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The effects of chronic exposure to light of adult female Wistar rats on growth and function of pituitary adrenocorticotropes (ACTH cells) were examined. The animals were exposed to continuous light of 600 lux for 95 days, starting on day 30 of age. Control rats were kept under a 12:12 h light-dark cycle, at ambient temperature. ACTH-producing cells were studied using the peroxidase-antiperoxidase immunohistochemical procedure and blood samples were collected for hormone analyses. In animals exposed to a chronic light-treatment all morphometric parameters measured throughout the present study i.e.: ACTH cell volume, nuclear volume and relative volume density were increased by 22% and the differences between this group and the controls were statistically significant (p<0.05). The concentration of plasma ACTH was elevated by 13% in light-exposed group in comparison with the control and this difference was statistically significant (p<0.05), as well. These findings suggest that continuous exposure to light is specifically involved in growth and secretory activity of ACTH cells of adenohypophysis of rat females.

Effects of intracerbroventricularly (ICV) administered octreotide on gonadotrophic cells (FSH and LH) of adult Wistar female rats were examined by immunocytochemical and morphometric methods. The animals received ICV three 1.0 mg doses of octreotide dissolved in 10 mL saline every second day. The controls were treated with equivalent volume of physiological saline by the same schedule. FSH-and LH-producing cells were examined using peroxidase-antiperoxidase immunocytochemical procedure. Morphometric and stereologic examinations were performed to evaluate changes in the number, volume and volume densities of gonadotrophic cells. In females treated with octreotide, the gonadotrophic cells were smaller and often pycnotic, while the number of FSH-and LH-immunopositive cells per unit area (mm 2) was significantly reduced. Octreotide also induced a significant reduction of the FSH-and LH-immunoreactive cells volume, as well as of their volume densities. On the basis of these results it can be concluded that octeotride, centrally administered to adult female rats provokes changes in immunocytochemical and morphometric features of both types of gonadotrophic cells.

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