VMH lesions and reactivity to electric footshock in the rat: The effect of early testosterone level

A positive relationship was observed between the level of early testosterone and the extent of VMH lesion-induced behavioral change in adulthood: low and high testosterone levels in the first days of life produced quantitatively different VMHLesion effects on behavior.

Abstract

Abstract Reactivity to electric footshock before and after lesions in the ventromedial hypothalamic nucleus (VMH) was measured in neonatally castrated adult male rats and their gonadally intact adult female littermates. The sexual differentiation of the VMH for the control of aversive thresholds begins before birth, since neonatal castrates with no perinatal testosterone replacement had higher adult footshock thresholds than their female littermates and showed a male-typical VMH lesion effect on behavior. Masculinization of the VMH, however, is not complete at birth. A positive relationship was observed between the level of early testosterone and the extent of VMH lesion-induced behavioral change in adulthood: low and high testosterone levels in the first days of life produced quantitatively different VMH lesion effects on behavior.