Journal of Neuroscience, Vol 14, 1789-1794, Copyright © 1994 by Society for Neuroscience
Sex differences in the effects of testosterone and its metabolites on vasopressin messenger RNA levels in the bed nucleus of the stria terminalis of rats
GJ De Vries, Z Wang, NA Bullock and S Numan
Department of Psychology, University of Massachusetts, Amherst 01003.
Male rats have about two times as many steroid-responsive vasopressin-
immunoreactive (AVP-ir) neurons in the bed nucleus of the stria terminalis
(BST) as female rats. This sex difference does not depend on differences in
circulating hormone levels, since it persists in males and females that are
treated with similar levels of testosterone. To analyze the cellular basis
of this sex difference, we compared the effects of testosterone and its
metabolites on AVP mRNA expression in the BST of males and females that
were gonadectomized at 3 months of age. When rats received implants of
Silastic tubing filled with testosterone, males had more cells that were
labeled for AVP mRNA and more labeling per cell than females. When, in a
second experiment, rats received implants of either empty tubing, or tubing
with dihydrotestosterone (DHT), estradiol (E), or E plus DHT, hardly any
labeled cells were found in rats with empty implants. E treatment
significantly stimulated AVP mRNA expression in both sexes, but
significantly more so in males, which had more cells that were labeled for
AVP mRNA and more labeling per cell than females. DHT treatment by itself
did not stimulate AVP mRNA expression, but when given in combination with
E, it significantly increased the number of cells over that of animals
treated with E alone. This increase was seen in males only. However, in
both sexes, it increased the labeling per cell over that of animals treated
with E only, but more so in males than in females.(ABSTRACT TRUNCATED AT
250 WORDS)