Korean J Physiol Pharmacol.  2003 Jun;7(3):169-174.

Effects of gamma-Aminobutyric Acid on Intrinsic Cholinergic Action in Exocrine Secretion of Isolated, Perfused Rat Pancreas

Affiliations
  • 1Department of Physiology, College of Medicine and Ilsong Institute of Life Science, Hallym University, Chuncheon, Gangwon 200-702, Korea. hjpark@hallym.ac.kr
  • 2Department of Physiology, College of Medicine, Konyang University, Nonsan, Chungnam 320-711, Korea.

Abstract

gamma-Aminobutyric acid (GABA) has been reported to enhance exocrine secretion evoked not only by secretagogues but also by intrinsic neuronal excitation in the pancreas. The pancreas contains cholinergic neurons abundantly that exert a stimulatory role in exocrine secretion. This study was undertaken to examine effects of GABA on an action of cholinergic neurons in exocrine secretion of the pancreas. Intrinsic neurons were excited by electrical field stimulation (EFS; 15 V, 2 msec, 8 Hz, 45 min) in the isolated, perfused rat pancreas. Tetrodotoxin or atropine was used to block neuronal or cholinergic action. Acetylcholine was infused to mimic cholinergic excitation. GABA (30microM) and muscimol (10microM), given intra-arterially, did not change spontaneous secretion but enhanced cholecystokinin (CCK; 10 pM) -induced secretions of fluid and amylase. GABA (3, 10, 30microM) further elevated EFS-evoked secretions of fluid and amylase dose-dependently. GABA (10, 30, 100microM) also further increased acetylcholine (5microM) -induced secretions of fluid and amylase in a dose-dependent manner. Bicuculline (10microM) effectively blocked the enhancing effects of GABA (30microM) on the pancreatic secretions evoked by either EFS or CCK. Both atropine (2microM) and tetrodotoxin (1microM) markedly reduced the GABA (10microM) -enhanced EFS- or CCK-induced pancreatic secretions. The results indicate that GABA enhances intrinsic cholinergic neuronal action on exocrine secretion via the GABAA receptors in the rat pancreas.

Keyword

Acetylcholine; Cholecystokinin; Pancreatic intrinsic neuron; GABA receptor; Pancreatic exocrine secretion

MeSH Terms

Acetylcholine
Amylases
Animals
Atropine
Bicuculline
Cholecystokinin
Cholinergic Neurons
gamma-Aminobutyric Acid*
Muscimol
Neurons
Pancreas*
Rats*
Receptors, GABA
Tetrodotoxin
Acetylcholine
Amylases
Atropine
Bicuculline
Cholecystokinin
Muscimol
Receptors, GABA
Tetrodotoxin
gamma-Aminobutyric Acid
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