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Abstract #24 — Peripheral opioid receptor mediated analgesia in inflamed dental pulps
AAE Abstracts of Papers
Vol. 19, No. 4, April 1993
191
(Abstract #24, continued)
Abstract #22 - Concentration of CGRP in symptomatic and asymptomatic human pulp tissue. H.K. Kanning*, D.L. Carnes University of Texas, San Antonio, Texas Calcitonin gene-related peptide (CGRP) is a neuropeptide which is involved in inflammation, and which may have a stimulating effect on dentin production in responseto noxious insult_ CGRP immunoreactive nerve fibers have been shown to increase beneath the injured dentin of rat molars. Information on human subjects relating to CGRP is minimal however. The purpose of this study was to determine the concentration of CGRP in symptomatic and asymptomatic human dental pulp tissue. The control group consisted of pulp tissue collected from 20 asymptomatic third molars. The test group consisted of pulp tissue collected from 17 symptomatic teeth with deep caries having a clinical diagnosis of irreversible pulpitis. The teeth were extracted and immediately placed in liquid nitrogen. The teeth were split longitudinally, the pulp tissues were removed, homogenized in radioimmunoassay buffer and frozen at 4C. A radioimmu noassayfor CGRP was performed using rabbit antiserum to human CGRP and '2Sl-humanCGRP. CGRP values determined in pulp samples were normalized to total protein by the Pierce BCA method. CG RP was present in both symptomatic and asymptomatic human pulp tissue. Significantly higher levels of CGRP were found in pulp tissue samples from symptomatic teeth, as compared to CGRP levels found in asymptomatic pulp tissue specimens (p < 0.01). The results indicate that CGRP levels are elevated in human pulp tissue which is undergoing an inflammatory response due to deep carious lesions. This study was supported, in part, by the Research and Education Foundation of the AAE.
Abstract #23 - Pharmacological regulation of neuropeptide secretion from dental pulp. K.M. Hargreaves*, D. Jackson, M. Engelstad, M. Garry University of Minnesota, Minneapolis, Minnesota We have previously developed an in vitro method for measuring secretion of calcitonin gene-related peptide (CGRP) from dental pulp (J Endo in press), in the present study, we evaluated whether catecholamines alter the evoked secretion of immunoreactive CGRP (iCGRP) from capsaicinsensitive fibers in dental pulp. Pulp tissue from bovine mandibular incisors was extracted, chopped into 200 pm cubes, and placed in 2cc chambers for in vitro superfusion. Following a baseline recovery period, oxygenated Krebs buffer (pH 7.4 @ 37°C) containing norepinephrine, clonidine arterenol (0.01nM-100 pM) or vehicle (n=6-11/group) was superfusedthrough thetissue before and aftera stimulatingpulse ofcapsaicin 30 pM), a neurotoxinthat selectively stimulates nociceptors. Levels of iCGRP were analyzed by a validated radioimmunoassay. NE produced a dosedependentsuppression of capsaicin-evoked iCGRP secretion, with maximal effects observed at 10nM (100% suppression; p < 0.01 ). Additional studies demonstrated that pre-treatment with both the alpha agonist clonidine (p < 0.01 ) and the beta agonist arterenot(p < 0.01 ) significantly suppressed capsaicinevoked secretion of iCGRP. Collectively, these studies indicate that adrenergic drugs inhibit afferent nerve activity in dental pulp. This observation suggests that catecholamine, such as epinephrineincluded in local anesthetic cartridges, may have a direct neural target for suppressing activity of peripheral pain fibers (nociceptors) in dental pulp. This study was supported in part by NIDR grants DE10096, K16 DE00270 and F32-DE05606.
Abstract #24- Peripheral opioid receptor mediated analgesia in inflamed dental pulps.
R. Uhle*, A. Reader, R. Nist, M. Beck, W. Meyers, J. Weaver Ohio State University, Columbus, Ohio Analgesia produced by opiates has classically been thought of as a centrally mediated phenomena. However, recent studies have shown
that opiate receptors are present peripherally on primary afferent nerves and that activation of these receptors can produce analgesia. To determine whether a low dose of fentanyl would produce analgesia, we measuredthe degreeofpain reliefobtainedwith fentanyt,administered via the periodontal ligament injection, in symptomatic, inflamed teeth. All subjects presented for emergency treatment and had a posterior tooth with a clinical diagnosis of irreversible pulpitis. Twenty subjects randomly received either 10ug of fentanyl citrate or saline placebo via the periodontal ligament injection in a double-blind manner. The subjects rated their pain prior to injection and rated pain intensity and pain relief for 60 minutes post-injection. Low dose fentanyl injected via the periodontal ligament injectionin inflamed teeth provided significantly (p = 0.0186) greater pain relief than the salineplacebo, as measured by ANOVA analysis. Since the dose of fentanyl usedin this study was less than the dose required to provide analgesia by a central mechanism, the results are consistent with a peripheral opiate receptor mechanism of action. This study was supported by the Graduate Students' Research Fund, Department of Endodontics, Ohio State University.
