| Abstract: | Repetitive stimulation of the locus coeruleus (up to 150 µA in strength) was accompanied by marked weakening of the inhibitory action of flexor reflex afferents and of the reciprocal inhibitory action on extensor motoneurons. Meanwhile stimulation of this sort had no significant effect on direct inhibition of flexor and extensor motoneurons, on the facilitatory action of flexor reflex afferents and the reciprocal inhibitory action on flexor motoneurons and also on dorsal root potentials. Intravenously injected pyrogallol had a similar action, but its effect was much weaker after spinalization of the animals or blocking of spinal cord conduction by cold. Enhancement of the monosynaptic reflex, which also was observed after injection of pyrogallol, was characterized by different temporal parameters; the intensity of this effect was unaffected both by spinalization and by cold block. These data, and also the results of experiments with partial divisions of the spinal cord, suggest that the effects of stimulation of the locus coeruleus are the result of activity of a descending coerulo-spinal tract, running in the ventral quadrant of the spinal cord.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 13, No. 1, pp. 39–47, January–February, 1981. |
