[Viscerosomatic convergence on the lumbar interneurons of the dorsal horn of the spinal cord in cats and rats].

Abstract

It is shown in experiments on spinalized cats under electrical stimulation of the pelvic nerve branch innervating the rectum as well as of the fibular nerve that 12 of 30 studied neurons to which the effect of these sources was converged were activated both by A- and by C-fibers. Reactions on stimulation of the fibular nerve were, apparently, mediated by the fibers with the conduction velocity not less than 2.2 m/sec. It is detected in experiments on spinalized rats that tension of the lower sections of the large intestine may evoke activation of neurons of the IV-V layers and inhibition of cells from the deeper layers. The inhibition evoked by the visceral stimulation in seven cases from 18 was provided by the effect directly on the postsynaptic membrane of these cells, in 11 cases it was localized in presynaptic (relative to them) structures. Naloxone, strychnine and atropine did not eliminate this inhibition which testifies against possible participation of opioids, glycines and acetylcholine in its creation. phaclofen, a blocker of the GABAB-receptors was also uneffective while bicuculline suppressed this inhibition in three cases from 12 which testifies to a probability of its participation in creation of GABAA-receptors.