Abstract #25 - Temporal and spatial characterization of the putpat response to injury. T.A. Bachman*, K.R. Baumgardner, M. Litz, W.T. Butler, R.N. D'Souza University of Texas, Houston, Texas, University of Iowa, Iowa City, Iowa Odo ntoblast differentiation du ring tooth developmentis controlled by a seriesof reciprocal interactionsbetweenthe ectodermal-derivedenamel organ and the neural crest-derived dental papilla. Although these events may be reiterated during repair, the biochemical and cellular interactions that lead to the formation of reparative dentin at the site of injury to the dentin-pulp (DP) complex are poorly understood. This study addresses the hypothesis that the odontoblast phenotype is involvedin the formation of reparativedentin. Cervicalcavitypreparations were placed within dentin of first molars in adult Sprague Dawley rats and tissue sections prepared from paraffin blocks at various intervals (days 0 to 14). Immunohistochemical methods were used to determine whether transforming growth factor-beta I(TGF-1), a growth factor know to play a central role in developmentand repair, localizedin cells and matrix during injury and repair. We also evaluatedwhether DSP, a dentin sialoprotein that marks odontoblast differentiation during development, was expressed by the replacement pool of cells subjacent to newly formed reparative dentin matrix. The temporal and spatial pattern of expression of TGF-1 during reparative dentin formation suggests a role for this factor as a biologic inducer of matrix formation in repair, immunoreactive £)SPwas also seen in the matrix and within replacement cells concomitant with the onset ot mineralization of reparative dentin. Our results suggest that cells related to the odontoblastic lineage synthesize and secrete reparative dentin matrix. Collectively, data from these studies will increase understanding of the DP complex and its reaction to the carious process and to restorative procedures. This study was supported by NIDR Grants R37 DE05092 and K16 DE00175.
Abstract #26 - Detection of IL-2 in healthy and inflamed dental pulps.
J. Bailey*, C. Rauschenberger University of Maryland, Baltimore, Maryland Hahn eta/., 1989, reported that irreversible pulpitis was associated with an increase in T tymphocytes (T-cells) responsible forthe regulativn of pulpal immunopathologicchanges under carious lesions. Interleukin2 (IL-2) is a growth factor responsible for T-cell proliferation and maturation, and may signal pathologic pulpal changes. The purpose of this study was to determine if IL-2 could be detected in dental pulps clinically diagnosed as heatthy or irreversibly inflamed. Healthy pulp tissues were obtained from 18 impacted third molars and the inflamed
Vol. 19, No. 4, April 1993
191
(Abstract #24, continued)
Abstract #22 - Concentration of CGRP in symptomatic and asymptomatic human pulp tissue. H.K. Kanning*, D.L. Carnes University of Texas, San Antonio, Texas Calcitonin gene-related peptide (CGRP) is a neuropeptide which is involved in inflammation, and which may have a stimulating effect on dentin production in responseto noxious insult_ CGRP immunoreactive nerve fibers have been shown to increase beneath the injured dentin of rat molars. Information on human subjects relating to CGRP is minimal however. The purpose of this study was to determine the concentration of CGRP in symptomatic and asymptomatic human dental pulp tissue. The control group consisted of pulp tissue collected from 20 asymptomatic third molars. The test group consisted of pulp tissue collected from 17 symptomatic teeth with deep caries having a clinical diagnosis of irreversible pulpitis. The teeth were extracted and immediately placed in liquid nitrogen. The teeth were split longitudinally, the pulp tissues were removed, homogenized in radioimmunoassay buffer and frozen at 4C. A radioimmu noassayfor CGRP was performed using rabbit antiserum to human CGRP and '2Sl-humanCGRP. CGRP values determined in pulp samples were normalized to total protein by the Pierce BCA method. CG RP was present in both symptomatic and asymptomatic human pulp tissue. Significantly higher levels of CGRP were found in pulp tissue samples from symptomatic teeth, as compared to CGRP levels found in asymptomatic pulp tissue specimens (p < 0.01). The results indicate that CGRP levels are elevated in human pulp tissue which is undergoing an inflammatory response due to deep carious lesions. This study was supported, in part, by the Research and Education Foundation of the AAE.
