title: Differential depressive action of two mu and delta opioid ligands on neuronal responses to noxious stimuli in the thalamic ventrobasal complex of rat.
abstract: In the present investigation the effects of selective agonists for mu (Tyr-D-Ala-Me-Phe-Gly-ol (DAGO)) and delta (Tyr-D-Thr-Gly-Phe-Leu-Thr (DTLET)) opioid receptors on neuronal activities induced by noxious cutaneous stimuli in the rat ventrobasal (VB) thalamus were analyzed. The two agonists produced a clear depressive action on thermal as well as mechanical noxious stimuli. The depressive action of DTLET (3 mg/kg i.v.) was lower and of shorter duration than that of DAGO (2 mg/kg i.v.). However, this effect is unambiguously related to the selective stimulation of opioid receptors since a consistent effect was also observed for a dose as low as 1.5 mg/kg i.v. of DTLET. Moreover, DTLET effect needs a high concentration of naloxone (0.5 mg/kg i.v.) to be reversed, while DAGO effect is totally reversed with 0.1 mg/kg i.v.
mesh_terms: D000200:Action Potentials; D000818:Animals; D004594:Electrophysiology; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D004745:Enkephalins / Q000494:pharmacology*; D006358:Hot Temperature; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009474:Neurons / Q000503:physiopathology; D009842:Oligopeptides / Q000494:pharmacology*; D010146:Pain / Q000503:physiopathology*; D010812:Physical Stimulation; D051381:Rats; D011919:Rats, Inbred Strains; D011957:Receptors, Opioid / Q000187:drug effects*; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D013788:Thalamus / Q000187:drug effects* / Q000503:physiopathology
chemical_list: D004745:Enkephalins; D009842:Oligopeptides; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009270:Naloxone; C037653:deltakephalin