A CONVULSANT, 3-MERCAPTOPROPIONIC ACID, DECREASES THE LEVEL OF GABA AND GAD IN RAT PANCREATIC-ISLETS AND BRAIN

To investigate the properties of the gamma-aminobutyric acid (GABA) sy nthesizing enzyme, glutamate decarboxylase (GAD), in the brain and the pancreatic islets of the rat, GABA concentration in the brain and the pancreatic islets was measured after intraperitoneal administration o f 3-mercaptopropionic acid (3-MP) at 25 mg/kg. 60 min after the admini stration of 3-MP, GABA concentration in the hypothalamus, the superior colliculus and the hippocampus of the brain decreased by 20-30% and i n the pancreatic islets by 35%. The concentration in the pancreatic ac ini did not change. Western blotting showed that GAD activity in the p ancreatic of 3-MP compared to the control. The activity of GAD in the pancreatic islets as well as brain can be modified by a convulsant, in this case 3-MP. These results suggest the properties of GAD may be si milar in the pancreatic islets and brain.