Efekti oktreotida na acth ćelije hipofize mužjaka pacova

Abstract

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.

Postoje veoma različita, a često i suprotstavljena mišljenja o efektima sintetskih somatostatina na lučenje adrenokortikotropnog hormona (ACTH) iz hipofize. Mogući mehanizam inhibicije lučenja ACTH je preko inhibicije lučenja CRF iz hipotalamusa. U ovom radu su ispitivani efekti intracerebroventrikularno (i.c.v) ubrizganog analoga somatostatina Oktreotida, na rast ACTH ćelija adenohipofize mužjaka Wistar pacova. Sve eksperimentalne životinje su primile tri doze od po 1.0 µg Oktreotida rastvorenog u 10 µL fiziološkog rastvora, svakog drugog dana. Kontrole su tretirane na isti način fiziološkim rastvorom. Pacovi su žrtvovani pet dana posle poslednje injekcije. ACTH ćelije su imunocitohemijski bojene metodom peroksidaza-antiperoksidaza (PAP). Telesna masa, apsolutna i relativna masa hipofize nisu bile statistički značajno promenjene u poređenju sa odgovarajućom kontrolom (p>0.05). Karakteristike imunohistohemijski obojenih ACTH ćelija kontrolnih pacova su: lokalizacija između kapilara, zvezdast oblik sa citoplazmatičnim produžecima između drugih ćelija. Male specifične sekretorne granule raspoređene su po periferiji citoplazme. Oblik i lokalizacija ACTH ćelija životinja tretiranih Oktreotidom nisu bili značajno promenjeni u odnosu na kontrolu. Međutim, oktreotid je izazvao značajno smanjenje svih morfometrijskih parametara ovih ćelija (p>0.05). Zapremina ćelija je bila smanjena za 44%, jedara za 18%, a volumenska gustina za 31% (p<0.05) u poređenju sa odgovarajućom kontrolom. Na osnovu dobijenih rezultata može se zaključiti za Oktreotid deluje inhibitorno na rast ACTH ćelija adenohipofize mužjaka pacova.