Baclofen, a gamma-aminobutyric acid B agonist, modifies hormonal secretion in pituitary cells from infantile female rats.

Recent work from our laboratory has demonstrated that the activation of GABA B adenohypophyseal receptors by baclofen inhibits pituitary hormone secretion under basal (PRL) or stimulated conditions (PRL and LH) in adult female rats, suggesting a hypophyseal site of action in addition to the central site previously described. Since different patterns of hormone secretion are observed in infantile and adult rats, the purpose of the present study was to determine whether GABA B pituitary receptors were involved in endocrine responses at early stages of development. Pituitary cells of 12 day-old female rats were cultured in vitro and the effect of baclofen was determined in the presence or absence of stimulatory factors.