Abstract
The flexor reflex of acute (40–48 h after mid-thoracic spinal transection) and chronic (at least 2 months after transection) spinal rats was evoked by tetanic electrical stimulation of both hindfeet and recorded on a polygraph using a transducer connected to the left hindfoot. The flexor reflex in the chronic spinal rat was more responsive to electrical stimulation and to the actions of drugs studied than was the flexor reflex in the acute spinal rat. In chronic spinal rats, d-amphetamine, methoxamine, LSD, tryptamine, and 5-hydroxytryptophan (5-HTP) facilitated the flexor reflex and induced spontaneous movements. These facilitative effects were seen in acute spinal rats only when much larger i.p. doses of amphetamine, methoxamine, and LSD were used. Small i.v. doses of tryptamine also produced the facilitation. The facilitation caused by LSD and tryptamine, but not 5-HTP, in chronic spinal rats was antagonized by cyproheptadine. These observations suggest that chronic spinal rats were more sensitive to the drugs than acute spinal rats and support the hypothesis that the mode of action of LSD is similar to that of tryptamine but different from that of 5-HTP since cyproheptadine antagonized the facilitative effects of LSD and tryptamine but not those of 5-HTP.
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Andén, N.-E., Corrodi, H., Fuxe, K.: Hallucinogenic drugs of the indolealkylamine type and central monoamine neurons. J. Pharmacol. Exp. Ther. 179, 236–249 (1971)
Andén, N.-E., Corrodi, H., Fuxe, K., Hökfelt, T.: Evidence for a central 5-hydroxytryptamine receptor stimulation by lysergic acid diethylamide. Br. J. Pharmacol. 34, 1–7 (1968)
Andén, N.-E., Fuxe, K., Hökfelt, T.: The importance of the nervous impulse flow for the depletion of the monoamines from the central neurons by some drugs. J. Pharm. Pharmacol. 18, 630–632 (1966)
Andén, N.-E., Häggendal, J., Magnusson, T., Rosengren, E.: The time course of the disappearance of noradrenaline and 5-hydroxytryptamine in the spinal cord after transection. Acta Physiol. Scand. 62, 115–118 (1964a)
Andén, N.-E., Magnusson, T.: An improved method for fluorimetric determination of 5-hydroxytryptamine in tissues. Acta Physiol. Scand. 69, 87–94 (1967)
Andén, N.-E., Magnusson, T., Rosengren, E.: On the presence of dihydroxyphenylalanine decarboxylase in nerves. Experientia 20, 328–329 (1964b)
Bell, J. A., Martin, W. R.: Studies of tryptamine and lysergic acid diethylamide (LSD) on cutaneous C-fiber and polysynaptic reflexes in the cat. J. Pharmacol. Exp. Ther. 190, 492–500 (1974)
Bell, J. A., Martin, W. R.: The absence of an effect of L-tryptophan on the C-fiber reflex in the chronic spinal cat. Life Sci. 20, 1087–1090 (1977)
Bell, J. A., Martin, W. R., Sloan, J. W., Buchwald, W. F.: The effect of L-tryptophan on spinal cord C-fiber reflexes. J. Pharmacol. Exp. Ther. 196, 373–379 (1976)
Brawley, P., Duffield, C. J.: The pharmacology of hallucinogens. Pharmacol. Rev. 24, 31–64 (1972)
Cannon, W. B., Rosenblueth, A.: The supersensitivity of denervated structures: a law of denervation. New York: MacMillan Company 1949
Carlsson, A., Falck, B., Fuxe, K., Hilarp, N. A.: Cellular localization of monoamines in the spinal cord. Acta Physiol. Scand. 60, 112–119 (1964)
Carlsson, A., Magnusson, T., Rosengren, E.: 5-Hydroxytryptamine in the spinal cord normally and after transection. Experientia 19, 359 (1963)
Dahlström, A., Fuxe, K.: Evidence for the existence of monoamine neurons in the central nervous system. III. Experimentally induced changes in the intraneuronal amine levels of bulbospinal neuron system. Acta Physiol. Scand. 64 [Suppl.] 247 (1965)
Häggendal, J., Dahlström, A.: The time course of noradrenaline decrease in rat spinal cord following transection Neuropharmacology 12 349–354 (1973)
Isbell, H., Logan, C. R., Miner, E. J.: Studies on lysergic acid diethylamide (LSD-25). III Attempts to attenuate the LSD-reaction in man by pretreatment with neurohumoral blocking agents. Arch. Neurol. Psychiatr. 81, 20–27 (1959)
Martin, W. R., Eades, C. G.: Pharmacological studies of spinal cord adrenergic and cholinergic mechanisms and their relation to physical dependence on morphine. Psychopharmacologia (Berl.) 11, 195–223 (1967)
Martin, W. R., Eades, C. G.: The action of tryptamine on the dog spinal cord and its relationship to the agonistic actions of LSD-like psychotogens. Psychopharmacologia (Berl.) 17, 242–257 (1970)
Martin, W. R., Eades, C. G.: Cross tolerance to tryptamine in the LSD tolerant dog. Psychopharmacologia (Berl.) 27, 93–98 (1972)
Martin, W. R., Sloan, J. W.: Effects of infused tryptamine in man. Psychopharmacologia (Berl.) 18, 231–237 (1970)
Martin, W. R., Sloan, J. W., Buchwald, W. F., Clements, T. H.: Neurochemical evidence for tryptaminergic ascending and descending pathways in the spinal cord of the dog. Psychopharmacologia (Berl.) 43, 131–134 (1975)
Martin, W. R., Sloan, J. W., Vaupel, D. B., Bell, J. A., Nozaki, M.: Tryptamine in the brain and spinal cord: its role in the LSD response. In: Trace amines and the brain, E. Usdin and M. Sandler, eds., pp. 83–102. New York: Marcel Dekker 1976
McCouch, G. P., Austin, G. M., Liu, C. N., Liu, C. Y.: Sprouting as a cause of spasticity. J. Neurophysiol 21, 205–216 (1958)
Nozaki, M., Bell, J. A.: Responses of flexor reflex to LSD, tryptamine, 5HTP, methoxamine and d-amphetamine in acute and chronic spinal rats. Fed. Proc. 35, 270 (1976)
Shibuya, T., Anderson, E. G.: The influence of chronic cord transection on the effects of 5-hydroxytryptophan, L-tryptophan and pargyline on spinal neuronal activity. J. Pharmacol. Exp. Ther. 164, 185–190 (1968)
Taber, C. A., Anderson, E. G.: Paradoxical blockade by p-chlorophenylalanine of 5-hydroxytryptophan facilitatory actions on spinal reflexes. J. Pharmacol. Exp. Ther. 187, 229–238 (1973)
Vaupel, D. B., Martin, W. R.: Actions of methoxamine and tryptamine and their interactions with cyproheptadine and phenoxybenzamine on cat spinal cord segmental reflexes. J. Pharmacol. Exp. Ther. 196, 87–96 (1976)
Wikler, A., Frank, K.: Hindlimb reflexes of chronic spinal dogs during cycles of addiction to morphine and methadone. J. Pharmacol. Exp. Ther. 94, 382–400 (1948)
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Nozaki, M., Bell, J.A., Vaupel, D.B. et al. Responses of the flexor reflex to LSD, tryptamine, 5-hydroxytryptophan, methoxamine, and d-amphetamine in acute and chronic spinal rats. Psychopharmacology 55, 13–18 (1977). https://doi.org/10.1007/BF00432811
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DOI: https://doi.org/10.1007/BF00432811