Effect of maternal zinc deficiency or food restriction on rat fetal pancreas. I. Procarboxypeptidase A and chymotrypsinogen.

Maternal zinc deficiency lowered the protein, zinc and zymogen content of the day 19 rat fetal pancreas. Pregnant Sprague-Dawley rats were fed a zinc-deficient diet (0.4 +/- 0.1 ppm zinc) and libitum or a zinc-supplemented control diet (100 ppm zinc) either ad libitum or with restricted intake. At day 19 of pregnancy, the pancreata from zinc-deficient fetuses contained 50% less zinc and 15% less cellular protein than did fetal pancreas from normal or restricted intake controls, although DNA content was normal. Zymogen granulation of pancreatic acinar cells from zinc-deficient fetuses was decreased. The two major proteolytic zymogens of the rat fetal pancreas--procarboxypeptidase A, a zinc metalloprotein, and chymotrypsinogen--were each 30% lower per cell in zinc-deficient fetuses than in controls. Zinc-deficient fetuses taken from large litters of seven or more young per litter had lower levels of procarboxypeptidase A and chymotrypsinogen in the pancreata than did fetuses taken from smaller litters. The results suggest that exocrine zymogen accumulation is lower than normal in the pancreata of zinc-deficient fetuses, irrespective of the zinc dependency of the enzyme proteins involved.