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Progesterone antagonist (RU 486) for cervical dilation, labor induction, and delivery in monkeys: Effectiveness in combination with oxytocin
Progesterone antagonist (RU 486) for cervical dilation, labor induction, and delivery in monkeys: Effectiveness in combination with oxytocin Jean Philippe Wolf, MD,. Michael Sinosich, PhD," Ted L. Anderson, PhD,. Andre Ulmann, MD: Etienne E. Baulieu, MD,c and Gary D. Hodgen, PhD" Norfolk, Virginia, and Paris, Frana A progesterone antagonist (RU 486), combined with oxytocin, was effective in achieving cervical dilation, labor induction, and early delivery in near-term monkeys. Effects of RU 486 included accelerated flow of colostrum and transiently enhanced weight gain in infants. No overt toxicity on fetuses, mothers, or newborns was detected with the use of a single oral dose of 25 mg. (AM J OSSTET GVNECOL 1989;160:45-7.)
Key words: Progesterone antagonist, RU 486, cervical dilation, labor induction, oxytocin, breast milk
The advent of the potent progesterone antagonist RU 486 has stimulated considerable interest to examine its potential for gynecologic and obstetric indications. Among such applications are management problems common to labor and delivery, in which progesterone plays a principal role in the physiology of advanced pregnancy. I. 2 On the basis of our previous studies evaluating dose, interval, and route of administration in our primate model,' we examined whether RU 486 may be useful alone or with oxytocin in effecting cervical dilation, myometrial contractility, and delivery. In our pilot studies, we noticed overt milk flow before the onset of labor when RU 486 was administered to near-term pregnant monkeys. Thus we examined alterations in breast milk production and composition after RU 486 treatment. In addition, we examined what impact such alterations might have on neonatal nutrition as measured by infant growth rates.
Material and methods Pregnant cynomolgus monkeys (Macaca fasclcularis), weighing 4.1 to 6.2 kg, were divided randomly into four groups: (I) untreated controls (n = Il); (2) RU 486
From the Jones Institute for Reproductive Medlcine,a Department of Obstetrics and Gynecology, Eastern Vlrgznza Medical School, Med!cal College of Hampton Roads, Roussel Uclaf,b and Unzte 33 INSERM,' Hop!tal de Blcetre. Presented in part at the Thirty-fifth Annual Meetzng of the Socze(v For Gynecologic Investigation, Baltimore, Maryland, March 17-
20,1988.
Reprznt requests: Gary D. Hodgen, PhD, Professor and SCientific Director, The Jones Institute for ReproductIVe Medlczne, Department of Obstetrics and G,vnecology, Eastern Virginia Medical School, Medical College of Hampton Roads, 855 W. Brambleton Avenue, Suite B, Noifolk. VA 23510.
Age (weeks)
Fig. l. Comparison of infant monkey weight gain from birth to 6 weeks of age between the control group (open squares, n = 10) and after use of RU 486 with or without oxytocin (closed squares, n = 30) for cervical dilation and labor induction (Asterisk * indicates significant differences [analysis of variance], p < 0.05).
alone (n = 19), (3) oxytocin alone (n = 7); and (4) RU 486 plus oxytocin (n = 14), A single oral dose of RU 486 (25 mg) was administered at 6:00 PM on day 160 of pregnancy (term = 167 ± 3.3 days). Cervical dilation and labor induction were assessed by either visual inspection or manual palpation after 12 hours and repeated if delivery had not occurred within 24 hours. Oxytocin (20 U, intravenously) was given either alone or 12 hours after RU 486 administration, with subsequent assessment of cer-
45
46
Wolf et al.
January 1989 Am J Obstet Gynecol
Table I. Effects of RU 486 alone and in combination with oxytocin on cervical dilation, labor induction, and delivery in monkeys
Monkey groups
n
Control RU 486 Oxytocin RU 486 with oxytocin
11 19 7 14
Deltvery within 48 hr:f:
CervIcal dtlation*
Intensity of contractwns Inducedt
+ +(15)
+(2) + +(7) ++(13)
Fetus I
+ + (II)
2
I 12§
I
Placenta
I
2 I
Ilil
* Cervical dilation:
- = <0.5 cm; + = 0.5 to 1.0 cm; and + + = > 1.0 cm (number of monkeys in parentheses). tRhythmic myometrial contractions typical of spontaneous labor and delivery: - = none detected; + = mild contractions, not sufficient for delivery; + + = powerful contractions needed to accomplish natural delivery (number of monkeys in parentheses). :j: If vaginal delivery was not accomplished within 48 hours, cesarean section was performed, controls excepted. § Delivery: day 162.5 ± 1.5 vs day 167.3 ± 2.4 (p < 0.05). II One retained placenta.
