Participação dos receptores dos terminais aferentes primários no efeito antinociceptivo da acupuntura na dor inflamatória aguda e neuropática

Abstract

Pain is characterized by a resultant response from the central integration of peripheral nerve impulses triggered by local stimuli. The nociception is the transductional of mechanical thermal and chemical stimuli into electrical impulses via nociceptors. Such impulses are conducted through primary afferents, C-δ and A, which detect noxious stimuli and express the TRPV1 receptor. Acupuncture is an effective pain treatment that brings therapeutic benefits as analgesia. Because of this, the present study aims to investigate the role of different receptors of nociceptive afferent A-δ and C fibers, in the conduction of stimuli produced by acupuncture in control of the process of acute and neuropathic inflammatory hyperalgesia by action of histamine, bradykinin, substance P, glutamate, serotonin, and acetylcholine. Mice were evaluated by digital vonFrey test. After induction of inflammatory hyperalgesia by i.pl CFA administration or neuropathic hyperalgesia (CCI Chronic Constriction of the sciatic nerve), it was administered 20μL of either glutamate or histamine or bradykinin or serotonin or substance P or acetylcholine in the right hind leg at acupoint E36. After application of the CFA i.pl, the dose of 0,03μg dose was effective to ACh. For bradykinin and histamine, the dose of 30 μg was obtained. For serotonin and glutamate, 3μg, 0,3μg and 0,03μg were effective and substance P, 0,03μg was effective. After the CCI 0,3μg and 3μg acetylcholine altered the hyperalgesic effect, and glutamate, bradykinin, histamine, serotonin and substance P. In addition, all doses were effective in accordance with their respective times. The results supports the hypothesis that these mediators are involved in the effect of acupuncture in manual models of inflammatory and neuropathic pain.