GALANIN NEURONS EXHIBIT ESTROGEN-RECEPTOR IMMUNOREACTIVITY IN THE FEMALE RAT MEDIOBASAL HYPOTHALAMUS

Galanin has been shown to augment the hypothalamic luteinizing hormone releasing hormone and pituitary luteinizing hormone release and to play an important role in the feedback effects of ovarian steroids on pituitary hormone secretion. To further characterize estrogen effects an galanin, we tested for the existence of estrogen receptors in arcuate nucleus galanin-producing cells. Hypothalamic vibratome sections from colchicine-pretreated female rats were double immunolabeled for estrogen receptor and galanin. Neurons which exhibited immunoreactivity for either estrogen receptor or galanin were distributed throughout the hypothalamus; and a population of neurons, located predominantly in the mediobasal hypothalamus, displayed immunoreactivity for both galanin and estrogen receptor. These results raise the possibility that estrogen may act directly on galanin-producing arcuate nucleus neurons to regulate pituitary hormone secretion.