title: Adrenergic regulation of capsaicin-sensitive neurons in dental pulp.
abstract: Alpha adrenergic agonists (e.g. vasoconstrictors) represent one of the most commonly used drug classes in dentistry. Although adrenergic agonists have potent vascular effects, recent studies suggest that capsaicin-sensitive nociceptors may express adrenoceptors, suggesting that these drugs may directly modulate the function of an important class of pain-signaling neurons in peripheral tissues. In this study, we tested the hypothesis that adrenergic agonists inhibit activation of peripheral terminals of capsaicin-sensitive fibers innervating dental pulp. Pretreatment with epinephrine or clonidine significantly inhibited capsaicin-evoked release of immunoreactive calcitonin gene-related peptide from superfused bovine dental pulp. These studies suggest that adrenergic agonists may reduce postoperative pain in part via a direct inhibition of capsaicin-sensitive nociceptors. This finding may lead to the development of selective, peripherally acting, adrenergic analgesics. Moreover, because neuropeptide release alters blood flow, it is possible that the vascular effects of these drugs are caused by both vasoconstriction and inhibition of peripheral neuropeptide release.
authors.affiliation: Department of Endodontics, UTHSCSA School of Dentistry, San Antonio, TX 78229-3900, USA.
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Hargreaves
authors.forename: Douglass L
authors.initials: DL
authors.lastname: Jackson
authors.forename: Walter R
authors.initials: WR
authors.lastname: Bowles
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism; D002211:Capsaicin / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002417:Cattle; D003000:Clonidine / Q000494:pharmacology; D003782:Dental Pulp / Q000187:drug effects / Q000294:innervation*; D004837:Epinephrine / Q000494:pharmacology; D007473:Ion Channels / Q000037:antagonists & inhibitors; D036421:Nerve Fibers, Unmyelinated / Q000187:drug effects; D009619:Nociceptors / Q000187:drug effects*; D010146:Pain / Q000503:physiopathology; D011942:Receptors, Adrenergic, alpha / Q000187:drug effects; D011955:Receptors, Drug / Q000037:antagonists & inhibitors / Q000187:drug effects
chemical_list: D000316:Adrenergic alpha-Agonists; D007473:Ion Channels; D011942:Receptors, Adrenergic, alpha; D011955:Receptors, Drug; D015740:Calcitonin Gene-Related Peptide; C071423:capsazepine; D003000:Clonidine; D002211:Capsaicin; D004837:Epinephrine