ABSTRACT
The effect of three members of benzodiazepines [diazepam, bromazepam and clonazepam] and two antiepileptic drugs [sodium valproate and phenytoin] on the content of acetyl choline [ACh] in the whole rat's brain and its different areas has been investigated. A.Ch. was determined by the toad's rectus abdominis muscle bioassay [Richter and Crossland, 1949]. The five drugs given either in acute schedule for 24 hours or as short term medication for five days, produced very highly significant increase in A.Ch. content both in whole rat's brain and its different areas. The increase of A.Ch. in whole rat's brain was [+ 114% and +89%] by diazepam, [+ 129% and + 100%] by bromazepam, [+ 50% and +24%] by phenytoin, [+ 17% and +24%] by sodium valproate and [+ 2% and +31%] by clonazepam for 24 hours and five days respectively. The effect of diazepam and bromazepam was more profound than sodium valproate and phenytoin in thalamus and hypothalamus and hind brain; [+ 275% and +509%] and [+ 93% and +129%] and [+ 100% and +139%] by bromazepam. In contrast, the effect of phenytoin and sodium valproate was more pronounced than the benzodiazepine members in the cerebral cortex and midbrain; [+ 160% and +115%], [+ 100% and + 111%] and [+ 80% and +157%] by sodium valproate