vical and myometrial status within IS minutes. Except in the control group, cesarean section was performed if delivery had not occurred within 48 hours after the initial treatment. All infants were weighed at birth and weekly through 6 weeks of age. Differences were distinguished with one-way analysis of variance. Breast milk was expressed manually and collected before, during, and after treatment with RU 486 or oxytocin; we assessed the relative abundance of immunoglobulins, which are characteristic of colostrum milk, using two-dimensional immunoelectrophoresis." Results
Table I illustrates that RU 486 was effective in promoting cervical dilation by simultaneously shortening and softening the cervix. However, such treatment did not reliably induce the uterine contractions necessary for successful parturition. Oxytocin administered alone was ineffective at achieving delivery. However, vaginal delivery was realized within 4 hours (16 hours after initial RU 486 administration) in nine of 14 cases when oxytocin followed RU 486. In 12 of 14 cases, vaginal delivery was achieved within 36 hours after oxytocin (48 hours after initial RU 486 treatment). Among all treatment groups, 48 of 49 fetuses delivered alive were thriving at 6 weeks of age. One died of unknown causes after 23 days (RU 486 plus oxytocin treatment), whereas there were two stillbirths (one control and one RU 486 treatment). Immunoglobulins were detected in normal colostrum milk from control females I day after spontaneous delivery. Interestingly, RU 486 treatment (with or without oxytocin) uniformly resulted in precocious appearance of colostrum immunoglobulins in breast milk within 12 hours of initial treatment, even before the onset oflabor. Babies nursing from mothers treated with RU 486 demonstrated transient but significant (P < 0.05) increased weight gains compared with in-
fants in the control group during the initial 3 weeks of neonatal life (Fig. 1); thereafter, no differences were apparent among groups. Comment
Whereas progesterone exerts an array of fundamental physiologic actions in advanced pregnancy, administration of RU 486 to near-term pregnant monkeys appears to manifest differential effects on cervical "ripening," myometrial contractility, and milk production/composition before and after delivery. Although as much as 25 mg/kg of RU 486 administered intramuscularly in our pilot studies induced abruptio placentae, no overt toxicity on fetuses, mothers, or newborns was detected at the oral dose applied here. Since infant growth rates were transiently accelerated among mothers given RU 486 and colostrum production and globulin composition were accelerated in pregnant monkeys soon after RU 486 treatment, we speculate that aQtagonism of progesterone may have transiently amplified nutritive milk constituents, including protein. lipids, and saccharides. Evidence has been presented that withdrawal of progesterone is a requisite "trigger" to initiate lactogenesis in rats,5 although there appears to be no subsequent correlation between progesterone levels and breast milk once lactogenesis has been established." Data presented here suggest that a similar relationship between progestin action and lactation may also exist in primates. Although RU 486 reliably precipitated cervical dilation within 12 hours, it was not effective alone in labor induction and delivery, nor was oxytocin administered alone effective in this model. However, administration of oxytocin after RU 486 had achieved opening and softening of the cervix advanced delivery by 4.8 ± 2.1 days (p < 0.05). Since control females and those receiving RU 486 alone or in conjunction with oxytocin were similarly examined by manual and visual ins pec-
Volume 160 Number 1
tion, labor induction was not a function of tactile stimuli. These data indicate that RU 486 may be a useful adjunct to oxytocin for labor induction. Whereas these findings require cautious interpretation because of limited observations, we believe progesterone antagonists deserve continued study as adjunctive agents in perinatal management. We thank Lynn Sharpe and Janice Hammond for their excellent technical contributions, Martha Forrester for assistance in preparation of graphic materials, and Dara Leary for typing and editorial assistance.
RU 486 for cervical dilation and labor induction
2. Hodgen CD, Stouffer RL, Barber DL, Nixon WE. Serum estradiol and progesterone during pregnancy and the status of the corpus luteum at delivery in cynomolgus monkeys (Macaca fasciculans). Steroids 1977;30:295. 3. Wolf JP, Chillik CF, Itskovitz J, et al. Transplacental passage of a progesterone antagonist in monkeys. AM J OBSTET CYNECOL 1988:159:238. 4. Sinosich MJ, Teisner B, Davey M. Crudzinskas JC. Pregnancy-associated plasma protein-A: interaction with heparin in crossed affinity immunoelectrophoresis. Aust NZ J Med 1981; 11 :42g.. 5. Kuhn NJ. Progesterone withdrawal as the lactogenic trigger in the rat. J Endocrinol 1969;44:39. 6. Herrenkohl LR. The effects of lactation of progesterone injections administered during late pregnancy in the rat. Proc Soc Exp BioI Med 1971;138:39.
