Somatostatin acts by inhibiting pituitary TSH cells in female rats

Abstract

The effects of intracerebroventricularly (i.c.v.) administered synthetic somatostatins (SRIH-14 and SRIH-28) on pituitary TSH cells of adult female rats were studied. The animals were i.c.v. injected with three 1.0 μg (5 μ1) doses of SRIH-14 or SRIH-28 every second day and sacrificed five days after the last dose. The controls received an equivalent volume of saline in the same manner according to the same schedule. The pituitary glands were excised and used for immunohistochemical and morphometric evaluation. The results obtained demonstrated a somatostatin-related decrease in relative pituitary weight. The morphometric analyzes showed decreased volumetric density of TSH-immunoreactive cells in SRIH-treated groups, but this difference was more expressed in SRIH-14- treated animals than in those receiving SRIH-28. On the basis of these results it can be concluded that centrally administered somatostatins inhibit TSH cells.Ispitivani su efekti intracerebroventrikularno (i.c.v.) injiciranih sintetičkih somatostatina (SRIH-14 i SRIH-28) na hipofizne TSH ćelije adultnih ženki pacova. Životinje su i.c.v. injicirane satri doze od po 1 μg SRIH-14 ili -28 rastvorenog u 5 pi fiziološkog rastvora svaki drugi dan, a žrtvovane 5 dana posle poslednje injekcije. Kontrole su tretirane odgovarajućom dozom fiziološkog rastvora. Hipofize su izolovane i pripremljene za imunocitohemijska i morfometrijska ispitivanja. Oba somatostatina izazivaju smanjenje relativne težine hipofize. Morfometrijska analiza pokazuje da je u obe tretirane grupe životinja volumenska gustina TSH-imunoreaktivnih ćelija smanjena te razlike su značajnije izražene u grupi životinja tretiranih sa SRIH-14 u odnosu na one tretirane sa SRIH-28. Na osnovu dobijenih rezultata možemo zaključiti da centralno aplikovani somatostatini inhibiraju TSH ćelije hipofize.nul