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 cockroach. 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 phystostigmine (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 system.