meta-Chlorophenylpiperazine decreases slow-wave sleep in humans

Sleep Disturbances in Schizophrenia

Sleep disturbances are prevalent in patients with schizophrenia and play a critical role in the morbidity and mortality associated with the illness. Subjective and objective assessments of sleep in patients with schizophrenia have identified certain consistent findings. Findings related to the sleep structure abnormalities have shown correlations with important clinical aspects of the illness. Disruption of specific neurotransmitter systems and dysregulation of clock genes may play a role in the pathophysiology of schizophrenia-related sleep disturbances. Antipsychotic medications play an important role in the treatment of sleep disturbances in these patients and have an impact on their sleep structure.

Serotonin conflict in sleep-feeding

Short sleep duration has been suggested to be a risk factor for weight gain and adiposity. Serotonin (5-HT) substantially contributes to the regulation of sleep and feeding behavior. Although 5-HT predominately promotes waking and satiety, the effects of 5-HT depend on 5-HT receptor function. The 5-HT1A, 5-HT1B, 5-HT2A, 5-HT2C, 5-HT6, and 5-HT7 receptors reportedly contribute to sleep-waking regulation, whereas the 5-HT1B and 5-HT2C receptors contribute to the regulation of satiety. The 5-HT1B and 2C receptors may therefore be involved in the regulation of sleep-feeding. In genetic studies, 5-HT1B receptor mutant mice display greater amounts of rapid eye movement sleep (REMS) than wild-type mice, while displaying no effects on waking or slow wave sleep (SWS). On the other hand, 5-HT2C receptor mutant mice exhibit increased wakefulness and decreased SWS, without any effect on REMS. Moreover, the 5-HT2C receptor mutants display leptin-independent hyperphagia, leading to a middle-aged onset of obesity, whereas 5-HT1B receptor mutants do not display any effect on food intake. Thus, the genetic deletion of 5-HT2C receptors results in sleep loss-associated hyperphagia, leading to the late onset of obesity. This is a quite different pattern of sleep-feeding behavior than is observed in disturbed leptin signaling, which displays an increase in sleep-associated hyperphagia. In pharmacologic studies, 5-HT1B and 5-HT2C receptors upregulate wakefulness and downregulate SWS, REMS, and food intake. These findings suggest that 5-HT1B/2C receptor stimulation induces sleep loss-associated anorexia. Thus, the central 5-HT regulation of sleep-feeding can be dissociated. Functional hypothalamic proopiomelanocortin and orexin activities may contribute to the dissociated 5-HT regulation.

Antagonism of serotonergic 5-HT2A/2C receptors: mutual improvement of sleep, cognition and mood?

Serotonin [5-hydroxytryptamine (5-HT)] and 5-HT receptors are involved in sleep and in waking functions such as cognition and mood. Animal and human studies support a particular role for the 5-HT(2A) receptor in sleep, which has led to renewed interest in this receptor subtype as a target for the development of novel pharmacological agents to treat insomnia. Focusing primarily on findings in healthy human volunteers, a review of the available data suggests that antagonistic interaction with 5-HT(2A) receptors (and possibly also 5-HT(2C) receptors) prolongs the duration of slow wave sleep and enhances low-frequency (< 7 Hz) activity in the sleep electroencephalogram (EEG), a widely accepted marker of sleep intensity. Despite certain differences, the changes in sleep and the sleep EEG appear to be remarkably similar to those of physiologically more intense sleep after sleep deprivation. It is currently unclear whether these changes in sleep are associated with improved vigilance, cognition and mood during wakefulness. While drug-induced interaction with sleep must be interpreted cautiously, too few studies are available to provide a clear answer to this question. Moreover, functional relationships between sleep and waking functions may differ between healthy controls and patients with sleep disorders. A multimodal approach investigating subjective and objective aspects of sleep and wakefulness provides a promising research avenue for shedding light on the complex relationships among 5-HT(2A/2C) receptor-mediated effects on sleep, the sleep EEG, cognition and mood in health and various diseases associated with disturbed sleep and waking functions.

