5-Hydroxytryptamine agonistic action of methysergide and the absence of supersensitivity to 5-HT agonists in spinal flexor reflexes in rats.
H Ono, M Miyamoto, M Kobayashi, H Fukuda
Neuropharmacology September 1987 DOI: 10.1016/0028-3908(87)90101-8 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Animal experiment Peer reviewed |
|---|---|
| Population | Acute spinal rats transected at C1, some pretreated with intracisternal 5,6-dihydroxytryptamine two weeks earlier |
| Interventions | 5-HTP 5-MeODMT PCA LSD methysergide cyproheptadine 5 6-dihydroxytryptamine |
| Topics | Serotonin |
| Key findings | Intravenous 5-HTP, 5-MeODMT, PCA, LSD, and methysergide each enhanced flexor reflexes in acute spinal rats. Cyproheptadine blocked enhancement by 5-MeODMT, LSD, and methysergide but not by 5-HTP or PCA. After 5,6-dihydroxytryptamine, supersensitivity occurred to 5-HTP and subsensitivity to PCA, but not to 5-MeODMT, LSD, or methysergide. The authors suggest methysergide may have an agonistic action on spinal 5-HT receptors. |
Abstract
The intravenous administration of L-5-hydroxytryptophan (5-HTP), 5-methoxy-N,N-dimethyltryptamine (5-MeODMT), p-chloroamphetamine (PCA), LSD and methysergide to acute spinal rats, transected at C1, stimulated the flexor reflexes induced by electrical stimulation applied to the skin of the toe. The enhancement produced by 5-HTP, 5-MeODMT and PCA, was not antagonized by the prior administration of a dose of LSD or methysergide, although the enhancement produced by 5-MeODMT, LSD and methysergide, but not that produced by 5-HTP and PCA, was antagonized by cyproheptadine. In rats treated with 5,6-dihydroxytryptamine (intracisternal administration, 2 weeks previously) supersensitivity was observed to the effects of 5-HTP, a precursor of 5-HT, while subsensitivity was observed for the effects of PCA, a releaser of 5-HT. However, no supersensitivity was observed for the effects of 5-MeODMT, LSD and methysergide. These results suggest that methysergide may have an agonistic action on the 5-HT receptors in spinal cord and that supersensitivity to 5-HTP in rats treated with 5,6-dihydroxytryptamine was due to the lack of uptake of 5-HT into terminals of descending 5-HT fibres or to the change in 5-HT receptors which were not sensitive to 5-MeODMT, LSD, methysergide or cyproheptadine.
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| 3,4-Methylenedioxymethamphetamine and 3,4-methylenedioxyamphetamine destroy serotonin terminals in rat brain: quantification of neurodegeneration by measurement of [3H]paroxetine-labeled serotonin uptake sites. Rat brain | 1987 | Animal experiment | |
| Comparison of the monoamine transporters from human and mouse in their sensitivities to psychostimulant drugs Human and mouse dopamine, norepinephrine, and serotonin transporters expressed in cells | 2006 | In vitro laboratory study |
Citations in the library
Cites 2
- Increased behavioural response to 5-methoxy-N,N-dimethyltryptamine but not to RU-24969 after intraventricular 5,7-dihydroxytryptamine administration. European Journal of Pharmacology September 3, 1984
- Nociception is enhanced by the intrathecal injection of 5-methoxy-N,N-dimethyltryptamine in the rat. Neuroscience Letters December 13, 1982