Evaluation of in vitro incubation systems for the study of gonadotropin release

A detailed study was undertaken in order to determine if a pituitary-half incubation system were a suitable model for the study of anterior pituitary response to estradiol and LHRH. Considerable variation in the gonadotropin content of randomized pituitary halves was observed. Much less variation was found in matched halves. During the initial thirty minutes incubation of pituitary halves, a large spontaneous release of gonadotropins was observed. Time course secretion studies indicated that by four hours incubation, in the presence of 50 ng/ml LHRH, cumulative secretion of LH and FSH had far exceeded that of controls. Elevations in both cumulative secretion and rate of secretion were evident within 15-30 minutes of incubation. Regardless of LHRH dose, only 2-4% of either gonadotropin was secreted. Estradiol in the range of 10, 100, 500, 1,000 and 50,000 pg/ml had no significant effect on pituitary response to LHRH or on basal release, tissue levels or total gonadotropin. Based on these results, it was concluded that while the pituitary-half incubation system may be suitable for studying LHRH induced gonadotropin secretion, it is apparently of insufficient sensitivity to allow the collection of meaningful data concerning the effects of estradiol alone on gonadotropin secretion or estradiol modulation of LHRH induced gonadotropin secretion.