Selected endocrine parameters of the adult male chimpanzee

This study provides baseline data on reproductive endocrine parameters of the male chimpanzee. A colony group of 47 male chimpanzees were classified by age as juvenile, ages 4-6 years (n = 7); adolescent, ages 7-9 (n = 9); and adult, ages 10-33 years (n = 31). Blood samples (n = 112) obtained from these animals [juveniles (n = ll), adolescents (n = 25), and adults (n = 76)] were analyzed for testosterone (T), luteinizing hormone (LH), and follicle stimulating hormone (FSH). There was a significant increase (mean ± SE) in T (ng/ml) between the juvenile (0.2 ± 0.1) and adolescent group (2.4 ± 0.3) and between the adolescent (2.4 ± 0.3) and the 10-14‒year-old adult age group (4.2 ± 0.2). T peaked at 15-24 years of age and then declined. There was a significant difference in T between animals aged 20-24 years (5.3 ± 0.4) and 25-29 years (3.0 ± 0.4). There was no significant change in serum LH (mlU/ml) with age. Serum FSH (mlU/ml) increased significantly between 4-6 years of age (90.0 ± 11.6) and 10-14 years of age (120.5 ± 8.3), plateaued between 10 and 19 years of age and was significantly lower in males older than 20 years (92.6 ± 4.2). Blood samples (n = 5) obtained from an experimental group of six adult male chimpanzees, ages 10 to 15 years, were analyzed for T, LH, and FSH, Pituitary response to challenge with exogenous GnRH and to hypotha-lamic stimulation with NMA also was assessed. T, LH, and FSH in the experimental group did not differ significantly from animals of equivalent age in the colony group. Challenge with 50, 100, 200, and 500μg GnRH stimulated LH release. The response was not directly dose related. Challenge with 3 and 6 mg/kg NMA stimulated LH release. The response was dose related. © 1993 Wiley-Liss, Inc.