Sex-Steroid Effects on Perifused Pituitary

Sex steroids are known to affect growth and growth hormone (GH) secretion throughout mammalian life. Early studies on the imprinting effects of testosterone (T) on growth and GH secretion in rats (1) showed that neonatal gonadectomy (GX) caused significant disruption of GH secretion in adult male rats. Treatment of neonatally GX male rats with T during neonatal and adult life restored a significant component of the GH pulsatile pattern. The presence of the ovary prevented the imprinting effect of T that would occur if female rats had otherwise undergone neonatal GX (2). These imprinting effects most likely involve the brain as the primary target.