Pituitary and gonadal function in hypogonadotrophic hypogonadal (hpg) mice bearing hypothalamic implants

GnRH receptor values are 30-50% of normal in pituitaries of hpg male mice, and testicular LH receptors only 8% of normal (160.4 +/- 17.6 and 2013 +/- 208.1 fmol/testis respectively). In male hpg mice bearing fetal preoptic area (POA) hypothalamic implants for 10 days there was no change in pituitary GnRH receptors, pituitary gonadotrophin content, or seminal vesicle weight. However, testicular weights and LH receptors were doubled in 4/10 mice and 2 had increased serum FSH levels. Between 26 and 40 days after implantation pituitary GnRH receptors and pituitary LH increased to normal male levels, although at 40 days serum and pituitary FSH concentrations had reached only 50% of normal values. Testicular and seminal vesicle weights increased more than 10-fold by 40 days after implantation and LH receptors to 70% of normal. In hpg female mice bearing hypothalamic implants for 30-256 days pituitary gonadotrophin concentrations were normal, even though GnRH receptors reached only 60% of normal values (6.18 +/- 0.4 and 9.8 +/- 0.4 fmol/pituitary respectively). Serum FSH was substantially increased from values of less than 30 ng/ml in hpg mice to within the normal female range in hypothalamic implant recipients. Ovarian and uterine weights increased after hypothalamic grafting from only 4-5% to over 74% of normal values. LH receptors increased from 6.5 +/- 1.3 fmol/ovary for hpg mice to 566.9 +/- 39.2 fmol/ovary for implant recipients. Vaginal opening occurred about 23 days after implantation and these animals displayed prolonged periods of oestrus.(ABSTRACT TRUNCATED AT 250 WORDS)