Pancreatic Response of Anaesthetized and Conscious Rats to Bolus Injection of Cholecystokinin-Pancreozymin

Abstract

Pancreatic secretion was studied in anaesthetized rats tested immediately after surgery or in conscious rats tested 48 h after the cannulation of the pancreatic duct. Pancreatic flow, protein output and enzyme output were measured over a 30-min period in the unstimulated state and after the intravenous injection of bolus doses of cholecystokinin-pancreozymin (CCK-PZ) ranging from 1·25 to 20 Crick-Harper-Raper units (CHRU). Each animal received three doses of CCK-PZ, as either ascending or descending doses.In anaesthetized rats there was a linear relationship between the log-dose of CCK-PZ and the flow, protein and enzyme output with both the ascending and descending doses. In contrast, in conscious rats flow was unaffected by CCK-PZ, and protein output was greatest after the first dose, whether this was given in the ascending or descending doses. At all CCK-PZ levels flow in anaesthetized rats was less than that seen in conscious animals, but at doses of CCK-PZ above 5·00 CHRU protein output was greater in anaesthetized rats than in conscious rats.Ultrastructural studies of the pancreas showed areas of focal cytoplasmic degeneration and possible blockage of the duct with cellular debris after administration of high doses of CCK-PZ to conscious rats. These changes may be responsible for the reduced protein output with the second and third dose of CCK-PZ in these animals. No such changes were seen in anaesthetized rats after similar doses of CCK-PZ.These studies show fundamental differences in the response of the pancreas to CCK-PZ in anaesthetized .and conscious rats. The mechanism for this difference is not clear, but it may represent a change in the normal response to CCK-PZ in the anaesthetized rats as a result of the effects of acute operative trauma, possibly acting through changes in pancreatic blood flow.Additional keyword: autophagosome

Pancreatic Response to Bolus Injection of Cholecystokinin-pancreozymin in Anaesthetized and Conscious Rats Fed Raw Soyaflour

“…Rats were fed RSF for at least 1 month, by which time maximal pancreatic growth had occurred (Crass and Morgan 1982;Oates and Morgan 1982). The results with rats fed RSF were compared with the previously published data for animals fed stock cubes (Oates and Morgan 1981). The cubes used in these studies contained only traces of trypsin inhibitor (approximately 500 Ilg of trypsin inhibited per gram of cubes) and were stated by the manufacturer to consist of 52 % carbohydrate, 22 % protein and 5 % fat.…”

“…In particular, it might be predicted that the enlarged pancreas of anaesthetized rats would respond to CCK with an increased flow and protein output and that in the conscious animal the pancreas would tolerate higher doses of CCK before inhibition occurs. The present study, therefore, compares the pancreatic response of rats fed RSF to the same stimuli used previously, with that of animals fed cubes reported in Oates and Morgan (1981).…”

“…Details of the surgical procedure are given in Oates and Morgan (1981). Surgery involved the cannulation of the external jugular vein and pancreatic duct.…”

“…Animals fed cubes and RSF were studied concurrently and were housed under the same conditions. Rats fed cubes (Oates and Morgan 1981) or RSF (present study) were tested while either anaesthetized or conscious.…”

“…In a previous paper (Oates and Morgan 1981), pancreatic secretion was studied in rats fed a stock cube diet. Two experimental conditions were used: anaesthetized animals were studied immediately after surgery and conscious rats were tested 48 h after surgery.…”