Cyamemazine as an anxiolytic drug on the elevated plus maze and light/dark paradigm in mice

Intra-amygdala circuits of sleep disruption-induced anxiety in female mice

Combining mouse genetics, electrophysiology, and behavioral training and testing, we explored how sleep disruption may affect the function of anxiety-controlling circuits, focusing on projections from the basolateral nucleus of the amygdala (BLA) to CRF-positive cells in the lateral division of the central amygdala (CeL). We found in Crh-IRES-Cre::Ai14(tdTomato) reporter female mice that 6 hours of sleep disruption during their non-active (light) cycle may be anxiogenic. Notably, the AMPAR/NMDAR EPSC amplitude ratio at the BLA inputs to CRF-CeL cells (CRF CeL ), assessed with whole-cell recordings in ex vivo experiments, was enhanced in slices from sleep-disrupted mice, whereas paired-pulse ratio (PPR) of the EPSCs induced by two closely spaced presynaptic stimuli remained unchanged. These findings indicate that sleep disruption-associated synaptic enhancements in glutamatergic projections from the BLA to CRF-CeL neurons may be postsynaptically expressed. We found also that the excitation/inhibition (E/I) ratio in the BLA to CRF CeL inputs was increased in sleep-disrupted mice, suggesting that the functional efficiency of excitation in BLA inputs to CRF CeL cells has increased following sleep disruption, thus resulting in their enhanced activation. The latter could be translated into enhanced anxiogenesis as activation of CRF cells in the CeL was shown to promote anxiety-like behaviors.

Anticonvulsant effects of Cymbopogon giganteus extracts with possible effects on fully kindled seizures and anxiety in experimental rodent model of mesio-temporal epilepsy induced by pilocarpine

ETHNOPHARMACOLOGICAL RELEVANCE

Epilepsy is a neurological disorder of the brain characterized by periodic and unpredictable occurrence of a transient behavior alteration due to the rhythmic, synchronous and disordered firing of brain neuron. Worldwide, approximately 50 million people currently live with epilepsy and close to 80% of people with epilepsy live in poor countries. However, it was noticed in many countries worldwide that people with epilepsy and their families suffer from stigma and discrimination and that situation exposes them to high psychological conditions such as depression and anxiety as well as more physical problems including bruising and fractures from injuries related to seizures. However, several plants-based products used for epilepsy and anxiety treatments in different system of folk medicine have exhibited a significant anti-epileptic and antianxiety activities using animal models with fewer side effects.

AIM OF THE STUDY

The study aimed at evaluating the antiepileptic, status post-epilepticus and anxiolytic effects of Cymbopogon giganteus decoction in rat model induced by pilocarpine.

MATERIALS AND METHODS

A total of 90 rats were partitioned into 7 groups and treated as follow: animals of groups I (normal control) and II (considered the negative control) received distilled water (10 mL/kg); while groups III, IV, V, and VI were treated with the C. giganteus extract at 34, 85, 170 and 340 mg/kg p.o, respectively; and the group VII (considered positive control) received sodium valproate at 300 mg/kg, i.p. After 40 min post-treatment, a single dose of n-methyl-scopolamine (1 mg/kg, i.p) was administered to animals of groups (II, III, IV, V, VI, VII) followed by pilocarpine (360 mg/kg, i.p). Animal of group I (normal group) received distilled water. Rats were further observed for 6 h to evaluate the severity and the duration of the acute seizures of epilepsy according to Racine scale. Anxious behavior status post-epilepticus was also assessed in the same rats used above in the Elevated Plus Maze and number of entries into the open or closed arms and the time spent on either open or closed arms of the platform were recorded. Animals were also evaluated on Open Field Test and the number of rearing, crossing, grooming, defecation and center time were registered.

RESULTS

C. giganteus decoction significantly (P < 0.05) reduced the animal mortality, the number and duration of convulsions and effectively increased the latency of convulsions. The plant extract significantly (P < 0.05) improved GSH level and SOD activity, reduced MDA and CAT activity, increased GABA level and decreased GABA-t activity in hippocampus. The anxiety induced by pilocarpine was also significantly (P < 0.05) inhibited by the extract of the plant.

CONCLUSIONS

Thus, C. giganteus has demonstrated its antiepileptic and anxiolytic activities in rat model and may be used as preventive measure for patients suffering from epilepsy seizures and anxiety.

