Effects of Light Deprivation upon the Spermatogenic and Steroidogenic Elements of Hamster Testes

Abstract

The effects of light deprivation (LD) on the spermatogenic and steroidogenic elements of the testis were examined after hamsters were deprived of light for 0, 12, 22 or 42 days. The approach consisted of determining some of the principal biochemical constituents of the testis, examining the metabolism of radioactive glucose, lysine and acetate by the testis in vitro, and measuring circulating levels of testosterone. The results indicate that exposure to constant darkness significantly reduces (p <0.01) the weight of the testes, seminal vesicles and ventral prostate glands. The number of sperm, spermatids and late spermatocytes decreased with increasing periods of LD, but the concentration of protein, DNA and RNA in the testes were not altered (p>0.20) despite a 6-fold reduction in testis weight. The incorporation of lysine-U-¹⁴C into trichloroacetic acid precipitable material was greater (p<0.01) in atrophied than in control testes, whereas the capacity of testes to catabolize glucose via anaerobic and aerobic pathways decreased markedly (p<0.01) with increasing intervals of LD. The in vitro synthesis of testosterone-¹⁴C from acetate-l-¹⁴C and the concentration of testosterone in peripheral plasma of LD hamsters was significantly lower (p <0.01) than in control animals maintained on a standard 14–10 photoperiod. The results suggest that LD interferes with the synthesis and secretion of testosterone by the steroidogenic elements of the testis and that this in turn could be one of the major factors contributing to the striking alterations noted in the morphology and the in vitro metabolism of the spermatogenic elements of the testis after LD. (Endocrinology89: 791, 1971)