title: Gonadal hormones modulate the responsiveness to local β-blocker-induced antinociception in the temporomandibular joint of male and female rats.
abstract: BACKGROUND
  We have previously demonstrated that blockade of β-adrenoreceptors (β-AR) located in the temporomandibular joint (TMJ) of rats suppresses formalin-induced TMJ nociceptive behaviour in both male and female rats, but female rats are more responsive. In this study, we investigated whether gonadal hormones modulate the responsiveness to local β-blocker-induced antinociception in the TMJ of rats.
  
  
  METHODS
  Co-administration of each of the selective β1 (atenolol), β2 (ICI 118.551) and β3 (SR59230A)-AR antagonists with equi-nociceptive concentrations of formalin in the TMJ of intact, gonadectomized and hormone-treated gonadectomized male and female rats.
  
  
  RESULTS
  Atenolol, ICI 118.551 and SR59230A significantly reduced formalin-induced TMJ nociception in a dose response fashion in all groups tested. However, a lower dose of each β-AR antagonist was sufficient to significantly reduce nociceptive responses in gonadectomized but not in intact and testosterone-treated gonadectomized male rats. In the female groups, a lower dose of β1 -AR antagonist was sufficient to significantly reduce nociceptive responses in gonadectomized but not in intact or gonadectomized rats treated with progesterone or a high dose of oestradiol; a lower dose of β2 -AR antagonist was sufficient to significantly reduce nociceptive responses in gonadectomized but not in intact and gonadectomized rats treated with low or high dose of oestradiol.
  
  
  CONCLUSIONS
  Gonadal hormones may reduce the responsiveness to local β-blocker-induced antinociception in the TMJ of male and female rats. However, their effect depends upon their plasma level, the subtype of β-AR and the dose of β-blockers used.
authors.affiliation: Department of Physiological Sciences, Laboratory of Orofacial Pain, Piracicaba Dental School, State University of Campinas - UNICAMP, Piracicaba, Brazil.
authors.forename: N C
authors.initials: NC
authors.lastname: Fávaro-Moreira
authors.forename: L W
authors.initials: LW
authors.lastname: Okoti
authors.forename: R
authors.initials: R
authors.lastname: Furini
authors.forename: C H
authors.initials: CH
authors.lastname: Tambeli
mesh_terms: D058673:Adrenergic beta-3 Receptor Antagonists / Q000494:pharmacology; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001262:Atenolol / Q000494:pharmacology; D005260:Female; D042341:Gonadal Hormones / Q000494:pharmacology*; D008297:Male; D059225:Nociception / Q000187:drug effects*; D010146:Pain / Q000188:drug therapy*; D010147:Pain Measurement / Q000379:methods; D011412:Propanolamines / Q000494:pharmacology*; D017208:Rats, Wistar; D013704:Temporomandibular Joint / Q000187:drug effects*; D013705:Temporomandibular Joint Disorders / Q000188:drug therapy*
chemical_list: C097869:3-(2-ethylphenoxy)-1-(1,2,3,4-tetrahydronaphth-1-ylamino)-2-propanol oxalate; D058673:Adrenergic beta-3 Receptor Antagonists; D000319:Adrenergic beta-Antagonists; D042341:Gonadal Hormones; D011412:Propanolamines; D001262:Atenolol