Naloxone inhibition of stress-induced increase in prolactin secretion

It is concluded that endorphins may be responsible for increased release of PRL during stressful conditions and inhibited the stress-induced rises in serum prolactin.

Abstract

Naloxone, an opiate antagonist that acts by binding to opiate receptors in the brain, was given to rats stressed by immobilization or heat in an attempt to inhibit stress-induced release of prolactin. Both stresses resulted in approximately a 5-fold increase in serum prolactin concentration. Naloxone, at a dose of 0.2 mg/kg b.w. completely or partially inhibited the stress-induced rises in serum prolactin, and reduced serum prolactin concentrations in unstressed rats to below control values. It is concluded that endorphins may be responsible for increased release of PRL during stressful conditions.