake by 1-alkyl-2-acetyl-Sn-glycero-3-phosphocholine (plateletactivating-factor) in rabbit platelets: possible involvement of the lipoxygenase pathway. Arch Biochem Biophys 1983;233:33-9. Yu J, Wells H, Ryan WJ, Lloyd WS. Effects of prostaglandins and other drugs on the cyclic AMP content of cultured bone cells. Prostaglandins 1976;12:501-13.
Reprint requests to: Dr. Rosemary Dziak Department of Oral Biology SUNY Buffalo Foster Hall Buffalo, NY 14214
in orthodontic
Abbas H. Mohammed,
tooth movement
BDS, MS,* Dimltris N. Tatakis, DDS,** and Rosemary Dzlak, PhD**
United’ Arab Emirates and Buffalo, N.Y.
Prostagiandins (PGs) and leukotrienes (LTs) are products of arachidonic acid conversion. PGs have an established role in mediating orthodontic tooth movement. The role of LTs in modulating or mediating orthodontic tooth movement was investigated in this study. One hundred thirty-two Sprague-Dawley rats were used; the animals weighed 300 to 400 gm with equal numbers of male and female rats. They were divided into five main groups of 24 animals each and a sham,group of 12 animals. An orthodontic appliance was placed and activated on all the animals except the sham group; in this group the appliances were not active. Each main group was given one of the following treatments daily: distilled water, 5% gum arabic solution, PG.synthesis inhibitor indomethacin, LT synthesis inhibitor AA881, and a combination of both drugs. Each group was divided into six subgmups of four animals; the animals were killed at either 1, 3, 5, 7, 10, or 14, days, and tooth movement measured. The three sham subgroups received distilled water and were killed at 1, 7, or 10 days. The first maxillary molar (the moved tooth) and surrounding tissues were removed from all animals in the sham group and the subgroups killed at 1, 7, and 10 days in the gum arabic solution group and the LT synthesis inhibitor group. Prostaglandin E, (PGE,) and leukotriene B, (LTB,) were extracted, measured with radioimmunoassay @IA), and standardized per milligram of protein in the sample. A significant inhibition of tooth movement occurred beginning on day 7 in the indomethacin, AA861, and combination groups; there was no significant difference among these groups. The leukoitriene inhibitor AA861 caused a significant LTB, inhibition and a significant increase in PGE, production. These findings suggest that LTs might have a role in mediating orthodontic tooth movement. (AM J ORTHOD DENTOFAC ORTHOP 1989;95:231-7.)
A
lthough the exact mechanism for conversion of orthodontic force into cellular response is not understood, gn:at advances recently have been achieved in discovering $e role some factors such as cyclic adenosine monophosphate (CAMP),” calcium,4 collagenase,5 and prostaglandins (PGs)~-~may play in mediating tooth movement in response to orthodontic force. Although the involvement of PGs in mediating orthodontic tooth movement is well established,” the exact role of PGs and other factors is not very clear. PGs are products of the conversion of arachidonic acid through the cyclooxygenase pathway. Leukotrienes (LTs) are compounds, closely related to PGs, that are produced by the conversion of arachidonic acid via the lipoxygenase pathway. In the orthodontic movement of teeth, it is reasonable to expect a perturbation of the levels of LTs in addition to PGs. Many studies have shown that challenges to tissues by various stimuli will cause the release of both the cyclooxygenase and lipoxygenase jproducts.“-‘4 There is an interaction between the cyclooxygenase and lipoxygenase pathways Supported in part by NIDR Grant DE07034. *Ministry of Health, Abu-Dhabi, United Arab Emirates. **Department of Oral Biology, State University of New York at Buffalo.
and modulation of one pathway will usually be reflected in the modulation of the other.“,13,‘5,16 Recent data show that LTs are produced by bone tissuei and that inhibition of LT synthesis combined with mechanical stress blocks bone resorption and enhances bone formation.18~1g Therefore the modulation or mediation of orthodontic tooth movement by LTs in addition to PGs is not unlikely. The purpose of this study was to investigate the potential role of LTs and their interaction with PGs in mediating orthodontic tooth movement in the rat using the selective 5’lipoxygenase inhibitor AA861 ?’ MATERIALS AND METHODS
AA861, 2,3,5-trimethyl-6-( 12-hydroxy-S’lO-dodecadiynyl)-1,6benzoquinone was a generous gift from Dr. Masao Mishikawa, Takeda Chemical Industries, Osaka, Japan. This drug has been shown to be a selective inhibitor of the lipoxygenase pathway of arachidonic acid conversion. 14,20-22 Orthodontic
tooth movement
The experimental animals used in this study were 132 Sprague-Dawley rats of approximately the same age, weighing 300 to 400 gm. They were divided into 231
232
Mohammed,
Tatakis,
and
Am. J. Or&d.
