Baclofen, a GABA derivative, inhibits stress-induced prolactin release in the rat

The effect of baclofen, beta-(4-chlorophenyl)GABA, on prolactin secretion was investigated in rats under several experimental conditions. In adult male rats subjected either to immuobilization, ether, swimming or cold stress there was a rapid increase of serum prolactin levels; acute pretreatment with baclofen, 10 mg/kg i.p. inhibited the hormone response to all these stresses. The same blocking effect of the drug was observed in prepubertal male and female rats and in adult gonadectomized animals. In basal conditions, i.e. in undisturbed male rats, baclofen did not change the hormone titers significantly. Taken together our results indicate that baclofen blocks prolactin release when release of the hormone is dynamically stimulated by stress and this effect is relatively independent of the endocrine status of the rat.