Summary
The release of total tritium and 3H-5hydroxytryptamine (5-HT) evoked by electrical stimulation from prelabelled rat hypothalamic slices was studied. Lysergic acid diethylamide (LSD) decreased while methiothepin increased both total tritium and 3H-5-HT overflow. The proportion of total tritium present as 3H-5-HT was equivalent under control conditions and in the presence of methiothepin and slightly increased in the presence of LSD. Whereas the addition of the 5-HT uptake blocker, citalopram, did not modify the evoked release of total tritium, the monoamine oxidase inhibitor, pargyline, decreased it. In the presence of either of these drugs the proportion of 3H-5-HT was increased. In the presence of citalopram, the inhibition by LSD was reduced on both the release of total tritium and of 3H-5HT. It thus appears that changes in electrically evoked total tritium overflow in general reflect changes in 3H-5-HT release. When uptake inhibitors or monoamine oxidase inhibitors are present in the medium, the situation is, however, more complex and results from experiments measuring only the release of total tritium should be interpreted with caution.
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Baumann PA, Waldmeier PC (1981) Further evidence for negative feedback control of serotonin release in the central nervous system. Naunyn-Schmiedeberg's Arch Pharmacol 317:36–43
Classen K, Göthert M, Schlicker E (1984) Effects of DU 24565 (6-nitroquipazine) on serotoninergic and noradrenergic neurones of the rat brain and comparison with the effects of quipazine. Naunyn-Schmiedeberg's Arch Pharmacol 326:198 -202
Feuerstein TJ, Lupp A, Hertting G (1987) The serotonin (5-HT) autoreceptor in the hippocampus of the rabbit: role of 5-HT biophase concentration. Neuropharmacology 26:1071–1080
Galzin AM, Moret C, Verzier B, Langer SZ (1985) Interaction between tricyclic and nontricyclic 5-hydroxytryptamine uptake inhibitors and the presynaptic 5-hydroxytryptamine inhibitory autoreceptors in the rat hypothalamus. J Pharmacol Exp Ther 235:200–211
Göthert M, Schlicker E (1983) Autoreceptor-mediated inhibition of 3H-5-hydroxytryptamine release from rat brain cortex slices by analogues of 5-hydroxytryptamine. Life Sci 32:1183–1191
Göthert M, Schlicker E, Köstermann F (1983) Relationship between transmitter uptake inhibition and effects of α-adrenoceptor agonists on serotonin and noradrenaline release in the rat brain cortex. Naunyn-Schmiedeberg's Arch Pharmacol 322: 121–128
Green AR, Heal DJ (1985) The effects of drugs on serotoninmediated behavioural models. In: Green AR (ed) Neuropharmacology of serotonin. Oxford University Press, Oxford, pp 326–365
Kalén P, Strecker RE, Rosengren E, Björklund A (1988) Endogenous release of neuronal serotonin and 5-hydroxyindoleacetic acid in the caudate-putamen of the rat as revealed by intracerebral dialysis coupled to high-performance liquid chromatography with fluorimetric detection. J Neurochem 51:1422–1435
Langer SZ, Moret C (1982) Citalopram antagonizes the stimulation by lysergic acid diethylamide of presynaptic inhibitory serotonin autoreceptors in the rat hypothalamus. J Pharmacol Exp Ther 222:220–226
Moret C, Briley M (1986) Dihydroergocristine-induced stimulation of the 5-HT autoreceptor in the hypothalamus of the rat. Neuropharmacology 25:169–174
Moret C, Briley M (1988) Sensitivity of the response of 5-HT autoreceptors to drugs modifying synaptic availability of 5-HT. Neuropharmacology 27:43–49
Middlemiss DN (1984) Stereoselective blockade at [3H]5-HT binding sites and at the 5-HT autoreceptor by propranolol. Eur J Pharmacol 101:289–293
Middlemiss DN (1986) Blockade of the central 5-HT autoreceptor by β-adrenoceptor antagonists. Eur J Pharmacol 120:51–56
Sleight AJ, Marsden CA, Martin KF, Palfreyman MG (1988) Relationship between extracellular 5-hydroxytryptamine and behaviour following monoamine oxidase inhibition and L-tryptophan. Br J Pharmacol 93:303–310
Squires RF (1978) Monoamine oxidase inhibitors: animal pharmacology. In: Iversen LL, Iversen SD, Snyder SH (eds) Handbook of Psychopharmacology. Vol 14. Affective disorders: drug actions in animals and man. Plenum Press, New York, pp 1–58
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Moret, C., Briley, M. Modulation by drugs of the release of total tritium and 3H-5-HT from rat hypothalamic slices. Naunyn-Schmiedeberg's Arch Pharmacol 341, 398–403 (1990). https://doi.org/10.1007/BF00176330
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DOI: https://doi.org/10.1007/BF00176330