Dziak
Dent&c. Orthop. March 1989
Table I. Tooth movement measurement in millimeters for the different groups
Distilled water group
Appliance usage
5% gum arabic group
5 mglkg body weight indomethacin group
20 mglkg body weight AA861 group
Indomethacinl AA861 combined group
(days)
Mean
SD
Mean
SD
Mean
SD
Mean
SD
Mean
SD
1 3 5 7 10 14
0.203 0.203 0.240 0.288 0.375 0.474
0.0239 0.0146 0.0316 0.0225 0.0122 0.0646
0.203 0.248 0.240 0.315 0.374 0.438
0.0144 0.0118 0.0178 0.0178 0.0063 0.0225
0.198 0.205 0.221 0.247 0.257 0.302
O.Oi 18 0.0122 0.0125 0.0777 0.0155 0.0262
0.203 0.242 0.247 0.255 0.270 0.330
0.0110 0.0050 0.0155 0.0122 0.0285 0.0426
0.202 0.245 0.244 0.250 0.286 0.326
0.0166 0.0168 0.0147 0.0177 0.0449 0.0440
Table II. Prostaglandin E, production in different groups compared by Tukey-HSD Procedure Group Sham Gum arabic AA861
Number
control
8 8 8
PGEJmg protein Mean + SD (pg) 19.05 24.80 68.96
+ 27.44 2 26.60 -t- 54.41
Statistical signz$cance NS NS p < 0.05
five groups of 24 animals in addition to a sham group of 12 animals. Each group was further divided into subgroups of four animals each. These subgroups had an equal number of male and female animals. After anesthetizing with ketamine (44 mg/kg body weight) and xylazine (2 mg / kg / body weight), an orthodontic appliance described in detail in pi,;vious studies’ was placed on all animals including the sham groups in which the appliances were not activated. The’ appliance delivered a 60 gm mesial tipping force to the maxillary first molar. During the experiment .the animals were fed ground rat chow and water ad libitum. A 1Zhour light/dark cycle was maintained and. the 24 animals in each main group were given one of the following daily treatments starting after the appliances were placed: Group A-The leukotriene synthesis inhibitor AA861 (20 mg/kg body weight) in 5% gum arabic solution Group B -Brostaglandin synthesis inhibitor indomethacin (5 mg/kg body weight) suspended in distilled water Group C-Gum arabic control, 5% solution Group D-Distilled water control Group E-Combination of both drugsindomethacin and AA861 The sham group received a 5% gum arabic solution.
