Activity and androgenic control of glycolytic enzymes in the epididymis and epididymal spermatozoa of the rat

Abstract

1. Procedures were developed for the extraction and assay of glycolytic enzymes from the epididymis and epididymal spermatozoa of the rat. 2. The epididymis was separated into four segments for analysis. When rendered free of spermatozoa by efferent duct ligation, regional differences in enzyme activity were apparent. Phosphofructokinase, glycerol phosphate dehydrogenase and glucose 6-phosphate dehydrogenase were more active in the proximal regions of the epididymis, whereas hexokinase, lactate dehydrogenase and phosphorylase were more active in the distal segment. These enzymes were less active in the epididymis of castrated animals and less difference was apparent between the proximal and distal segments. However, the corpus epididymidis from castrated rats had lower activities of almost all enzymes compared with other epididymal segments. 3. Spermatozoa required sonication to obtain satisfactory enzyme release. Glycolytic enzymes were more active in spermatozoa than in epididymal tissue, being more than 10 times as active in the case of hexokinase, phosphoglycerate kinase and phosphoglycerate mutase. 4. The specific activities of a number of enzymes in the epididymis were dependent on the androgen status of the animal. These included hexokinase, phosphofructokinase, aldolase, glyceraldehyde phosphate dehydrogenase, phosphoglycerate kinase, pyruvate kinase, glycerol phosphate dehydrogenase, glucose 6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and phosphorylase. 5. The caput and cauda epididymidis differed in the extent to which enzyme activities changed in response to an altered androgen status. The most notable examples were hexokinase, phosphofructokinase, aldolase, phosphoglycerate kinase, 6-phosphogluconate dehydrogenase and phosphorylase.

Effects of castration on specific glycoprotein secretions of the epididymis in the rabbit and hamster

“…These observations suggest that there is a rapid cessation of macromolecule production and secretion, a conclusion supported by evidence from long-term studies showing that protein synthesis, and other metabolic processes in the epididymis, are much reduced after castration but can be restored by androgen replacement therapy (Allen & Slater, 1958;Martan, 1969;Hamilton, Jones & Fawcett, 1969;Brooks, 1976).…”

Investigation by luminal perfusion of the transfer of compounds into the epididymis of the anaesthetized rat

“…This could be a source of energy for spermatozoa in situ, which have been shown to utilize glucose in vitro (Geer, Kelly, Pohlman & Yemm, 1975;Brooks, 1976 …”

Luminal secretion of myo-inositol by the rat epididymis perfused in vitro

“…In other studies there was also no synthesis of inositol from glucose (Eisenberg & Bolden, 1964) Robinson & Fritz (1979) exceeds the activity of phosphoglucose isomerase 12-fold (Brooks, 1976a), using the epididymal protein content given by Brooks (1976b), so loss of tritium from the Ci-position of glucose 6-phosphate during glycolysis (Hammerstedt, 1975) should be minimal, although the conflicting reports on the activity of the relevant enzymes in rat epididymal tissue (Robinson & Fritz, 1979;Maeda & Eisenberg, 1980;Hasegawa & Eisenberg, 1981) need clarification and bear directly on the results of this study. The observations may also relate to the presence of endogenous pools of metabolites which were not equilibrated during the experiments, although work on tissue slices indicates that intracellular glucose is very low in glucose-containing medium (Brooks, 1979).…”

“…This precursor may also arise from epididymal glycogen, which can spare the utilization of glucose in tissue slices and provide lactate in the absence of glucose (Brooks, 1978). In support of this, the total activity of phosphorylase exceeds that of hexokinase (Brooks, 1976a), and intracellular glycogen is lost after castration (Cavazos, 1958) when inositol secretion is reduced (Pholpramool, White & Setchell, 1982). On the other hand, the conversion of inositol to phosphatidylinositol by caudal tissue and epithelium from the vas deferens in vitro (Voglmayr, 1974) reveals phospholipid as a possible alternative store of inositol.…”