REM sleep suppression induced by selective monoamine oxidase inhibitors

The Defensive Activation Theory: REM Sleep as a Mechanism to Prevent Takeover of the Visual Cortex

Regions of the brain maintain their territory with continuous activity: if activity slows or stops (e.g., because of blindness), the territory tends to be taken over by its neighbors. A surprise in recent years has been the speed of takeover, which is measurable within an hour. These findings lead us to a new hypothesis on the origin of REM sleep. We hypothesize that the circuitry underlying REM sleep serves to amplify the visual system's activity periodically throughout the night, allowing it to defend its territory against takeover from other senses. We find that measures of plasticity across 25 species of primates correlate positively with the proportion of rapid eye movement (REM) sleep. We further find that plasticity and REM sleep increase in lockstep with evolutionary recency to humans. Finally, our hypothesis is consistent with the decrease in REM sleep and parallel decrease in neuroplasticity with aging.

Dreaming under antidepressants: a systematic review on evidence in depressive patients and healthy volunteers

Sleep related symptoms of depression include sleep fragmentation, early morning awakening, decreased rapid eye movement (REM) sleep latency, increased REM density, and more negative dream content. Most tricyclic antidepressants (ADs) increase total sleep time and decrease wake time after sleep onset, while many selective serotonin reuptake inhibitors (SSRIs) have an opposite effect. However, almost all ADs prolong REM sleep latency and reduce the amount of REM sleep. Case reports and research data indicate a strong effect of ADs on dream recall and dream content. We performed a systematic review (1950 to August 2010) about ADs impact on dreaming in depressive patients and healthy volunteers. Twenty-one clinical studies and 25 case reports were eligible for review and document a clear AD effect on dreaming. The major finding, both in depressed patients and in healthy volunteers, is a decrease of dream recall frequency (DRF) under ADs. This is a rather consistent effect in tricyclic ADs and phenelzine, less consistently documented also for SSRIs/serotonin norepinephrine reuptake inhibitors (SNRIs). Tricyclic ADs induce more positive dream emotions. Withdrawal from tricyclic ADs and from the monoamine oxidase inhibitors phenelzine and tranylcypromine may cause nightmares. Intake and even more withdrawal of SSRIs/SNRIs seem to intensify dreaming, which may be experienced in different ways; a potential to cause nightmares has to be taken into account. Though there are clear-cut pharmacological effects of ADs on DRF and dream content, publications have been surprisingly scarce during the past 60 years. There is evidence of a gap in neuropsychopharmacological research. AD effects on dreams should be recognized and may be used in treatment.

Why does rem sleep occur? A wake-up hypothesis

Brain activity differs in the various sleep stages and in conscious wakefulness. Awakening from sleep requires restoration of the complex nerve impulse patterns in neuronal network assemblies necessary to re-create and sustain conscious wakefulness. Herein I propose that the brain uses rapid eye movement (REM) to help wake itself up after it has had a sufficient amount of sleep. Evidence suggesting this hypothesis includes the facts that, (1) when first going to sleep, the brain plunges into Stage N3 (formerly called Stage IV), a deep abyss of sleep, and, as the night progresses, the sleep is punctuated by episodes of REM that become longer and more frequent toward morning, (2) conscious-like dreams are a reliable component of the REM state in which the dreamer is an active mental observer or agent in the dream, (3) the last awakening during a night's sleep usually occurs in a REM episode during or at the end of a dream, (4) both REM and awake consciousness seem to arise out of a similar brainstem ascending arousal system (5) N3 is a functionally perturbed state that eventually must be corrected so that embodied brain can direct adaptive behavior, and (6) cortico-fugal projections to brainstem arousal areas provide a way to trigger increased cortical activity in REM to progressively raise the sleeping brain to the threshold required for wakefulness. This paper shows how the hypothesis conforms to common experience and has substantial predictive and explanatory power regarding the phenomenology of sleep in terms of ontogeny, aging, phylogeny, abnormal/disease states, cognition, and behavioral physiology. That broad range of consistency is not matched by competing theories, which are summarized herein. Specific ways to test this wake-up hypothesis are suggested. Such research could lead to a better understanding of awake consciousness.