Daytime Ayahuasca administration modulates REM and slow-wave sleep in healthy volunteers

OBJECTIVES

Ayahuasca is a traditional South American psychoactive beverage and the central sacrament of Brazilian-based religious groups, with followers in Europe and the United States. The tea contains the psychedelic indole N,N-dimethyltryptamine (DMT) and beta-carboline alkaloids with monoamine oxidase-inhibiting properties that render DMT orally active. DMT interacts with serotonergic neurotransmission acting as a partial agonist at 5-HT(1A) and 5-HT(2A/2C) receptor sites. Given the role played by serotonin in the regulation of the sleep/wake cycle, we investigated the effects of daytime ayahuasca consumption in sleep parameters.

MEASUREMENTS AND RESULTS

Subjective sleep quality, polysomnography (PSG), and spectral analysis were assessed in a group of 22 healthy male volunteers after the administration of a placebo, an ayahuasca dose equivalent to 1 mg DMT kg(-1) body weight, and 20 mg d-amphetamine, a proaminergic drug, as a positive control. Results show that ayahuasca did not induce any subjectively perceived deterioration of sleep quality or PSG-measured disruptions of sleep initiation or maintenance, in contrast with d-amphetamine, which delayed sleep initiation, disrupted sleep maintenance, induced a predominance of 'light' vs 'deep' sleep and significantly impaired subjective sleep quality. PSG analysis also showed that similarly to d-amphetamine, ayahuasca inhibits rapid eye movement (REM) sleep, decreasing its duration, both in absolute values and as a percentage of total sleep time, and shows a trend increase in its onset latency. Spectral analysis showed that d-amphetamine and ayahuasca increased power in the high frequency range, mainly during stage 2. Remarkably, whereas slow-wave sleep (SWS) power in the first night cycle, an indicator of sleep pressure, was decreased by d-amphetamine, ayahuasca enhanced power in this frequency band.

CONCLUSIONS

Results show that daytime serotonergic psychedelic drug administration leads to measurable changes in PSG and sleep power spectrum and suggest an interaction between these drugs and brain circuits modulating REM and SWS.

Sleep in schizophrenia patients and the effects of antipsychotic drugs

Insomnia is a common feature in schizophrenia. However, it seldom is the predominant complaint. Nevertheless, severe insomnia is often seen during exacerbations of schizophrenia, and may actually precede the appearance of other symptoms of relapse. The sleep disturbances of either never-medicated or previously treated schizophrenia patients are characterized by a sleep-onset and maintenance insomnia. In addition, stage 4 sleep, slow wave sleep (stages 3 and 4), non-REM (NREM) sleep in minutes and REM latency are decreased. The atypical antipsychotics olanzapine, risperidone, and clozapine significantly increase total sleep time and stage 2 sleep. Moreover, olanzapine and risperidone enhance slow wave sleep. On the other hand, the typical antipsychotics haloperidol, thiothixene, and flupentixol significantly reduce stage 2 sleep latency and increase sleep efficiency. Future research should address: (1) the sleep patterns in subtypes of schizophrenia patients; (2) the role of neurotransmitters other than dopamine in the disruption of sleep in schizophrenia; (3) the functional alterations in CNS areas related to the pathophysiology of schizophrenia during NREM sleep and REM sleep (brain imaging studies); (4) the short-term, intermediate-term, and long-term effects of atypical antisychotics on sleep variables.

The application of the principles of clinical drug development to pharmacological challenge tests of the serotonergic system

Pharmacological challenge tests of the serotonergic system have extensively been used during the past 20 years and new tests are in development. It is of crucial importance to standardize challenge tests to ascertain that observed variability is due to the state of the challenged system and not caused by variability of the test itself. This is even more important now that challenge tests increasingly are used in complex studies (e.g. in combination with neuroimaging and in large population studies with repeated tests over time). The Guideline for Good Clinical Practice may be of great help in the standardization of these tests. This is a recently developed guideline for pharmaceutical drug-development, which increasingly is used as a reference for all research in humans. To exemplify the possible usefulness of this approach, we apply it to meta-chlorophenylpiperazine, one of the most commonly used drugs in serotonergic challenge tests. We conclude that much can be learned from the development of this particular challenge. In the discussion, we address general issues that emerged from this review and their relevance to the development of future challenge tests.

