Seasonal Changes in Immunoreactivity of Inhibin/Activin Subunits in the Epididymis of Wild Ground Squirrels (<i>Citellus dauricus</i> Brandt)

Abstract

The inhibin/activin subunits (α, βA and βB) have been found in epididymal tissue of many mammals, but there have been no data available for wild seasonal breeders so far. The aim of this study was to investigate the immunoreactivities of inhibin/activin α, βA and βB subunits in the epididymis of wild ground squirrels during the breeding and nonbreeding seasons. Immunohistochemistry and Western blotting were performed to detect the epididymal immunolocalizations and immunoreactivities of the three subunits. Strong immunostaining of α subunit was present in the interstitial part of the caput epididymis and epithelial parts of the corpus epididymis and cauda epididymis during the breeding season, whereas no α subunit was found in the nonbreeding season. βA and βB subunits were expressed in all cell types of the epithelium throughout the whole seasonal cycle, and immunostaining in the breeding season was likely stronger compared with that of the nonbreeding season. These results suggested that the epididymis might be a potential source of inhibin and activin in the wild male ground squirrel, and the secretion of epididymal inhibin and activin showed distinct seasonal changes. Furthermore, inhibin and activin might function as paracrine and/or autocrine factors that have an effect on the epididymis.

Seasonal expressions of SPAG11A and androgen receptor in the epididymis of the wild ground squirrels (<em>Citellus dauricus</em> Brandt)

“…It was similar with other seasonal breeding mammals including Neotropical bat, 28 dromedary camel, 29 sand rat, 30 which showed larger epididymis during their reproductive period. The seasonal variation of epididymal mass shown in the present study was in agreement with the previous reports in this species, 26 indicating that the epididymal mass was greatest in the breeding season. Furthermore, we found that the thickness of the epididymal lamina propria significantly decreased during the breeding season when compared with that in the non-breeding season.…”

“…25 Therefore, seasonal change of morphological and histological characteristic of epididymis were observed in seasonal breeding mammals. 24,26,27 The present results illustrated that the epididymis significantly expanded with abundant sperms during the breeding season. It was similar with other seasonal breeding mammals including Neotropical bat, 28 dromedary camel, 29 sand rat, 30 which showed larger epididymis during their reproductive period.…”

Seasonal expression of extracellular signal regulated kinases in the colon of wild ground squirrels (Spermophilus dauricus)

“…The wild ground squirrel (Spermophilus dauricus) has the characteristic of the typical seasonal reproduction, which made it a good material for studying seasonal reproduction [14] . Usually they enter the breeding season from April to May, followed by several months of activity, and their hibernation begins in October [15][16] . Up to the date, there is no related study between the expression of ERK1/2 in the colon and wild ground squirrels.…”