REFERENCES 1. Hodgen CD, Dufau ML, Catt KJ, Tullner WW. Estrogens, progesterone and chorionic gonadotropin in pregnant rhesus monkeys. Endocrinology 1972;91 :896.
Vascular catecholamine sensitivity during pregnancy in the ewe Margaret K. McLaughlin, PhD, Tara Mathews Keve, BS, and Rosemary Cooke, BS Burlington, Vermont Four pregnant and four castrated ewes were chronically instrumented for the measurement of external iliac blood flow to test the hypothesis that pregnancy alters Ct-adrenergic sensitivity in a major regional circulation. Complete dose-response curves were generated to methoxamine, phenylephrine, and norepinephrine. Pregnancy was associated with no change in methoxamine sensitivity, an increase in phenylephrine sensitivity, and a decrease in norepinephrine sensitivity. These differential changes in drug sensitivity suggest (1) the Ct,-receptor population is functionally similar between the two groups of animals, (2) uptake 1 is inhibited, and (3) either catechol-O-methyltransferase activity is increased or the Ct2- or j3-receptor population changes in this circulation during pregnancy. These data illustrate the complexity of the change in the adrenergic system during pregnancy. (AM J OBSTET GYNECOL 1989;160:47-53.)
Key words: Sheep, circulation, catecholamines, skeletal muscle, norepinephrine, phenylephrine, methoxamine
It is well recognized that marked changes occur in vascular reactivity in women with pregnancy-induced hypertension or preeclampsia even before they dem-
From the Department of Obstetncs and Gynecology, The University of Vermont College of MedlCZne. Supported zn part bv United States Public Health Service Grant No. HD20447. Presented at the Thir(v-second Annual Meeting of the Society for Gynecologic InvestigatIon, PhoeniX, Arizona, March 20-23, 1985 Reprint requests: Margaret K. McLaughhn, PhD. Department of Obstetncs and Gynecology. The UniveTSlty of Verlnont College of Medlczne, Burlzngton, VT 05405.
onstrate other symptoms of the disease. l This generated interest in the characterization of reactivity changes during normal and hypertensive pregnancies. The majority of these studies focused on the vascular reactivity to angiotensin II. There is a clear attenuation in the vascular response to the pressor effects of angiotensin II during normal pregnancy in several species including human beings." Changes that occur in response to adrenergic stimulation during pregnancy are far less clear. This study is an extension of earlier work in which we examined the vascular reactivity to a single adrenergic agent,
47
Key words: Progesterone antagonist, RU 486, cervical dilation, labor induction, oxytocin, breast milk
The advent of the potent progesterone antagonist RU 486 has stimulated considerable interest to examine its potential for gynecologic and obstetric indications. Among such applications are management problems common to labor and delivery, in which progesterone plays a principal role in the physiology of advanced pregnancy. I. 2 On the basis of our previous studies evaluating dose, interval, and route of administration in our primate model,' we examined whether RU 486 may be useful alone or with oxytocin in effecting cervical dilation, myometrial contractility, and delivery. In our pilot studies, we noticed overt milk flow before the onset of labor when RU 486 was administered to near-term pregnant monkeys. Thus we examined alterations in breast milk production and composition after RU 486 treatment. In addition, we examined what impact such alterations might have on neonatal nutrition as measured by infant growth rates.
Material and methods Pregnant cynomolgus monkeys (Macaca fasclcularis), weighing 4.1 to 6.2 kg, were divided randomly into four groups: (I) untreated controls (n = Il); (2) RU 486
From the Jones Institute for Reproductive Medlcine,a Department of Obstetrics and Gynecology, Eastern Vlrgznza Medical School, Med!cal College of Hampton Roads, Roussel Uclaf,b and Unzte 33 INSERM,' Hop!tal de Blcetre. Presented in part at the Thirty-fifth Annual Meetzng of the Socze(v For Gynecologic Investigation, Baltimore, Maryland, March 17-
20,1988.
Reprznt requests: Gary D. Hodgen, PhD, Professor and SCientific Director, The Jones Institute for ReproductIVe Medlczne, Department of Obstetrics and G,vnecology, Eastern Virginia Medical School, Medical College of Hampton Roads, 855 W. Brambleton Avenue, Suite B, Noifolk. VA 23510.
