Efekti oktreotida na acth ćelije hipofize mužjaka pacova
A somatostatin analogue octreotide inhibits pituitary ACHT cells in rat males
Velkovski, Saško D.
Starčević, Vesna P.
Article (Published version)
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The results on the effects of synthetic somatostatins on the secretion of ACTH have been rather conflicting, but some authors reported that somatostain is involved in the regulation of ACTH secretion in rats of both sexes. The inhibitory mechanism of ACTH secretion could operate through the inhibition of CRF release from the hypothalamus. In the present study, we have investigated the effects of Octreotide, a somatostain analogue given intracerebroventricularly (i.c.v) in low doses, on morphometric characteristics of pituitary adrenocorticotropes (ACTH cells) in adult Wistar rat males. The animals were i.c.v. given three 1.0 µg doses of Octreotide dissolved in 10 µL saline every second day. The controls were treated in the same way with the same volume of saline. ACTH-producing cells were studied using the peroxidase-antiperoxidase (PAP) immunohistochemical procedure. Body weight, as well as absolute and relative pituitary weights were not significantly changed in comparison with the corresponding controls (p>0.05). The characteristics of immunohistochemicaly labelled ACTH cells in intact rat males were as follows: localization between the capillaries stellate in shape with the cytoplasmatic processes among neighbouring cells. The nucleus follows the shape of the cell body. Small specific secretory granules were distributed mainly at the periphery of the cytoplasm. The shape, and localization of ACTH immunoreactive cells in Octreotide-treated animals were not significantly changed in comparison with the controls. Octreotide treatment significantly decreased all morphometric parameters measured, i.e. volume of ACTH cells and their nuclei by 44% and 18% respectively, as compared to the controls (p<0.05). Volume densities were also significantly decreased (by 31%; p<0.05) comparing to the corresponding controls. These results indicate that Octreotide applied i.c.v. exerts a significant inhibitory effect on the immunohistochemical and morphometric characteristics of ACTH cells in rat males.