Wake and sleep EEG provide biomarkers in depression

Both wake and sleep electroencephalogram (EEG) provide biomarkers of depression and antidepressive therapy, respectively. For a long time it is known that EEG activity is altered by drugs. Quantitative EEG analysis helps to delineate effects of antidepressants on brain activity. Cordance is an EEG measure with a superior correlation with regional brain perfusion. Prefrontal quantitative EEG cordance appears to be a predictor of the response to antidepressants. Sleep EEG shows characteristic changes in depression as impaired sleep continuity, desinhibition of REM sleep and changes of nonREM sleep. Elevated REM density (a measure for frequency of rapid eye movements) characterizes an endophenotype in family studies of depression. REM-sleep changes including a more distinct REM rebound after sleep deprivation are found in animal models of depression. Most antidepressants suppress REM sleep in depressed patients, normal controls and laboratory animals. REM suppression appears to be a distinct, but not an absolute requirement for antidepressive effects of a compound. Sleep-EEG variables like REM latency or certain clusters of variables were shown to predict the response to the treatment with a certain antidepressant or even the course of the disorder for several years. Some of these predictive sleep-EEG markers of the longterm course of depression appear to be closely related to hypothalamo-pituitary-adrenocortical system activity.

A New Hypothesis for Sleep: Tuning for Criticality

We propose that the critical function of sleep is to prevent uncontrolled neuronal feedback while allowing rapid responses and prolonged retention of short-term memories. Through learning, the brain is tuned to react optimally to environmental challenges. Optimal behavior often requires rapid responses and the prolonged retention of short-term memories. At a neuronal level, these correspond to recurrent activity in local networks. Unfortunately, when a network exhibits recurrent activity, small changes in the parameters or conditions can lead to runaway oscillations. Thus, the very changes that improve the processing performance of the network can put it at risk of runaway oscillation. To prevent this, stimulus-dependent network changes should be permitted only when there is a margin of safety around the current network parameters. We propose that the essential role of sleep is to establish this margin by exposing the network to a variety of inputs, monitoring for erratic behavior, and adjusting the parameters. When sleep is not possible, an emergency mechanism must come into play, preventing runaway behavior at the expense of processing efficiency. This is tiredness.

Noradrenergic neurons expressing Fos during waking and paradoxical sleep deprivation in the rat

Noradrenaline is known to induce waking (W) and to inhibit paradoxical sleep (PS or REM). Both roles have been exclusively attributed to the noradrenergic neurons of the locus coeruleus (LC, A6), shown to be active during W and inactive during PS. However, the A1, A2, A5 and A7 noradrenergic neurons could also be responsible. Therefore, to determine the contribution of each of the noradrenergic groups in W and in PS inhibition, rats were maintained in continuous W for 3h in a novel environment or specifically deprived of PS for 3 days, with some of them allowed to recover from this deprivation. A double immunohistochemical labeling with Fos and tyrosine hydroxylase was then performed. Thirty percent of the LC noradrenergic cells were found to be Fos-positive after exposure to the novel environment and less than 2% after PS deprivation. In contrast, a significant number of double-labeled neurons (up to 40% of the noradrenergic neurons) were observed in the A1/C1, A2 and A5 groups, after both novel environment and PS deprivation. After PS recovery and in control condition, less than 1% of the noradrenergic neurons were Fos-immunoreactive, regardless of the noradrenergic group. These results indicate that the brainstem noradrenergic cell groups are activated during W and silent during PS. They further suggest that the inhibitory effect of noradrenaline on PS may be due to the A1/C1, A2 and to a lesser degree to A5 neurons but not from those of the LC as previously hypothesized.

Associations of a regulatory polymorphism of monoamine oxidase-A gene promoter (MAOA-uVNTR) with symptoms of depression and sleep quality

OBJECTIVE

To examine the relationships among the variable number of tandem repeats in the monoamine oxidase-A linked polymorphic region allelic variation (MAOA-uVNTR) and the symptoms of depression and sleep quality. The monoamine oxidase-A (MAOA) gene, which plays a vital role in degradation of neurotransmitters such as serotonin, norepinephrine, and dopamine, contains a polymorphism in its promoter region (MAOA-uVNTR) that affects transcriptional efficiency. MAOA-uVNTR genotype has been associated with both psychological and physical measures.

METHODS

The sample consisted of 74 males enrolled in a case/control study of caregivers for relatives with dementia. Age- and race-adjusted linear regression models were used to examine the association between low versus high MAOA-uVNTR activity alleles, symptoms of depression (Center for Epidemiological Studies of Depression), and sleep quality ratings (Pittsburgh Sleep Quality Index).

RESULTS

MAOA-uVNTR alleles associated with less transcriptional activity were related to increased symptoms of depression (p < .04; Cohen's d = 0.52) and poorer sleep quality (p < .04; Cohen's d = 0.31).

