PARTICIPATION OF OPIOID RECEPTORS IN THE MODULATION OF THE ANALGESIC RESPONSE BY ADRENAL AND GONADAL GLANDS
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Data
1991-01-01
Autores
Molina, N.
Bedrandecastro, MTB
Pescinini, I. A.
Baiochi, A. L.
Bedrandecastro, J. C.
Título da Revista
ISSN da Revista
Título de Volume
Editor
Associação Brasileira de Divulgação Científica (ABRADIC)
Resumo
The involvement of opioid receptors in the analgesic response was evaluated by the tail-immersion test in simultaneously adrenalectomized and ovariectomized female Wistar rats (210-250 g). The reaction time (mean +/- SEM) for tail withdrawal from hot water decreased significantly 2 weeks after surgery (3.52 +/- 0.20 s) when compared to intact animals (6.09 +/- 0.23 s). Hormonal replacement with dexamethasone (50-mu-g/day) did not affect reaction time (3.38 +/- 0.19 s). However, this response was restored by combined adrenal and gonadal steroid substitution (estradiol 5-mu-g/day and progesterone 1.5-mu-g 6 h before the tests) therapy (5.11 +/- 0.45 s in animals treated with dexamethasone plus estradiol and 5.04 +/- 0.43 s in animals treated with dexamethasone plus estradiol plus progesterone). Naloxone (2 mg/kg) decreased the reaction time of animals treated with adrenal and gonadal steroids (5.11 +/- 0.45 vs 4.15 +/- 0.44 s and 5.04 +/- 0.43 vs 3.87 +/- 0.28 s, respectively, before and after naloxone) but failed to decrease it in rats treated with dexamethasone only (3.88 +/- 0.18 vs 4.34 +/- 0.25 s, before and after naloxone). These observations indicate that gonadal steroids are the most important steroid factors involved in the reaction time to tail immersion in hot water and confirm other reports that the opioid pathways modulating the neuronal circuitry require the presence of these hormones.
Descrição
Palavras-chave
OPIOID, NALOXONE, ADRENAL GLANDS, GONADS, NOCICEPTION, DEXAMETHASONE, ESTRADIOL, PROGESTERONE
Como citar
Brazilian Journal of Medical and Biological Research. São Paulo: Associação Bras Divulg Cientifica, v. 24, n. 12, p. 1261-1264, 1991.