All drugs were administered orally with a 10 ml hypodermic syringe fitted with a special needle. In each group of 24 rats, one subgroup of four rats were killed with an ether overdose at either 1, 3, 5, 7, 10, or 14 days. Each rat was decapitated and tooth movement was determined by measuring the space created between the first and second maxillary molars with a calibrated thickness gauge. Meashrsment of leukotriene and prostaglandln levels at site of tooth movement
The maxillae of the animals that received.the leukotriene inhibitor and gum arabic solution and were killed at 1, 7, and 10 days were dissected free with curved scissors. The tissues were immersed immediately in liquid N, and maintained in a - 70” C freezing condition for further preparation. In general the time lapse between animal death and freezing of the maxillae was less than 30 seconds. The three sham subgroups that were sacrificed at 1, 7, and 10 days were subjected to the same procedure of dissection and freezing the maxillae. These time periods were chosen to represent the early and late phases of the tooth movement cycle. The procedure used in this experiment to prepare the tissue for extraction of leukotrienes and prostagiandins has been used in previous studies.5,23The roots of the first molar and tissue adjacent to them were removed from the excised maxillae with a straight handpiece and separating disk. The tissues remained frozen throughout this period and were handled consistently. These procedures were designed to minimize any degradation of the arachidonic acid metabolites. Each sample was homogenized in 3 ml of distilled water while bathing the test tube containing the sample in 5% methanol at - 20” C to avoid heat generation. One milliliter of the tissue homogenate was used for the extraction of either the leukotrienes or prostaglandins; 0.5 ml of the tissue homogenate was used for
Volume 95 Number
Leukotrienes
3
in orthodontic
tooth movement
233
Table III. Student’s t test comparison of
leukotriene B, production between control and AA86 1 groups * c;roup ‘1. Gum arabic AA861 *The
inhibition
9 8
control
was significant
at p < 0.001,
33.40 16.92
t 15.12 ” 8.60
df 15
protein measurement by means of the spectrophotometric method of Lowry and associates.25 LTB, and PGE, were extracted,25.26 measured with a commercially available radioimmunoassay,” and standardized per milligram of protein in the tissue sample. The differences among groups were assessed statistically by analysis of variance, Tukey-HSD, and Student’s t test. RESULTS
During the course of the experiment, the animals tolerated the appliance well and no side effects were observed from the administration of the different drugs. Tooth movement measurement
The measurements for all the groups are presented in Table I. In the control groups (the 5% gum arabic solution group and the distilled water group), the appliance produced a characteristic tooth movement cycle with three different phases (Fig. 1). A rapid tooth movement occurred on the first day caused by the compression of the tissues surrounding the, teeth. A second phase of 4 to 5 days’ duration followed; there was no tooth movement during this phase because of formation of the hyalinization zone. Finally the late tooth movement phase occurred during the period from day 7 to the end of the experiment when the animals were killed. A general one-factor ANOVA test showed a significant difference in tooth movement (p < 0.001) between the groups because of the effect of three factors: (1) type of treatment, (2) period (days) that the appliance was left on the teeth, and (3) the interaction between days and treatment. There was no significant difference in tooth movement between the two control groups at the 0.05 significance level using the Tukey-HSD procedure. in the three experimental groups (the indomethacin group, the AA861 group, and the combined indometh*Du Pont NEN Medical
Products,
North Billerica,
Mass
Time
(Days)
Fig. 1. Tooth movement cycle for gum arabic control group showing the three characteristic phases: (1) compression early phase (day l), (2) delayed hyaiinization period (days 4 and 5), and (3) late rapid tooth movement (day 5 to the end of the experimental period).
acin and AA861 group), tooth movement was inhibited compared to the two control groups (Table I). The Tukey-HSD procedure showed that the difference in tooth movement among each of the three experimental groups and each of the.two control groups was significant at the p < 0.05 level. There was no significant difference between any pair of the experimental groups (Table I) at the 0.05 level. Superimposition of the different tooth movement cycles during the experimental period showed that the indomethacin treatment group had the least tooth movement (Fig. 2). However, there was no significant difference between the indomethacin and the other groups at the day 3 and day 5 time points at the 0.05 significance level. On day 7, all three experimental groups showed significant reduction in tooth movement when compared with controls. The tooth movement in the three experimental groups produced cycles that were very similar from day 5 to the end of the experimental period. The differences among the experimental groups were not statistically significant. Prostaglandln
production
The measurements in picograms of PGEJmg protein for the sham, the gum arabic control, and the leukotriene synthesis inhibitor groups are presented in Table II. Prostaglandin levels were not detectable in some samples most likely because of the size of tissue sample. In some subgroups this resulted in an insufficient number of observations to perform a comparison of the different subgroups at each of the time points. However, within each treatment group, there appeared
234
Mohammed, 0.5 -
Conlrol lndomethacin AA861
.----. - - . .._ -...
04
AA86lelndomelh
- ----.
-
Am. J. Orthod.
