Effects of some anticonvulsant drugs on brain GABA level and GAD and GABA-T activities.
The effect of anticonvulsant drugs was examined on brain GABA levels and GAD and GABA-T activities. The level of GABA was increased by the treatment with diphenylhydantoin. The drug had no effect on GABA-T activity, whereas GAD activity was inhibited. Carbamazepine increased the GABA level but did not effect GAD and GABA-T activities. Diazepam had no effect on GABA level and GAD activity, whereas it caused a slight inhibition of GABA-T activity. Phenobarbital administration decreased GABA level only at the higher concentration. Clonazepam effected only GAD activity. Some anticonvulsant drugs generally increase brain GABA level; however the lack of correlation with an effect on the GAD and GABA-T activities indicate that other factors than metabolism, such as membrane transport processes, are involved in the mechanism of action of anticonvulsant drugs.
D000612:4-Aminobutyrate Transaminase / Q000037:antagonists & inhibitors*; D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology*; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002220:Carbamazepine / Q000494:pharmacology; D002998:Clonazepam / Q000494:pharmacology; D003975:Diazepam / Q000494:pharmacology; D008297:Male; D051379:Mice; D010088:Oxidoreductases / Q000037:antagonists & inhibitors*; D010634:Phenobarbital / Q000494:pharmacology; D010672:Phenytoin / Q000494:pharmacology; D014635:Valproic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D000927:Anticonvulsants; D002220:Carbamazepine; D005680:gamma-Aminobutyric Acid; D002998:Clonazepam; D014635:Valproic Acid; D010672:Phenytoin; C036322:GABA dehydrogenase; D010088:Oxidoreductases; D000612:4-Aminobutyrate Transaminase; D003975:Diazepam; C004651:dipropylacetamide; D010634:Phenobarbital