Fertility in Hypophysectomized Pituitary Grafting : Part i Function and · Male Rats

Male rats underwent hypophysectomy and graft procedures, and a normal control group (C) was also established. In the hypophysectomy-plus-pituitary graft (HC) group, a suspension of neonatal rat pituitary cells (cortical ce lls in the hypophysectomy-plus-cortical graft [CC] group) was implanted into the third ventride. Four weeks later, the surviving hypophysectomy only H (n=21), HC (n=21), and CC (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 HC group had higher LH than the H and CC 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 HC than in the H and CC rats (p<0.05). Only control rats had detectable testosterone. HC rats (52.4%) were more sexuallyactive than H (5.3%) and CC (5.5%) animals (p<O.OO1). Histologically, grade 3 thyroidal and testicular atrophy predominated in the H and CC groups (17 [89.5%] and 15 [83.3%] rats, respectively), whereas grade 2 atrophy predominated in the HC animals (17 [81 %]). Implantation of neonatal pituitary grafts into the third ventride of hypophysectomized rats caused LH secretion to rise, but not enough to stimulate testosterone secretion.