[Comparison of the effects of analgesia-producing peripheral and central stimulations in cats. Effect of nalorphine (author's transl)].

The effects of weak intensity percutaneous peripheral stimulations (SPPc) on the transmission of nociceptive messages induced by stimulation of the dental pulp have been studied on anaesthetized cats. 1. The jaw opening reflex (ROG) and the evoked potentials in the thalamic center median (CM), by stimulation of the dental pulp, disappear after a mean of 30 min after the start of SPPc. 2. These effects are analogous to those obtained by stimulation of the periaqueductal gray matter (St.GC) or by I.V. morphine injection. 3. The I.V. injection of the morphine antagonist (Nalorphine) blocks both the effects of the SPPc and those of the St.GC. 4. The authors put forth the hypothesis of a common mechanism of action of the SPPc and the St.GC which, through the liberation of endogenous morphinomimetic substances, would activate descending inhibitor impulses.