Abstract #23 - Pharmacological regulation of neuropeptide secretion from dental pulp. K.M. Hargreaves*, D. Jackson, M. Engelstad, M. Garry University of Minnesota, Minneapolis, Minnesota We have previously developed an in vitro method for measuring secretion of calcitonin gene-related peptide (CGRP) from dental pulp (J Endo in press), in the present study, we evaluated whether catecholamines alter the evoked secretion of immunoreactive CGRP (iCGRP) from capsaicinsensitive fibers in dental pulp. Pulp tissue from bovine mandibular incisors was extracted, chopped into 200 pm cubes, and placed in 2cc chambers for in vitro superfusion. Following a baseline recovery period, oxygenated Krebs buffer (pH 7.4 @ 37°C) containing norepinephrine, clonidine arterenol (0.01nM-100 pM) or vehicle (n=6-11/group) was superfusedthrough thetissue before and aftera stimulatingpulse ofcapsaicin 30 pM), a neurotoxinthat selectively stimulates nociceptors. Levels of iCGRP were analyzed by a validated radioimmunoassay. NE produced a dosedependentsuppression of capsaicin-evoked iCGRP secretion, with maximal effects observed at 10nM (100% suppression; p < 0.01 ). Additional studies demonstrated that pre-treatment with both the alpha agonist clonidine (p < 0.01 ) and the beta agonist arterenot(p < 0.01 ) significantly suppressed capsaicinevoked secretion of iCGRP. Collectively, these studies indicate that adrenergic drugs inhibit afferent nerve activity in dental pulp. This observation suggests that catecholamine, such as epinephrineincluded in local anesthetic cartridges, may have a direct neural target for suppressing activity of peripheral pain fibers (nociceptors) in dental pulp. This study was supported in part by NIDR grants DE10096, K16 DE00270 and F32-DE05606.
Abstract #24- Peripheral opioid receptor mediated analgesia in inflamed dental pulps.
R. Uhle*, A. Reader, R. Nist, M. Beck, W. Meyers, J. Weaver Ohio State University, Columbus, Ohio Analgesia produced by opiates has classically been thought of as a centrally mediated phenomena. However, recent studies have shown
that opiate receptors are present peripherally on primary afferent nerves and that activation of these receptors can produce analgesia. To determine whether a low dose of fentanyl would produce analgesia, we measuredthe degreeofpain reliefobtainedwith fentanyt,administered via the periodontal ligament injection, in symptomatic, inflamed teeth. All subjects presented for emergency treatment and had a posterior tooth with a clinical diagnosis of irreversible pulpitis. Twenty subjects randomly received either 10ug of fentanyl citrate or saline placebo via the periodontal ligament injection in a double-blind manner. The subjects rated their pain prior to injection and rated pain intensity and pain relief for 60 minutes post-injection. Low dose fentanyl injected via the periodontal ligament injectionin inflamed teeth provided significantly (p = 0.0186) greater pain relief than the salineplacebo, as measured by ANOVA analysis. Since the dose of fentanyl usedin this study was less than the dose required to provide analgesia by a central mechanism, the results are consistent with a peripheral opiate receptor mechanism of action. This study was supported by the Graduate Students' Research Fund, Department of Endodontics, Ohio State University.
Abstract #25 - Temporal and spatial characterization of the putpat response to injury. T.A. Bachman*, K.R. Baumgardner, M. Litz, W.T. Butler, R.N. D'Souza University of Texas, Houston, Texas, University of Iowa, Iowa City, Iowa Odo ntoblast differentiation du ring tooth developmentis controlled by a seriesof reciprocal interactionsbetweenthe ectodermal-derivedenamel organ and the neural crest-derived dental papilla. Although these events may be reiterated during repair, the biochemical and cellular interactions that lead to the formation of reparative dentin at the site of injury to the dentin-pulp (DP) complex are poorly understood. This study addresses the hypothesis that the odontoblast phenotype is involvedin the formation of reparativedentin. Cervicalcavitypreparations were placed within dentin of first molars in adult Sprague Dawley rats and tissue sections prepared from paraffin blocks at various intervals (days 0 to 14). Immunohistochemical methods were used to determine whether transforming growth factor-beta I(TGF-1), a growth factor know to play a central role in developmentand repair, localizedin cells and matrix during injury and repair. We also evaluatedwhether DSP, a dentin sialoprotein that marks odontoblast differentiation during development, was expressed by the replacement pool of cells subjacent to newly formed reparative dentin matrix. The temporal and spatial pattern of expression of TGF-1 during reparative dentin formation suggests a role for this factor as a biologic inducer of matrix formation in repair, immunoreactive £)SPwas also seen in the matrix and within replacement cells concomitant with the onset ot mineralization of reparative dentin. Our results suggest that cells related to the odontoblastic lineage synthesize and secrete reparative dentin matrix. Collectively, data from these studies will increase understanding of the DP complex and its reaction to the carious process and to restorative procedures. This study was supported by NIDR Grants R37 DE05092 and K16 DE00175.
Abstract #26 - Detection of IL-2 in healthy and inflamed dental pulps.
J. Bailey*, C. Rauschenberger University of Maryland, Baltimore, Maryland Hahn eta/., 1989, reported that irreversible pulpitis was associated with an increase in T tymphocytes (T-cells) responsible forthe regulativn of pulpal immunopathologicchanges under carious lesions. Interleukin2 (IL-2) is a growth factor responsible for T-cell proliferation and maturation, and may signal pathologic pulpal changes. The purpose of this study was to determine if IL-2 could be detected in dental pulps clinically diagnosed as heatthy or irreversibly inflamed. Healthy pulp tissues were obtained from 18 impacted third molars and the inflamed