Presynaptic alpha 2-adrenoceptor function and sleep in man: studies with clonidine and idazoxan

Sleep disturbances in autism spectrum disorder: Animal models, neural mechanisms, and therapeutics

Sleep is crucial for brain development. Sleep disturbances are prevalent in children with autism spectrum disorder (ASD). Strikingly, these sleep problems are positively correlated with the severity of ASD core symptoms such as deficits in social skills and stereotypic behavior, indicating that sleep problems and the behavioral characteristics of ASD may be related. In this review, we will discuss sleep disturbances in children with ASD and highlight mouse models to study sleep disturbances and behavioral phenotypes in ASD. In addition, we will review neuromodulators controlling sleep and wakefulness and how these neuromodulatory systems are disrupted in animal models and patients with ASD. Lastly, we will address how the therapeutic interventions for patients with ASD improve various aspects of sleep. Together, gaining mechanistic insights into the neural mechanisms underlying sleep disturbances in children with ASD will help us to develop better therapeutic interventions.

When the Locus Coeruleus Speaks Up in Sleep: Recent Insights, Emerging Perspectives

For decades, numerous seminal studies have built our understanding of the locus coeruleus (LC), the vertebrate brain’s principal noradrenergic system. Containing a numerically small but broadly efferent cell population, the LC provides brain-wide noradrenergic modulation that optimizes network function in the context of attentive and flexible interaction with the sensory environment. This review turns attention to the LC’s roles during sleep. We show that these roles go beyond down-scaled versions of the ones in wakefulness. Novel dynamic assessments of noradrenaline signaling and LC activity uncover a rich diversity of activity patterns that establish the LC as an integral portion of sleep regulation and function. The LC could be involved in beneficial functions for the sleeping brain, and even minute alterations in its functionality may prove quintessential in sleep disorders.

Effects of olanzapine, risperidone and haloperidol on sleep after a single oral morning dose in healthy volunteers

OBJECTIVES

To compare the effects of typical and atypical antipsychotic drugs on sleep activity and subjective sleep quality.

DESIGN

Randomised, double-blind, placebo-controlled, four-period cross-over, clinical trial was used to evaluate the effects of active treatments on objective and subjective sleep variables.

SETTING

Sleep laboratory evaluation.

PARTICIPANTS

Twenty healthy young volunteers, both sexes.

INTERVENTIONS

Single oral morning administrations of olanzapine 5 mg, risperidone 1 mg, haloperidol 3 mg and placebo.

MEASUREMENTS AND RESULTS

Five polysomnographic nights were evaluated: one control night and one after each intervention. Significant increase in total sleep time, sleep efficiency, slow wave sleep (SWS) and rapid eye movement (REM) sleep with decreases in wake time were observed after olanzapine. Decreases in wake time, REM sleep and stage shifts together with increases in stage 2 were obtained after risperidone. Haloperidol showed only a tendency to increase sleep efficiency and stage 2 and to decrease wake time. Olanzapine showed decreases in power density in frequencies higher than 10 Hz during all sleep stages and in frequencies lower than 5 Hz range in SWS; decreases in the dynamics of spindle frequency activity (SFA) in the second and fourth non-rapid eye movement (NREM) episodes were also obtained. Risperidone presented increases in the 3.6-10.8 Hz frequency range in NREM sleep stages and in stage 2. Haloperidol also showed increases in NREM sleep stages and in stage 2, but these were in frequencies higher than 10 Hz, with increases in the dynamics of SFA in the first NREM episode. Only a significant improvement in subjective sleep quality was observed after olanzapine.

CONCLUSIONS

Antipsychotics showed different sleep changes as their neurochemical profiles were distinct. These changes were observed even when the drug was administered 15 h before going to bed.

Effects of reboxetine on sleep and nocturnal cardiac autonomic activity in patients with dysthymia

Antidepressants may have sleep and autonomic side-effects. The acute and long-term effect of reboxetine (2 mg b.i.d.) on sleep and cardiac autonomic activity was compared with that of placebo in a single-blind study. Twelve patients affected by dysthymia underwent four polysomnographic studies at baseline (placebo); at night 3 (reboxetine; acute effect); at night 9 (reboxetine; intermediate-term effect); and at night 122 (reboxetine; chronic effect). After the first administration, reboxetine increased time awake after sleep onset, number of awakenings, percentage of stages 1 and 2 non-rapid eye movement (REM), and reduced the amount of stages 3-4 non-REM, but all these effects disappeared by continuing treatment. However, reboxetine caused a persistent suppression of REM sleep, which was accompanied by an increase of REM sleep latency. The spectral analysis of heart rate variability showed a trend towards an increase in sympathetic activity with both acute and intermediate reboxetine use. Long-term treatment with 4 mg reboxetine does not cause significant changes in cardiac autonomic function.

