Glutamate-glutamine cycle and aging in striatum of the awake rat: effects of a glutamate transporter blocker.
This study investigated the effects of aging on the actions of a specific glutamate reuptake blocker, L-trans-pyrrolidine-2, 4-dicarboxylic acid (PDC), in extracellular glutamate and glutamine in striatum of the awake rat. Microdialysis experiments were performed on young (2-3 months), middle-aged (12-14 months), aged (27-32 months) and very aged (37 months) male Wistar rats. Local infusion of PDC (1-4 mM) in striatum increased the dialysate concentration of glutamate and decreased dialysate concentration of glutamine in all the age-groups. In young rats, decreases of dialysate glutamine were correlated with increases of dialysate glutamate. The same profile glutamine/glutamate as in young rats was found in middle-aged, aged and very aged rats, which suggests that the action of glutamate on the glutamate-glutamine cycle in striatum of the awake rat is not modified as a consequence of aging. We also found a significant correlation between the increases of glutamate produced by PDC and the basal dialysate concentration of glutamine, a relationship that did show a significant change with age. Although the significance of this latter finding remains to be elucidated, it may be important to understand the changes in glutamate-glutamine cycle during aging.
Segovia
G
G
Department of Physiology, Faculty of Medicine, Universidad Complutense, Madrid, Spain.
Del Arco
A
A
Prieto
L
L
Mora
F
F
D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors*; D000375:Aging / Q000378:metabolism*; D027322:Amino Acid Transport System X-AG; D000818:Animals; D003342:Corpus Striatum / Q000378:metabolism*; D003998:Dicarboxylic Acids / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism*; D005973:Glutamine / Q000378:metabolism*; D008297:Male; D014179:Neurotransmitter Uptake Inhibitors / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar
D018528:ATP-Binding Cassette Transporters; D027322:Amino Acid Transport System X-AG; D003998:Dicarboxylic Acids; D014179:Neurotransmitter Uptake Inhibitors; D011759:Pyrrolidines; D005973:Glutamine; D018698:Glutamic Acid; C083486:pyrrolidine-2,4-dicarboxylic acid