Testicular Damage Associated with Zinc Deficiency in Pre- and Postpubertal Rats: Response to Zinc Repletion

These studies concern histological changes in the testes of pre- and postpubertal zinc-deficient and repleted rats. Three experiments in volved a total of 69 rats. In experiment 1, 12 weanling rats were fed a zinc-deficient (0.5 ppm) diet, ad libitum; 11 were fed a zinc-sufficient (100 ppm) diet and pair-fed to the zinc-deficient group; and 10 were fed the zinc-sufficient diet, ad libitum. After 26 days of being fed the different diets, one testis with the epididymis was surgically removed (hemicastrated) from each animal for histological examination. The rats fed the zinc-deficient diet were then fed the zinc-sufficient diet, ad libitum, for 30 or 41 days. Pair-feeding between the zinc-sufficient group and the zinc-deficient-repleted group was continued. The results indicated that 26 days of zinc depletion caused general immaturity of the testis and varied degrees of degeneration of the germinal epithelium compared to controls. After the zinc repletion period of 30 or 41 days, the remaining testis, epididymis, and sperm count were normal in all previously deficient animals. In experiment 2, 10 weanling rats were fed a marginally zinc-deficient diet (4 ppm) for 90 days and after hemicastration showed degenerative changes in the testes. All animals were then fed a zinc-sufficient (100 ppm) diet, with two animals killed every 15 days during a period of 75 additional days. The degenerative changes were not completely reversed during the 75-day repletion period, and only 4 out of 10 testes showed definite improvement. In experiment 3, 26 weanling rats were fed a zinc-adequate diet (15 ppm) for 42 days at which time 3 were killed to assure adequacy of the diet for maintenance of the testes and to confirm sexual maturity. When 12 of these postpubertal animals were fed the deficient diet for up to 68 days, a wide range of testicular damage occurred. Forty-two days of zinc repletion of the remaining 11 postpubertal rats, did not reverse the damage. In toto, the experiments suggest that a prepubertal short-term zinc deficiency resulted in degenerative changes that were repaired by repletion. In contrast, the degenerative changes of the testes of postpubertal zinc-deficient rats were not reversible to any significant extent. pre-pubertal zinc deficiency post-pubertal zinc deficiency testicular damage and repair