Antipsychotic drugs and sudden cardiac death: A literature review of the challenges in the prediction, management, and future steps

Sudden cardiac death (SCD) is relatively uncommon, yet it is a deadly consequence of some antipsychotic medications in patients with psychiatric disorders. The widespread concerns about the adverse cardiac effects associated with antipsychotics and their unpredictable nature have led to a restriction on the use of some antipsychotic medications. Recent progress has been made in the identification of important genetic factors that may contribute to the adverse complication of antipsychotic drugs, suggesting that high-risk individuals can be identified prior to initiating therapy. In addition, some high-tech smart wearable medical devices have recently been developed, allowing users to record and analyze the electrocardiogram (ECG) in couple with artificial intelligence (AI) technologies, and notifying of irregular heart rhythms or arrhythmias, a medical condition well documented in most SCD cases. In this literature review, we summarize recent advances in understanding the link between SCD and antipsychotic drug usage, as well as in utilizing wearable medical devices for monitoring of cardiac arrhythmias. New strategies for improving the care of patients receiving antipsychotic medications are proposed. As it is now possible to evaluate the risk of SCD in patients on antipsychotic medications, preventative measures and close monitoring may be used to detect the early signs of adverse cardiac events and SCD.

[Cyamemazine (Tercian®): Exploration of extrapyramidal syndrome cases contained in the French pharmacovigilance database]

PURPOSE

Cyamemazine (Tercian^®) is currently the most widely prescribed neuroleptic in France. This widespread use is due to its anxiolytics properties and to a claimed good safety profile. Although, prescription of cyamemazine is not devoid of the risks associated with the use of neuroleptics: extrapyramidal syndromes. This study aims at describing extrapyramidal syndromes induced by cyamemazine registered in the French pharmacovigilance database.

METHODS

All spontaneous reports of extrapyramidal syndromes in the French pharmacovigilance database between 1st January 1985 and 31th December 2015 were described and analyzed.

RESULTS

During this period 132 cases following cyamemazine intake were reported in the French pharmacovigilance database. The extrapyramidal syndromes were considered as "serious" in 77% of cases. More than 80% of the cases were described with a dosage of cyamemazine under 100mg/day and no correlation between drug dose and seriousness of the cases were found. Thirty-six cases were described with a monotherapy of cyamemazine.

CONCLUSION

We should keep in mind that despite its widespread use in various indications (e.g. anxiolytic) cyamemazine remains a neuroleptic and could induce extrapyramidal syndromes even with low dosage. Careful monitoring should be performed when introducing and with long-term use of cyamemazine, mostly in elderly patients or patient already being treated with neuroleptics.

Newtonoate as an active principle of Newtonia griffoniana for anxiolytic activity in Swiss mice

BACKGROUND

Newtonia griffoniana (Mimosaceae) is a Central African rain forest tree, whose bark extracts are used in Cameroonian folk medicine for the treatment of anxiety and sleep disorders.

METHODS

We evaluated the anxiolytic effects of N. griffoniana stem bark methanol extract and its major isolated constituent 2,3,4-trihydroxybutylpentatriacontanoate (newtonoate) on the elevated plus maze.

RESULTS

Significant increases in the percentage of entries into open arms were induced by both N. griffoniana extract (100 and 150 mg/kg BW; p<0.01) and newtonoate (doses of 3 and 15 mg/kg BW; p<0.05). Conversely, decreases in the percentage of entries into closed arms were observed at the same doses. In addition, N. griffoniana methanol extract (100 mg/kg) and the isolated newtonoate (30 mg/kg) induced significant (p<0.01 and p<0.05, respectively) increases in the time spent in the open arms, while inducing a decrease in the time spent in the closed arms. Newtonoate treatment also decreased head dipping number at doses of 3 and 15 mg/kg, while N. griffoniana methanol extract induced the same effect at 200 mg/kg.

CONCLUSIONS

These results suggest that N. griffoniana bark extract has anxiolytic properties, which justify its use in folk medicine. Such effects are at least partly mediated by newtonoate.

Psychotropic drugs in mixture alter swimming behaviour of Japanese medaka (Oryzias latipes) larvae above environmental concentrations

Psychiatric pharmaceuticals, such as anxiolytics, sedatives, hypnotics and antidepressors, are among the most prescribed active substances in the world. The occurrence of these compounds in the environment, as well as the adverse effects they can have on non-target organisms, justifies the growing concern about these emerging environmental pollutants. This study aims to analyse the effects of six psychotropic drugs, valproate, cyamemazine, citalopram, sertraline, fluoxetine and oxazepam, on the survival and locomotion of Japanese medaka Oryzias latipes larvae. Newly hatched Japanese medaka were exposed to individual compounds for 72 h, at concentrations ranging from 10 μg L(-1) to 10 mg L(-1). Lethal concentrations 50 % (LC50) were estimated at 840, 841 and 9,136 μg L(-1) for fluoxetine, sertraline and citalopram, respectively, while other compounds did not induce any significant increase in mortality. Analysis of the swimming behaviour of larvae, including total distance moved, mobility and location, provided an estimated lowest observed effect concentration (LOEC) of 10 μg L(-1) for citalopram and oxazepam, 12.2 μg L(-1) for cyamemazine, 100 μg L(-1) for fluoxetine, 1,000 μg L(-1) for sertraline and >10,000 μg L(-1) for valproate. Realistic environmental mixture of the six psychotropic compounds induced disruption of larval locomotor behaviour at concentrations about 10- to 100-fold greater than environmental concentrations.

