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Chapter 20 Electrophysiological evidence for the activation of descending inhibitory controls by nociceptive afferent pathways

1988; Elsevier BV; Linguagem: Inglês

10.1016/s0079-6123(08)62795-8

1875-7855

Daniel Le Bars, Luis Villanueva,

Acupuncture Treatment Research Studies

This chapter presents the electrophysiological evidence for the activation of descending inhibitory controls by nociceptive afferent pathways. The three routes of administration of morphine used for alleviating pain in man—systemic, intrathecal, intracerebroventricular (ICV)—can be correlated with a reduction of diffuse noxious inhibitory controls (DNIC). The two opposite manipulations, the activation of DNIC by counter irritation procedures and its blocking by morphine, lead in therapeutic terms to the same end point—that is, hypoalgesia. This anomaly reflects the complexity of the spinal systems and provides an insight into the role of the convergent neurons in the encoding of nociceptive and non-nociceptive sensory information. The existence within a neuronal population, of gradients of activity, at least for convergent cells in the rat, should be taken into consideration in pharmacological and biochemical studies concerning nociceptive transmission toward higher centers. The future trends of the research lie in determining the supraspinal circuitry that subserves DNIC.