EFFECT OF NALOXONE ON THE SECRETION OF CORTICOSTERONE INDUCED BY GAMMA-HYDROXYBUTYRIC ACID IN MALE-RATS

The effect of intraperitoneally administered γ‐hydroxybutyrate on the hypothalamo‐hypophysial‐adrenocortical axis was studied. A significant increase in plasma corticosterone was induced by the administration of γ‐hydroxybutyrate (100 mg/kg). The lack of antagonism of this action of γ‐hydroxybutyrate by picrotoxin or bicuculline pretreatments (GABAergic antagonists), suggests independence from the GABAergic system. Neither dopaminergic nor serotoninergic systems intervened in the γ‐hydroxybutyrate‐stimulating effect on the hypothalamo‐hypophysial‐adrenocortical axis. Both corticosterone release and synthesis in adrenocortical cells was not significantly affected by γ‐hydroxybutyrate, suggesting that this is possibly due to a central action of γ‐hydroxybutyrate. The increase in corticosterone levels was probably mediated by an opioid receptor, since a strong similarity existed between the effects of γ‐hydroxybutyrate and those of morphine. Moreover, the results show that the opioid‐receptor involvement was demonstrated by the naloxone‐sensitivity of the γ‐hydroxybutyrate effects. Copyright © 1990, Wiley Blackwell. All rights reserved