Anxiolytic and sedative activities of aqueous leaf extract of Dichrocephala integrifolia (Asteraceae) in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Dichrocephala integrifolia (Asteraceae) is commonly used in the folk medicine in Cameroon to treat various ailments including headaches, jaundice, filariasis, neuritis and children's night agitation. It is also known to have anxiolytic properties. Since there were no scientific data supporting the above claims, we therefore aimed to evaluate the anxiolytic and sedative effects of the aqueous leaf extract of D. integrifolia.

MATERIALS AND METHODS

The extract used was obtained after maceration of leaves of D. integrifolia in water at room temperature. The anxiolytic effect was tested by the elevated plus-maze (EPM) and Open Field tests while the sedative effect was evaluated by the diazepam-induced sleep test.

RESULTS

D. integrifolia significantly induced an increase in the percentage of entries into open arms and a decrease in percentage of entries into closed arms at the dose of 22 mg/kg BW. The extract also induced a decrease of rearing and head dipping at the doses of 22 and 40 mg/kg BW during the EPM test. In addition, D. integrifolia extract induced a significant increase of crossing and time spent at the center of the experimental set at the dose of 40 mg/kg BW during the open field test. Lastly, D. integrifolia caused a significant reduction of the latency to sleep and an increase of total sleep time at the doses of 22 and 40 mg/kg BW in the diazepam-induced sleep test.

CONCLUSION

The results obtained in this study suggest that the aqueous leaf extract of D. integrifolia is endowed with anxiolytic and sedative properties, which justify its traditional use.

Synthesis of deuterium-labeled cyamemazine and monodesmethyl cyamemazine

A novel approach is presented for the synthesis of cyamemazine maleate and N-desmethyl cyamemazine maleate using a 10-(amino-2-methylpropyl)phenothiazine derivative. This method was successfully applied to the synthesis of [(2) H6 ]cyamemazine maleate and N-desmethyl-[(2) H3 ]cyamemazine maleate.

Potential role of cortical 5-HT(2A) receptors in the anxiolytic action of cyamemazine in benzodiazepine withdrawal

The antipsychotic cyamemazine is a potent serotonin 5-HT(2A) receptor (5-HT(2AR)) antagonist. A positron emission tomography (PET) study in human patients showed that therapeutic doses of cyamemazine produced near saturation of 5-HT(2AR) occupancy in the frontal cortex, whereas dopamine D(2) occupancy remained below the level for motor side effects observed with typical antipsychotics. Recently, numerous studies have revealed the involvement of 5-HT(2AR) in the pathophysiology of anxiety and a double-blind, randomized clinical trial showed similar efficacy of cyamemazine and bromazepam in reducing the anxiety associated with benzodiazepine withdrawal. Therefore, we reviewed the above articles about 5-HT(2AR) and anxiety in order to understand better the anxiolytic mechanisms of cyamemazine in benzodiazepine withdrawal. The 5-HT(2AR) is the most abundant serotonin receptor subtype in the cortex. Non-pharmacological studies with antisense oligodeoxynucleotides and genetically modified mice clearly showed that cortical 5-HT(2AR) signaling positively modulates anxiety-like behavior. With a few exceptions, most other studies reviewed here further support this view. Therefore, the anxiolytic efficacy of cyamemazine in benzodiazepine withdrawal can be due to a 5-HT(2AR) antagonistic activity at the cortical level.

Anxiolytic activity evaluation of four medicinal plants from Cameroon

Afrormosia laxiflora (A. laxiflora), Chenopodium ambrosioides (C. ambrosioides), Microglossa pyrifolia (M. pyrifolia) and Mimosa pudica (M. pudica) are plants used in traditional medicine in Cameroon to treat insomnia, epilepsy, anxiety, and agitation. They were evaluated for their anxiolytic like activity in mice. Animal models (elevated plus maze and stress-induced hyperthermia tests) were used. The four plants showed anxiolytic activity. In stress-induced hyperthermia test, A. laxiflora, C. ambrosioides, M. pyrifolia and M. pudica significantly antagonised the increase of temperature. ΔT° decreased from 0.75°C in the control group to 0.36°C at the dose of 110 mg/kg for A. laxiflora; from 1°C in the control group to -1.1°C at the dose of 120 mg/kg for C. ambrosioides; from 1.7°C in the control group to 0.2°C at the dose of 128 mg/kg for M. pyrifolia and from 1.3°C in the control group to 0.5°C at the dose of 180 mg/kg for M. pudica. In the elevated plus maze test, the four plants increased the number of entries into, percentage of entries into, and percentage of time in open arms. A. laxiflora, C. ambrosioides and M. pudica also reduced the percentage of entries and time in closed arms. In addition, C. ambrosioides, M. pyrifolia and M. pudica showed antipyretic activity by reducing the body temperature. The results suggested that C. ambrosioides, M. pyrifolia and M. pudica posses anxiolytic-like and antipyretic activities while A. laxiflora possesses only anxiolytic-like properties. These plants could be helpful in the treatment of anxiety and fever in traditional medicine in Cameroon.

