Effects of dietary manganese deficiency on rat pancreatic amylase mRNA levels.

Manganese deficiency is associated with increased pancreatic amylase activity in rats. The present study investigated whether this increase in amylase activity is associated with increased pancreatic amylase messenger RNA (mRNA) levels. Weanling rats were fed a high carbohydrate diet containing either 40 micrograms Mn/g (control) or 0.5 microgram Mn/g (deficient) for 4 to 8 wk. Mn deficiency was confirmed by determining hepatic Mn content, which was significantly lower in Mn-deficient rats than in controls. Pancreatic RNA from both groups of rats was hybridized with 32P-labeled complementary DNAs for amylase and trypsinogen. Amylase mRNA levels were increased in rats fed Mn-deficient diets for both 4 wk (200%) and 8 wk (250%) when compared with respective control levels. In contrast, Mn deficiency was not associated with alterations in trypsinogen mRNA levels. Serum levels of insulin and corticosterone, hormones known to increase pancreatic amylase mRNA, were not affected by Mn deficiency. These observations suggest that Mn may participate in the regulation of amylase gene expression in a manner that is independent of insulin and corticosterone.