Interactions of gamma-L-glutamyltaurine with excitatory aminoacidergic neurotransmission.
The in vitro effects of gamma-L-glutamyltaurine on different stages of excitatory aminoacidergic neurotransmission were tested with gamma-D-glutamyltaurine as reference. gamma-L-Glutamyltaurine enhanced the K(+)-stimulated release of [3H]glutamate from cerebral cortical slices (25% at 0.1 mM) and slightly inhibited the uptake by crude brain synaptosomal preparations (about 10% at 1 mM). gamma-L-Glutamyltaurine was also a weak displacer of glutamate and its agonists from their binding sites in brain synaptic membrane preparations, being, however, less selective to quisqualate (QA) sites than gamma-D-glutamyltaurine. The basal influx of Ca2+ into cultured cerebellar granular cells was not affected by 1 mM gamma-L-glutamyltaurine, but the glutamate- and its agonist-activated influx was significantly inhibited in low-Mg2+ (0.1 mM) and Mg(2+)-free media. The glutamate-evoked increase in free intracellular Ca2+ and the kainate-activated formation of cGMP in cerebellar slices were both markedly inhibited by 0.1 mM gamma-L-glutamyltaurine. We propose that gamma-L-glutamyltaurine may act as endogenous modulator in excitatory aminoacidergic neurotransmission.
Varga
V
V
Department of Biomedical Sciences, University of Tampere, Finland.
Janáky
R
R
Marnela
K M
KM
Saransaari
P
P
Oja
S S
SS
D000375:Aging / Q000378:metabolism; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D005973:Glutamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017470:Receptors, Glutamate / Q000187:drug effects / Q000378:metabolism*; D013237:Stereoisomerism; D009435:Synaptic Transmission / Q000187:drug effects*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*; D013654:Taurine / Q000031:analogs & derivatives* / Q000494:pharmacology
D005971:Glutamates; D017470:Receptors, Glutamate; D005973:Glutamine; D013654:Taurine; D001224:Aspartic Acid; D018698:Glutamic Acid; C020903:glutaurine; D006152:Cyclic GMP; D011188:Potassium; D007608:Kainic Acid; D002118:Calcium