Effects of methylglyoxal on central and peripheral cholinergic responses

Methylglyoxal (MG) has been shown to have a depolarizing effect on the giant interneurones of the isolated 6th abdominal ganglion of the cock-roach. This effect of MG was inhibited by concentrations of nicotine, d-tubocurarine and physostigmine which blocked transmission at the cholinergic cercal nerve-giant interneurone synapse. MG (5 X 10(-5) to 5 X 10(-4) M) produced concentration-dependent contractures of the isolated frog rectus abdominis muscle which were inhibited by d-tubocurarine (10(-4) M) and physostigmine (10(-6) M). MG enhanced the action of acetylcholine and inhibited KCl-evoked contractures whereas it had no effect on the response to carbachol. It is concluded that MG appears to act as a cholinomimetic in both the peripheral and central nervous systems.