Tatakis, and Dziak
Dentofac. Orthop. March 1989
Student’s t test comparison between the gum arabic and AA861 treated groups was performed. This showed that leukotriene B, production was significantly reduced (p < 0.001) as a result of the application of the AA861 drug (Table III). DISCUSSION
23456789
IO
II
12
13
14
lime IDays)
Fig. 2. Superimposition of tooth movement cycles for different groups. The three experimental groups differ significantly from the gum arabic control group in tooth movement during the late tooth movement phase; there were no significant differences among the groups. The points are the mean values from Table I.
to be no differences in prostaglandin levels as a function of time of treatment. Therefore a pooled mean for all the observations was calculated for each group. The leukotriene synthesis inhibitor group showed the highest prostaglandin production as compared with the gum arabic control and sham groups. An analysis of variance showed a signficant (0.01 < p < 0.05) difference among the groups that was caused by the type of treatment. The Tukey-HSD procedure was used to determine which pair(s) had a significant difference. The leukotriene synthesis inhibitor caused a significant prostaglandin production compared with the sham group (p < 0.05) (Table II). Leukotriene B, (LTB,) measurements
In this experiment we were unable to obtain a measurable level for the leukotriene B, in the sham group. Low basal levels and inadequate tissue sample size might account for these undetectable amounts. A mesurable reading for the leukotriene B, was obtained in the gum arabic control and in the leukotriene synthesis inhibitor groups. However, the number in some subgroups was not high enough (for example, two observations) to perform a comparison among the different subgroups. Therefore pooled means for the gum arabic control and for the leukotriene inhibition groups were calculated. Leukotriene B, production in tissue adjacent to orthodontically moved maxillarty first molars was reduced because of the administration of the leukotriene synthesis inhibitor AA861 as compared with the 5% gum arabic (control) treatment.
In agreement with previous studies,23,27the orthodontic appliance produced a characteristic three-phase tooth movement cycle in 14 days (Fig. 1). These three phases were most evident in the control groups. It is theoretically possible that the recorded measurements of movements of the first molar in the experimental groups presented herein are not accurate indications of the in situ movements. In this model movement of the first molar is measured against the second. It is possible that the drugs themselves modify mesial migration of the second molar. Since the stability of the second molar was not tested under the various experimental conditions, the data for the treated animals do have the potential to be quantitatively different from those actually recorded. However, the prostaglandin synthesis inhibitor indomethacin did cause a significant reduction (p < 0.05) in tooth movement in this study. These results are in agreement with the previously reported effect of indomethacin in orthodontic tooth movement using other model systems.4’9 This finding supports the validity of our model for testing the effect of other drugs on tooth movement. The leukotriene synthesis inhibitor AA861 caused a significant inhibition of leukotriene production in tissues adjacent to the moved teeth, as would be expected for this drug. A well-known observation in the literature is that inhibition of one pathway of arachidonic acid conversion will shunt the effect into an increase in the conversion via the other pathway. Inhibition of the lipoxygenase pathway has been reported to potentiate the cyclooxygenase pathway conversion of arachidonic acid and increase prostaglandin production.‘3,‘5,28”’ The leukotriene inhibition group in this experiment had a significant increase in prostaglandin production compared with the gum arabic control group in accordance with the results observed in the other systems referenced previously. However, in spite of the increased prostaglandin level and the established role of prostaglandin in mediating orthodontic tooth movement,416-‘0 a selective inhibition of leukotriene synthesis caused a significant reduction in tooth movement in this experiment . There are several potential mechanisms through which leukotriene might affect tooth movement. Lipoxygenase products have been implicated in the
Volume 95 Number 3
mediation of an inflammatory response. 32-34Inflammation has been suggested as an important factor in initiating the bone remodeling response incidental to orthodontic tooth movement. “~~3~~Therefore leukotriene inhibition might result in a weaker bone remodeling response via inhibition of an inflammatory response. Collagenase has been postulated to be an important enzyme in mediating tooth movement.’ Macrophages or monocytes induce some cells such as fibroblasts3’ and chondrocytes” to synthesize collagenase. Leukotriene product(s) seems to be obligatory for these cells to synthesize collagenase since leukotriene inhibition has been reported to induce inhibition of collagenase production.3” A similar conclusion may be drawn regarding the synthesis/ secretion of collagenase by fibroblast-like cells, which are the pioneer cells in the invasion of the hyalinized zone,36’39and osteoblast cells, which have been reported to be involved in collagenase production in bone.40 Therefore inhibition of collagenase synthesis by the leukotriene synthesis inhibitor might lead to a delay in resolution of the hyalinized zone and bone matrix, which ultimately leads to a delay in tooth movement. However, collagenase is only one among several factors reported to be involved in initiating the bone remodeling response incidental to orthodontic force application. Moreover the action of collagenase is mediated by prostaglandins,4’ which are not inhibited by the leukotriene synthesis inhibitor, but on the contrary appear to be increased. These considerations indicate that the reduction of tooth movement in the leukotriene synthesis inhibitor group was probably not caused by collagenase inhibition alone. Leukotriene-facilitated calcium movement also is present in the neutrophil during the expression of chemotactic activity. It was found that leukotriene products, especially LTB, and 5hydroxyeicosatetraenoic acid (ZGHETEI), cause both an intracellular redistribution of calcium and an increase in the plasma membrane permeability to calcium uptake.42 Lipoxygenase pathway products also mediate the action of plateletactivating factor by induction of increased calcium uptake43 by platelets. Since inhibition of calcium uptake has been reported to induce inhibition of bone resorption” and reduced tooth moveml:nt,4 inhibition of LT synthesis might influence tooth movement via inhibition of bone cell calcium movement. This suggestion is in agreement with previous observations,‘8.‘9 which reported that the inhibition of leukotriene combined with mechanical stress blocke’d the bone resorptive effect in pressure areas.
