Extracellular taurine in the substantia nigra: taurine-glutamate interaction.
Taurine has been proposed as an inhibitory transmitter in the substantia nigra (SN), but the mechanisms involved in its release and uptake remain practically unexplored. We studied the extracellular pool of taurine in the rat's SN by using microdialysis methods, paying particular attention to the taurine-glutamate (GLU) interaction. Extracellular taurine increased after cell depolarization with high-K(+) in a Ca(2+)-dependent manner, being modified by the local perfusion of GLU, GLU receptor agonists, and zinc. Nigral administration of taurine increased the extracellular concentration of gamma-aminobutyric acid (GABA) and GLU, the transmitters of the two main inputs of the SN. The modification of the glial metabolism with fluocitrate and L-methionine sulfoximine also changed the extracellular concentration of taurine. The complex regulation of the extracellular pool of taurine, its interaction with GABA and GLU, and the involvement of glial cells in its regulation suggest a volume transmission role for taurine in the SN.
García Dopico
José
J
Unidad de Investigación del Hospital Universitario de Canarias, La Laguna, Tenerife, Canary Islands, Spain.
Perdomo Díaz
Juan
J
Alonso
Teofilo Jorge
TJ
González Hernández
Tomás
T
Castro Fuentes
Rafael
R
Rodríguez Díaz
Manuel
M
D018663:Adrenergic Agents / Q000633:toxicity; D000818:Animals; D001224:Aspartic Acid / Q000032:analysis; D001923:Brain Chemistry; D002118:Calcium / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004533:Egtazic Acid / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000633:toxicity; D005110:Extracellular Space / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D007608:Kainic Acid / Q000032:analysis; D007649:Ketamine / Q000633:toxicity; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D017551:Microdialysis / Q000379:methods; D016202:N-Methylaspartate / Q000032:analysis / Q000494:pharmacology; D016627:Oxidopamine / Q000633:toxicity; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013378:Substantia Nigra / Q000187:drug effects / Q000378:metabolism*; D013654:Taurine / Q000378:metabolism*; D013997:Time Factors; D015032:Zinc / Q000494:pharmacology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000032:analysis / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018663:Adrenergic Agents; D002614:Chelating Agents; D018691:Excitatory Amino Acid Antagonists; D013654:Taurine; D001224:Aspartic Acid; D018698:Glutamic Acid; D004533:Egtazic Acid; D005680:gamma-Aminobutyric Acid; D016202:N-Methylaspartate; D007649:Ketamine; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid; D016627:Oxidopamine; D015032:Zinc; D011188:Potassium; D007608:Kainic Acid; D002118:Calcium