Sleep-wake mechanisms and drug discovery: sleep EEG as a tool for the development of CNS-acting drugs

Sleep laboratory investigations constitute a unique noninvasive tool to analyze brain functioning, Polysomnographic recordings, even in the very early phase of development in humans, are mandatory in a developmental plan of a new sleep-acting compound. Sleep is also an interesting tool for the development of other drugs acting on the central nervous system (CNS), Indeed, changes in sleep electroencephalographic (EEG) characteristics are a very sensitive indication of the objective central effects of psychoactive drugs, and these changes are specific to the way the drug acts on the brain neurotransmitter systems. Moreover, new compounds can be compared with reference drugs in terms of the sleep EEG profile they induce. For instance, cognitive enhancers involving cholinergic mechanism have been consistently demonstrated to increase rapid eye movement (REM) sleep pressure, and studying drug-induced slow wave sleep (SWS) alteration is a particularly useful tool for the development of CNS compounds acting at the 5-HT(2A/C) receptor, such as most atypical antipsychotics and some antidepressant drugs. The sleep EEG profile of antidepressants, and particularly their effects on REM sleep, are specific to their ability to enhance noradrenergic or serotonergic transmission, it is suggested that the effects of noradrenergic versus serotonergic reuptake inhibition could be disentangled using specific monoamine depletion tests and by studying drug effects on sleep microsiructure.

Sleep-wake effects of meta-chlorophenyl piperazine and mianserin in the behaviorally depressed rat

The present study examined the effects of meta-chlorophenyl piperazine (mCPP) and mianserin on the sleep-wake cycle of the clomipramine-induced behaviorally screened depressed rats. Six-hour polygraphic recordings were made between 06:00 and 12:00 h, after a single injection of either saline or mianserin or mCPP into the lateral cerebral ventricle (i.c.v.) of both the depressed (n=12) and control rats (n=12). The injection of mCPP in the depressed rats caused a significant reduction in the total duration and number of rapid eye movement (REM) sleep episodes while it increased the REM sleep onset latency compared to the control saline injections. The injection of mianserin in the depressed rats also caused a significant reduction in the total duration and number of REM sleep episodes without changing the REM sleep latency. These results demonstrate for the first time that the central administration of mCPP and mianserin could act as an antidepressant in the clomipramine-induced rat model of depression.

Effect of risperidone on sleep in schizophrenia: a comparison with haloperidol

The aim of the present study is to determine the effect of the atypical antipsychotic drug, risperidone on sleep measures in patients with schizophrenia by polysomnography. Sleep measures were compared in five schizophrenic patients who were receiving risperidone alone and five schizophrenic patients who were receiving haloperidol alone. There were no differences between these two groups in their demographic characteristics or doses of antipsychotic medication. The slow wave sleep period was significantly longer in the risperidone-treated group than in the haloperidol-treated group. There were, however, no other significant differences in sleep variables between these groups. This difference in the effect on sleep between risperidone and haloperidol may be due to their differential actions on serotonin (5-HT2) receptors. Risperidone, which is known to be a serotonin-dopamine antagonist, has the potential to improve the quality of sleep in schizophrenic patients.

Synthesis and structure-activity relationship of 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives: a novel series of 5-HT(2A/2C) receptor antagonists. Part 1

The synthesis of a series of novel 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives as well as their 5-HT(2A/2C) and H(1) receptor binding affinities are described. The in vivo activity as potential anxiolytics of the synthesised compounds was measured in a mCPP challenge test. One of the compounds, 2a, proved to be a potent 5-HT(2A/2C) receptor antagonist showing as well oral activity and therefore could be considered as a potential anxiolytic/antidepressant agent.

Effects of the selective activation of 5-HT3 receptors on sleep: a polysomnographic study in healthy volunteers

The respective role of various classes of central serotonin (5-HT) receptors in the regulation of sleep-wakefulness cycles has been the subject of many studies. Notably, it has been reported that 5-HT1A/B receptors are involved in the regulation of rapid eye movement sleep (REMS) and that 5-HT2A/C receptors participate in the control of slow wave sleep (SWS), but the role of 5-HT3 receptors is less well characterised. In this study we investigated the effects of SR 57227A, a potent and selective 5-HT3 agonist, on the sleep EEG of normal young male volunteers. SR 57227A (2.5, 5, 10, 20, 40 mg o.d. and 20 mg b.i.d.) or placebo were administered during 7 consecutive days in seven groups of ten subjects using a parallel group design. Sleep EEG recordings were performed on days 6 and 7 after an habituation session. SR 57227A produced a dose-dependent shift of REMS toward the end of the night without changing REMS and SWS duration nor altering sleep continuity. It suggests a role for the 5-HT3 receptor in the human sleep-wakefulness cycle and particularly in REMS regulation.

