Histochemical Observations of Oxidative Enzymes in Irradiated Testis and Epididymis

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Abstract
The histochemical distribution of oxidative enzyme systems was observed in testes and epididymides of mice that had received a single whole-body irradiation or a single local irradiation with X-rays or gamma-rays. The enzymatic activities of succinic, [alpha]-glycerophosphate, and glucose-6-phosphate dehydrogenases in the germinal epithelia showed a progressive decrease postirradiation, particularly after whole-body exposure. Irradiated testes and epididymides exhibited the histochemical changes associated with morphological damages irrespective of the kind of radiation used. In the degenerated seminiferous tubules of the testes, succinic dehydrogenase activity in immature cells such as spermatogonia conspicuously decreased after whole-body X-irradiation. [alpha]-Glycerophosphate dehydrogenase activity of spermia in the shrunken testicular tubules and epididymal canals was low, with some variation during a few days after whole-body irradiation. Glucose-6-phosphate dehydrogenase was absent in all testicular cells on the first day, but it remained normal in interstitial Leydig cells of the degenerating testes. The histochemical dehydrogenase activities examined showed a more rapid and marked decrease after whole-body exposure than those obtained after local exposure. In tissues gamma-irradiated by local exposure, the maximal decrease in the enzyme activities which occurred about the sixteenth day was followed by a recovery toward the end of the experiment, especially in glucose-6-phosphate dehydrogenase activity. The significance of these alterations suggests that testicular oxidative metabolism generally decreases after irradiation, but the specific nature of these changes and their causes still remain unclear.