The clinical implications of mouse models of enhanced anxiety

Mice are increasingly overtaking the rat model organism in important aspects of anxiety research, including drug development. However, translating the results obtained in mouse studies into information that can be applied in clinics remains challenging. One reason may be that most of the studies so far have used animals displaying 'normal' anxiety rather than 'psychopathological' animal models with abnormal (elevated) anxiety, which more closely reflect core features and sensitivities to therapeutic interventions of human anxiety disorders, and which would, thus, narrow the translational gap. Here, we discuss manipulations aimed at persistently enhancing anxiety-related behavior in the laboratory mouse using phenotypic selection, genetic techniques and/or environmental manipulations. It is hoped that such models with enhanced construct validity will provide improved ways of studying the neurobiology and treatment of pathological anxiety. Examples of findings from mouse models of enhanced anxiety-related behavior will be discussed, as well as their relation to findings in anxiety disorder patients regarding neuroanatomy, neurobiology, genetic involvement and epigenetic modifications. Finally, we highlight novel targets for potential anxiolytic pharmacotherapeutics that have been established with the help of research involving mice. Since the use of psychopathological mouse models is only just beginning to increase, it is still unclear as to the extent to which such approaches will enhance the success rate of drug development in translating identified therapeutic targets into clinical trials and, thus, helping to introduce the next anxiolytic class of drugs.

Behavioral disinhibition and reduced anxiety-like behaviors in monoamine oxidase B-deficient mice

Monoamine oxidase (MAO) B catalyzes the degradation of beta-phenylethylamine (PEA), a trace amine neurotransmitter implicated in mood regulation. Although several studies have shown an association between low MAO B activity in platelets and behavioral disinhibition in humans, the nature of this relation remains undefined. To investigate the impact of MAO B deficiency on the emotional responses elicited by environmental cues, we tested MAO B knockout (KO) mice in a set of behavioral assays capturing different aspects of anxiety-related manifestations, such as the elevated plus maze, defensive withdrawal, marble burying, and hole board. Furthermore, MAO B KO mice were evaluated for their exploratory patterns in response to unfamiliar objects and risk-taking behaviors. In comparison with their wild-type (WT) littermates, MAO B KO mice exhibited significantly lower anxiety-like responses and shorter latency to engage in risk-taking behaviors and exploration of unfamiliar objects. To determine the neurobiological bases of the behavioral differences between WT and MAO B KO mice, we measured the brain-regional levels of PEA in both genotypes. Although PEA levels were significantly higher in all brain regions of MAO B KO in comparison with WT mice, the most remarkable increments were observed in the striatum and prefrontal cortex, two key regions for the regulation of behavioral disinhibition. However, no significant differences in transcript levels of PEA's selective receptor, trace amine-associated receptor 1 (TAAR1), were detected in either region. Taken together, these results suggest that MAO B deficiency may lead to behavioral disinhibition and decreased anxiety-like responses partially through regional increases of PEA levels.

Anticonvulsant, anxiolytic, and sedative properties of the roots of Nauclea latifolia Smith in mice

Root bark of Nauclea latifolia Smith (Rubiaceae) was evaluated for its anticonvulsant, anxiolytic, and sedative activity in mice. Animal models (maximal electroshock-, pentylenetetrazol-, and strychnine-induced convulsions; N-methyl-D-aspartate-induced turning behavior; elevated plus maze; stress-induced hyperthermia; open field; and diazepam-induced sleep) were used. The decoction from the bark of the roots of N. latifolia strongly increased the total sleep time induced by diazepam. It also protected mice against maximal electroshock-, pentylenetetrazol-, and strychnine-induced seizures. In addition, turning behavior induced by N-methyl-D-aspartate was inhibited. N. latifolia antagonized, in a dose-dependent manner, stress-induced hyperthermia and reduced body temperature. In the elevated plus maze, N. latifolia increased the number of entries into, percentage of entries into, and percentage of time in open arms, and reduced rearing, head dipping, and percentage of time in closed arms. In the open field test, N. latifolia increased crossing and reduced rearing and defecation. It could be concluded that the decoction of N. latifolia, used in traditional medicine in Cameroon in the treatment of fever, malaria, insomnia, anxiety and epilepsy seemed to possess, sedative, anticonvulsant, anxiolytic and antipyretic properties in mice.

5-HT receptor subtypes involved in the anxiogenic-like action and associated Fos response of acute fluoxetine treatment in rats

RATIONALE

We have recently reported that acute treatment with the selective serotonin reuptake inhibitor fluoxetine exacerbates escape responses to airjet and facilitates airjet-induced activation of locus coeruleus (LC) neurons.

