Erowid References Database
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Barasi S, Roberts MHT.
“The action of 5-hydroxytryptamine antagonists and precursors on bulbo-spinal facilitation of spinal reflexes”.
Brain Res. 1973;52:385-388.
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Abstract
There is now considerable biochemical and histological evidence that 5-hydroxy-typtamine (5-HT) may act as a neurotransmitter or neuroregulator in the mammalian central nervous system Physiological confirmation of such a role for 5-HT containing, adherents requires that stimulation of these afferents gives a postsynaptic efiect which can be shown to be mimicked by-5-HT and to be blocked by 5-HT antagonists. This preliminary report describes an attempt to identify such a response in spinal motoneurones and to study its pharmacological characteristics. Forty-eight rats were prepared with,Fluothane anaesthesia for study of the motoneurone pool by exposure of the lumbo-sacral cord. L6 and L7 dorsal and central roots were cut and laid upon silver wire electrodes. Experiments were also conducted in 13 unanaesthetised decerebrate preparations. These preparations were immobilized with Flaxedil and all dorsal roots entering the lumbar enlargement sectioned bilaterally. A concentric bipolar steel electrode of 0.5 mm diameter was stereotactically oriented into the region of the nucleus raphe medianus at coordinates .AP 0.35; L 0.0; H2.6, using the coordinates of König and Klippel7. The loca-tion of the electrode tip was histologically confirmed at a later date in all experimental animals. Three different types of investigation were conducted. In the first the mono-svnaptic response (MSR) evoked from the dorsal root and recorded from the cut -entral root was used as an index of the excitability of the motoneurone pool. The following drugs were administered intravenous lysergic acid diethylamide (LSD), cinanserin hydrochloride and L-tryptophan. The second series of experiments involved intracellular recordings with either NaCI-filled single barrel glass microelec.rodes or '-barrelled micropipettes prepared in the manner described by Roberts and Straughanii. Three barrels of these pipettes were filled with ionised solutions of drugs to facilitate their local-application by microiontophoresis. The drugs used were 5-ciroxytryptamine bimaleate (5-HT) (0.2 M; pH 3.5), cinanserin hydrochloride n M; pH 3) and methysergide bimaleate (0.2 M; pH 3). For the third type of experiment, single barrel glass microelectrodes broken to a tip diameter of 1.0 mcm were
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