Determination of biologically active LH in the serum of male rhesus monkeys (Macaca mulatta)

Abstract

The in vitro bioassay for luteinizing hormone [LH], using mouse Leydig cells, was modified for the direct measurement of serum LH in the male rhesus monkey. Assay validation showed good reliability in terms of accuracy, precision and sensitivity (1.5 mIU/ml). Basal LH concentrations in laboratory-maintained monkeys with and without anesthesia were not significantly different from those in free-ranging, feral monkeys. LH-RH [luteinizing hormone releasing hormone], (50 .mu.g i.v.) elicited a 30-fold increase in LH concentrations after 30 min. LH levels in castrated adult monkeys were approximately 50 times the normal levels. Intact and castrated juvenile males had only very low LH levels. LH from the serum of an adult male castrate was further characterized by Sephadex G100 column chromatography. The in-vitro bioassay provides a preferable alternative to the heterologous radioimmunoassay method for the routine determination of LH in the rhesus monkey.