CONCLUSIONS

Individuals with less active MAOA-uVNTR alleles may be at increased risk for depressive symptoms and poor sleep.

Mammalian sleep

This review examines the biological background to the development of ideas on rapid eye movement sleep (REM sleep), so-called paradoxical sleep (PS), and its relation to dreaming. Aspects of the phenomenon which are discussed include physiological changes and their anatomical location, the effects of total and selective sleep deprivation in the human and animal, and REM sleep behavior disorder, the latter with its clinical manifestations in the human. Although dreaming also occurs in other sleep phases (non-REM or NREM sleep), in the human, there is a contingent relation between REM sleep and dreaming. Thus, REM is taken as a marker for dreaming and as REM is distributed ubiquitously throughout the mammalian class, it is suggested that other mammals also dream. It is suggested that the overall function of REM sleep/dreaming is more important than the content of the individual dream; its function is to place the dreamer protagonist/observer on the topographical world. This has importance for the developing infant who needs to develop a sense of self and separateness from the world which it requires to navigate and from which it is separated for long periods in sleep. Dreaming may also serve to maintain a sense of 'I'ness or "self" in the adult, in whom a fragility of this faculty is revealed in neurological disorders.

Rapid tryptophan depletion reverses phenelzine-induced suppression of REM sleep

Treatment with the monoamine oxidase inhibitor phenelzine completely suppressed rapid eye movement (REM) sleep in five depressed patients. Hypothesizing that increased serotonergic neurotransmission eliminated REM sleep, we administered a tryptophan-free amino acid drink (TFD) known to reduce plasma tryptophan and brain levels of serotonin. The TFD reversed the REM sleep suppression, while the control drink (TFD plus tryptophan) had virtually no effect on sleep. Neither TFD nor control drink affected mood, total sleep time, sleep efficiency or the all-night electroencephalogram power spectra in non-rapid eye movement (NREM) sleep. We report the first non-disruptive, double-blind method for studying human subjects overnight with and without REM sleep. It opens up a novel strategy for investigating the functions of REM sleep, and the roles of serotonin and REM sleep in the regulation of NREM sleep and mood.

Clinical pharmacology of psychotropic drugs

No Abstract

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 link between sleep and depression: the effects of antidepressants on EEG sleep

The assumption that sleep dysregulation is more than a mere epiphenomenon of depression is based on several observations: sleep disturbances are strongly associated with the depressive state; a number of sleep manipulations can alleviate symptoms of depression in some patients; and the majority of antidepressants bring about remarkable changes in sleep polygraphic variables. An obvious question is whether changes in sleep physiological processes are intimately involved in the pathogenesis and recovery from depression. One way to elucidate the link between sleep and depression is to examine whether the influence of antidepressants on sleep is related to clinical improvements in depressives. For that purpose, the effects of antidepressants on EEG sleep and their importance for the treatment of depression are summarized against the background of two existing hypotheses concerning the link between sleep and depression: one hypothesis concerning the role of REM; the other concerning the role of non-REM sleep. EEG sleep studies on the use of antidepressants in depressives have not produced clear evidence of the involvement of REM sleep or non-REM sleep in the mechanisms underlying clinical change. Furthermore, the role of sleep physiological mechanisms during treatment with antidepressants is still unclear. To interpret the effects of antidepressants on EEG sleep in terms of sleep physiological processes more fundamental sleep research is necessary. Also, more comparative studies of antidepressants with similar therapeutic effects but different pharmacological profiles are needed in both healthy and depressed subjects to further quantify the impact of EEG sleep modification in the recovery from depression and to differentiate between pharmacological and sleep-related aspects.

Pharmacological aspects of human and canine narcolepsy

Narcolepsy-cataplexy is a disabling neurological disorder that affects 1/2000 individuals. The main clinical features of narcolepsy, excessive daytime sleepiness and symptoms of abnormal REM sleep (cataplexy, sleep paralysis, hypnagogic hallucinations) are currently treated using amphetamine-like compounds or modafinil and antidepressants. Pharmacological research in the area is facilitated greatly by the existence of a canine model of the disorder. The mode of action of these compounds involves presynaptic activation of adrenergic transmission for the anticataplectic effects of antidepressant compounds and presynaptic activation of dopaminergic transmission for the EEG arousal effects of amphetamine-like stimulants. The mode of action of modafmil is still uncertain, and other neurochemical systems may offer interesting avenues for therapeutic development. Pharmacological and physiological studies using the canine model have identified primary neurochemical and neuroanatomical systems that underlie the expression of abnormal REM sleep and excessive sleepiness in narcolepsy. These involve mostly the pontine and basal forebrain cholinergic, the pontine adrenergic and the mesolimbic and mesocortical dopaminergic systems. These studies confirm a continuing need for basic research in both human and canine narcolepsy, and new treatments that act directly at the level of the primary defect in narcolepsy might be forthcoming.

