[The effect of metabotropic glutamate receptors on longitude of posttetanic reaction in spinal motoneurons of frog].

Effects of metabotropic glutamate receptors of the duration of posttetanic changes in monosynaptic excitatory postsynaptic potentials (mEPSP), evoked by afferent and reticulospinal input stimulation, were investigated in lumbar motoneurons of the frog isolated spinal cord. It was found that application of MAP4 (25 microM), a selective antagonist of group III of these receptors, prolonged posttetanic potentiation and depression of synaptic transmission, whereas activation of this group of metabotropic glutamate receptors by L-AP4 (1 mM), a selective agonist of these receptors, suppressed the amplitude of synaptic responses, but did not affect the dynamics of development of posttetanic changes. The NMDA receptor antagonist AP5 (50 microM), added to the perfusing solution, blocked completely the effects produced by MAP4.

[The potentiation of postsynaptic potentials under the influence of glutamate and agonists in the motoneurons of the frog Rana ridibunda].

Effects of glutamate and agonists (aspartate, NMDA, quisqualate, AMPA, kainate) on dorsal root and reticulomotoneuronal excitatory postsynaptic potentials (EPSPs), as well as on spontaneous postsynaptic potentials (PSP), were studied in the motoneurons of isolated frog spinal cord. Depolarizing responses were evoked by glutamate or agonists bath application. Amplitude of the response decreased in conditions of TTX-block or replacement of Ca2+ by Mn2+, Mg2+ or Co2+ in perfusing solution.