Effects of Cholecystokinin, Food Intake and Cephalic Stimuli on Plasma Levels of Amylase, Lipase, and Immunoreactive Cationic Trypsinogen in Rats

Abstract

Plasma levels of amylase, lipase, and immunoreactive cationic trypsinogen (ICT) were monitored in conscious rats to study the effects of cholecystokinin octapeptide (CCK-8) plus secretin administration, cephalic stimuli, and food intake. Stepwise increasing doses of CCK-8 (1, 5, 15, 30 Ivy dog units: IDU/kg/h) caused significant dose-related increases in plasma levels of each enzyme in a similar manner as those previously observed for response patterns of CCK-induced exocrine protein secretion in the same species. ICT showed the greatest response to CCK-8 with a maximal concentration 30 times above basal levels resulting in the steepest slope of the dose-response curve. Plasma lipase showed a maximal response that was 5 times above the basal level, while the plasma amylase level was increased only by 50% at the maximal response. Computed ED₅₀ of CCK-8 for each enzyme confirmed this relative sensitivity of the response: 3.0, 8.7, 11.0 IDU/kg/h for ICT, lipase, and amylase, respectively. Plasma levels of amylase and lipase did not change significantly in response to the intake of either a liquid diet or fiber pellets containing no caloric value. Plasma ICT levels, however, were elevated significantly by 23 and 53% at the time when the liquid diet or fiber pellets were given and when cephalic stimulation appeared maximally induced. The increased levels declined thereafter and were no longer significantly different from the basal levels for postprandial 2 h. These results indicate that the response patterns of plasma ICT, amylase, and lipase to CCK-8 appear to parallel that of exocrine protein secretion and that plasma ICT levels provide superior sensitivity over amylase and lipase determination as a plasma parameter for either pharmacological or physiological stimulation of the exocrine pancreas. Furthermore, cephalic stimuli have been shown to mediate the response to food intake.

Species- and Dose-Specific Pancreatic Responses and Progression in Single- and Repeat-Dose Studies with GI181771X

“…In healthy rats, the parotid gland contributes more amylase to the circulation than the pancreas, and this end point has limited utility in monitoring pancreatic injury in this species (Nagy et al 2001). Exposure to cerulein or CCK has been reported by others to cause transient increases in serum amylase and especially serum lipase activity consistent with the stimulation of pancreatic secretions (Tsukamoto et al 1986; Kruse, Lasson, and Hage 1999). Decreases in amylase activity were noted in both 7-day and 26-week studies but not in the 4-week study (i.e., only high-dose males with significant decrease in amylase activity); this may reflect reduction in exocrine pancreatic secretory activity.…”

Mouse intragastric infusion (iG) model

“…These include the roles of a segment within the normal food intake route in neuroendocrine mechanisms of cephalic, GI and metabolic responses to nutrient intake 1–7 . Mechanisms of inhibition of gastric emptying or postgastric satiety are studied by using iG or intraduodenal infusion of a liquid diet in mice that have been given receptor antagonists for intestinal or pancreatic endocrine peptides such as cholecystokinin or amylin 8,9 .…”

Serum feline trypsin-like immunoreactivity following administration of ceruletide to healthy cats

“…[8][9][10][11][12] Administration of secretin together with cholecystokinin octapeptide (CCK-8) or the synthetic CCK analogue ceruletide to healthy dogs led to an increase in serum TLI, 13,14 and a similar response was seen in healthy dogs given CCK-8 or ceruletide alone. 14,15 Administration of secretin in combination with CCK-8 caused a significant doserelated increase in serum TLI in rats, 16 and in rats with experimentally induced pancreatic fibrosis, the change in plasma immunoreactive cationic TLI in response to cerulein administration depended on the degree of fibrosis. 17 Thus, measuring the change in serum fTLI in response to administration of a pancreatic stimulant may be useful in diagnosing chronic pancreatitis in cats in which serum fTLI is not increased.…”