Significant Changes in the Activity of L-glutamic Acid Decarboxylase of Mouse Hypothalamus After Peripheral Injection of Cholecystokinin-8 and Caerulein.

The activity of one of the metabolizing enzymes of ɣ- aminobutyric acid, (GABA), was determined in mouse hypothalamus after peripheral injections of cholecystokinin-8 (CCK-8) and caerulein (CLN). The activity of this rate-limiting enzyme, L-glutamic acid decarboxylase, (GAD), did not change thirty minutes after peripheral injections of either CCK-8 or CLN in doses of 50g/kg body weight. However, the activity of GAD started to increase 24 hours after injection and continued to increase by 15 to 17%, five days after injections. Based on the in vitro models, it has been shown that there are no direct interactions between CCK-8 and CLN and the enzyme GAD. These data probably support indirect but specific interactions between CCK-8, CLN and the enzyme GAD.