Neonatalno aplikovan somatostatin ima neposredan i odložen inhibitorni uticaj na GH ćelije hipofize

Abstract

The immediate and prolonged effects of neonatal SRIH-14 treatment on pituitary somatotrophs (GH) were investigated. Female rats were injected s.c. twice a day with 20 _g of SRIH-14/100g b.w., for five consecutive days (from 3rd to 7th day of life). Animals were sacrificed at different life periods: at neonatal (8th day), juvenile (16th day), peripubertal (38th day) and adult (80th day) period of life. GH cells were studied using the peroxidase-antiperoxidase immunocytochemical procedure. Morphometry and stereology were used to evaluate changes in the number of GH-immunoreactive cells per unit area, their volume and volume density. After SRIH-14 treatment, the most prominent decrease of all measured parameters was observed in the neonatal period. SRIH-14 induced a significant decrease of GH cell volumes and volume densities in the juvenile, peripubertal and adult periods of life. The number of GH-positive cells was significantly decreased when examined immediately after treatment, but significantly increased in adult females. Body weight, absolute or relative pituitary weights were not affected in any of the examined age groups. These findings suggest that neonatal SRIH-14 treatment exerts a significant immediate and prolonged inhibitory effect on GH cells, but does not affect the growth rate in female rats.

Ispitivan je neposredan i odložen efekat neonatalnog tretmana somatostatinom (SRIH-14) na somatotropne (GH) ćelije. Ženke pacova su dva puta dnevno s.c. tretirane sa 20 _g SRIH-14/100g t.m. u toku pet dana (od 3. do 7. dana života) i žrtvovane u različitim periodima života: u neonatalnom (8. dan) juvenilnom (16. dan), peripubertalnom (38. dan) i adultnom (80. dan) periodu. GH ćelije su imunocitohemijski obeležene metodom peroksidaza-antiperoksidaza a morfometrijskim i stereološkim metodama određivani su broj GH ćelija po jedinici površine, njihov volumen i volumenska gustina. Nakon somatostatinskog tretmana, najznačajnije smanjenje svih merenih parametara utvrđeno je u neonatalnom periodu. SRIH-14 je izazvao značajno smanjenje volumena i volumenske gustine GH ćelija u juvenilnom, peripubertalnom i adultnom periodu života. Broj GH-pozitivnih ćelija po mm2 je bio značajno smanjen kada je ispitivan neposredno nakon tretmana, ali je bio značajno povećan kod adultnih ženki. Telesna masa, kao i apsolutne i relativne mase hipofiza nisu bile izmenjene ni u jednoj od ispitivanih starosnih grupa. Dobijeni rezultati ukazuju da neonatalni tretman somatostatinom izaziva značajan neposredan i odložen inhibitoran uticaj na GH ćelije, ali ne utiče na stopu rasta kod ženki pacova.