Effects of sex hormones on congenital kyphosis in Ishibashi rats

Abstract

We examined the influence of estrogen and testosterone on the development of congenital kyphosis in Ishibashi rats. Neither hormone caused a growth spurt. Estrogen suppressed the spinal growth and the progression of kyphosis in both sexes, and accelerated narrowing of the epiphyseal plates, which became apparent at 6 weeks after birth in females and 8 weeks in males. In both sexes, maturity of the spine was accelerated and trabeculae were hypertrophied by estrogen. Testosterone suppressed the progression of kyphosis in males, but not in females. Histologically, testosterone had no effects on growth cartilage, but did produce thinning of the bone trabeculae in males.