MORPHOMETRIC ANALYSIS OF GH-IMMUNOREACTIVE CELLS AFTER GH RELEASE INDUCED BY TREATMENT WITH ESTROGEN IN ADULT MALE-RATS

In order to elucidate the response of somatotropic cells to the influence of gonadal steroids on the regulation of growth hormone secretory patterns, a morphometric analysis was carried out on the GH-immunoreactive cells of adult male rats treated chronically with intramuscular injections of estradiol valerate. The morphometric and morphological results obtained were correlated to the serum levels of GH at the moment of sacrifice. Treatment with a daily dose of 125-mu-g of estradiol vaterate over 15 d was seen to lead to an increase (p < 0.01) in the serum GH values accompanied by a decrease in the intensity of reaction of the GH-cells and, morphometrically, a reduction in their size (p < 0.01) due to a decrease in the cytoplasmic area (p < 0.01), but without significant changes in the nuclear area. Our results suggest that in male rats estrogens enhance the release of the intracellular GH pool but that they do not affect hormone synthesis to a great extent.