Compartmentalization of lysosomal enzymes in cauda epididymis of normal and castrated rats

The mammalian epididymis is an organ particularly rich in acid hydrolases, consistent with a developed lysosomal apparatus. However, some of these enzymes could also play a role in an extracellular environment, since they are actively secreted by the epithelium. In this study the authors measured the activity of five acid hydrolases distributed between the epithelium, fluid, small vesicles, and spermatozoa of the rat cauda epididymis in adult rats, and compared with that distribution under conditions of deprivation of luminal testosterone and testicular compounds (hemicastration). Lysosomal enzymes are differently compartmentalized in rat cauda epididymis. Most of beta-galactosidase (beta-GAL) and aryl sulfatase (approximately 70%) were found in soluble form within the fluid. Some 60% of N-acetyl-beta-D-glucosaminidase (beta-NAG) and alpha-mannosidase (alpha-MAN) become transiently bound to sperm, and beta-glucuronidase (beta-GLU) was mostly concentrated in the epithelium. After remotion of testis this distribution changed, as the retention of alpha-MAN, beta-GAL, beta-GLU, and beta-NAG by the epididiymal tissue increased. The increase of beta-GLU followed an increase of synthesis of the enzyme. The distribution of enzymes in the epididymis from the contralateral side was similar to that in normal rats. The different roles for each enzyme in the epididymis are discussed.