Comptes rendus des seances de l'Academie des sciences. Serie D, Sciences naturelles
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C. R. Acad. Sci., D, Sci. Nat. · Sep 1980
[Depression by morphine of various descending inhibitory controls modulating the transmission of nociceptive information at the spinal level in the rat].
Recording from convergent neurones--i. e. those responding to both non-noxious and noxious cutaneous stimuli--in the dorsal horn of the intact anaesthetized Rat, two distinct effects are seen after application of noxious stimuli: there is an activation of units of the segmental pool, along with a very powerful inhibition of the remaining neuronal population (diffuse noxious inhibitory controls, DNIC). Morphine at doses inadequate to directly depress the activity of these units specifically blocks the inhibition. Since DNIC is dependent upon supraspinal mechanisms, these observations show that morphine is capable of depressing certain descending inhibitory controls, at least when these are induced by noxious peripheral stimuli.
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C. R. Acad. Sci., D, Sci. Nat. · Jan 1980
[Role of serotonin in the diffuse inhibitory controls induced by nociceptive stimulation].
In the anaesthetized Rat, the entire population of dorsal horn convergent neurones is differentially affected by a noxious stimulus: while exciting the segmental pool, it strongly inhibits the remaining population. The inhibitory effects, which involve supraspinal mechanisms, are reduced to a great extent in parachlorophenylalanine pretreated animals. The role of raphé-spinal serotonergic pathways in nociception is discussed.