Age (weeks)
Fig. l. Comparison of infant monkey weight gain from birth to 6 weeks of age between the control group (open squares, n = 10) and after use of RU 486 with or without oxytocin (closed squares, n = 30) for cervical dilation and labor induction (Asterisk * indicates significant differences [analysis of variance], p < 0.05).
alone (n = 19), (3) oxytocin alone (n = 7); and (4) RU 486 plus oxytocin (n = 14), A single oral dose of RU 486 (25 mg) was administered at 6:00 PM on day 160 of pregnancy (term = 167 ± 3.3 days). Cervical dilation and labor induction were assessed by either visual inspection or manual palpation after 12 hours and repeated if delivery had not occurred within 24 hours. Oxytocin (20 U, intravenously) was given either alone or 12 hours after RU 486 administration, with subsequent assessment of cer-
45
46
Wolf et al.
January 1989 Am J Obstet Gynecol
Table I. Effects of RU 486 alone and in combination with oxytocin on cervical dilation, labor induction, and delivery in monkeys
Monkey groups
n
Control RU 486 Oxytocin RU 486 with oxytocin
11 19 7 14
Deltvery within 48 hr:f:
CervIcal dtlation*
Intensity of contractwns Inducedt
+ +(15)
+(2) + +(7) ++(13)
Fetus I
+ + (II)
2
I 12§
I
Placenta
I
2 I
Ilil
* Cervical dilation:
- = <0.5 cm; + = 0.5 to 1.0 cm; and + + = > 1.0 cm (number of monkeys in parentheses). tRhythmic myometrial contractions typical of spontaneous labor and delivery: - = none detected; + = mild contractions, not sufficient for delivery; + + = powerful contractions needed to accomplish natural delivery (number of monkeys in parentheses). :j: If vaginal delivery was not accomplished within 48 hours, cesarean section was performed, controls excepted. § Delivery: day 162.5 ± 1.5 vs day 167.3 ± 2.4 (p < 0.05). II One retained placenta.
vical and myometrial status within IS minutes. Except in the control group, cesarean section was performed if delivery had not occurred within 48 hours after the initial treatment. All infants were weighed at birth and weekly through 6 weeks of age. Differences were distinguished with one-way analysis of variance. Breast milk was expressed manually and collected before, during, and after treatment with RU 486 or oxytocin; we assessed the relative abundance of immunoglobulins, which are characteristic of colostrum milk, using two-dimensional immunoelectrophoresis." Results
Table I illustrates that RU 486 was effective in promoting cervical dilation by simultaneously shortening and softening the cervix. However, such treatment did not reliably induce the uterine contractions necessary for successful parturition. Oxytocin administered alone was ineffective at achieving delivery. However, vaginal delivery was realized within 4 hours (16 hours after initial RU 486 administration) in nine of 14 cases when oxytocin followed RU 486. In 12 of 14 cases, vaginal delivery was achieved within 36 hours after oxytocin (48 hours after initial RU 486 treatment). Among all treatment groups, 48 of 49 fetuses delivered alive were thriving at 6 weeks of age. One died of unknown causes after 23 days (RU 486 plus oxytocin treatment), whereas there were two stillbirths (one control and one RU 486 treatment). Immunoglobulins were detected in normal colostrum milk from control females I day after spontaneous delivery. Interestingly, RU 486 treatment (with or without oxytocin) uniformly resulted in precocious appearance of colostrum immunoglobulins in breast milk within 12 hours of initial treatment, even before the onset oflabor. Babies nursing from mothers treated with RU 486 demonstrated transient but significant (P < 0.05) increased weight gains compared with in-
fants in the control group during the initial 3 weeks of neonatal life (Fig. 1); thereafter, no differences were apparent among groups. Comment
Whereas progesterone exerts an array of fundamental physiologic actions in advanced pregnancy, administration of RU 486 to near-term pregnant monkeys appears to manifest differential effects on cervical "ripening," myometrial contractility, and milk production/composition before and after delivery. Although as much as 25 mg/kg of RU 486 administered intramuscularly in our pilot studies induced abruptio placentae, no overt toxicity on fetuses, mothers, or newborns was detected at the oral dose applied here. Since infant growth rates were transiently accelerated among mothers given RU 486 and colostrum production and globulin composition were accelerated in pregnant monkeys soon after RU 486 treatment, we speculate that aQtagonism of progesterone may have transiently amplified nutritive milk constituents, including protein. lipids, and saccharides. Evidence has been presented that withdrawal of progesterone is a requisite "trigger" to initiate lactogenesis in rats,5 although there appears to be no subsequent correlation between progesterone levels and breast milk once lactogenesis has been established." Data presented here suggest that a similar relationship between progestin action and lactation may also exist in primates. Although RU 486 reliably precipitated cervical dilation within 12 hours, it was not effective alone in labor induction and delivery, nor was oxytocin administered alone effective in this model. However, administration of oxytocin after RU 486 had achieved opening and softening of the cervix advanced delivery by 4.8 ± 2.1 days (p < 0.05). Since control females and those receiving RU 486 alone or in conjunction with oxytocin were similarly examined by manual and visual ins pec-
Volume 160 Number 1
tion, labor induction was not a function of tactile stimuli. These data indicate that RU 486 may be a useful adjunct to oxytocin for labor induction. Whereas these findings require cautious interpretation because of limited observations, we believe progesterone antagonists deserve continued study as adjunctive agents in perinatal management. We thank Lynn Sharpe and Janice Hammond for their excellent technical contributions, Martha Forrester for assistance in preparation of graphic materials, and Dara Leary for typing and editorial assistance.
