Sexual function and fertility in hypophysectomized adult male rats after pituitary grafting: Part I

Abstract

Male rats underwent hypophysectomy and graft procedures, and a normal control group (C) was also established. In the hypophysectomy-plus-pituitary graft (HG) group, a suspension of neonatal rat pituitary cells (cortical cells in the hypophysectomy-plus-cortical graft [CG] group) was implanted into the third ventricle. Four weeks later, the surviving hypophysectomy only H (n = 21), HG (n = 21), and CG (n = 21) rats were evaluated for copulation/ejaculation/fertility. Endocrine target organs were histologically examined, and serum levels of luteinising hormone (LH) and testosterone were compared among the four groups. LH response to endogenous (cold stress) and exogenous (gonadotropin-releasing hormone injection) stimuli was also assessed in the experimental groups. The HG group had higher LH than the H and CG groups (0.89 ± 0.2 pg/ml versus 0.58 ± 0.2 pg/ml and 0.47 ± 0.3 pg/ml, respectively; p < 0.05), but lower LH than controls (p < 0.05). The LH response to exogenous and endogenous stimuli was greater in the HG than in the H and CG rats (p < 0.05). Only control rats had detectable testosterone. HG rats (52.4%) were more sexually active than H (5.3%) and CG (5.5%) animals (p < 0.001). Histologically, grade 3 thyroidal and testicular atrophy predominated in the H and CG groups (17 [89.5%] and 15 [83.3%] rats, respectively), whereas grade 2 atrophy predominated in the HG animals (17 [81%]). Implantation of neonatal pituitary grafts into the third ventricle of hypophysectomized rats caused LH secretion to rise, but not enough to stimulate testosterone secretion.