Expression of glycoprotein 330 and sulfated glycoprotein-2 in epithelial principal cells of the normal adult rat epididymis and after castration, ligation and hypophysectomy

Sulfated glycoprotein-2 (SGP-2) has been shown to be secreted by the epididymal principal cells whereupon it binds to sperm where it is possibly involved in transporting lipids to or from their surface or providing them with a protective coat. However, SGP-2 also appear to be endocytosed by principal cells along the epididymis. Recently, it has been demonstrated that glycoprotein 330 (gp330), a low density lipoprotein receptor-related protein, can mediate the endocytosis of SGP-2 in the nonciliated cells of the efferent ducts and cultured cells (Kounnas et al., 1995; Morales et al., 1996). The purpose of the present study were in part to correlate the expression of SGP-2 with gp330 along the epididymis to determine if gp330 was essential for SGP-2 internalization. In addition, experiments were carried out to determine which factor(s) are involved in the regulation of expression of these two proteins. The epididymides were fixed by perfusion with Bouin's fixative and examined with anti-SGP-2 and anti-gp330 antibodies using light microscope immunocytochemistry. (Abstract shortened by UMI.