Stimulatory and inhibitory effects of serotonergic hallucinogens on spinal mono- and polysynaptic reflex pathways in the rat.
Neuropharmacology July 1, 1992 DOI: 10.1016/0028-3908(92)90141-b (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Rat spinal cord |
| Interventions | 5-MeODMT DOI ketanserin ritanserin propranolol MDL 72222 |
| Dose | 5-MeODMT: 1 and 100 micrograms/kg; DOI: 1-100 micrograms/kg; ketanserin: 100 micrograms/kg; ritanserin: 100 micrograms/kg; propranolol: 1 mg/kg; MDL 72222: 1 mg/kg |
| Topics | Serotonin |
| Citations | 23 |
| Key findings | The two hallucinogens both increase motoneuron activity through 5-HT2 receptors, but only 5-MeODMT inhibits the monosynaptic reflex pathway. |
Abstract
The effects of two 5-HT-related hallucinogens on rat spinal mono- and polysynaptic reflex pathways in the rat were investigated. 5-Methoxy-N,N-dimethyltryptamine (5-MeODMT, 1 and 100 micrograms/kg, i.v.), an indolealkylamine agent, produced a dose-dependent decrease in the monosynaptic reflex, whereas 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI, 1-100 micrograms/kg), a phenylalkylamine agent, produced a dose-dependent increase in the monosynaptic reflex. Both agents increased the polysynaptic reflex. The 5-HT2 receptor antagonists ketanserin (100 micrograms/kg) and ritanserin (100 micrograms/kg) blocked the effects of DOI on the monosynaptic reflex but only partially blocked the 5-MeODMT-induced effect on the monosynaptic reflex. These antagonists inhibited the change in polysynaptic reflex, induced by DOI but not by 5-MeODMT. Neither propranolol (1 mg/kg) nor 3-tropanyl-3,5-dichlorobenzoate (MDL 72222, 1 mg/kg) antagonized the effect of either agent. 5-Methoxy-N,N-dimethyltryptamine and DOI increased the excitability of motoneurons and this effect was inhibited by ketanserin. These results indicate that the two types of hallucinogens possess both common and distinct characteristics, with regard to their action on the spinal reflex: (1) both increase the activity of motoneurons through 5-HT2 receptors but (2) only 5-MeODMT has an inhibitory action on the pathway of the monosynaptic reflex.