Onodera K, Sakurada S, Furuta S, Yonezawa A, Arai K, Hayashi T, Katsuyama S, Sato T, Miyazaki S, Kisara K. Differential involvement of opioid receptors in stress-induced antinociception caused by repeated exposure to forced walking stress in mice.
Pharmacology 2000;
61:96-100. [PMID:
10940783 DOI:
10.1159/000028387]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We examined the effects of repeated exposure to forced walking stress for 6 h once a day for 0, 6 and 9 consecutive days on formalin-induced paw licking in mice. In each observation period, stress-induced antinociception (SIA) was observed only in the late phase (from 10 to 30 min), but not in the early phase (from 0 to 10 min) of formalin-induced paw licking in mice. Moreover, it was hard to develop tolerance even by daily exposure to stress for 6 days, although SIA for 9 days decreased compared with those for 0 and 6 days. Naloxone (10 mg/kg), an opioid-receptor antagonist, was effective in reducing the SIA induced by forced walking stress for 6 days and/or 9 days, but not for 0 days. Furthermore, the experiments with selective opioid-receptor antagonists, beta-funaltrexamine (mu) naltrindol (delta), or nor-binaltorphimine (kappa) demonstrated that SIA induced by forced walking stress for 9 successive days may be mediated through opioid delta- and kappa-receptors. Finally, although SIA seemed to be a unitary phenomenon, the present results strengthened the idea that SIA is induced by exposure to forced walking stress with characteristics dependent on the duration of exposure.
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