Abstract
The time course of different pharmacological effects of l-5-hydroxytryptophan (5-HTP) during continued treatment was studied in rats. 5-HTP was administered three times daily at 100 mg/kg IP in combination with the peripheral decarboxylase inhibitor carbidopa (10 mg/kg) for 14 days. 5-HTP induced a pronounced increase of the threshold for maximal electroconvulsions, decreased body temperature and body weight and induced characteristic “wet-dog” shake behaviour. Whereas the anticonvulsant effect increased during the 14 days of treatment, tolerance developed to the excitatory and, less rapidly, to the hypothermic and anorexigenic effects of 5-HTP. Biochemical determinations showed marked increases in 5-HTP and its metabolites, 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid, in both plasma and brain throughout the period of treatment. The mechanisms underlying the different time-courses of the functional effects of 5-HTP during continued treatment are not clear, but effects on catecholaminergic systems as well as regional differences in 5-HT increases in the brain might be involved.
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Awazi N, Guldberg HC (1978) On the interaction of 5-hydroxytryptophan and 5-hydroxytryptamine with dopamine metabolism in rat striatum. Naunyn-Schmiedeberg's Arch Pharmacol 303:63–72
Bedard P, Pycock CJ (1977) “Wet-dog” shake behaviour in the rat: a possible quantitative model of central 5-hydroxytryptamine activity. Neuropharmacology 16:663–670
Blundell JE, Leshem MB (1975) The effect of 5-hydroxytryptophan on food intake and on the anorexic action of amphetamine and fenfluramine. J Pharm Pharmacol 27:31–37
Bogdanski DF, Weissbach H, Udenfried S (1958) Pharmacological studies with the serotonin precursor, 5-hydroxytryptophan. J Pharmacol Exp Ther 122:182–194
Buus Lassen J (1978) Potent and long-lasting potentiation of two 5-hydroxytryptophan-induced effects in mice by three selective 5-HT uptake inhibitors. Eur J Pharmacol 47:351–358
Chadwick D (1981) CSF monoamine metabolites in epileptic patients. In: Morselli PL, Lloyd KG, Löscher W, Meldrum B, Reynolds EH (eds) Neurotransmitters, Seizures, and Epilepsy. Raven Press, New York, pp 293–304
Colpaert FC, Janssen PAJ (1983) The head-twitch response to intraperitoneal injection of 5-hydroxytryptophan in the rat: antagonistic effects of purported 5-hydroxytryptamine antagonists and of pirenperone, an LSD antagonist. Neuropharmacology 22:993–1000
Corne SJ, Pickering RW, Warner BT (1963) A method for assessing the effects of drugs on the central actions of 5-hydroxytryptamine. Br J Pharmacol 20:106–120
De La Torre JC, Mullan S (1970) A possible role for 5-hydroxytryptamine in drug-induced seizures. J Pharm Pharmacol 22:858–859
Feldberg W, Lotti VJ (1967) Temperature responses to monoamines and an inhibitor of monoamine oxidase injected into the cerebral ventricles of rats. Br J Pharmacol 31:152–161
Fuxe K, Butcher LL, Engel J (1971) DL-5-hydroxytryptophan-induced changes in central monoamine neurons after peripheral decarboxylase inhibition. J Pharm Pharmacol 23:420–424
Garattini S (1980) Recent studies on anorectic agents. TIPS 1:354–356
Iadarola MJ, Gale K (1981) Cellular compartments of GABA in brain and their relationship to anticonvulsant activity. Mol Cell Biochem 39:305–330
Joseph MH, Baker HF (1976) The determination of 5-hydroxytryptophan and its metabolites in plasma following administration to man. Clin Chim Acta 72:125–131
Kellogg C (1976) Audiogenic seizures: relation to age and mechanisms of monoamine neurotransmission. Brain Res 106:87–103
