Excitatory sulphur amino acid-evoked neurotransmitter release from rat brain synaptosome fractions.
The neuroactive sulphur-containing amino acids L-cysteate (CA), L-cysteine sulphinate (CSA), L-homocysteine sulphinate (HSA), S-sulpho-L-cysteine (SC) and L-homocysteate (HCA) evoked the release of previously accumulated D-[3H]aspartate from rat brain cerebrocortical and cerebellar synaptosome fractions in a manner that was wholly Ca2+-independent. However, analysis of endogenous release by hplc revealed the presence of both Ca2+-dependent and -independent component of L-glutamate release but only a Ca2+-independent component of L-aspartate release. CA, CSA, HSA and SC but not HCA evoked the release of previously accumulated [3H]GABA from synaptosome fractions by a mechanism shown to comprise both a Ca2+-dependent and -independent component. The specific antagonists of the N-methyl-D-aspartate (NMDA) receptor, 3-[(+/-)-2-carboxypiperazin-4-yl]propyl-l-phosphonic acid (CPP) and the relatively selective competitive quisqualate (QUIS)/kainate (KA) receptor antagonist, 6-cyano-7-dinitroquinoxalinedione (CNQX), were ineffective in blocking the excitatory sulphur amino acid-evoked release of either D-[3H]aspartate, [3H]GABA or of endogenous established transmitter amino acids.
Dunlop
J
J
Department of Biochemistry and Microbiology, University of St. Andrews, Scotland, U.K.
Mason
H
H
Grieve
A
A
Griffiths
R
R
D000596:Amino Acids / Q000378:metabolism* / Q000502:physiology; D000603:Amino Acids, Sulfur / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D018377:Neurotransmitter Agents / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013574:Synaptosomes / Q000187:drug effects / Q000378:metabolism*
D000596:Amino Acids; D000603:Amino Acids, Sulfur; D018377:Neurotransmitter Agents; D017459:Receptors, Amino Acid; D011956:Receptors, Cell Surface