Clonidine effects on all-night human sleep: opposite action of low- and medium-dose clonidine on human NREM-REM sleep proportion

Norepinephrine (NE) is considered to play a permissive role in the occurrence of rapid eye movement (REM) sleep. Clonidine is an NE alpha-2-receptor agonist, which has been considered to act mainly on the autoreceptors of presynaptic noradrenergic neurons to reduce their release of NE. However, previous studies of clonidine effects on REM sleep have produced controversial results and the effects of clonidine remain uncertain. To clarify the pharmacological effects of clonidine on human sleep, the sleep electroencephalograms (EEG) recorded from 15 young normal subjects after a single administration of either a low (25 micro g) or medium (150 micro g) dose of clonidine were examined, and fast Fourier transformation (FFT) spectral analyses of the C3-A2 EEG were performed. Low-dose clonidine significantly increased the amount of REM sleep and decreased the amount of non-REM (NREM) sleep during the second one-third of the drug nights compared to the corresponding hours of baseline night recordings. In contrast, medium-dose clonidine significantly decreased REM and increased NREM on drug nights compared to baseline nights in the entire night. The opposite actions of low and medium doses of clonidine on NREM-REM proportion may indicate that low-dose clonidine mainly affects the alpha-2-receptors on locus coeruleus-NE neurons presynaptically, reducing the release of NE, whereas medium-dose clonidine acts more post-synaptically.

Effects of drugs on sleep

Many commonly prescribed medications and substances of abuse can have significant effects on sleep and wakefulness. Chronic use or abuse of certain drugs may lead to the development of substance-related sleep disorders. Primary sleep disorders, such as apnea, periodic movement disorders, and parasomnias, may be exacerbated by various drugs. This article summarizes the effects of widely used medications and recreational drugs on sleep.

The neuropsychology of REM sleep dreaming

Recent PET imaging and brain lesion studies in humans are integrated with new basic research findings at the cellular level in animals to explain how the formal cognitive features of dreaming may be the combined product of a shift in neuromodulatory balance of the brain and a related redistribution of regional blood flow. The human PET data indicate a preferential activation in REM of the pontine brain stem and of limbic and paralimbic cortical structures involved in mediating emotion and a corresponding deactivation of dorsolateral prefrontal cortical structures involved in the executive and mnemonic aspects of cognition. The pontine brainstem mechanisms controlling the neuromodulatory balance of the brain in rats and cats include noradrenergic and serotonergic influences which enhance waking and impede REM via anticholinergic mechanisms and cholinergic mechanisms which are essential to REM sleep and only come into full play when the serotonergic and noradrenergic systems are inhibited. In REM, the brain thus becomes activated but processes its internally generated data in a manner quite different from that of waking.

Effects of drugs on sleep

Many commonly prescribed medications and substances of abuse can have significant effects on sleep and wakefulness. Chronic use or abuse of certain drugs may lead to the development of substance-related sleep disorders. Primary sleep disorders, such as apnea, periodic movement disorders, and parasomnias, may be exacerbated by various drugs. This article summarizes the effects of widely used medications and recreational drugs on sleep.

Idazoxan and response to typical neuroleptics in treatment-resistant schizophrenia. Comparison with the atypical neuroleptic, clozapine

BACKGROUND

We investigated whether antagonism of alpha 2 adrenergic receptors would augment treatment response in schizophrenia, by administering idazoxan, an alpha 2 antagonist drug, to treatment-resistant patients on typical neuroleptics.

METHOD

Seventeen hospitalised treatment-resistant patients with DSM-III-R schizophrenia or schizoaffective disorder were studied on typical neuroleptic treatment, on treatment with idazoxan plus typical neuroleptic, and after discontinuation of idazoxan, in fixed, non-random order, and under double-blind, placebo-controlled conditions.

RESULTS

The addition of idazoxan to fluphenazine treatment resulted in significant reductions of global psychosis and total, positive and negative symptoms on the Brief Psychiatric Rating Scale, compared to neuroleptic treatment alone. Symptom improvement significantly correlated with idazoxan-induced changes in indices of noradrenergic function. In a subgroup of patients, idazoxan plus typical neuroleptic treatment compared favourably with clozapine treatment, when both were compared to typical neuroleptic treatment alone.

