The effects of human chorionic gonadotropin on immunopositive ACTH cells in peripubertal female rats

Abstract

Human chorionic gonadotropin (hCG) is very important in controlling the secretory activity of hormone producing cells in the female pituitaries. The aim of the present study was to examine the morphometric parameters of immunohistochemically labeled ACTH cells in peripubertal female rat pituitaries, after hCG treatment. Female rats, in peripubertal period (36th day), were divided into two groups, each of seven animals. The experimental group received two injections of hCG (i.p., 50 IU/kg b.w.), at the 36th and 37th day after birth. The controls were treated by the same schedule, with equivalent the volume of saline. lmmunopositive ACTH-producing cells were studied using the peroxidase-anti-peroxidase immunohistochemical procedure. The cell volume, nuclear volume and volume density of ACTH cells were determined by the morphometrical method. In peripubertal females treated with hCG the absolute pituitary weights were increased (p<0.05) by 32.9%, in comparison with the controls. The ACTH cell and nuclei volume as well as their volume density, in hCG treated group, were significantly increased by 39.2%, 39.1% and 15.4% respectively, compared to the controls. In control female rats, immunohistochemically labeled ACTH cells were stellate shaped, with the cytoplasmic processes among neighbouring cells, and localized between the capillaries. Small, specific secretory granules were distributed mainly at the periphery of the cytoplasm. The shape and localization of ACTH immunopositive cells in hCG treated female rats were not significantly changed in comparison with the controls. In conclusion the application of hCG caused the significant increase of morphometric parameters of pituitary ACTH cells in peripubertal female rats.