Androgen-dependent synthesis/secretion of caltrin, calcium transport inhibitor protein of mammalian seminal vesicle.

Effects of androgen status on the synthesis and secretion of rat caltrin have been studied by three different procedures: a) immunocytochemistry in seminal vesicle tissues; b) polyacrylamide gel electrophoresis and Western immunostaining of seminal vesicle secretion; and c) evaluation of trypsin inhibitory activity of the seminal vesicle secretion. Rat caltrin has been immunolocalized in cells of the secretory epithelium, specifically in the electron-lucent halo of secretory granules which store and transport proteins to the lumen. No caltrin immunoreaction was detected 14 days postcastration, and the ultrastructure of the epithelial cells was markedly altered. SDS-PAGE and Western blotting of the seminal vesicle secretion revealed alterations in the protein pattern and loss of the caltrin-related immunoreactive bands. The 54-kDa caltrin-precursor protein and the 6.2-kDa active caltrin were absent. Trypsin inhibitory activity of the seminal secretion was reduced about 50% in castrated animals. Daily testosterone administration restored both the protein pattern and immunoreactivity of the seminal vesicle secretion, and, as expected, reversed the morphological alterations of the gland after 7 days of treatment. Trypsin--inhibitor effect of the secretion also returned to normal levels after fourteen days of testosterone administration. Data suggest that the synthesis and secretion of caltrin are testosterone-dependent processes.