Olanzapine increases slow-wave sleep: evidence for blockade of central 5-HT(2C) receptors in vivo

BACKGROUND

The study aimed to determine the effects of the atypical antipsychotic agent, olanzapine, on the polysomnogram in healthy subjects. We predicted that olanzapine, via serotonin(2C) (5-HT(2C)) receptor blockade, would increase slow-wave sleep (SWS).

METHODS

We studied the effects of single evening doses of olanzapine (5 mg and 10 mg orally) on the polysomnogram of 9 healthy male volunteers, using a placebo-controlled, double-blind, cross-over design.

RESULTS

Compared to placebo, the 5-mg and 10-mg doses of olanzapine significantly increased SWS, sleep continuity measures, and subjective sleep quality. In addition, 10 mg of olanzapine suppressed rapid eye movement (REM) sleep and increased REM sleep latency.

CONCLUSIONS

Olanzapine (5 mg and 10 mg) produced substantial (59.1% and 83.3%) and highly significant dose-related increases in SWS in humans probably via blockade of brain 5-HT(2C) receptors. 5-HT(2C) receptor antagonism may account for some of the therapeutic and adverse effects of olanzapine therapy.

Prenatal stress is associated with depression-related electroencephalographic sleep changes in adult male rats: a preliminary report

1. Prenatal stress in rats has been shown to produce long-term behavioral, neuroendocrine and neurochemical changes. These changes may model aspects of human depressive illness. 2. In this pilot investigation, adult male offspring exposed to stress in utero and non-stressed controls were studied using 24-hour electroencephalographic sleep recordings. 3. Prenatally stressed animals demonstrated reduced latency to the onset of rapid eye movement (REM) sleep, prolongation of the first REM episode, and diminished slow-wave sleep. 4. Although preliminary, the observed changes parallel those seen in studies of human depression. These data further support the face validity of the prenatal stress model as a potential tool for future studies on the pathophysiology of depressive disorder.

Age-related effect of ritanserin on the sleep-waking phases in rats

The age-related effect of the specific 5-hydroxytryptamine-2A/2C (5-HT(2A/2C)) antagonist ritanserin at two doses 0.63 mg/kg and 2.5 mg/kg) on six sleep-waking phases in young, middle-aged, and old male Wistar rats was electroencephalographically (EEG) examined. Only in the young and middle-aged rats, ritanserin enhanced slow wave sleep and reduced wakefulness in a dose-dependent manner. Ritanserin suppressed paradoxical sleep, such that this effect did not depend on the age. Although the effect of ritanserin on slow wave sleep was significantly smaller in the old compared to the young and the middle-aged rats, ritanserin produced an apparent sleep-improving effect in the old age group.

Brain 5-HT neurotransmission during paroxetine treatment

BACKGROUND

Animal experimental studies suggest that repeated administration of selective serotonin reuptake inhibitors (SSRIs) produces complex adaptive changes in brain serotonin (5-HT) pathways. The effect of these adaptive changes on different aspects of brain 5-HT neurotransmission and their clinical consequences are not well understood.

METHOD

We studied the effect of repeated administration of the SSRI, paroxetine (20 mg daily), on the cortisol responses to the 5-HT precursor, 5-hydroxytryptophan (5-HTP), in healthy subjects and depressed patients.

RESULTS

In healthy subjects, following one week of paroxetine treatment there was a large increase in the cortisol response to 5-HTP. This increase had all but disappeared following 3 weeks treatment. In contrast, in depressed patients treated with paroxetine for 8 weeks, the cortisol response to 5-HTP was significantly increased.

CONCLUSIONS

SSRI treatment in depressed patients produces a persistent increase in the cortisol response to 5-HTP, a probable measure of neurotransmission at central 5-HT2 receptors. Potentiation of 5-HT2 neurotransmission is unlikely to account for the efficacy of SSRIs in major depression but might underlie their actions in obsessive-compulsive disorder and also perhaps certain of their adverse effects, notably sexual dysfunction.

