Influence of castration of the neonatal rat on the pharmacological reactivity of the isolated vas deferens.

Abstract

The present study was undertaken to analyze the effects of castration of neonates performed on Days 1, 3, 5, 10, and 15 after birth on the development of the male accessory genitalia and the responsiveness of the isolated vas deferens of the adult rat to acetylcholine (ACh). acetyl-β-methylcholine (MECh), adrenaline (A), noradrenaline (NA), and barium chloride (BaCl2). No spontaneous contractions were observed throughout the experiments. In addition to a drastic inhibition of accessory genitalia development and an increase in adrenal gland weight, castration of neonates induced the appearance of supersensitivity of the isolated vas deferens to BaCl2 (all groups), ACh (all groups except Day 5), and MECh (Days 1 and 15) allied to subsensitivity to A (Days 1 and 15) and NA (Day 1). The relative responsiveness to the latter four agonists and the intrinsic activity of MECh and NA were also increased in most groups. It is concluded that castration of neonates markedly alters accessory genitalia development and the pharmacological responsiveness of the vas deferens of the adult rat to several agonists.