Depolarization-evoked release of glutamate, aspartate and gamma-aminobutyric acid from rat dorsal spinal cord slices does not originate from capsaicin-sensitive neurons.
A release of endogenous glutamate (Glu), aspartate (Asp) and gamma-aminobutyric acid (GABA) from rat dorsal spinal cord slices was evoked by a 60 mM K(+)-depolarization (calcium dependent) and by 50 microM veratridine (tetrodotoxin sensitive) indicating a neuronal exocytosis mechanism. No release of the 3 amino acids investigated was obtained with the selective C-fiber excitant capsaicin (1 microM) and after impairment of afferent C-fibers the amount of amino acids released by K(+)-depolarization or veratridine was not reduced. These results suggest that amino acids may be exclusively transmitters of capsaicin-insensitive nerve structures in the rat dorsal spinal cord.
Department of Experimental and Clinical Pharmacology, University of Graz, Austria.
J
J
Donnerer
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism*; D002211:Capsaicin / Q000494:pharmacology*; D005971:Glutamates / Q000378:metabolism*; D018698:Glutamic Acid; D007150:Immunohistochemistry; D009467:Neuromuscular Depolarizing Agents / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology; D014701:Veratridine / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D005971:Glutamates; D009467:Neuromuscular Depolarizing Agents; D001224:Aspartic Acid; D018698:Glutamic Acid; D013779:Tetrodotoxin; D005680:gamma-Aminobutyric Acid; D014701:Veratridine; D011188:Potassium; D002211:Capsaicin