Leukotrienes
in orthodontic
tooth movement
235
In the group in which both the prostaglandin synthesis inhibitor indomethacin and the leukotriene synthesis inhibitor AA861 were given together, a significant reduction in tooth movement occurred. However, there was no additive effect in the reduction in tooth movement compared with the groups in which AA861 and indomethacin were given separately. This lack of additivity could be attributed to many possible causes: 1. The administration of the two drugs together could have resulted in an interaction that led to interference with their proper actions and ended in reduced effect. 2. The doses administered may have been too low to express the full effect of the drugs, especially with an increased availability of arachidonic acid. 3. The leukotrienes and prostaglandins might mediate different steps in a cascade of events that results in initiation of the signal for the bone remodeling response incidental to orthodontic tooth movement. Prostaglandins may increase the cell membrane permeability to calcium and leukotrienes may be important as an intracellular calcium mobilizer with both of these effects interrelated. Inhibition of either effect can interfere with the whole cascade of events. This interference can make the effect of another disturbance occurring further down the pathway nondetectable. CONCLUSIONS 1. A significant reduction in tooth movement occurred in the indomethacin group as compared with the control groups. 2. AA861, the specific S’lipoxygenase inhibitor, inhibited leukotriene production in tissue adjacent to orthodontically treated teeth and caused an increase in prostaglandin production. 3. Inhibition of leukotriene synthesis resulted in a significant inhibition of tooth movement. These results suggest that leukotriene production is important in the mediation of orthodontic tooth movement. A solid knowledge of the biochemical mediators of orthodontic tooth movement and their mechanisms of action should provide a rationale for better and faster orthodontic treatment. Our studies suggest that leukotrienes in addition to prostaglandins might have future clinical applications that could result in enhanced tooth movement. Moreover clinical use of leukotriene inhibitors for the control of allergic and inflammatory conditions may soon become more common as research
Am. J. Orthod.
236 Mohammed, Tatakis, and Dziak continues on the synthesis of such specific drugs as AA861. Our results suggest that the use of these drugs should be a factor considered by the orthodontist in evaluating the success of the tooth movement protocol.
19. 20.
REFERENCES
1. Davidovich Z, Shanfeld JL. Cyclic AMP level in alveolar bone of orthodontically treated cats. Arch Oral Biol 1975;20:567-74. 2. Tell GPE, CuatrecasasP, VanWyk JJ, Hintz RL. Somatomedin: inhibition of adenylate cyclase activity in subcellular membranes of various tissues. Science 1973;180:312-5. 3. Shanfeld J, Jones J, Laster L, Davidovich S. Biochemical aspects of orthodontic tooth movement: l-cyclic nucleotide and prostaglandin concentrations in tissue surrounding orthodontically treated teeth in vivo. AM J ORTHOD DENTOFAC ORTHOP 1986;
21.
22.
90:139-48.
