[Selective sensitivity of synaptosomal cyclases to glutamic acid].

Electron cytochemical studies have been made of the effect of various concentrations of the glutamic acid on localisation of adenylate and guanylate cyclases in synaptosomes from the brain cortex of rats. It was found that the glutamic acid (10(-3) M) stimulates the activity of intrasynaptosomal adenylate cyclase, but does not affect postsynaptic pool of the enzyme. The effect of glutamate on guanylate cyclase results in the increase of the frequency of the reaction both in synaptosomal and postsynaptic membranes. It is suggested that in the conduction of glutamate signal, guanylate cyclase--cGMP, but not adenylate cyclase--cAMP, system may be involved, although activation of intrasynaptosomal adenylate cyclase indicates its participation in presynaptic processes.