Hormonal regulation of somatostatin messenger RNA.

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.