4. Yamasaki K. The role of cyclic AMP, calcium, and prostaglandins in induction of osteoclastic bone resorption associated with experimental tooth movement. J Dent Res 1983;62:877-81. 5. King GJ, Collier J. A bone resorptive agent extracted from orthodontically treated tissues of the rat. Angle Orthod 1986;56: 299308. 6. Yamasaki K, Miura F, Suda T. Prostaglandin as a mediator of bone resorption induced by experimental tooth movement in rats. J Dent Res 1980;59: 1635-42. 7. Yamasaki K, Shibata Y, Fukuhora T. The effect of prostaglandiis on experimental tooth movement in monkeys. J Dent Res 1982;61:1444-6. 8. Yarnasaki K, Shibata Y, Imai S, Tani Y, Shibasaki Y, Fukuhora T. Clinical application of prostaglandin E,(PGE,) upon orthodontic tooth movement. AM J ORTHOD 1984;85:508-18. 9. Chumbley AB, Tuncay OC. The effect of indomethacin (an aspirin-like drug) on the rate of orthodontic tooth movement. AM J ORTHOD
1986;89:312-4.
10. Mostofa YA, Weaks-Dybuig M, Osdoby P. Orchestration of tooth movement. AM J ORTHOD 1983;83:245-50. Il. Engineer DM, Piper PG, Strais P. Interaction between the release of SRA-A and of prostaglandins. Br 3 Pharmacol 1972;57: 460- 1. 12. Liebig R, Bemauer W, Peskar BA. Prostaglandin, slow-reacting substance, and histamine release from anaphylactic guinea-pig hearts, and its pharmacological modification. Naunyn Schrniedebergs Arch Pharmacol 1975;289:65-76. 13. Bach MK, Brashler JR, Smith HW, Fitzpatric FA, Sun FF, McGuire JC. 6,9 Depoxy-6,9-(phenylimino)- 6,8-prostaglandin II, (U-60-257). A new inhibition of leukotriene C and D synthesis in in vitro studies. Prostaglandin 1982;23:759-70. 14. Schulz R, Seeger W. Release of leukotrienes into the perfusate of calcium-ionophore stimulated rabbit lung. Biochem Pharmacol 1986;35:183-93. 15. Ham EA, Egan RW, Soderman DD, Gale PH, Kuehl FA. Peroxidase-dependent deactivation of prostacyclin synthatase. J Biol Chem 1979;254:2191-4. 16. Walker JL. The regulatory function of prostaglandins in the release of histamine and SRS-A from passively sensitized human lung tissues. Adv Biosci 1972;9:235-40. 17. Offenbacher S, Dole BM, Van Dyke TE. Endotoxin mediated leukotriene release from bone culture. J Dent Res 1986(Abstract 1643);65:351. 18. Collins JL, Daniel JW, Cederquist R, Simmelink JW, Enlow
23. 24.
Dent&c. Orthop. March 1989
DH. Stimulation of bone development by mechanical stressand inhibition of leukotriene biosynthesis. J Dent Res 1987(Abstract 1771);66:328. Collins JL, Daniel JW, Cederquist R, Enlow DH. The role of leukotrienes in force induced bone development. J Dent Res 1987(Abstract 1772);66:328. Yoshiioto T, Yokoyama C, Ochi K, et al. 2,3,5-Tiimethyl-6(12-hydroxy-5,10-dodecadiynyl)l,4-b (AA861), a selective inhibitor of 5-lipoxygenase reaction and the biosynthesis of slowreacting substance of anaphylaxis. Biochim Biophys Acta 1982;713:470-3. Uzumaki H, Yamamoto S, Kato R. Effects of lipoxygenase and cyclooxygenase inhibitors on the induction of omithine decarboxylase by 12-O tetradecanoyl phorbol-13-acetate and isoproterenol in mouse tissue in vivo. Carcinogenesis 1986;7:289-94. Nakadate T, Yamamoto S, Aizu E, Kato R. Inhibition of 12.0tetradecanoylphorbol-13-acetate induced increase in vascular permeability in mouse skin by lipoxygenase inhibitors. Jpn J Pharmacol 1985;36:161-8. King GJ, Fischlschweiger W. The effect of force magnitude on extractable bone resorptive activity and cemental cratering in orthodontic tooth movement. J Dent Res 1982;61:775-9. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ. Protein measurement with the folin phenol reagent. J Biol Chem 1951; 1931265-76.
