Involvement of δ-opioid receptors in the effects induced by endogenous enkephalins on learned helplessness model

摘要: Pharmacological, neurochemical and behavioural findings support a possible role of endogenous opioids in clinical depression. There is evidence from animal studies that delta-opioid receptors are involved several responses to opioids, including motivational activities. In the present study, mixed enkephalin catabolism inhibitor, RB 101 (N(R,S)-2-benzyl-3[(S)-(2-amino-4-methylthiobutyldithio]-1-oxoprop yl)-L-phenylalanine benzyl ester) (1.25, 2.5 5 mg/kg), induced dose-dependent antidepressant-like effect learned helplessness model. Thus, reversed escape deficits rats previously subjected inescapable shocks, suggesting involvement enkephalins Similar effects were observed after administration selective receptor agonist, BUBU (Tyr-D.Ser-(O-tert-butyl)-Gly-Phe-Leu-Thr(O-Tet-butyl-OH) (1 2 mg/kg). Moreover, antagonized by naltrindole (NTI) (0.1 which points preferential this enkephalin-controlled behaviour. As has been reported be almost devoid opiate-related side-effects, it could represent promising alternative treatment depressive patients who unresponsive to, or intolerant of, classical antidepressants.