Effects of pyroglutamic acid on corticostriatal glutamatergic transmission.
The effects of L-pyroglutamic acid, a molecule structurally derived from L-glutamic acid (Glu), were measured on the high affinity of uptake of glutamic acid from striatal synaptosomes of the rat and on the binding of [L-3H]glutamic acid to striatal membranes. The results showed a competitive inhibition of the high affinity transport of glutamic acid by L-pyroglutamic acid in vitro with no effect on the uptake of gamma-aminobutyric acid (GABA). An inhibition of the binding of [L-3H]glutamic acid to striatal membranes was also detected. Significant high affinity uptake of [L-3H]pyroglutamic acid was evident in synaptosomes from the striatum. A regional distribution study of the uptake processes for [L-3H]glutamic acid and [L-3H]pyroglutamic acid in different areas of the brain showed a similar distribution, suggesting that an uptake of [L-3H]pyroglutamic acid, although weak, occurs in glutamatergic nerve terminals. This proposal was further reinforced by measuring the effects of a large cortical lesion involving frontal and parietal areas on the uptake of [L-3H]glutamic acid and [L-3H]pyroglutamic acid in synaptosomes from the striatum. The results showed a large decrease in the uptake processes of both labelled molecules showing that the uptake of [L-3H]pyroglutamic acid, as for glutamic acid mainly occurred in corticostriatal nerve terminals, although other uptake sites are not excluded.
D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D003342:Corpus Striatum / Q000502:physiology*; D005971:Glutamates / Q000502:physiology*; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D011760:Pyrrolidinones / Q000494:pharmacology*; D011761:Pyrrolidonecarboxylic Acid / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D009435:Synaptic Transmission / Q000187:drug effects*; D013574:Synaptosomes / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000502:physiology
D005971:Glutamates; D011760:Pyrrolidinones; D005680:gamma-Aminobutyric Acid; D011761:Pyrrolidonecarboxylic Acid