Effect of protein malnutrition on glycoprotein synthesis by testes of 20-day-old rats

The effects of protein malnutrition during the nursing period on glycoprotein biosynthesis by testes of 20-day-old rats was studied. Pregnant Wistar rats were housed individually. On the day of delivery they were divided into two groups: one was fed a control diet (25% casein) and the other a low-protein diet (8% casein) for a period of 20 days. Body and testis weights of pups suckled by the malnourished mothers were significantly lower than those of the pups suckled by normally-fed mothers. The seminiferous tubules o malnourished rats showed a significant decrease in diameter and in the stage of development of spermatogenesis. Whole testes of normally-fed 20-day-old rats showed significantly greater [2-3H]mannose incorporation into glycoproteins than did the testes of malnourished rats of the same age. The microsomes of normally-fed rats showed significantly higher GDP: mannose polyprenyl mannosyl transferase activity than did microsomes from malnourished rats, and this difference increased when exogenous dolichyl-phosphate was added to the incubation medium. These results indicate that protein malnutrition decreases GDP: mannose polyprenyl mannosyl transferase activity in the microsomes of testes from 20-day-old rats.