The effect of the narcotic antagonists naloxone, naltrexone and nalorphine on spinal cord c-fiber reflexes evoked by electrical stimulation or radiant heat

doi:10.1016/0014-2999(77)90354-5

European Journal of Pharmacology

Volume 42, Issue 2, 21 March 1977, Pages 147-154

https://doi.org/10.1016/0014-2999(77)90354-5 Get rights and content

Abstract

C-fiber reflexes were recorded from an S₁ ventral root in the acute decrebrate low spinal cat following stimulation of the ipsilateral superficial peroneal nerve or application of radiant heat to the metacarpel footpad. Naloxone when administered i.v. increased the electrically evoked C-fiber reflex to 158% (±23.8% S.E.M.) of control 10 min after administration; whereas, naltrexone, 0.0025 mg/kg, increased the C-fiber reflex to 206 ± 26.1% (S.E.M.) of control. Naloxone in a dose of 0.050 mg/kg increased the radiant heat evoked ventral root reflex to 161 ± 19.5% of control. Nalorphine, 1 mg/kg, facilitated the electrically evoked C-fiber reflex to f282 ± 75% of control. These finding that naloxone and naltrexone facilitated these reflexes in doses too small to have non-specific excitatory effects and that nalorphine facilitated the C-fiber reflex at a dose level that is depressant to the flexor reflex in the chronic spinal dog are consistent with a hypothesis that these are due to antagonism of a naturally occuring opiate-like inhibitory substance.

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^☆: From the U.S. Department of Health, Education and Welfare, Public Health Service, Alcohol, Drug Abuse and Mental Health Administration.

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The effect of the narcotic antagonists naloxone, naltrexone and nalorphine on spinal cord c-fiber reflexes evoked by electrical stimulation or radiant heat☆

Abstract

Brain Res.

Jap. J. Pharmacol.

Intern. J. Neuropharmacol.

Brain Res.

Intern. J. Neuropharmacol.

Life Sci.

Life Sci.

Life Sci.

Life Sci.

Antagonism of stimulation-produced analgesia by naloxone, a narcotic antagonist

Science

Studies of tryptamine and lysergic acid diethylamide (LSD)_on cutaneous C-fiber and polysynaptic reflexes in the cat

J. Pharmacol. Exptl. Therap.

Naloxone and related compounds

Patterns of discharge evoked in cutaneous nerves and their significance for sensation

Advan. Neurol.

Effects of morphine and naloxone on dorsal horn neurons in the cat

Can.J . Physiol. Pharmacol.

Release of histamine from skin and muscle in the cat by opium alkaloids and other histamine liberators

J. Physiol.