Hormonal and cholinergic influences on pancreatic lysosomal and digestive enzymes in rats

Hormonal and cholinergic influences on lysosomal and digestive enzyme activities in pancreatic tissue were studied in normal adult rats. Hormonal stimulation by the cholecystokinin analogue, caerulein, induced a marked enhancement of the activities of cathepsin D and N-acetyl-beta-D-glucosaminidase in pancreatic tissue, whereas the activities of amylase and lipase tended to decrease. Acid phosphatase activity was not affected. Further, caerulein was found to induce a significant increase of cathepsin D output in bile-pancreatic juice. This output largely parallelled that of amylase. Cholinergic stimulation by the muscarinic agonist carbachol, at a dose level giving the same output of amylase as caerulein, did not affect pancreatic activities of cathepsin D and N-acetyl-beta-D-glucosaminidase. Further, cholinergic stimulation induced an increase of amylase activity and a slight decrease of acid phosphatase activity in pancreatic tissue. Lipase activity was not affected. No apparent effect on cathepsin D output in bile-pancreatic juice was encountered after cholinergic stimulation. The activities of neither the digestive nor the lysosomal enzymes were influenced by the administration of secretin. The results suggest a possible lysosomal involvement in caerulein-induced secretion and/or inactivation of pancreatic digestive enzymes, whereas cholinergic stimulation seems to act through different mechanisms.