Effects of dietary imbalances on spermatogenesis in CD-1 mice and CD rats.

Nutritional toxicology is now a well established discipline for somatic cells, but no such approach is widely used yet in studies of reproductive toxicology. Reduced dietary intake in mice is known to impair spermatogenesis, and animals in toxicity studies frequently show reduced food intake after dosing. Furthermore, although many human groups have nutritionally inadequate diets, the impact of dietary imbalances on the reproductive system has not been systematically examined. A series of experiments was conducted to dissect the spermatogenic response to dietary alterations in mice and rats. It was found that in mice, the increase in abnormal sperm after such treatment was the result of a lack of calories, while the decrease in sperm counts may have been caused by a lack of protein. In rats, dietary restriction was found only to deplete sperm numbers, probably because of a lack of calories and/or non-energetic components of the diet. Additionally, it was shown that a protein-free diet causes a multiplicity of effects on germ cells, some of which are different in mice and rats. A low-fat diet had an adverse effect on sperm numbers and a similar, but much more pronounced effect was observed in both species fed a carbohydrate-free diet. These alterations of spermatogenic endpoints and the species differences observed, have considerable implications for reproductive toxicology.