Journal of Neuroscience, Vol 1, 1142-1147, Copyright © 1981 by Society for Neuroscience
The influence of gonadectomy, androgen exposure, or a gonadal graft in the neonatal rat on the volume of the sexually dimorphic nucleus of the preoptic area
CD Jacobson, VJ Csernus, JE Shryne and RA Gorski
Although the volume of the sexually dimorphic nucleus of the preoptic area
(SDN-POA) of the adult rat has been shown to be modified by the hormone
environment early in postnatal life, the present study was performed to
clarify several fundamental questions related to this process. This study
was designed to evaluate the ability of exogenous testosterone propionate
(TP), or a gonadal graft, to influence SDN-POA volume in rats which were
gonadectomized as neonates. Orchidectomy on day 1 resulted in an
approximately 50% decrease in adult SDN-POA volume; however, the influence
of the testes on their resulting SDN-POA volume was replaced affectively by
the administration of 100 micrograms or 1 mg of TP on postnatal day 2 or by
a testicular (but not ovarian) graft on the day of castration. In the
female, ovariectomy on postnatal day 1 failed to alter SDN-POA volume
relative to that of sham-operated females. Exogenous TP, but neither
testicular nor ovarian grafts, resulted in a larger SDN-POA volume when
observed in the adult female. Thus, the development of the SDN-POA of the
neonatal male is significantly influenced by the hormonal activity of the
testes at this time period. While the SDN-POA of the neonatal female is
potentially responsive to androgen, the role played by the ovaries in the
development of the SDN-POA remains unclear. In addition, the different
response of the developing male and female SDN-POA to a testicular graft
suggests that the hormonal sensitivity of this nucleus may differ in the
two sexes.
Previous Article | Next Article
