@article{6d84b267203b469d979cb457aaa0174f,
title = "Glutamate-induced analgesia: Blockade and potentiation by naloxone",
abstract = "Injection of 0.5 μl l-sodium glutamate (60 mM) into the periaqueductal gray matter of the rat resulted in a short-lived analgesia as assessed by the tail-flick method. Naloxone (1 mg/kg) attenuated glutamate-induced analgesia when injected 30 min but not 5 min before testing. Paradoxically, a higher dose of naloxone (10 mg/kg) significantly potentiated glutamate analgesia when injected 5 min but not 30 min before testing. Moreover, this higher dose also potentiated analgesia when injected 5 min prior to 12 mM glutamate, a dose of glutamate previously found to be ineffective in causing analgesia. Microinjections of either 60 mM or 1 M KCl failed to elicit analgesia, indicating the specificity of the glutamate effect. Taken together with several other lines of evidence, the present findings suggest that glutamate-induced analgesia may be mediated by processes quite different from those underlying morphine analgesia. It is further suggested that a dose-related naloxone antagonism is not a necessary criterion for assessing endogenous opioid activity.",
keywords = "analgesia, glutamate, naloxone, periaqueductal gray matter",
author = "Gideon Urca and Nahin, {Richard L.} and Liebeskind, {John C.}",
note = "Funding Information: We wish to thank Dr. Y. Sarne for his valuable suggestions concerning this manuscript. The naloxone used was a gift from Endo Laboratories (Garden City, N.Y.). This research was supported by N.I.H. Grant NS 07628.",
year = "1980",
month = jun,
day = "23",
doi = "10.1016/0006-8993(80)90902-6",
language = "אנגלית",
volume = "192",
pages = "523--530",
journal = "Brain Research",
issn = "0006-8993",
publisher = "Elsevier B.V.",
number = "2",
}