Radioimmunoassay studies on plasma and pituitary LH levels and the half-life of circulating LH in intact and castrated gerbils.

Abstract

Pituitary and plasma LH and the half-life of circulating LH were measured in individual male Mongolian gerbils using a double antibody radioimmunoassay which was shown to be specific for LH in the gerbil. Pituitary LH was not changed within 4 days after castration, but was greatly increased by 54 days. Plasma LH concentration was increased within 24 hours after castration and was 10-30 times greater than control values after 4 days. Although plasma LH continued to rise gradually, approximately doubling between 4 and 54 days, considerable variation in LH levels was observed between consecutive samples. The half-life of ovine LH and endogenous and exogenous gerbil LH in the male gerbil was approximately 40 mins. The mean half-life of endogenous LH in 44-day castrates was not different from that of iv-injected homologous LH in non-castrates as determined by measuring the rate of LH disappearance from the blood after hypophysectomy. The circulating half-life of ivinjected ovine 125I-LH in the gerbil was deter...