Cholinergic activation of phosphoinositide metabolism during soman-induced seizures.

In the present study we investigated the role of the cholinergic pathway in phosphoinositide metabolism activation observed during soman-induced convulsions. We thus studied the effect of atropine sulphate, a muscarinic antagonist (20 mg kg-1, i.p.), on IP3 levels in rat hippocampus. We demonstrated that initially, the increase of IP3 is closely seizure-related. On the other hand, after 10 min of seizures, the IP3 enhancement and the seizure activity are no longer correlated. After 20 min of seizures, atropine failed to inhibit soman-induced IP3 enhancement, suggesting that the activation of another neurotransmitter system(s) linked to PPI turnover succeeds the cholinergic stimulation.