L-glutamate activates peripheral nociceptors.
The chemosensitivity of nociceptive afferents has been investigated using the isolated spinal-cord-tail preparation of the neonatal rat. L-glutamate applied to exposed rat tail skin stimulated nociceptive reflexes (ED50 = 136 microM). The action of L-glutamate was selective, since other constitutive L-amino acids or D-glutamate were inactive at a concentration of 10 mM. The known algogens bradykinin, acetylcholine, serotonin and potassium ions also stimulated nociceptive reflexes. Histamine (1 mM) and substance P (0.1 mM) had no observable effect. L-glutamate, which is released from macrophages, could therefore contribute to inflammation-related nociception by stimulation of cutaneous nociceptive nerve endings.
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Department of Neurosciences, Sterling Winthrop Pharmaceuticals Research Division, Rensselaer, NY 12144.
Hildebrand
L M
LM
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D001920:Bradykinin / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology; D005971:Glutamates / Q000494:pharmacology*; D018698:Glutamic Acid; D009046:Motor Neurons / Q000187:drug effects* / Q000502:physiology; D009475:Neurons, Afferent / Q000187:drug effects*; D009619:Nociceptors / Q000187:drug effects* / Q000502:physiology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology; D013116:Spinal Cord / Q000187:drug effects; D013623:Tail
D005971:Glutamates; D012701:Serotonin; D018698:Glutamic Acid; D000109:Acetylcholine; D011188:Potassium; D002211:Capsaicin; D001920:Bradykinin