RU 486 for cervical dilation and labor induction
2. Hodgen CD, Stouffer RL, Barber DL, Nixon WE. Serum estradiol and progesterone during pregnancy and the status of the corpus luteum at delivery in cynomolgus monkeys (Macaca fasciculans). Steroids 1977;30:295. 3. Wolf JP, Chillik CF, Itskovitz J, et al. Transplacental passage of a progesterone antagonist in monkeys. AM J OBSTET CYNECOL 1988:159:238. 4. Sinosich MJ, Teisner B, Davey M. Crudzinskas JC. Pregnancy-associated plasma protein-A: interaction with heparin in crossed affinity immunoelectrophoresis. Aust NZ J Med 1981; 11 :42g.. 5. Kuhn NJ. Progesterone withdrawal as the lactogenic trigger in the rat. J Endocrinol 1969;44:39. 6. Herrenkohl LR. The effects of lactation of progesterone injections administered during late pregnancy in the rat. Proc Soc Exp BioI Med 1971;138:39.
REFERENCES 1. Hodgen CD, Dufau ML, Catt KJ, Tullner WW. Estrogens, progesterone and chorionic gonadotropin in pregnant rhesus monkeys. Endocrinology 1972;91 :896.
Vascular catecholamine sensitivity during pregnancy in the ewe Margaret K. McLaughlin, PhD, Tara Mathews Keve, BS, and Rosemary Cooke, BS Burlington, Vermont Four pregnant and four castrated ewes were chronically instrumented for the measurement of external iliac blood flow to test the hypothesis that pregnancy alters Ct-adrenergic sensitivity in a major regional circulation. Complete dose-response curves were generated to methoxamine, phenylephrine, and norepinephrine. Pregnancy was associated with no change in methoxamine sensitivity, an increase in phenylephrine sensitivity, and a decrease in norepinephrine sensitivity. These differential changes in drug sensitivity suggest (1) the Ct,-receptor population is functionally similar between the two groups of animals, (2) uptake 1 is inhibited, and (3) either catechol-O-methyltransferase activity is increased or the Ct2- or j3-receptor population changes in this circulation during pregnancy. These data illustrate the complexity of the change in the adrenergic system during pregnancy. (AM J OBSTET GYNECOL 1989;160:47-53.)
Key words: Sheep, circulation, catecholamines, skeletal muscle, norepinephrine, phenylephrine, methoxamine
It is well recognized that marked changes occur in vascular reactivity in women with pregnancy-induced hypertension or preeclampsia even before they dem-
From the Department of Obstetncs and Gynecology, The University of Vermont College of MedlCZne. Supported zn part bv United States Public Health Service Grant No. HD20447. Presented at the Thir(v-second Annual Meeting of the Society for Gynecologic InvestigatIon, PhoeniX, Arizona, March 20-23, 1985 Reprint requests: Margaret K. McLaughhn, PhD. Department of Obstetncs and Gynecology. The UniveTSlty of Verlnont College of Medlczne, Burlzngton, VT 05405.
onstrate other symptoms of the disease. l This generated interest in the characterization of reactivity changes during normal and hypertensive pregnancies. The majority of these studies focused on the vascular reactivity to angiotensin II. There is a clear attenuation in the vascular response to the pressor effects of angiotensin II during normal pregnancy in several species including human beings." Changes that occur in response to adrenergic stimulation during pregnancy are far less clear. This study is an extension of earlier work in which we examined the vascular reactivity to a single adrenergic agent,
47