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Estrogen and progesterone regulate opiate receptor densities in multiple brain regions
1Department of Physiology, University of Maryland School of Medicine, Baltimore 21201.
Endocrinology
|February 1, 1990
Summary
Estrogen and progesterone influence the brain's opiate system. These hormones decrease opiate receptors in the hypothalamus, affecting reproductive functions and responses to pain relief medications.
Area of Science:
- Neuroendocrinology
- Reproductive Biology
- Pharmacology
Background:
- Estrogen and progesterone modulate hypothalamic functions, potentially via the endogenous opiate system.
- These steroid hormones are known to suppress physiological responses to opiate peptides.
Purpose of the Study:
- To investigate if steroid-induced desensitization to opiates involves the down-regulation of opiate receptors.
- To quantify changes in naloxone-binding sites within key hypothalamic regions.
Main Methods:
- Autoradiographic techniques were employed to measure naloxone-binding site density.
- Measurements were taken in intact, ovariectomized, and hormone-treated (estrogen, estrogen + progesterone) rats at various times.
Main Results:
- Ovariectomy led to increased naloxone-binding sites in all examined hypothalamic regions compared to intact rats.
- Estrogen treatment decreased binding site density, with estrogen plus progesterone causing a more pronounced reduction.
Conclusions:
- Steroid hormones, estrogen and progesterone, down-regulate hypothalamic opiate receptors.
- This steroid-induced suppression of opiate receptors provides a mechanism for observed changes in sensitivity to exogenous opiates.