Pancreatic exocrine secretion and plasma concentration of some gastrointestinal hormones in response to abomasal infusion of starch hydrolyzate and/or casein1

Abstract

Eight Angus steers (290 +/- 8 kg), surgically prepared with pancreatic pouch-duodenal reentrant cannulas and abomasal infusion catheters were used in a replicated 4 x 4 Latin square experiment to investigate the effects of abomasal infusion of starch hydrolyzate (SH) and/or casein on pancreatic exocrine secretion and plasma concentration of hormones. Steers were fed a basal diet of alfalfa (1.2 x NEm) in 12 equal portions daily. Abomasal infusion treatments (6-L total volume infused per day) were water (control), SH [2.7 g/(kg BW x d)], casein [0.6 g/(kg BW x d)], and SH + casein. Periods were 3 d for adaptation and 8 d of full infusion. Pancreatic juice and jugular blood samples were collected over 30-min intervals for 6 h on d 11. Weight and pH of pancreatic samples were measured, and a 10% subsample was composited and frozen until analysis of total protein and pancreatic enzyme activities. The remaining sample was returned to the duodenum. Plasma was harvested and frozen until analyzed. Pancreatic juice (67 mL/h) and protein (1.8 g/h) secretion rates were not affected by nutrient infusion. There were SH x casein interactions for all pancreatic enzyme secretions (U/h; alpha-amylase, P < 0.03; trypsin, P < 0.08; and chymotrypsin, P < 0.03) and plasma insulin concentration (P < 0.10). Secretion of pancreatic enzymes was increased by SH (trypsin) and casein (alpha-amylase, trypsin, and chymotrypsin) but not when SH + casein were infused together. Glucose (P < 0.10) and cholecystokinin octapeptide concentrations (CCK-8; P < 0.05) were increased by SH, but glucagon was decreased (P < 0.10). Casein decreased (P < 0.10) plasma CCK-8 concentrations. These data indicate that positive effects of postruminal casein on enzyme secretion were inhibited by SH, emphasizing the complexity of the regulatory mechanisms involved in dietary adaptation of pancreatic exocrine secretion. Changes in hormone concentration may not relate directly to changes in enzyme secretion.

Effect of Oral Administration of Intact Casein on Gastrointestinal Hormone Secretion and Pancreatic α-Amylase Activity in Korean Native Steer

“…The CCK secretion in response to fatty acids and proteins increases pancreatic protease levels and activity in the small intestine of rats (Hara et al, 2000). Further, there are many reports on the connection between increased blood plasma CCK in response to protein injection into the small intestine and regulation of secretion in the exocrine gland of the pancreas (Tachibana et al, 1995; Swanson et al, 2004). Therefore, our results demonstrated that an increase in duodenal CCK and secretin levels upon oral administration of IC increased pancreatic α-amylase secretion.…”

Regulation of pancreatic exocrine secretion in goats: differential effects of short‐ and long‐term duodenal phenylalanine treatment

“…Therefore, it is hypothesized that phenylalanine may also regulate PES by stimulating CCK secretion in ruminants. However, previous reports have shown that luminal protein decreases α‐amylase secretion in non‐ruminants (Brannon, 1990) and increases α‐amylase secretion in ruminants (Richards et al., 2003; Swanson et al., 2004), which indicates that regulation of nutrient factors on PES may have species differences. Therefore, it can be speculated that phenylalanine has different effects on PES in ruminants from that in non‐ruminants.…”

Pancreatic mass, cellularity, and α-amylase and trypsin activity in feedlot steers fed diets with increasing corn silage inclusion

“…Responses to dietary or post-ruminal infusion treatment has been variable and inconsistent. Although the total content of pancreatic trypsin activity has been shown to increase with plane of nutrition (Wang et al 1998) and dietary CP concentration (Swanson et al 2008a), neither post-ruminal casein infusion (Richards et al 2003;Swanson et al 2004), post-ruminal partially hydrolyzed starch infusion (Swanson et al 2004), or different dietary protein sources (Khorasani et al 1990) have been observed to influence pancreatic secretion of trypsin activity. In the current experiment, although there were linear decreases in the concentration and content of trypsin activity with increasing corn silage inclusion, there were also significant cubic effects.…”

“…Although the total pancreatic content of active trypsin has been reported to increase with plane of nutrition (Wang et al 1998) or dietary crude protein (CP) concentration (Swanson et al 2008a), neither postruminal casein infusion (Richards et al 2003;Swanson et al 2004), post-ruminal partially hydrolyzed starch infusion (Swanson et al 2004) or different dietary protein sources (Khorasani et al 1990) have been observed to influence pancreatic secretion of active trypsin.…”

“…Pancreatic a-amylase and trypsin are responsible for the partial hydrolysis of starch and protein, respectively, in the small intestine. Pancreatic exocrine function is influenced by nutritional as well as genetic factors Swanson and Miller 2008). In high concentrate feedlot diets, significant amounts of dietary starch reach the small intestine (Theurer 1986) where there may be limitations in starch digestion due to inadequate a-amylase secretion Harmon et al 2004).…”