EFFECT OF MARGINAL OR SEVERE DIETARY ZINC-DEFICIENCY ON TESTICULAR DEVELOPMENT AND FUNCTIONS OF THE RAT

The effects of marginal (MZD) and severe (SZD) zinc-deficient diets on testicular function and development were studied in rats maintained o n dietary treatment for 6 weeks after weaning. SZD produced variable d egrees of histological changes as compared with pair-fed controls, inc luding a significant decrease in the diameter of seminiferous tubules (p < .05) with variable degree of maturation arrest in different stage s of spermatogenesis. No significant histological changes were obtaine d in testes of MZD rats. MZD rats exhibited significant decreases in s erum levels of testosterone (62.6%, p < .001) and progesterone (18.2%, p < .05) with no changes in that of FSH or LH. SZD rats showed marked decreases in serum levels of testosterone (17.8-fold, p < .001) and p rogesterone (28.8%, p < .001), whereas FSH showed an increase (34.4%, p < .05) as compared with respective controls. In vitro acute stimulat ion by hCG on testicular tissue preparation obtained from MZD rats res ulted in much less androgen production (sum of androstenedione, testos terone, and androstanediol) (72.4%, p < .001) as compared with control s. Testicular androgen contents (sum of androstenedione, testosterone, and androstanediol) decreased significantly in MZD and SZD rats, with the latter showing the greatest decrease. SZD rats were asospermic, w hereas MZD rats exhibited marked decrease in sperm counts (by 22.9%, p < .05) as compared with respective controls. The results reflect a di rect action of zinc deficiency on testicular steroidogenesis and stron gly support the idea that hypogonadism of zinc deficiency results main ly from changes in testicular steroidogenesis or indirectly from Leydi g cell failure.