Kilian M, Frey H-H (1973) Central monoamines and convulsive thresholds in mice and rats. Neuropharmacology 12:681–692
Kimball AW, Burnett WT, Doherty DG (1957) Sampling methods for screening compounds in radiation protection studies with mice. Radiat Res 7:1–12
Kobinger W (1958) Beeinflussung der Cardiazolkrampfschwelle durch veränderten 5-HT-Gehalt des Zentralnervensystems. Naunyn-Schmiedeberg's Arch Exp Pathol Pharmakol 233:559–566
Koe BK, Weissman A (1966) p-Chlorophenylalanine: a specific depletor of brain serotonin. J Pharmacol Exp Ther 154:499–516
Löscher W, Pagliusi SR, Müller F (1984) l-5-Hydroxytryptophan. Correlation between anticonvulsant effect and increases in levels of 5-hydroxyindoles in plasma and brain. Neuropharmacology 23:1041–1048
Luscombe G, Jenner P, Marsden CD (1983) Alterations in brain 5-HT and tryptamine content during indoleamine-induced myoclonus in guinea pigs. Biochem Pharmacol 32:1857–1864
Magnussen I, Jensen TS, Rand JH, Van Woert MH (1981) Plasma accumulation and metbolism of orally administered single dose l-5-hydroxytryptophan in man. Acta Pharmacol Toxicol 49:184–189
Magyar RL, Gillin JC, Wyatt RJ (1978) Tolerance to the increased locomotor activity produced by l-5-hydroxytryptophan following peripheral decarboxylase inhibition in mice. Psychopharmacology 56:343–350
Matz DR, Rolf LH, Brune GG (1980) 5-Hydroxytryptamine and idiopathic grand mal seizures. In: Canger R, Angeleri F, Penry JK (eds) Advances in Epileptology: XIth Epilepsy International Symposium. Raven Press, New York, pp 363–366
Modigh K (1972) Central and peripheral effects of 5-hydroxytryptophan on motor activity in mice. Psychopharmacologia 23:48–54
Ng LKY, Chase TN, Colburn RW, Kopin IJ (1972) Release of 3H-dopamine by l-5-hydroxytryptophan. Brain Res 45:499–505
Schmidt D (1980) Neurotransmitter and Epilepsien. Klinische Gesichtspunkte zur Rolle der biogene Amine, der γ-Aminobuttersäure und Taurin für die Anfallsbereitschaft von Patienten mit Epilepsie. Nervenarzt 51:582–590
Van Woert MH, Chung Hwang E (1979) Myoclonus. In: Vinken PJ, Bruyn GW (eds) Handbook of Clinical Neurology, vol 38. North Holland Publishing Co., Amsterdam, pp 575–593
Van Woert MH, Rosenbaum D, Howieson J, Bower MB (1977) Long-term therapy of myoclonus and other neurologic disorders with l-5-hydroxytryptophan and carbidopa. New Engl J Med 296:70–75
Van Woert MH, Magnussen IB, Hee Lowe Y, Chung Hwang E (1982) Study of serotonin in neuropsychiatric disorders. J Histochem Cytochem 30:824–827
Vickers S, Stuart EK, Bianchine JR, Hucker HB, Jaffe ME, Rhodes RE, Vandenheuvel WJA (1974) Metabolism of carbidopa [l-(-)-α-hydrazino-3,4-dihydroxy-α-methylhydrocinnamic acid monohydrate], an aromatic amino acid decarboxylase inhibitor in the rat, dog, rhesus monkey, and man. Drug Metab Dispos 2:9–22
Wyatt RJ, Kaplan J, Vaughan T (1973) Tolerance and dependence to serotonin: a speculation. Arch Gen Psychiatr 29:597–599
Yap CY, Taylor DA (1983) Involvement of 5-HT2 receptors in the wet-dog shake behaviour induced by 5-hydroxytryptophan in the rat. Neuropharmacology 22:801–804
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Pagliusi, S.R., Löscher, W. Development of tolerance to the wet-dog shake behaviour but not the increase in seizure threshold induced by l-5-hydroxytryptophan during continued treatment in rats. Psychopharmacology 86, 118–124 (1985). https://doi.org/10.1007/BF00431695
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DOI: https://doi.org/10.1007/BF00431695