[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. Excitatory amino acid antagonists (kynurenate, CNQX, APV, argiopine) also reduced depolarizing response amplitude. DR and RF EPSPs significantly increased in amplitude (and spontaneous PSP in amplitude and frequency) during depolarization, evoked by glutamate or agonists. The potentiation reached up to 300 %. Potentiation diminished with depolarization decay. Sometimes several minutes depression of EPSPs was observed after the depolarizing response. There was no potentiation of the spontaneous PSPs in conditions of TTX-block or replacement of Ca2+ by Mn2+ in perfusing solution. The data obtained suggest rather presynaptic, than postsynaptic mechanism of the potentiation. We found no depressant effect of glutamate or agonists on postsynaptic glutamate receptors, at least for 10 minutes contact. Effects of more prolonged applications and some changes of EPSP amplitude after depolarizing response appear to be associated with other types of glutamate receptors.
Kurchavyĭ
G G
GG
Kalinina
N I
NI
Mel'ian
Z E
ZE
Veselkin
N P
NP
D000818:Animals; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology*; D066298:In Vitro Techniques; D017774:Long-Term Potentiation / Q000187:drug effects* / Q000502:physiology; D008839:Microelectrodes; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology; D011895:Rana ridibunda / Q000502:physiology*; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors
D018690:Excitatory Amino Acid Agonists; D018691:Excitatory Amino Acid Antagonists; D018698:Glutamic Acid
Potentsiatsiia postsinapticheskikh potentsialov pod vliianiem glutamata i agonistov v motoneĭronakh liagushki Rana ridibunda.