Effects of taurine on depolarization-evoked release of amino acids from rat cortical synaptosomes

• Published in: Brain research Vol. 627; no. 2; pp. 181 - 185
• Main Authors: Kamasaki, Yoshinori, Maeda, Kazuhisa, Ishimura, Masahiko, Omura, Hideshi, Itoh, Tadao
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 12.11.1993; Amsterdam Elsevier; New York, NY
• Subjects: Amino Acids - pharmacology; Animals; Aspartate; Aspartic Acid - metabolism; Basal Metabolism; Biological and medical sciences; Calcium - physiology; Central nervous system; Central neurotransmission. Neuromudulation. Pathways and receptors; Cerebral Cortex - drug effects; Cerebral Cortex - metabolism; Cerebral Cortex - ultrastructure; Fundamental and applied biological sciences. Psychology; GABA; GABA-A Receptor Antagonists; gamma-Aminobutyric Acid - metabolism; Glutamate; Glutamates - metabolism; Glutamic Acid; Male; Membrane Potentials - drug effects; Neurotransmitter Agents - metabolism; Potassium - pharmacology; Presynaptic receptor; Rat cortex; Rats; Rats, Wistar; Synaptosomes; Synaptosomes - drug effects; Synaptosomes - metabolism; Taurine; Taurine - pharmacology; Vertebrates: nervous system and sense organs; Taurine; Presynaptic receptor; GABA; Aspartate; Rat cortex; Synaptosomes; Glutamate; Cerebral cortex; Rat; Rodentia; Central nervous system; Depolarization; Vertebrata; Synaptosome; Mammalia; Neuromediator; Aminoacid; Release; Brain (vertebrata)
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/0006-8993(93)90318-H

Effects of taurine on endogenous aspartic acid (Asp), glutamic acid (Glu) and γ-aminobutyric acid (GABA) release has been investigated using synaptosomes prepared from rat cerebral cortex. Although basal release of these amino acids was not affected, taurine inhibited KCl (30 mM)-evoked overflow of Asp, Glu and GABA in a concentration-dependent manner with potencies (IC 50) of 1 μM, 0.8 μM and 5 nM, respectively. Taurine (10 μM) maximally inhibited K +-evoked Asp, Glu and GABA overflow by 28, 37 and 65%, respectively. Phaclofen (10 μM, a GABA B receptor antagonist), but not bicuculline (10 μM, a GABA A receptor antagonist), counteracted the inhibition of GABA overflow, although the inhibition of Asp and Glu overflow was not attenuated. These data suggest that taurine may inhibit GABA release through the activation of presynaptic GABA B autoreceptors and, at high concentration, also act on Asp- and Glu-nerve terminals to regulate release of excitatory amino acids in rat cortex.