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 da ssified 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 = 1 12) obtained from these animals [juveniles (n = 11), adolescents (n = 25), and adults (n = 76)] were analyzed for testosterone (T), luteiniz ing 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 adoles cent(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 signif icant difference in T between animals aged 20-24 years (5.3 +/- 0.4) a nd 25-29 years (3.0 +/- 0.4). There was no significant change in serum LH (mIU/ml with age. Serum FSH (mIU/ml) increased significantly betwe en 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 l ower in males older than 20 years (92.6 +/- 4.2). Blood samples (n = 5 ) obtained from an experimental group of six adult male chimpanzees, a ges 10 to 15 years, were analyzed for T, LH, and FSH. Pituitary respon se to challenge with exogenous GnRH and to hypothalamic stimulation wi th 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 500 mu g GnRH stimulated LH r elease. The response was not directly dose related. Challenge with 3 a nd 6 mg/kg NMA stimulated LH release. The response was dose related. ( C) 1993 Wiley-Liss, Inc.