Seasonal Changes in Morphology and Immunoreactivity of PDGF-A and its Receptor PDGFR-α in the Epididymis of Wild Ground Squirrels (<i>Citellus dauricus</i> Brandt)

Abstract

Abstract. The platelet-derived growth factor (PDGF) system is expressed and can exert its biological role in the male reproductive system including the maintenance of morphological structure and function of the epididymis. The aim of this study was to clarify the relationship between the PDGF system and seasonal changes in morphology of the wild ground squirrel epididymis during the breeding and nonbreeding seasons. Hematoxylin-eosin (HE) staining was used to observe the epididymal morphology and histology. Immunohistochemistry and Western blotting were performed to detect the immunoreactivities of PDGF-A and B and PDGFR-α. Significant seasonal changes in epididymal morphology were observed in the breeding and nonbreeding seasons. The proportions of the three compartments (interstitial tissue, epithelium and lumen of the duct) revealed distinct variances. Strong immunostaining of PDGF-A was present in the myoid cell and on the sperm in the breeding season, whereas there was a faint signal in the myoid cell in the nonbreeding season. PDGFR-α was expressed in all cell types of the epithelium throughout the whole seasonal cycle, and immunostaining of PDGFR-α in the breeding season was significantly stronger compared with that of the nonbreeding season. PDGF-B was not detected in the epididymis of wild ground squirrels. These results suggested that seasonal morphological changes in epididymis were correlated with immunoreactivities of PDGF-A and its receptor PDGFR-α and that PDGF-A and PDGFR-α might function as paracrine, autocrine or apocrine factors in wild ground squirrels. Key words: Epididymis, Immunoreactivity, PDGF-A, PDGFR-Α, Wild ground squirrel (J. Reprod. Dev. 58: [353][354][355][356][357][358][359] 2012) T he mammalian epididymis plays an important role in preparing male germ cells for fertilization [1]. On the basis of histological and ultrastructural differences, the epididymis can be grossly divided into three regions including the caput, corpus and cauda epididymis. Each region of the epididymis has a different function: the caput and corpus carry out early and late sperm maturational events, respectively, while the cauda region primarily serves as a storage site for functionally mature spermatozoa [2]. As a main male accessory reproductive organ, the epididymis is highly responsive to androgen. Castration could induce a remarkable decrease in weight and function of the epididymis [3]. Besides, recent studies on the ERKO [4,5] and anti-estrogen [6,7] effects on male reproduction showed that estrogen also plays an important role in maintaining the function of the epididymis.It is now widely reported that a group of polypeptide growth factors play vital roles in mediating the androgen/estrogen-regulated process [8][9][10][11][12]. The platelet-derived growth factor (PDGF) is one of them. PDGFs are members of the PDGF/vascular endothelial growth factor (PDGF/VEGF) family, which comprises a series of 30-to 34-kd homodimers and heterodimers formed by a combination of 4 polypeptides, PDGF-A, B, C and D,...

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

“…On the other hand, during the nonbreeding season, only small epithelial cells and a cramped epididymal lumen could be found; meanwhile, no sperm was observed in the epididymis. This result was consistent with those of our previous studies, which described in detail the seasonal changes in epididymal morphology [24]. The epithelial heights of the caput, corpus and cauda epididymis in the breeding and nonbreeding seasons are shown in Fig.…”

“…The testis and epididymis of this species exhibits distinct seasonal morphology changes from the breeding season to the nonbreeding season [21,22,23,24]. Our published results have indicated that seasonal changes in the distribution of inhibin/activin α, β A and β B subunits and activin signaling proteins were accompanied by changes in testicular activity in male ground squirrels and other mammals [21, 22, 25,26,27,28,29].…”

Exploring the Molecular Characteristics and Role of PDGFB in Testis and Epididymis Development of Tibetan Sheep

“…The epididymis is where sperm mature and are stored, and its morphology structure and maintenance of function are regulated by multiple growth factors, including testicular factors [ 26 , 27 ]. This study found that the PDGF is involved in regulating activity in wild ground squirrel epididymal cells via a paracrine/autocrine manner and in sperm maturation and storage during the breeding season [ 28 ]. Procathepsin L, which is involved in epididymal functional differentiation, is expressed and secreted in the epididymis under locally restricted conditions, and this process is directly regulated by PDGF [ 29 ].…”

“…Its molecular weight is 27.39 kD, its total atomic number is 3863, and its theoretical isoelectric point (pI) is 9.54. Of the 241 amino acids in the protein, there are a total of 20 amino acid residues (Supplementary Table S1), the most abundant of which is arginine (28), accounting for 11.6% of the total content. There are a total of 29 negatively charged amino acid residues (Asp + Glu) and 43 positively charged amino acid residues (Arg + Lys).…”