Lab Anim Res.  2013 Mar;29(1):19-26.

Age-associated changes in pancreatic exocrine secretion of the isolated perfused rat pancreas

• Jiang ZE
• Jiang C
• Chen B
• Koh CS
• Yong JH
• Park DH
• Won MH
• Lee YL

Abstract

Gut functions, such as gastrointestinal motility, gastric secretion and pancreatic secretion, were reduced with age. Glucose tolerance is impaired, and the release of insulin and beta-cell's sensitivity on glucose are reduced with age. However, a lot of controversial data have been reported as insulin concentrations after glucose ingestion are either higher or no different in elderly and young subjects. Thus, this study was aimed to investigate whether aging could affect pancreatic exocrine secretion and its action mechanisms. An isolated perfused rat pancreatic model was used to exclude the effects of external nerves or hormones. Pancreatic secretion was increased by CCK under 5.6 mM glucose background in the isolated perfused pancreas of young (3 months), 12 months and 18 months aged rats. There was no significant difference between young and aged rats. In 3 months old rats, CCK-stimulated pancreatic secretion was potentiated under 18 mM glucose background. However, the potentiation effects of endogenous insulin and CCK were not observed in 12 and 18 months old rats. Exogenous insulin also potentiated CCK-stimulated pancreatic secretion in 3 months old rats. Similarly, exogenous insulin failed to potentiate CCK-stimulated pancreatic secretion as that of 3 months old rats. Wet weight of pancreas and amylase content in pancreatic tissue were not changed with age. These results indicate that pancreatic exocrine secretion is reduced with age and endogenous insulin secretion and/or action is involved in this phenomenon.

Keyword

Aging; glucose; insulin; cholecystokinin; exocrine secretion

MeSH Terms

Aged
Aging
Amylases
Animals
Cholecystokinin
Eating
Gastrointestinal Motility
Glucose
Humans
Insulin
Pancreas
Rats
Amylases
Cholecystokinin
Glucose
Insulin

Figure

• 

  Figure 1 Effect of cholecystokinin (CCK; 5 pmol) in pancreatic volume flow of the isolated rat pancreas under 5.6 mM glucose (G) background. Each point (○; 3 months old rats (M), ■; 12 months old rats (M), ♦; 18 months old rats (M) and bar (□; 3M, ■; 12M, ▨; 18M) represent the mean±S.E of 6 experiments. Cumulative volume flow was calculated from the sum of CCK effect minus basal secretion for 60 min. ND; no significant difference.

• 

  Figure 2 Effect of cholecystokinin (CCK; 5 pmol) in pancreatic amylase output of the isolated rat pancreas under 5.6 mM glucose (G) background. Each point (○; 3 months old rats (M), ■; 12 months old rats (M), ♦; 18 months old rats (M) and bar (□; 3M, ■; 12M, ▨; 18M) represent the mean±S.E of 6 experiments. Cumulative amlylase output was calculated from the sum of CCK effect minus basal secretion for 60 min. ND; no significant difference.

• 

  Figure 3 Effect of cholecystokinin (CCK; 5 pmol) in pancreatic volume flow of the isolated rat pancreas under 18 mM glucose (G) background. Each point (○; 3 months old rats (M), ■; 12 months old rats (M), ♦; 18 months old rats (M) and bar (□; 3M, ■; 12M, ▨; 18M) represent the mean±S.E of 6 experiments. Cumulative volume flow was calculated from the sum of CCK effect minus basal secretion for 60 min *; The value is significantly (P<0.05) different from that of 3 months old rats. ND ; no significant difference.

• 

  Figure 4 Effect of cholecystokinin (CCK; 5 pmol) in pancreatic amylase output of the isolated rat pancreas under 18 mM glucose (G) background. Each point (○; 3 months old rats (M), ■; 12 months old rats (M), ♦; 18 months old rats (M) and bar (□; 3M, ■; 12M, ▨; 18M) represent the mean±S.E of 6 experiments. Cumulative volume flow was calculated from the sum of CCK effect minus basal secretion for 60. min. *; The value is significantly (P<0.05) different from that of 3 months old rats. ND ; no significant difference.

• 

  Figure 5 Effect of endogenous and exogenous insulin on cholecystokinin (CCK)-stimulated pancreatic volume flow and amylase output in the isolated rat pancreas. Each bar (□; 3 months old rats (M), ■; 12 months old rats (M), ▨; 18 months old rats (M)) represents the mean±S.E. of 5 experiments. *; The value is significantly (P<0.05) different from CCK-stimulated pancreatic volume flow and amylase output under 18 mM glucose (G) and exogenous insulin (INS) background of 3 months old rats. +; The value is significantly (P<0.05) different from CCK-stimulated pancreatic volume flow and amylase output under 18 mM glucose (G) and exogenous insulin (INS) background in each 3 months old pancreata.

• 

  Figure 6 Amylase activity in pancreatic tissue. Each bar (□; 3 months old rats (M), ■; 12 months old rats (M), ▨; 18 months old rats (M)) represents the mean±S.E. of 5-6 experiments. ND : no significant difference.

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