Stereospecific modulation of GABA(A) receptor function by urocanic acid isomers.
Eur J Pharmacol
; 400(1): 11-7, 2000 Jul 14.
Article
em En
| MEDLINE
| ID: mdl-10913580
ABSTRACT
A deamination product of histidine, urocanic acid, accumulates in the skin of mammals as trans-urocanic acid. Ultraviolet (UV) irradition converts it to the cis-isomer that is an important mediator in UV-induced immunosuppression. We have recently shown that urocanic acid interferes with the agonist binding to GABA(A) receptors. We now report that the effects of urocanic acid on binding of a convulsant ligand (t-butylbicyclo[35S]phosphorothionate) to GABA(A) receptors in brain membrane homogenates are dependent on pH of the incubation medium, the agonistic actions being enhanced at the normal pH of the skin (5.5). Using Xenopus laevis oocytes expressing recombinant rat alpha1beta1gamma2S GABA(A) receptors, the low pH potentiated the direct agonistic action of trans-urocanic acid under two-electrode voltage-clamp, whereas cis-urocanic acid retained its low efficacy both at pH 5.5 and 7.4. The results thus indicate clear differences between urocanic acid isomers in functional activity at one putative receptor site of immunosuppression, the GABA(A) receptor, the presence of which in the skin remains to be demonstrated.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Ácido Urocânico
/
Receptores de GABA-A
/
Moduladores GABAérgicos
Limite:
Animals
Idioma:
En
Revista:
Eur J Pharmacol
Ano de publicação:
2000
Tipo de documento:
Article
País de afiliação:
Finlândia