Stimulation of synaptosomal D-[(3)H]aspartate transport by substance P in rat brain.
The effect of the neuropeptide, substance P, on the transport of D-[(3)H]aspartate into rat striatal synaptosomes was studied. Almost 90% of the total transport of D-[(3)H]aspartate was sodium-dependent and the maximum rate (V(max)) of this transport was increased by 34% of control by 2.5 nM substance P (EC(50)=0.52 nM). In contrast, sodium-independent transport was inhibited by substance P. The NK(1) antagonist, L706303 (500 nM) blocked the stimulation of D-[(3)H]aspartate transport by 2.5 nM substance P, but did not alter D-aspartate uptake in the absence of substance P. These results indicate that high affinity glutamate transporters in the brain may be under positive regulation by substance P, and suggest a previously-unidentified mechanism of control of glutamate transport.
Department of Biochemistry, University College Dublin, Belfield, 4, Dublin, Ireland.
J
J
Healy
A
A
Downes
G J
GJ
McBean
D018528:ATP-Binding Cassette Transporters / Q000187:drug effects* / Q000378:metabolism; D027322:Amino Acid Transport System X-AG; D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001921:Brain / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D018698:Glutamic Acid / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013373:Substance P / Q000378:metabolism / Q000494:pharmacology*; D013574:Synaptosomes / Q000187:drug effects* / Q000378:metabolism*; D014316:Tritium
D018528:ATP-Binding Cassette Transporters; D027322:Amino Acid Transport System X-AG; D014316:Tritium; D001224:Aspartic Acid; D013373:Substance P; D018698:Glutamic Acid