The effect of benzodiazepines on the 5-HT agonist-induced head-twitch response in mice.
European journal of pharmacology July 7, 1988 DOI: 10.1016/0014-2999(88)90802-3 via PubMed
Summary
AI-generated from the abstractFour benzodiazepines (diazepam, clonazepam, oxazepam, and clobazam) potentiated head-twitch responses in mice induced by directly acting serotonin receptor agonists (5-MeODMT, quipazine, mescaline) but not by the indirectly acting agonist 5-HTP, which was sometimes inhibited. The potentiation of 5-MeODMT by clonazepam (10 mg/kg) was not blocked by flumazenil, bicuculline, or serotonin depletion, nor mimicked by muscimol (which inhibited head-twitches). These findings suggest the potentiation occurs postsynaptically and is not mediated by benzodiazepine receptors. Failure to potentiate 5-HTP responses likely results from reduced serotonin neuronal activity via benzodiazepine receptors, since co-administration of flumazenil and clonazepam potentiated 5-HTP effects while each alone had no effect.
Study at a glance
| Characteristics | Experimental study Peer reviewed |
|---|---|
| Population | Mice |
| Interventions | diazepam clonazepam oxazepam clobazam 5-MeODMT quipazine mescaline 5-HTP carbidopa flumazenil bicuculline p-chlorophenylalanine muscimol |
| Dose | clonazepam 10 mg/kg, carbidopa 25 mg/kg |
| Citations | 21 |
| Key finding | Benzodiazepines potentiate head-twitch responses to directly acting serotonin agonists via a postsynaptic mechanism not involving benzodiazepine receptors, but fail to potentiate responses to 5-HTP, likely due to reduced serotonin neuronal activity mediated by benzodiazepine receptors. |
Abstract
The effects of four benzodiazepines (diazepam, clonazepam, oxazepam and clobazam) were studied on the head-twitch response induced in mice by several 5-HT receptor agonists. All the benzodiazepines tested potentiated the effects of the directly acting agonists 5-methoxy-N,N-dimethyltryptamine (5-MeODMT), quipazine and mescaline, without themselves inducing head-twitches. In contrast, none of them potentiated head-twitches induced by the indirectly acting agonist 5-hydroxytryptophan (5-HTP; with carbidopa 25 mg/kg), and in some experiments a clear inhibition was seen. The clonazepam (10 mg/kg) potentiation of 5-MeODMT-induced head-twitches was not antagonised by flumazenil, (+)-bicuculline, or by pretreatment with p-chlorophenylalanine. Neither was it mimicked by muscimol, which inhibited head-twitches. These results indicate that the observed potentiation is not mediated by benzodiazepine receptors and that it occurs postsynaptically to the initiating 5-HT receptors. The inability of the benzodiapines to potentiate 5-HTP-induced head-twitches probably reflects a reduction in 5-HT neuronal activity mediated by benzodiazepine receptors, as co-administration of flumazenil and clonazepam potentiated the effects of 5-HTP whereas each compound alone had no effect.