Actions of Chlorpromazine and of Reserpine on Spinal Reflex Activity in the Cat

Abstract

These experiments are based on the finding that doses of chlorpromazine that do not modify conduction depress transmission in the inferior mesenteric ganglion of the cat (Krivoy, unpublished). If the synapse in the spinal cord resembles the ganglionic synapse, chlorpromazine should modify transmission in the spinal cord also. The present experiments were designed to study this possibility.Methods. In one preparation ( 1 ) , laminectomy was performed at the level of the last lumbar or first sacral segment to expose homolateral dorsal and ventral roots from the same spinal segment. The roots were mounted on electrodes. The skin edges around the incision were elevated and the trough so formed was filled with mineral oil maintained at 37°C. A second method(2) consisted of stimulating and recording through 2 pairs of electrodes applied to the same sciatic nerve, which had been cut distally. Electrical equipment and methods of recording have been described previously( 3), only the AC amplifier being used in these experiments. Bright silver electrodes were used with spinal roots, whereas wick electrodes were used for sciatic nerve experiments. The dorsal root or sciatic nerve was stimulated with biphasic pulses a t a frequency varying from .S-l/sec. with a stimulus duration of .l-.5 msec. Except where noted, stimulus intensity was SO-SO% maximal. All stimulus parameters were main-

Modulation of nociceptive withdrawal reflexes evoked by single and repeated nociceptive stimuli in conscious dogs by low‐dose acepromazine

“…2000). Our findings are consistent with previous studies where the phenothiazine derivative chlorpromazine suppressed monosynaptic reflexes but did not depress, or depressed slightly, polysynaptic reflexes in intact or decerebrated cats and rabbits (Dasgupta & Werner 1955; Krivoy 1957; Silvestrini & Maffii 1959). By applying repeated stimuli, TS was evoked.…”

Actions of morphine on the segmental reflex of the decerebrate‐spinal cat

“…Stimulation of the dorsal root and recording of the response reflexly evoked in the ventral root were by the techniques described previously (Krivoy, 1957;Krivoy & Huggins, 1961). The stimulating and recording electrodes were of bright silver.…”

Neuromuscular Pharmacology: Drugs and Muscle Spindles

“…This observation provides an appropriate explanation for the abolition by chlorpromazine of the rigidity induced by intercollicular section, and its much less marked effects on the rigidity of "anemic" decerebrate preparations (79). In inter collicularIy decerebrate preparations chlorpromazine also induces a decrease in the segmental monosynaptic reflex, and a somewhat less marked decrease of polysynaptic reflex potentials (79,108), a depression of posttetanic poten tiation of single motor neuron unit response to muscle stretch, but no change in the posttetanic potentiation of the monosynaptic reflex elicited by repeti tive electric shock conditioning of the muscle nerve (79). The low doses of chlorpromazine which alter fusimotor neuron activity have been generally found to have little effect in spinal preparations (128); however, Schulte & Henatsch (132), and Busch et al (24) noted that the tonic activity of alpha or gamma motor neurons, which could be observed in spinal animals or be induced reflexly, was also promptly abolished by chorpromazine.…”