Restoration of acetylcholinesterase activity by Euphorbia hirta in discrete brain regions of chronically stressed rats.

Several drugs of herbal origin are known to possess anxiolytic and antidepressant effects. In a recent study, we showed that extracts from Euphorbia hirta L. (Euphorbiaceae) (Eh) demonstrated anxiolytic effects in rats subjected to chronic immobilization stress (CIS) but not in rats that underwent forced swim stress (FSS). Acetylcholine and the cholinergic system are known to be involved in anxiety. However, whether the cholinergic system is involved in the anxiolytic actions of Eh are not known. In the current study, we evaluated the effects of Eh treatment of rats subjected to either CIS or FSS on acetylcholinesterase (AChE) activity in the frontal cortex, hippocampus, and septum. CIS increased the AChE activity in all three regions, while Eh treatment restored it to normal levels. FSS increased the AChE activity only in the septum, and Eh treatment marginally restored this to normal levels. Thus, these results indicate the involvement of the cholinergic system in the behavioral effects of Euphorbia hirta.