Jaffe BM, Behrman HR. Prostaglandins E, A, F. In: Jaffe BM, Behrman HR. eds. Methods of hormone radioimmunoassay. New York: Academic Press, 1978;19. 26. Jakschik BA, Harper T, Murphy RC. Methods in enzymology. In: Lands WEM, Smith WL, eds. Prostaglandin and arachidonate metabolites. Vol 6. New York: Academic Press, 1982:30-7. 27. Goldie RS, King GJ. Root resorption and tooth movement in orthodontically treated, calcium deficient, and lactating rats. AM 25.
J ORTHOD
1984;85:424-30.
28. Raisz LG, Martin TJ. Prostaglandin in bone and mineral metabolism. In: Peck WA, ed. Bone and mineral research annual II. Amsterdam: Excerpta, 1983:286-310. 29. Yue DK, Moehman S, Handelsman DJ, Delbridge L, Reeve T, Turtle JR. The effects of cycle-oxygenase and lipoxygenase inhibition on the collagen abnormalities of diabetic rats. Diabetes 1985;34:74-8. 30. Canonico PL, Judd MA, Koike K, Valdenergro CA, MacLeod RM. Arachidonates stimulates prolactin release in vitro: a role for the fatty acid and its metabolites as intracellular regulator(s) in mamatotrophs. Endocrinology 1985a;l lb:218-25. 3 1. Sullivan MH, Cooke BA. Effects of calmodulin and lipoxygenase inhibitors on LH (lutropin)- and LHRH (luliberin)-agoniststimulated steroidogenesis in rat Leydig cells. Biochem J 1985;232:55-9. 32. Samuelsson B. Leukotrienes: mediators of immediate hypersensitivity reactions and inflammation. Science 1983;220:568-75. 33. Samuelsson B. Leukotrienes and related compounds. Adv Prostaglandin Thromboxane Leukotriene Res 1985;15: 1-9. 34. Ford-Hutchinson A, Letts G. Biological actions of leukotrienes, state of the art lecture. Hypertension 1986;8(Suppl 11):l l-49. 35. Reitan K. Biomechanical principles and reactions. In: Graber TM, Swain BF, eds. Orthodontics: current principles and techniques. St. Louis: The CV Mosby Company, 1985:101-92. 36. Rygh P, Bowling K, Houlandsdal L, Williams W. Activation of the vascular system: a main mediator of periodontal fiber remodeling in orthodontic tooth movement. AM J ORTHOD 1986; 89:453-68.
Volume 95 Number 3 37. Dayer JM, K&ne SM, Russell RGG, Robinson DR. Production of collagenase and prostaglandms by isolated adherent rheumatoid synovial cells. Proc Nat1 Acad Sci USA 1976;73:945-9. 38. Nolan JC, Pickett WC. Studies on the effects of cycle-oxygenase and lipoxygenase inhibitors on the macrophage stimulated synthesis of collagenase by rabbit chondrocytes. Agents Actions 1985:17:73-6. 39. Rygh P. Elimination of hyalinized tissue associated with orthodontic tooth movement. Stand J Dent Res 1947b;82:57-73. 40. Sakamota S. Sakamoto M. Biochemical and immunohistochemical studies on collagenase in resorbing bone in tissue culture. J Periodont Res 1982;17:523-6. 41. Dowsett M, Eastmen AR, Easty DM, Easty GC, Powles TJ, Neville AM. Prostaglandin mediation of collagenase-induced bone resorprion. Nature 1976;263:72-4. 42. Naccache PH, Sha’afi RI, Bongeat P, Goetzl EJ. Mono and
Leukotrienes in orthodontic tooth movement 237
43.
44.
dihydroxyeicosatetraenoic acids alter calcium homeostasis in rabbit neutrophils. J Clin Invest 1981;67:1584-7. Lee TC, Malin LB, Synder F. Stimulation of calcium uptake by 1-alkyl-2-acetyl-Sn-glycero-3-phosphocholine (plateletactivating-factor) in rabbit platelets: possible involvement of the lipoxygenase pathway. Arch Biochem Biophys 1983;233:33-9. Yu J, Wells H, Ryan WJ, Lloyd WS. Effects of prostaglandins and other drugs on the cyclic AMP content of cultured bone cells. Prostaglandins 1976;12:501-13.
Reprint requests to: Dr. Rosemary Dziak Department of Oral Biology SUNY Buffalo Foster Hall Buffalo, NY 14214