CONCLUSIONS

The antagonism of alpha 2 receptors augmented therapeutic response to typical neuroleptic treatment in treatment-resistant patients with schizophrenia. This antagonism may contribute to clozapine's superior antipsychotic effects.

Effects of a newly developed transdermal clonidine delivery system (M-5041T) on EEG sleep-wake cycle in relation to plasma concentration in rabbits

1. The effects of a transdermal clonidine delivery system (M-5041T) on EEG sleep pattern with relation to plasma concentrations in unrestrained rabbits were investigated and compared with those of intravenous (i.v.) administration of clonidine. 2. Although M-5041T did not affect the EEG recorded from cortex and hippocampus at doses up to 2.5 mg/kg, slow theta waves in hippocampal EEG accompanied by low-voltage slow waves in cortex were induced at a higher dose of 12.5 mg/kg. On i.v. injection (0.25 mg/kg), EEG tracings with bursts of high-voltage slow waves in cortical EEG and slow theta waves in hippocampus were observed. 3. At doses of 0.5 and 2.5 mg/kg, M-5041T did not cause any alterations of the sleep-wake cycle, and plasma concentrations of 1-2 ng/ml were maintained for an 8-hr observation period. However, this delivery system significantly suppressed the incidence of rapid-eye movement sleep (REMS) from 11.9 to 4.7% and enhanced drowsiness (DW) from 9.0 to 21.0% during the 8-hr recording period at 12.5 mg/kg with a plasma concentration of up to 10 ng/ml. Contrary to transdermal administration, i.v. clonidine (0.25 mg/kg) completely blocked light and deep slow wave sleep as well as REMS with a plasma concentration indicated more than 10 ng/ml at 2 hr post administration. Recovery to a normal sleep-wake cycle was eventually established thereafter. The incidence of REMS and DW were significantly decreased from 11.9 to 6.3% and increased from 9.0 to 25.5%, respectively. 4. Concurrent monitoring of clonidine concentrations in cerebrospinal fluid (CSF) indicated that CSF concentrations after patching M-5041T, as well as i.v. clonidine, were almost equal to plasma levels. 5. These results suggest that alteration of the sleep-wake cycle with clonidine occurs depending upon brain concentrations, which increase to a level similar to that in plasma after administration, and that M-5041T at doses of less than 2.5 mg/kg could establish effective hypertensive therapy without obvious effects on the cycle.

Drugs and the sleep-wakefulness continuum

The circadian cycle of sleep and wakefulness in humans is controlled by the activity of many neurotransmitters. Studies of the effects of drugs on the central nervous system have elucidated some of the mechanisms that may be involved. Some transmitters are concerned with the basic control of sleep and wakefulness, influencing both alertness during the day and the pattern of nocturnal sleep. On the other hand, there are other transmitters that appear to be concerned primarily with the manifestation of wakefulness and vigilance, without a direct role in the process of sleep.

Role of lateral preoptic area alpha-1 and alpha-2 adrenoceptors in sleep-wakefulness and body temperature regulation

The preoptic area is anatomically divided into medial and lateral portions and both are involved in the regulation of sleep-wakefulness and body temperature. We have recently reported the specific role of the adrenoceptors, present in the medial preoptic area, in the regulation of those functions. In this study an attempt was made to investigate the specific participation and contribution of the lateral preoptic area alpha-1 and alpha-2 adrenoceptors in the regulation of sleep-wakefulness and body temperature. Sleep-wakefulness and rectal temperature were simultaneously recorded in freely moving rats, both during day and night, under normal condition and after bilateral local microinjection of either agonist or antagonist of alpha-1 and alpha-2 adrenoceptors into the lateral preoptic area. The results suggest that the lateral preoptic area alpha-2 adrenoceptors are predominantly involved in the regulation of sleep-wakefulness whereas alpha-1 adrenoceptors are more effective in thermoregulation.

Sleep and dreaming: induction and mediation of REM sleep by cholinergic mechanisms

The most important recent work on the neurobiology of sleep has focused on the precise cellular and biochemical mechanisms of rapid eye movement sleep mediation. Direct and indirect evidence implicates acetylcholine-containing neurons in the peribrachial pons as critical in the triggering and maintenance of rapid eye movement sleep. Other new studies provide support for the hypothesis that the cholinergic generator system is gated during waking by serotonergic and noradrenergic influences. A growing consensus regarding the basic neurobiology has stimulated new thinking about the brain basis of consciousness during waking and dreaming.