[Analgesia following electrostimulation of midbrain nuclei of rats with a pain syndrome of spinal origin].

The effect of electrostimulation of the mesencephalic grey matter and of the dorsal nucleus raphe on physiological pain produced by nociceptive stimulation (compression of the tail or the skin on the limb by a clamp) and on pathological pain (the pain syndrome of spinal origin) were studied in experiments on albino rats. Pathological pain was induced by creating a generator of pathologically enhanced excitation in the dorsal horn of the spinal cord by local disturbance of the inhibitory mechanisms with the aid of tetanus toxin. It was shown that electrostimulation of the indicated areas abolished both physiological and pathological pain. A conclusion was drawn that analgesia produced by electrostimulation of certain structure of the brain was connected not only with augmentation of the descending inhibition in the spinal cord as in the case of physiological pain caused by peripheral nociceptive stimulation (as shown by several authors), but also with the block of excitation at the supraspinal level. This mechanism should play a decisive role in analgesia realization in the pain syndrome of central origin, both under experimental and natural conditions.