The activity of pancreatic enzymes on different stages of metabolism in broiler chicks

The pancreas is one of the most important digestive organs releasing the enzymes which hydrolyze all main nutrients to monomers capable of absorption into blood and lymph. The production of hydrolytic enzymes within the cells of digestive glands is submitted to general principles of protein synthesis, and the mechanisms involved have been studied in detail (R.M. Case, 1998). It is not a case, however, for urgent transportation of these enzymes by specialized secretory cells (glandulocytes), a recretory process including the absorption of endogenous secrets from blood stream by glandulocytes with subsequent release of the immutable forms of these secrets within digestive juices. Exocrine secrets of digestive glands, therefore, contain two enzymatic pools: those synthesized de novo and recreted. Classic secretive physiology is focused on the first pool while second is often underestimated (G.F. Korot'ko, 2013). Analysis of enteropancreatic circulation of pancreatic enzymes (S.S. Rotman et al., 2002) supported the conclusion that under certain conditions only 25-50 % of total circulating pancreatic enzymes are synthesized de novo by the pancreas. Output of digestive enzymes into blood stream depends on the pancreas secretion. In this context the circulation of pancreatic enzymes in human and animals recently has drawn an attention, since these enzymes perform not only digestive but also regulatory function (R. Ramachandran et al., 2008; G.F. Korot'ko, 2011; R. Gružauskas et al., 2015). In the article the experimental data on the activities of pancreatic enzymes in pancreatic juice, duodenal chymus, blood serum, and feces in broiler chicks (Cobb 500, n = 6) are presented. The chicks were operated to collect the pancreatic juice according to unique poultry fistulation method (Ts.Zh. Batoev and S.Ts. Batoeva, 1970) allowing the sampling of pancreatic juice during the trial and redirection of the juice into the intestine thereafter without any detrimental effect on health and welfare of poultry. Blood pancreatic enzyme activity and activity in litter were also assayed. The post-feeding secretive dynamics of pancreatic juice and enzymes is presented. The results of our physiological investigation showed that complex-reflex regulatory phase of pancreatic secretion continues during 120 min after feeding with the subsequent transition to neuro-humoral phase (mediated by secretion of hormones secretin and cholecystokinine into the blood stream) when chymus reaches the intestine. Analysis of duodenal chymus showed for intestinal enzymatic activities a pattern similar to the dynamics in pancreatic juice although fluctuations in duodenal activities of amylase, lipase and proteases were less distinct. Our results recirculation into showed that the pancreatic enzyme pool in the body is mostly due to synthesis de novo. The pancreatic enzymes involved in intestinal digestion then mostly undergo the blood stream, only minor part of activated enzymes being excreted with feces. The enzymes enter the blood stream unevenly: for duodenum, the blood lipase activity is the least, blood amylase activity is intermediate and blood protease activity is high. The closest amylase/protease ratio in pancreatic juice and blood serum was determined; this parameter could be used in diagnostics of physiological condition of the pancreas in chicken.