Pubertal endocrinology of the baboon: Elevated somatomedin-c/insulin-like growth factor i at puberty

Abstract

Previous data suggested an increase in the rate of weight gain and linear growth in the baboon between 3 and 4yr of age, similar to the pubertal growth spurt in man.In thiscross-sectional study, radioimmunoassayable concentrations of somatomedin-C/insulin-like growth factor I (SM-C/IGF-I) were compared in prepubertal (<3 yr), pubertal (3–4 yr), and adult(>10 yr) animals. SM-C/IGF-I concentrations in prepubertalmales (0.97 ± 0.10 U/ml) were low and were not different fromthose in prepubertal females (0.98 ± 0.15 U/ml). Between 3 and4 yr, SM-C/IGF-I increased significantly in both sexes (8.87 ± 0.74 and 5.27 ± 0.52 U/ml, male and female, respectively) anddecreased (5.92 ± 1.2 and 2.75 ± 0.13 U/ml, respectively) inanimals greater than 10 yr of age. Sex differences were significantin the 3- to 4-yr-old animals (male greater than female, P <0.001). The pubertal elevation in SM-C/IGF-I concentrations is coincident with increases inindices of somatic growth and sexualmaturation in the baboon. These and other data suggest thatthis animal may be an appropriate model for studies to define hormonal mechanisms of pubertal growth. © 1982 by The Endocrine Society.