[Effect of dehydroepiandrosterone sulfate on stress reactivity: mu-opioid mechanism].

The dehydroepiandrosterone sulfate (DHEAS) effect on stress-reactivity and the role of mu-opioid receptors in it, were studied. The experiments were carried out in male rats. The shuttling in single or in multiple (19 days, for 1 hour a day) regimes served as the experimental stress influences. The estimation of stress-reactivity was carried out by the plasma corticosterone level. It had been shown that the subcutaneous injection of dehydroepiandrosterone sulfate in rats reduced the stress-induced increase in corticosterone levels under the multiple influences, whereas naltrexone (0.1 mg/kg, for 20 min before DHEAS injection) blocked this effect. There were no effects of DHEAS or naltrexone on corticosterone levels under the single stress influences.