OBJECTIVE

Here we aimed to identify the 5-HT receptor subtype(s) mediating the anxiogenic-like effects of acute fluoxetine in this paradigm and to study whether chronic fluoxetine treatment would alter these responses.

METHODS

The expression of the immediate early gene c-fos was used as a marker of neuronal activation.

RESULTS

Acute fluoxetine increased the airjet-induced escape behaviour and Fos expression in the LC of saline-pretreated rats. Pretreatment with the 5-HT(2C/2B) antagonist SB 206553, but not with the 5-HT1A antagonist WAY 100635, the 5-HT1B antagonist SB 224289 or the 5-HT3 antagonist Y-25130 inhibited the fluoxetine-induced increase in escape behaviour and the associated elevated LC Fos response. The selective 5-HT2C agonist MK-212 mimicked the anxiogenic response of fluoxetine. Chronic treatment with fluoxetine abolished the anxiogenic-like effect and led to a normalization of the enhanced fluoxetine-induced Fos response to airjet.

CONCLUSIONS

Taken together, the results indicate that the anxiogenic-like effect as well as the facilitated neuronal reactivity induced by acute fluoxetine in the airjet model is mediated primarily by activation of 5-HT2C receptors.

The alkaloid alstonine: a review of its pharmacological properties

Indole compounds, related to the metabolism of tryptophan, constitute an extensive family, and are found in bacteria, plants and animals. Indolic compounds possess significant and complex physiological roles, and especially indole alkaloids have historically constituted a class of major importance in the development of new plant derived drugs. The indole alkaloid alstonine has been identified as the major component of a plant-based remedy, used in Nigeria to treat mental illnesses by traditional psychiatrists. Although it is certainly difficult to compare the very concept of mental disorders in different cultures, the traditional use of alstonine is remarkably compatible with its profile in experimental animals. Even though alstonine in mice models shows a psychopharmacological profile closer to the newer atypical antipsychotic agents, it also shows important differences and what seems to be an exclusive mechanism of action, not entirely clarified at this point. Considering the seemingly unique mode of action of alstonine and that its traditional use can be viewed as indicative of bioavailability and safety, this review focuses on the effects of alstonine in the central nervous system, particularly on its unique profile as an antipsychotic agent. We suggest that a thorough understanding of traditional medical concepts of health and disease in general and traditional medical practices in particular, can lead to true innovation in paradigms of drug action and development. Overall, the study of this unique indole alkaloid may be considered as another example of the richness of medicinal plants and traditional medical systems in the discovery of new prototypic drugs.

Double-blind, comparative study of cyamemazine vs. bromazepam in the benzodiazepine withdrawal syndrome

Cyamemazine is an anxiolytic antipsychotic, which reduces ethanol withdrawal symptoms. Here, we investigated if cyamemazine can be also effective as substitute drug to facilitate benzodiazepine withdrawal. A total of 168 patients treated with benzodiazepines for at least 3 months and with a <18 score in the Hamilton Anxiety Rating Scale (HARS) were included in the study. Previous benzodiazepine treatment was withdrawn, and patients were randomized to a 4-week treatment with cyamemazine (25-50 mg q.d.) or bromazepam (3-6 mg q.d.), followed by 2 weeks of placebo. The primary efficacy variable was the maximal anxiety rebound as measured with the HARS during the 42 days of treatment. No statistically significant differences between treatment groups were found for the extent or incidence of rebound anxiety. Considering all dropout patients as withdrawal failures, after 6 months of follow-up, 56/84 patients in the cyamemazine group (66.7%) and 55/84 patients in the bromazepam group (65.5%) were successfully withdrawn. 28 patients in the cyamemazine group and 18 in the bromazepam group had an adverse event, including anxiety, insomnia, dry mouth and somnolence. No extra-pyramidal symptoms were reported. In conclusion, cyamemazine was comparable to bromazepam in ensuring successful benzodiazepine withdrawal and in controlling the acute benzodiazepine withdrawal syndrome. Cyamemazine may be useful to facilitate benzodiazepine withdrawal in those patients where bromazepam substitution is not appropriate.

Double-blind study of cyamemazine and diazepam in the alcohol withdrawal syndrome

OBJECTIVE

Cyamemazine is an original phenothiazine derivative which showed similar efficacy and tolerability to lorazepam during ethanol withdrawal in mice. This study investigated cyamemazine for its efficacy and tolerability in alcohol-dependent patients electing an alcohol withdrawal procedure, in comparison with diazepam.

METHOD

A multicenter, randomized, double-blind study in 89 alcohol-dependent patients (CIWA-Ar score between 10 and 30), electing an alcohol withdrawal procedure, was used to find effective doses of cyamemazine and to compare it with diazepam for efficacy and tolerability. On day 1 (D(1)), cyamemazine or diazepam (50 mg and 10 mg capsule, respectively) were administered at hourly intervals to reduce CIWA-Ar = 5, up to a maximum of eight administrations. Starting from D(2), the compounds were given twice a day in progressively decreasing doses during a maximum period of 13 days (D(end)).

