Contribution of endogenous opioids to gonadal hormones-induced temporomandibular joint antinociception.

Abstract

The authors have recently demonstrated that the high serum estradiol level during the proestrus phase of the estrous cycle and that the administration of estradiol or progesterone in ovariectomized female and of testosterone in orchiectomized male rats significantly decrease formalin-induced temporomandibular joint (TMJ) nociception. In this study, the authors investigate the contribution of endogenous opioids to this antinociceptive effect of gonadal hormones in the TMJ formalin test. The opioid receptor antagonist naloxone was administrated either in the surrounding of the trigeminal sensory complex or in the TMJ region. The antinociceptive effect induced by endogenous estradiol in proestrus females and by exogenous estradiol in ovariectomized females was blocked by the administration of naloxone in the surrounding of the trigeminal sensory complex, but not in the TMJ region. The antinociceptive effect induced by the administration of progesterone in ovariectomized females and of testosterone in orchiectomized males was blocked by the administration of naloxone either in the surrounding of the trigeminal sensory complex or in the TMJ region. The authors conclude that central and peripheral opioid mechanisms mediate the antinociceptive effect of progesterone and testosterone, and central opioid mechanisms mediate the antinociceptive effect of estradiol. These findings suggest that the enhanced pain perception during low gonadal hormone periods in women and animals may be mediated by a decrease in endogenous opioid activity. This suggestion helps explain the higher severity of some pain conditions, such as temporomandibular dysfunctions in women than in men, that have no hormonal fluctuations.

Are temporomandibular disorder symptoms and diagnoses associated with pubertal development in adolescents? An epidemiological study

“…Conversely, there are indications that male reproductive hormones may have a protective function in association with pain: animal studies have demonstrated that testosterone reduces formalin-induced temporomandibular joint nociception in rats [12]. This antinociceptive effect is probably mediated by the endogenous opioid system [5,11,12]. This may explain why in our study the prevalence of self-reported variables rose in girls, while falling in boys experiencing puberty.…”

Morphine Analgesia Modification in Normotensive and Hypertensive Female Rats after Repeated Fluoxetine Administration

“…Investigation of the role of endogenous opioids in antinociceptive action of sex hormones has demonstrated considerable nociception reduction both after administering testosterone to male rats post-inguinal orchiectomy, as well as after estradiol and progesterone administration to female rats post-ovariectomy [21]. Moreover, considerable reduction in formalin-induced temporomandibular joint (TMJ) nociception has been reported in the pro-oestrus cycle phase during which high estradiol levels are maintained [12].…”

Efetividade da laserterapia de baixa intensidade em mulheres com DTM dolorosa em função da ansiedade, cortisol salivar e ciclo menstrual: ensaio clínico randomizado controlado duplo-cego

“…Neste estudo foi encontrada correlação entre a sensibilidade à dor (LDP) e o cortisol salivar, apesar deste não ser considerado um marcador biológico preciso na dor crônica (LAMBERT et al, 2013;JASIM et al, 2014, JO et al, 2016 (JONES et al, 1997;DOEPEL et al, 2009;NILSSON et al, 2010;JASIM et al, 2014;SALAMEH et al, 2015;TOSATO et al, 2015;JO et al, 2016 (FISCHER et al, 2009;VILANOVA et al, 2015).…”

“…Os homens e as mulheres em fase de menopausa não apresentam flutuações hormonais significativas, portanto apresentam menor predisposição à DTM dolorosa (FISCHER et al, 2009 (TURNER et al, 2011;VILANOVA et al, 2015).…”