Effects of maternal protein restriction on vascular pattern and on protein expression of the epididymis of male Wistar rats at different phases of postnatal development

Maternal nutrition status plays a crucial role in the health and well-being of the fetus. Changes of testes and prostate as well as spermatic disorders were observed in adult animals whose mothers were subjected to protein restriction. However, there are no studies with this experimental model that focus the development and the vascular pattern of epididymis, as well as their reflexes in the expression of proteins of the epididymis. The aim of this study is to investigate the pattern of morphometric, immunohistochemical and protein expression of the epididymis of the Wistar rat offspring whose mothers were subjected to a low-protein diet during gestation and lactation. Pregnant females were divided into normoprotein (NP) group and low-protein (LP) group that received, respectively, diets containing 17% and 6% of protein during gestation and lactation. After weaning, the LP and NP male pups received the standard diet for rodents until the ages of 21, 44 and 120 days (PND), when they were euthanized. The epididymides were collected and processed according to histological, immunohistochemical and western blotting techniques. In the LP offspring, the smaller body size and low weight observed at birth remained until the PND 120, as well as the reduction of the male genital system organs weight for all analyzed ages. Maternal low-protein diet decreased testosterone serum levels in animals at PND 44, increased aldosterone serum levels in animals at PND 21 and did not altered estradiol serum levels in any age. In LP animals, the AR expression was decreased throughout epididymis at PND 44, whereas ERα expression was increased in epididymis corpus plus cauda at PND 21 and 44, and ERβ expression was reduced in epididymis initial segment plus caput at PND 120. Immunolocalization of these hormone receptors were observed in the nucleus and cytoplasm of epididymis epithelial cells and in the interstitial cells of this organ at all ages. The decrease of AQP9 expression on the initial segment plus caput as well as the increase of AQP1 and AQP9 expression on the corpus plus cauda were significant only in LP animals at PND 44. However, these alterations were also observed in LP animals at PND 21 and 120. The immunolocalization pattern of AQP1 and AQP9 was similar between LP and NP animals at all ages, in with AQP1 staining appearing on endothelial cells of vascular channels throughout the organ, while the immunolocalization of AQP9 was observed in the stereocilia of epididymis principal cells. The VEGFa expression in the epididymis was not different between NP and LP animals in none of the analyzed ages. However, the expression of its receptor (VEGFr-2) was lower on epididymis initial segment plus caput of LP animals at PND 21. Maternal protein restriction increased the Src 416 expression throughout epididymis at PND 21, whereas decreased the expression of this protein on epididymis initial segment plus caput at PND 44 and on epididymis corpus plus cauda at PND 120. Conversely, Src 527 expression was decreased in epididymis initial segment plus caput in LP animals at PND 21. Cldn-1 expression was increased only in the epididymis corpus plus cauda of LP animals at PND 44. The microvascular density (MVD) and the MDV/stroma index of LP animals at PND 21 and 44 were lower than those of NP animals at these ages. Although some of the changes observed for LP pups were not maintained until adulthood, we observed that the insufficient supply of proteins in early life altered the structure and the functioning of the epididymis in important periods of postnatal epididymal development. (AU)