RESULTS

At h(8) (8 h after the first treatment of D(1)), therapeutic success (CIWA-Ar score </= 5) was achieved in 32 out of 43 ITT patients treated with cyamemazine (74.4%), a value very similar to that of diazepam (32/44; 72.7%). Most such patients (29/32) were controlled with 2-6 capsules of cyamemazine (100-300 mg). In the PP population, cyamemazine (n = 28) was significantly non-inferior to diazepam (n = 33), with a threshold of 10% for non-inferiority bound and 2.5% for one-sided type I error rate. Such therapeutic similarity was confirmed by the analysis of other efficacy criteria. Safety analysis did not show substantial differences between the two treatments.

CONCLUSIONS

Cyamemazine showed similar efficacy and tolerability to diazepam for the treatment of alcohol withdrawal symptoms at therapeutic doses in the range 100-300 mg.

A positron emission tomography (PET) study of cerebral dopamine D2 and serotonine 5-HT2A receptor occupancy in patients treated with cyamemazine (Tercian)

RATIONALE

Cyamemazine (Tercian) is an antipsychotic drug with anxiolytic properties. Recently, an in vitro study showed that cyamemazine possesses high affinity for serotonin 5-HT(2A) receptors, which was fourfold higher than its affinity for dopamine D(2) receptors (Hameg et al. 2003).

OBJECTIVES

The aim of this study is to confirm these previous data in vivo in patients treated with clinically relevant doses of Tercian.

METHODS

Eight patients received 37.5, 75, 150 or 300 mg/day of Tercian depending on their symptomatology. Dopamine D(2) and serotonin 5-HT(2A) receptor occupancies (RO) were assessed at steady-state plasma levels of cyamemazine with positron emission tomography (PET), using [(11)C]raclopride and [(11)C]N-methyl-spiperone, respectively. The effective plasma level of the drug leading to 50% of receptor occupancy was estimated by fitting RO with plasma levels of cyamemazine at the time of the PET scan.

RESULTS

Cyamemazine induced near saturation of 5-HT(2A) receptors (RO=62.1-98.2%) in the frontal cortex even at low plasma levels of the drug. On the contrary, occupancy of striatal D(2) receptors increased with plasma levels, and no saturation was obtained even at high plasma levels (RO=25.2-74.9%). The effective plasma level of cyamemazine leading to 50% of D(2) receptor occupancy was fourfold higher than that for 5-HT(2A) receptors. Accordingly, individual 5-HT(2A)/D(2) RO ratios ranged from 1.26 to 2.68. No patients presented relevant increased prolactin levels, and only mild extrapyramidal side effects were noticed on Simpson and Angus Scale.

CONCLUSION

This in vivo binding study conducted in patients confirms previous in vitro findings indicating that cyamemazine has a higher affinity for serotonin 5-HT(2A) receptors compared to dopamine D(2) receptors. In the dose range 37.5-300 mg, levels of dopamine D(2) occupancy remained below the level for motor side effects observed with typical antipsychotics and is likely to explain the low propensity of the drug to induce extrapyramidal side effects.

Psychopharmacological profile of the alkaloid psychollatine as a 5HT2A/C serotonin modulator

Behavioral effects of psychollatine, a new glycoside indole monoterpene alkaloid isolated from Psychotria umbellata, was investigated in models of anxiety, depression, memory, tremor, and sedation related to 5-HT and/or GABA neurotransmission. The GABA antagonist picrotoxin and the 5-HT2 antagonist ritanserin were used to examine the role of GABA and 5-HT2 receptors in psychollatine-induced effects. In the light/dark and hole-board models of anxiety, diazepam (0.75 mg/kg) and psychollatine (7.5 and 15 mg/kg) showed anxiolytic-like effect at doses that do not increase sleeping time nor alter spontaneous locomotor activity. The anxiolytic effect of psychollatine was prevented by prior administration of ritanserin, but not of picrotoxin, indicating that 5-HT2 but not GABA receptors are implicated. In the forced swimming model of depression, psychollatine (3 and 7.5 mg/kg) effects were comparable to the antidepressants imipramine (15 mg/kg) and fluoxetine (20 mg/kg). Psychollatine suppressed oxotremorine-induced tremors in all doses. In the step-down learning paradigm, diazepam (0.85 mg/kg), MK-801 (0.15 mg/kg), and psychollatine 100 mg/kg impaired the acquisition of learning and memory consolidation, without interfering with retrieval. It is concluded that the effects of psychollatine at the central nervous system involve serotonergic 5HT2(A/C) receptors.

