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Sex difference in glucocorticoid binding in rat pituitary is estrogen dependent
1Department of Physiology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614.
Life Sciences
|January 1, 1990
Summary
Female rats have fewer pituitary corticosteroid receptors due to estrogen, impacting glucocorticoid feedback. This sex difference suggests altered sensitivity in females.
Area of Science:
- Endocrinology
- Neuroscience
- Molecular Biology
Background:
- Corticosteroid receptors in the pituitary regulate stress response and hormone feedback.
- Sex differences in hormonal regulation are increasingly recognized in various physiological processes.
Purpose of the Study:
- To investigate sex-dependent differences in pituitary corticosteroid receptor binding in rats.
- To determine the influence of gonadal hormones, specifically estrogen and progesterone, on these receptors.
Main Methods:
- Adrenalectomized adult male and female rats were used.
- Soluble corticosteroid binding was assayed using LH-20 columns with 3H-dexamethasone.
- Hormonal manipulations included ovariectomy, gonadectomy, and administration of estrogen or progesterone.
Main Results:
- Intact females exhibited significantly lower 3H-dexamethasone binding than intact males.
- Ovariectomy eliminated this sex difference, indicating a role for ovarian hormones.
- Estrogen administration to ovariectomized females resulted in fewer receptors compared to intact males, while progesterone had no effect.
- A sex difference was also observed in Type I (mineralocorticoid) receptors, with females having fewer.
Conclusions:
- Estrogen down-regulates functional corticosteroid receptors in the rat pituitary by approximately 20%.
- Lower receptor levels in females may reduce pituitary sensitivity to the negative feedback effects of glucocorticoids.
- These findings highlight a potential mechanism for sex-specific regulation of the hypothalamic-pituitary-adrenal (HPA) axis.
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