Effects of a Prolactin-Secreting Pituitary Tumor on Hypothalamic, Gonadotropic and Testicular Function in Male Rats

Abstract

The presence of a transplanted prolactin- and GH[growth hormone]-secreting pituitary tumor (Furth MtT.cntdot.W15) in inbred male rats increased hypothalamic LHRH [luliberin] and pituitary LH [luteinizing hormone] content, decreased serum LH and testosterone concentrations and induced very high serum prolactin values. The pituitary tumor also inhibited LH release by the in situ pituitary in response to orchidectomy, or orchidectomy and adrenalectomy, and reduced the LH response to LHRH administration. Testes weight was significantly reduced and adrenal weight was significantly increased in the rats carrying pituitary tumors. The inhibitory effects of the transplanted pituitary tumor on LH and testosterone secretion apparently were due to a reduction in hypothalamic LHRH release and a reduced responsiveness of the pituitary to LHRH.