Preclinical and clinical pharmacology of cyamemazine: anxiolytic effects and prevention of alcohol and benzodiazepine withdrawal syndrome

Several studies have suggested that the antipsychotic compound, cyamemazine, possesses anxiolytic properties in humans. The original pharmacological profile of cyamemazine (D(2), 5-HT(2A), 5-HT(2C), and 5-HT(3) receptor antagonist), which was established by binding, microdialysis and behavioral studies, is consistent with these observations. In the light/dark exploration test, cyamemazine demonstrated anxiolytic-like activity by acute, but not chronic administration. By chronic administration, however, cyamemazine increased the time spent in the open arms of the elevated plus maze (EPM) test demonstrating anxiolytic-like activity. The discrepancy between the results obtained in these tests by acute and chronic administration, could be due to a combination of dopamine D(2) receptor antagonism with antagonism of the 5-HT(2C) and 5-HT(3) receptors. The action of cyamemazine on both the dopaminergic system and 5-HT(3) receptors could also explain the activity of cyamemazine in the management of alcohol withdrawal demonstrated in preclinical studies. This potential indication for cyamemazine and its activity in benzodiazepine withdrawal syndrome have recently been investigated in clinical trials and the results of these studies are presented in this review.

Role of cyclic GMP in nitrous-oxide-induced anxiolytic-like behavior in the mouse light-dark exploration test

Nitric oxide (NO) has been implicated in the anxiolytic-like behavioral effects of nitrous oxide (N2O). This study was conducted to determine whether NO activates a soluble guanylyl cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway in the behavioral response to N2O in the light-dark exploration test. In mice pretreated with an sGC inhibitor, the increased light-compartment activity normally induced by N2O was significantly attenuated. Pretreatment with a cGMP phosphodiesterase inhibitor antagonized the anxiogenic effect of 15% N2O and enhanced the anxiolytic effect of 25% N2O, implying that cGMP reduces anxiety. These preliminary findings suggest that a signaling pathway involving NO and cGMP may mediate the behavioral effects of N2O.

Anxiolytic properties of the antipsychotic alkaloid alstonine

Anxiolytic properties may be a crucial feature of newer antipsychotics associated with the improvement of negative symptoms in schizophrenic patients. The indole alkaloid alstonine acts as an atypical antipsychotic in behavioral models, but differs in its dopamine and serotonin binding profile. The purpose of this study was to verify if alstonine possesses anxiolytic properties in mice. The hole-board and light/dark models were used; moreover, the participation of D(1), 5-HT(2), NMDA and gamma-aminobutyric acid (GABA) receptors was likewise investigated. Alstonine clearly behaves as anxiolytic in both hole-board and light/dark situations. Pretreatment with the 5-HT(2A/2C) serotonin receptor antagonist ritanserin reverted the effects of alstonine in both the hole-board and light/dark models, suggesting the involvement of these receptors in the alstonine mechanism of action. The involvement of glutamate NMDA receptors should also be considered, given that alstonine partially reversed the increase in locomotion induced by MK-801 in the hole board, as well as MK-801-induced hyperlocomotion in motor activity apparatus.

Acute fatal poisoning with cyamemazine

A case of fatal poisoning with cyamemazine is presented. The cyamemazine was identified in post-mortem blood using a specific gas chromatographic/mass spectrometry method. The autopsy blood concentration of cyamemazine was 1800 ng/ml. Chronic use of cyamemazine was demonstrated by the presence of the drug in hair. Two other drugs were also detected (bromazepam and trimeprazine). We think that this current blood concentration (1800 ng/ml) is a fatal blood concentration because of the negativity of the other parameters, but careful interpretation of analytical findings are important, the possibility that this death was a consequence of the toxicity of combined drugs could not be excluded. Not many therapeutics and toxic levels were previously reported in overdosage cases in which cyamemazine was involved. We consider that this concentration is only of guidance value for a fatal cyamemazine poisoning.

The mouse light/dark box test

The light/dark test is based on the innate aversion of rodents to brightly illuminated areas and on the spontaneous exploratory behaviour of rodents in response to mild stressors, that is, novel environment and light. The test apparatus consists of a small dark safe compartment (one third) and a large illuminated aversive compartment (two thirds). The test was developed with male mice. The strain, weight and age may be crucial factors. The extent to which an anxiolytic compound can facilitate exploratory activity depends on the baseline level in the control group. Differences between the type and severity of external stressors might account for the variable results reported by different laboratories. The light/dark test may be useful to predict anxiolytic-like or anxiogenic-like activity in mice. Transitions have been reported to be an index of activity-exploration because of habituation over time, and the time spent in each compartment to be a reflection of aversion. Classic anxiolytics (benzodiazepines) as well as the newer anxiolytic-like compounds (e.g. serotonergic drugs or drugs acting on neuropeptide receptors) can be detected using this paradigm. It has the advantages of being quick and easy to use, without requiring the prior training of animals.

