CHANGES IN THE LEVELS OF LUTEINIZING HORMONE AND TESTOSTERONE IN THE CIRCULATION OF AGEING MALE RATS

Abstract

Department of Physiology, Stanford University School of Medicine, Stanford, California 94305, U.S.A. (Received 26 September 1977) Pituitary-testicular function changes substantially with increasing age in male rats; the levels of testosterone and gonadotrophins in the circulation are reduced in old animals (Ghanadian, Lewis & Chisholm, 1976; Riegle & Meites, 1976; Chan, Leathem & Esashi, 1977). However, previous studies compared only young and very old rats (more than 18 months) and the development of age-related changes in the concentrations of testosterone and gonadotrophins has not been examined. Since ageing is a complex interaction of physiological changes over a prolonged period of time, information on the precise timing of the various changes is important in establishing functional relationships in the ageing process. This study investigates hormonal changes in a group of male rats between 8 and 21 months old. Adult male Long–Evans rats were housed three/cage in a temperature-controlled room with a 14