title: Spinal N-methyl-D-aspartate receptors may mediate the analgesic effects of emulsified halogenated anesthetics.
abstract: The present study was designed to investigate the relationship between spinal cord N-methyl-D-aspartate (NMDA) receptors and the analgesic effects of emulsified halogenated anesthetics. After having established the mouse model of analgesia by intraperitoneally or subcutaneously injecting appropriate doses of emulsified enflurane, isoflurane or sevoflurane, we intrathecally injected different doses of NMDA and then observed the effects on the pain threshold using the hot-plate test and the acetic acid-induced writhing test. The results showed that intrathecal injection of NMDA (2.5, 5 and 10 ng) did not affect the pain threshold on the hot-plate test or the writhing times in conscious mice (p > 0.05); in contrast, NMDA (2.5, 5 and 10 ng intrathecally) can significantly and dose dependently decrease the pain threshold on the hot-plate test (p < 0.05 or p < 0.01) and increase the writhing times (p < 0.05 or p < 0.01) in the mice treated with emulsified anesthetics. These results suggest that spinal NMDA receptors may be important targets for the analgesic effects of emulsified enflurane, isoflurane and sevoflurane.
authors.affiliation: Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical College and Jiangsu Province Institute of Anesthesiology, Xuzhou, PR China.
authors.forename: Li-Hua
authors.initials: LH
authors.lastname: Hang
authors.forename: Ti-Jun
authors.initials: TJ
authors.lastname: Dai
authors.forename: Yin-Ming
authors.initials: YM
authors.lastname: Zeng
mesh_terms: D000700:Analgesics / Q000008:administration & dosage / Q000494:pharmacology*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004655:Emulsions; D004737:Enflurane / Q000008:administration & dosage / Q000494:pharmacology; D018690:Excitatory Amino Acid Agonists / Q000008:administration & dosage / Q000494:pharmacology; D005260:Female; D007278:Injections, Spinal; D007530:Isoflurane / Q000008:administration & dosage / Q000494:pharmacology; D008738:Methyl Ethers / Q000008:administration & dosage / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D016202:N-Methylaspartate / Q000008:administration & dosage / Q000494:pharmacology; D009619:Nociceptors / Q000187:drug effects; D010147:Pain Measurement / Q000187:drug effects / Q000379:methods; D017288:Pain Threshold / Q000187:drug effects; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists / Q000502:physiology*; D000077149:Sevoflurane; D013116:Spinal Cord / Q000187:drug effects / Q000378:metabolism
chemical_list: D000700:Analgesics; D018685:Anesthetics, Inhalation; D004655:Emulsions; D018690:Excitatory Amino Acid Agonists; D008738:Methyl Ethers; D016194:Receptors, N-Methyl-D-Aspartate; D000077149:Sevoflurane; D016202:N-Methylaspartate; D004737:Enflurane; D007530:Isoflurane