Regulation of Sex Differences in Progesterone Receptor Expression in the Medial Preoptic Nucleus of Postnatal Rats

The medial preoptic nucleus (MPN) of the rat, an excellent model for understanding the mechanisms involved in sexual differentiation, is highly sensitive to gonadal hormones during both pre‐ and post‐natal life. Progesterone receptor (PR) expression is sexually dimorphic in the prenatal MPN. Males h...

Full description

Saved in:
Bibliographic Details
Published in:Journal of neuroendocrinology 2002-10, Vol.14 (10), p.761-767
Main Authors: Quadros, P. S., Goldstein, A. Y. N., De Vries, G. J., Wagner, C. K.
Format: Article
Language:English
Subjects:
Animals
castration
Female
Immunohistochemistry
Male
MPN
ontogeny
Orchiectomy
Ovariectomy
Ovary - physiology
Pregnancy
Preoptic Area - chemistry
Preoptic Area - growth & development
Rats
Rats, Sprague-Dawley
Receptors, Progesterone - analysis
Sex Characteristics
Testis - physiology
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The medial preoptic nucleus (MPN) of the rat, an excellent model for understanding the mechanisms involved in sexual differentiation, is highly sensitive to gonadal hormones during both pre‐ and post‐natal life. Progesterone receptor (PR) expression is sexually dimorphic in the prenatal MPN. Males have significantly higher levels of PR‐immunoreactivity (PRir) than females from approximately embryonic day 19 through at least the day of birth, suggesting that PR may play a role in sexual differentiation. Because the MPN is still sensitive to steroid hormones postnatally, the present study investigated PR expression in the MPN of males and females after birth using immunocytochemistry. Results indicate that a sex difference in PR expression persists until at least postnatal day (P) 28. However, females begin to express PR around P10. Because oestradiol regulates PR expression in the adult brain, this study also examined the influence of gonadal hormones on PR expression in the neonatal male and female MPN. Castration on the day of birth significantly reduced levels of PRir in the MPN by 24 h following surgery. Ovariectomy on P4, before the onset of ovarian steroidogenesis, prevented the induction of PR expression in the female MPN, observed in controls by P13. In both sexes, the presence of PRir in the MPN is dependent on gonadal hormone exposure. These findings suggest that differences in steroid secretion by the neonatal male and female gonads are responsible for producing sex differences in the level of PR expression in the postnatal MPN.
ISSN:0953-8194
1365-2826
DOI:10.1046/j.1365-2826.2002.00827.x