Constant low-dose oestradiol replacement accelerates skeletal maturation and growth in ovariectomized adolescent rhesus monkeys

The effects of oestradiol (OE2) on adolescent growth in female rhesus monkeys were evaluated by testing the hypothesis that, upon removal of the ovary, the increase in growth normally seen at the time of puberty would be abolished and that treatment with OE2 would restore it. Juvenile monkeys (n = 12) were ovariectomized and were given either an OE2-bearing silicone elastomer capsule implanted subcutaneously to simulate mid-pubertal concentrations ('treated =', n = 8) or no steroid treatment ('control =', n = 4). Females were studied from 18 to 42 months of age which, in intact females, typically encompasses the prepubertal period to the occurrence of first ovulation. Over the whole period, growth in body weight, crown-rump (CR) length and tibia length for control females were less than the 95% confidence limits of females treated with OE2. However, significant spurts of growth in both CR and tibia length occurred in the control as well as treated animals, although the peak velocities were somewhat lower for non-OE2-treated animals. Peak growth velocities occurred at an earlier chronological age in treated females, although at the same degree of skeletal maturity as found in control females. Skeletal maturity was significantly advanced in treated females from 27 months onward. Serum concentrations of nocturnal GH increased significantly with advancing age in both groups, with greater increases observed in treated females. Serum concentrations of IGF-I were higher in treated females until some 30 months of age, at which point concentrations increased in a similar fashion in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)