Intestinal Fat Suppresses Protein-Induced Exocrine Pancreatic Secretion in Chronically Bile-Pancreatic Juice-Diverted Rats

Abstract

Previously, we showed that the increase in pancreatic enzyme secretion was lower after feeding a casein diet containing fat than that after feeding a fat-free casein diet in chronically bile-pancreatic juice (BPJ)-diverted rats. In the present study, we determined whether the suppressive effects of fats on flow volume of BPJ and pancreatic enzyme secretion depend on delaying gastric emptying and examined the characteristics of the suppression with intraduodenal instillation of soybean oil or lecithin in BPJ-diverted rats. The study was conducted as three separate experiments using conscious rats with chronic BPJ diversion by means of a common bile-pancreatic duct catheter. The flow volume of BPJ and the secretion of pancreatic amylase and trypsin were determined after intraduodenal instillation of the test solution. Exocrine pancreatic secretion was strongly stimulated by administration of guanidinated casein hydrolysate (HGC, 150 mg/ml) in chronic BPJ-diverted rats. However, pancreatic secretion after administration of an emulsion containing HGC with either soybean oil (100 mg/ml) or mixed fat (50 mg/ml soybean oil + 50 mg/ml lecithin) was much lower than that after administration of HGC alone. In contrast, administration of the soybean oil emulsion without HGC resulted in a small, but significant increase in the volume of BPJ. The suppressive effects of soybean oil (100 mg/ml) on the increases in the BPJ flow and enzyme secretion were similar to those of sodium taurocholate (10 mg/ml), and there was no additive effect of soybean oil on taurocholate suppression. In conclusion, duodenally instilled soybean oil suppressed increases in flow volume of BPJ and pancreatic enzyme secretion induced by HGC in chronic BPJ-diverted rats, showing that the suppressive effect of the fat does not depend on delaying gastric emptying.

Sucrose fatty acid esters suppress pancreatic secretion accompanied by peptide YY release in pancreatico‐biliary diverted rats

“…We also found that the sucrose esters stimulate release of PYY, which is known to inhibit pancreatic exocrine secretion. Although we previously reported that dietary fats (corn oil and soybean oil) suppress protein‐induced pancreatic secretion in PBD rats (Hara et al 1994, 2000), it had not been clarified whether the fat (triglyceride) itself or fatty acids and monoacylglycerol released by fat digestion in the ileal lumen triggered the inhibitory mechanism. To address this issue, we used sucrose fatty acid esters, from which free fatty acids are not liberated in the intestinal lumen because these compounds are resistant to digestive enzymes.…”

“…After a 24 h fast, cannulae were implanted into the common bile–pancreatic duct, duodenum and upper ileum under pentobarbitone anaesthesia (sodium pentobarbitone, 40 mg (kg body weight) −1 i.p. ; Abbott Co., North Chicago, IL, USA), as previously described (Hira et al 1997; Hara et al 2000). Briefly, the small tip (7–8 mm) of a polyethylene catheter (SP 28; i.d.…”

“…Fatty acids released from triacylglycerol in the upper small intestine are responsible for the promotive effect of fat, and the action of the fatty acids mainly depends on cholecystokinin (CCK) secretion from the upper small intestine (Guimbaud et al 1997; McLaughlin et al 1999). In contrast, we previously showed that duodenal instillation of fat suppressed protein‐induced increases of exocrine pancreatic secretion in pancreatico‐biliary diverted (PBD) rats, but not in normal rats (Hara et al 1994, 2000). In PBD rats, dietary fats are not digested in the proximal intestine because bile–pancreatic juice (BPJ) is diverted to the distal intestine where the fats are rapidly digested owing to the presence of pancreatic enzymes.…”