Differential depressive action of two μ and δ opioid ligands on neuronal responses to noxious stimuli in the thalamic ventrobasal complex of rat |
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Authors: | J. M. Benoist V. Kayser G. Gacel J. M. Zajac M. Gautron B. Roques G. Guilbaud |
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Abstract: | In the present investigation the effects of selective agonists for μ (Tyr--Ala-Me-Phe-Gly-ol (DAGO)) and δ (Tyr--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. |
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Keywords: | Ventrobasal thalamus Rat Noxious stimulus Agonist specific opioid receptor |
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