The effects of dietary protein deficiency on rat testicular function.

Diets containing 0%, 5% and 10% protein were used for treatment periods of 30, 50, and 90 days respectively. Control rats were fed a diet containing 20% protein. Protein deficient rats failed to gain weight during the experiment. In addition, the weights of the testis, epididymis, prostate and seminal vesicle also decreased, with the 10% group less affected than the 0% and 5% groups. Testicular histology indicated retarded germ cell maturation in the 0% and 5% groups only. Overall testicular cell number and size were reduced in treated rats and there was a reduction in the diameter of the seminiferous tubule in these groups. Epididymal epithelial height was also reduced in protein deficient rats with a concomitant increase in the number of epididymal duct cross sections devoid of sperm. Protein deficiency caused significant reductions in testicular DNA, RNA and protein content. The proportion of motile epididymal sperm decreased in the 0% and 5% groups by 90% and 35% respectively. Epididymal sperm number decreased in both the 0% and 5% groups by 90% while the proportion of abnormal sperm increased by 65% and 61% respectively. Circulating androgen levels were also lowered by more than 50% on average in protein deficient animals.