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Hormonal regulation of somatostatin messenger RNA
F Baldino1, S Fitzpatrick-McElligott, T M O'Kane
1Cephalon, Inc., West Chester, Pennsylvania 19380.
Abstract:
The ability of gonadal steroids to regulate the expression of the somatostatin gene in several regions of the CNS was investigated with in situ hybridization histochemistry. The amount of somatostatin mRNA was found to be significantly decreased 2-3 weeks after ovariectomy or orchidectomy in the periventricular hypothalamus, the ventromedial nucleus of the hypothalamus, and the medial and central nuclei of the amygdala. Treatment of gonadectomized rats with estradiol benzoate or testosterone enanthate reversed this decrease in somatostatin mRNA. No significant effect was noted in the cerebral cortex or bed nucleus of the stria terminalis. In some regions, there was a high degree of convergence between the distribution of neurons containing estrogen/androgen receptors and somatostatin neurons that were responsive to gonadectomy. These results suggest that sex steroids regulate the expression of somatostatin through an action at the level of transcription.
Insights
Gonadal steroids, like estrogen and testosterone, regulate somatostatin gene expression in the brain. Sex hormone levels directly impact somatostatin mRNA in key brain regions involved in hormone regulation.
Area of Science:
- Neuroendocrinology
- Molecular Biology
- Gene Expression Regulation
Background:
- Gonadal steroids play crucial roles in regulating various physiological processes.
- The central nervous system (CNS) is a key target for sex steroid action.
- Somatostatin is a peptide hormone with diverse functions in the CNS.
Purpose of the Study:
- To investigate the influence of gonadal steroids on somatostatin gene expression in specific brain regions.
- To determine if sex steroids regulate somatostatin mRNA levels in the hypothalamus and amygdala.
- To explore the relationship between sex steroid receptors and somatostatin-producing neurons.
Main Methods:
- In situ hybridization histochemistry was used to quantify somatostatin mRNA levels.
- Ovariectomy and orchidectomy were performed to remove endogenous gonadal steroids.
- Treatment with estradiol benzoate and testosterone enanthate was administered to gonadectomized rats.
Main Results:
- Ovariectomy and orchidectomy significantly decreased somatostatin mRNA in the periventricular hypothalamus, ventromedial hypothalamus, and amygdala nuclei.
- Hormone replacement therapy with estradiol or testosterone reversed these decreases.
- No significant changes in somatostatin mRNA were observed in the cerebral cortex or bed nucleus of the stria terminalis.
Conclusions:
- Sex steroids, including estrogen and testosterone, modulate somatostatin gene expression in specific CNS regions.
- The observed effects suggest that gonadal steroids regulate somatostatin at the transcriptional level.
- There is a spatial correlation between estrogen/androgen receptor distribution and somatostatin neurons responsive to gonadectomy.