The influence of stress on nociception induced in temporomandibular joint / A influencia do estresse sobre a nocicepção induzida na articulação temporomandibular

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Recent studies have investigated he role of psychological factor in temporomandibular disorders (TMD). However, the mechanisms responsible for nociceptive changes induced by stress are not established. Thus, the aim of this study was to evaluate the effect of acute, sub-chronic and chronic stress on nociception induced by formalin injection in rats? temporomandibular joint (TMJ). The relation beetwen blood levels of adrenocorticotropin (ACTH), corticosterone, the levels of anxiety and nociceptive responses recorded after the various stress protocols was evaluated. Animals were initially submitted to one session of acute restraint stress (15 min; 30 min and 1 h), or exposed to sub-chronic stress (3 days-1h/day) or chronic stress (40 days-1h/day). After, animals were (1) killed immediately to collect blood for hormonal determinations by radioimmunoassay; or (2) submitted to the elevated plus-maze to evaluate anxiety; or (3) submitted to the TMJ formalin test to evaluate nociception. Finally, the role of serotoninergic and opioid systems in nociceptive changes induced by stress was evaluated. For this, the serotonin-selective reuptake inhibitor (fluoxetine 10 mg/Kg) and the opioid agonist (morphine 1-5 mg/Kg) were administered before the nociception tests. The results showed that all stress protocols increased significantly the levels of ACTH or corticosterone, as well as the anxiety behavior. In relation to nociception, the chronic stressed animals showed an increase in nociceptive responses (hyperalgesia). In this group, there was a reduction in the morphine analgesic effects, suggesting dysfunction in the endogenous opioid system. Fluoxetine had an analgesic effect in both stressed (hyperalgesic) and control groups (non-stressed), although the effect was more significant in the stressed-group. It was concluded that stress-induced hyperalgesia may result from changes in the serotoninergic and opioid systems, which can explain, at least in part, the important link between stress and orofacial pain

ASSUNTO(S)

articulação temporomandibular dor facial stress

ACESSO AO ARTIGO

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