The effects of paroxetine and nefazodone on sleep: a placebo controlled trial

We studied the effect of acute (1 day) and subacute (16 days) administration of the new antidepressant, nefazodone (400 mg daily), and the selective serotonin re-uptake inhibitor (SSRI), paroxetine (30 mg daily), on the sleep polysomnogram of 37 healthy volunteers using a random allocation, double-blind, placebo-controlled design. Compared to placebo, paroxetine lowered rapid eye movement (REM) sleep and increased REM latency. In addition, paroxetine increased awakenings and reduced Actual Sleep Time and Sleep Efficiency. In contrast, nefazodone did not alter REM sleep and had little effect on measures of sleep continuity. We conclude that in contrast to typical SSRIs, nefazodone administration has little effect on sleep architecture in healthy volunteers.

Acute and subchronic effects of nefazodone and imipramine on highway driving, cognitive functions, and daytime sleepiness in healthy adult and elderly subjects

The acute and subchronic effects of two dosages of a new serotonergic antidepressant, nefazodone, and those of the tricyclic imipramine were examined in a double-blind, crossover, placebo-controlled study. Twenty-four healthy subjects from two age groups (12 adults and 12 elderly from both sexes) received the four treatments (nefazodone, 100 and 200 mg twice daily; imipramine, 50 mg twice daily; and placebo) for 7 days with a 7-day washout period. Measurements were performed after the morning doses on day 1 and day 7. These included a standard over-the-road highway driving test, a psychomotor test battery, and sleep latency tests. Blood samples were taken on both days and analyzed to determine concentrations of parent drugs and their major metabolites. The main results showed that the reference drug, imipramine, had a detrimental effect after a single dose on lateral position control in the driving test, primarily in the adult group, that diminished after repeated dosing. Minor impairment on psychomotor test performance was found with both days. On the other hand, a single administration of both doses of nefazodone did not impair highway driving performance (even showed some improvement) and had no or only minor effects on psychomotor performance. After repeated dosing, nefazodone 200 mg twice daily (but not the 100-mg dose) produced slight impairment of lateral position control; dose-related impairment of cognitive and memory functions was found. The effects of nefazodone were generally in the same direction in both age groups. Significant correlations were found between steady-state concentrations of nefazodone in plasma (200-mg, twice-daily condition) as well as imipramine, and reaction time changes in a memory scanning task. Neither drug appeared to induce daytime sleepiness as measured by the sleep latency tests.

Effect of pharmacologic treatments on the sleep of depressed patients

Antidepressant drugs produce striking effects on sleep architecture that are best understood in terms of their interactions with the monoamine pathways controlling sleep and wakefulness. Many different antidepressant drugs, including tricyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs), and selective 5-hydroxytryptamine (5-HT; serotonin) reuptake inhibitors (SSRIs), decrease rapid eye movement (REM) sleep. The reduction in REM sleep produced by antidepressants may be an important part of their mechanism of action; however, the ability of new antidepressant compounds, such as nefazodone and moclobemide, to increase REM sleep throws doubt on this suggestion. The effects of antidepressants on slow-wave sleep (SWS) are quite diverse; in general, antidepressants having significant 5-HT2A/2C receptor antagonist properties increase SWS, whereas other drugs, such as SSRIs or MAOIs, either lower SWS or produce no change. Sleep continuity is improved acutely following administration of antidepressants with sedating properties such as certain TCAs, trazodone, and mianserin. Some nonsedating drugs (ritanserin and nefazodone) also improve sleep continuity measures, possibly through 5-HT2A/2C receptor blockade.

Slow wave sleep in humans: role of 5-HT2A and 5-HT2C receptors

We studied the effects of the 5-HT2 receptor antagonists, ritanserin and ketanserin, on the sleep of healthy volunteers in order to clarify the role of 5-HT2A and 5-HT2C receptors in the regulation of slow wave sleep (SWS) in humans. Ritanserin, 5 mg, produced a substantially larger increase in SWS (51.4%) than either ketanserin, 20 mg (17.2%) or ketanserin, 40 mg (24.4%). Ritanserin has a significantly higher affinity than ketanserin for 5-HT2C receptor binding sites in the human brain and, based on estimates of per cent occupancy by the two compounds at brain 5-HT2A and 5-HT2C receptors, we conclude that SWS in humans is primarily regulated by 5-HT2C receptors.