Castration induces changes in M6P receptors in rat epididymis. Implications in secretion of cathepsin D

CARVELLI L; BANNOUD N; AGUILERA C; MALOSSI AE; SOSA MA

San Luis

Congreso; XXVII Reunión Anual de la Sociedad de Biología de Cuyo; 2009

Sociedad de Biología de Cuyo

It is believed that the mammalian epididymis participates in the maturation of the sperm due to its secretory activity. High concentrations of several secreted acid hydrolases are found in the epididymal lumen. Moreover, some of these enzymes are secreted by the epididymal epithelium in an androgen-dependent fashion. In this study, we attempted to discern whether mannose-6-phosphate receptors (MPRs) regulate transport and secretion of lysosomal enzymes in the rat epididymis, and if these events are altered when the animals are subjected to hormonal manipulation. We observed that expression of cation-dependent- (CD-MPR) and cation-independent-MPR (CI-MPR) increased significantly in caudal epididymis of castrated rats by immunoblot. This increase was corroborated by quantitation of MPRs, by using binding assays. This change could be due to androgen deprivation, as a similar effect was observed after treatment with the anti-androgenic drug Flutamide. Furthermore, we observed that the CD-MPR was redistributed to the apical area of the epithelium on castrated rats by immunohistochemistry, which is compatible with the redistribution of the receptors toward lighter fractions in a Percoll gradient. Consistent with a possible involvement of the CD-MPR in the secretion, we observed an increase in procathepsin D levels in epididymal fluid after castration. We conclude, that the CD-MPR might be regulated by hormones and that this receptor is involved in the secretion of specific enzymes into the rat epididymis.