Affinity of cyamemazine, an anxiolytic antipsychotic drug, for human recombinant dopamine vs. serotonin receptor subtypes

Animal studies indicate that the anxiolytic properties of the antipsychotic agent cyamemazine may result from blockade of serotonin 5-HT(2C) receptors and to a lesser extent from blockade of serotonin 5-HT(3) receptors. Here, we used human recombinant receptors to determine the relative affinity of cyamemazine for serotonin and dopamine receptor subtypes. In addition, cyamemazine was tested in other brain receptor types and subtypes which are considered to mediate central nervous systems effects of drugs. Hence, cyamemazine affinity was determined in human recombinant receptors expressed in CHO cells (hD(2), hD(3), and hD(4.4) receptors, h5-HT(1A), h5-HT(2A), h5-HT(2C), and h5-HT(7), and hM(1), hM(2), hM(3), hM(4), and hM(5) receptors), L-cells (hD(1) receptor), and HEK-293 cells (h5-HT(3) receptors) or natively present in N1E-115 cells (5-HT(3) receptors) or in rat cerebral cortex (non-specific alpha(1)- and alpha(2)-adrenoceptors, GABA(A) and GABA(B) receptors, H(3) histamine receptors), and guinea-pig cerebellum (H(1) central and H(2) histamine receptors) membranes. Similarly to atypical antipsychotics, cyamemazine exhibited high affinity for: (i) h5-HT(2A) receptors (K(i)=1.5+/-0.7 nM, mean+/-SEM, N=3) and this was four times higher than for hD(2) receptors (K(i)=5.8+/-0.8 nM), (ii) h5-HT(2C) receptors (K(i)=11.8+/-2.2nM), and (iii) 5-HT(7) receptors (K(i)=22 nM). Conversely, cyamemazine exhibited very low affinity for h5-HT(3) receptors (K(i)=2.9+/-0.4 microM). In conclusion, similarly to atypical antipsychotic agents, cyamemazine, possesses high affinity for h5-HT(2A), h5-HT(2C), and h5-HT(7) receptors, a feature which can explain its low propensity to cause extrapyramidal adverse reactions in clinical practice. The high affinity for h5-HT(2C) receptors, but not for h5-HT(3) receptors, can account for the anxiolytic activity of cyamemazine in human subjects.

Molecular targets in the treatment of anxiety

Although the cathecholamine systems have long been the focus of drug therapy in anxiety and depression, the development of novel drugs specifically aimed at new targets within these traditional neurotransmitter systems and at targets outside of these systems is now propelling the field of drug development in anxiety. A greater understanding of regional brain networks implicated in stress, anxiety, and anxious behaviors has provided localized targets for anxiolytics. Within the serotonin and norepinephrine systems, increased understanding of postsynaptic receptor regulation with chronic treatment and cross-system effects of drug therapy have been critical in furthering our understanding of effective pharmacological interventions. Receptors within the glutamate, gamma-aminobutyric acid, and neuropeptide systems provide a rich diversity of drug targets, both in localization and function. While acknowledging significant clinical and biological differences between the various anxiety disorders, an important aspect of modern neurobiological research is to look for similarities among these disorders, given that they are highly comorbid with each other and often respond to the same spectrum of treatments. Here we review current views on both traditional and new molecular targets in the treatment of anxiety, realizing that the ultimate challenge in effective anxiolytic drug development may be achieving specificity in brain regions important in generating and sustaining anxiety.

5-HT2A receptor antagonist properties of cyamemazine in rat and guinea pig smooth muscle

5-HT(2A) receptor antagonism seems to explain the low incidence of extrapyramidal side effects with atypical neuroleptics. Whether the neuroleptic cyamemazine, which at low doses is also devoid of extrapyramidal side effects, possesses 5-HT(2A) receptor antagonist properties is unknown. Cyamemazine was tested for its ability to antagonize 5-HT(2A)-mediated responses in isolated rat aorta and guinea pig trachea and to displace [3H]ketanserin specifically bound to rat brain membranes. In isolated rat aorta, cyamemazine potently and competitively antagonized serotonin-dependent contractions (pA(2)=8.82+/-0.26, n=7; Schild's slope=1.02+/-0.29). In this test, cyamemazine was of similar potency as ketanserin (pA(2)=8.23). In isolated guinea pig trachea, cyamemazine reduced maximum contractile responses to serotonin with pIC(50)=7.92+/-0.35, (n=4), whereas ketanserin exhibited a pIC(50)=8.79. Finally, cyamemazine displaced [3H]ketanserin specifically bound to rat brain membranes with pK(i)=8.76+/-0.53 (n=3). In conclusion, cyamemazine behaves as a potent antagonist at 5-HT(2A) receptors, which compares well with the reference compound, ketanserin. Whether this 5-HT(2A) receptor antagonist action of cyamemazine can explain its low incidence of extrapyramidal side effects deserves further investigation.