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Estrogen modulates RGS9 expression in the nucleus accumbens
Jill L Sharifi1, Dana L Brady, James I Koenig
1Maryland Psychiatric Research Center, University of Maryland School of Medicine, Baltimore, MD 21228, USA. jsharifi@mprc.umaryland.edu
Neuroreport
|January 11, 2005
Summary
Estrogen reduces regulators of G-protein signaling 9 (RGS9) mRNA expression in the nucleus accumbens shell. This estrogen-induced change in RGS9 may enhance dopamine receptor signaling, potentially explaining gender differences in psychostimulant abuse.
Area of Science:
- Neuroscience
- Endocrinology
- Pharmacology
Background:
- Estrogen is known to influence behaviors mediated by dopamine receptors, particularly in response to psychostimulants.
- Regulators of G-protein signaling (RGS) proteins are critical modulators of G-protein coupled receptor activity, including dopamine receptors.
- Alterations in RGS protein expression may underlie estrogen's effects on dopamine signaling pathways.
Purpose of the Study:
- To investigate the effect of estrogen on the expression of RGS9 mRNA in specific brain regions.
- To determine if estrogen modulates dopamine receptor-mediated behaviors through changes in RGS9 expression.
- To explore the potential role of estrogen-regulated RGS9 in psychostimulant abuse patterns.
Main Methods:
- Ovariectomized (OVX) rats were treated with 17beta-estradiol implants or empty implants.
- Following treatment, rats received single injections of dopaminergic agents or saline.
- Quantitative analysis of RGS9 mRNA expression in the nucleus accumbens shell and core was performed.
Main Results:
- Estrogen administration significantly reduced RGS9 mRNA expression specifically in the nucleus accumbens shell of OVX rats.
- RGS9 mRNA expression was not altered in the nucleus accumbens core following estrogen treatment.
- Administration of D1/D2 dopamine receptor agonists or amphetamine did not affect RGS9 mRNA levels in either experimental group.
Conclusions:
- Estrogen selectively downregulates RGS9 mRNA expression in the nucleus accumbens shell.
- This estrogen-mediated reduction in RGS9 may enhance dopamine receptor signaling.
- The findings suggest a mechanism for estrogen's influence on psychostimulant effects, potentially contributing to gender-specific abuse vulnerabilities.