Growth retardation in premenarchial female rhesus monkeys during chronic administration of a GnRH agonist (leuprolide acetate)

Leuprolide acetate in depot form (0.75 mg/kg body weight/month, im) was administered to four female rhesus monkeys from 18-30 months of age, a period that includes the premenarchial growth spurt. They were compared to eight age matched controls. As anticipated, sexual maturation was blocked in the Leuprolide group and menarche did not occur. Growth was also severely retarded; no weight gain occurred during the study in the Leuprolide group as compared to a 25% weight gain (P = .004) in the control group. The Leuprolide group also lost muscle mass. Food intake normalized for body weight was not affected. Linear growth averaged 35% less in the Leuprolide group. Serum IGF-1 concentrations increased from 486±84 to 965±47 ng/mL (P = .0025) in the Leuprolide group and from 838±139 to 3,006±545 ng/mL (P = .0016) in the control group. These data suggest that premenarchial pituitary/gonadal suppression results in a distinctive pattern of growth retardation in monkeys.