Adenohypophysial mRNA Expression Level of GH Gene and Immunohistochemical Expression of Somatotrophs in Pregnant and Lactating Inhibin-α Immunoneutralized Female Wister Rats

Abstract

Inhibins and activins are members of TGF-β superfamily associated with reproductive processes. The role of passive immunization against endogenous inhibin-α subunit on pituitary mRNA expression level of GH gene and immunohistochemical expression of somatptrophs during pregnancy and lactation in primiparous female Wister rats, has been examined in this study. Forty eight pregnant females were assigned to 2 groups (24 per each). On 5th and 10th day of gestation, control (C) was injected with saline (100μl, i.p.) and treated (INHA) was injected with inhibin-α antiserum (1µg in 100μl of saline, i.p.). Each group was allocated to 3 equal subgroups: pregnancy, delivery, and lactation, were sacrificed on day 16 of gestation, at parturition, and 11th day of lactation, respectively. At the end of each subgroup period, females were anesthetized, dissected and adenohypophysis was removed and kept at -70 Cº for molecular evaluation and others kept in formaline (10%) for immunohistochemistry. Pituitary GH gene expression levels in INHA group increased significantly compared with control in all periods. Expression of pituitary somatotrophs showed higher number of positive stained cells and intensity of staining in INHA group during pregnancy, delivery and lactation. In comparison between periods, in both groups, higher score has been shown at delivery, whereas lowest score recorded at lactation. In conclusion, passive immunization against inhibin-α subunit at 5th and 10th day of pregnancy, perform potent role in GH secretion in primiparous female Wister rats.