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.

Circadian rhythms and the pharmacology of affective illness

The chronic effects of antidepressant drugs (ADs) on circadian rhythms of behavior, physiology and endocrinology are reviewed. The timekeeping properties of several classes of ADs, including tricyclic antidepressants, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, serotonin agonists and antagonists, benzodiazepines, and melatonin are reviewed. Pharmacological effects on the circadian amplitude and phase, as well as effects on day-night measurements of motor activity, sleep-wake, body temperature (Tb), 3-methoxy-4-hydroxyphenylglycol, cortisol, thyroid hormone, prolactin, growth hormone and melatonin are examined. ADs often lower nocturnal Tb and affect the homeostatic regulation of sleep. ADs often advance the timing and decrease the amount of slow wave sleep, reduce rapid eye movement sleep and increase or decrease arousal. Together, AD effects on nocturnal Tb and sleep may be related to their therapeutic properties. ADs sometimes delay nocturnal cortisol timing and increase nocturnal melatonin, thyroid hormone and prolactin levels; these effects often vary with diagnosis, and clinical state. The effects of ADs on the coupling of the central circadian pacemaker to photic and nonphotic zeitgebers are discussed.

Stress-related behavior and central norepinephrine concentrations in the REM sleep-deprived rat

Rapid eye movement sleep deprivation (REMd) is a potent stressor in the rat. Behavioral abnormalities are among the earliest overt symptoms of REMd, the mechanisms for which remain largely unknown. The phenomena of hyperphagia and weight loss that are associated with REMd may contribute to its later morbidity; however, little is known about the onset of these phenomena or the neurotransmitter mechanisms that are involved. The aim of this study was to determine whether the earliest effects of REMd on consumatory behavior in the rat and its performance in the swimming cylinder of Porsolt are related to changes in norepinephrine (NE) concentrations in the cerebral cortex and selected areas of the hypothalamus. Sprague-Dawley rats were divided into three groups (n = 6): the REMd group resided in a water tank on 6.5-cm diameter pedestals for 96 h; the tank control (TC) group resided in the water tank on 15-cm pedestals for 96 h; the cage controls (CC) remained in their home cages for the duration of the study. In the first series of experiments, body weights and caloric intake were recorded daily, along with the performance of all animals in the swimming cylinder of Porsolt. In the second series of experiments, body weights and caloric intake were recorded, but the Porsolt test was not employed and the brains were dissected after 96 h for NE analysis by HPLC. It was observed that the REMd group had lower immobility times (p < 0.05) in the Porsolt test after only 24 h, compared to groups TC and CC.(ABSTRACT TRUNCATED AT 250 WORDS)

Sleep patterns in depression and anxiety: theory and pharmacological effects

Sleep is invariably disrupted in patients who have depression and in patients with anxiety disorders. Depression and anxiety frequently coexist and are associated with disturbances in various neurotransmitters. The authors explore the relationship between sleep and the two disorders as well as the effects of antidepressants and anxiolytics on sleep architecture. The effects on sleep of various neurotransmitter systems implicated in depression and anxiety are outlined. Lastly, various theoretical models are proposed to account for the above mentioned phenomena and further directions for research are suggested.

Abnormal behavior associated with a point mutation in the structural gene for monoamine oxidase A

Genetic and metabolic studies have been done on a large kindred in which several males are affected by a syndrome of borderline mental retardation and abnormal behavior. The types of behavior that occurred include impulsive aggression, arson, attempted rape, and exhibitionism. Analysis of 24-hour urine samples indicated markedly disturbed monoamine metabolism. This syndrome was associated with a complete and selective deficiency of enzymatic activity of monoamine oxidase A (MAOA). In each of five affected males, a point mutation was identified in the eighth exon of the MAOA structural gene, which changes a glutamine to a termination codon. Thus, isolated complete MAOA deficiency in this family is associated with a recognizable behavioral phenotype that includes disturbed regulation of impulsive aggression.

The new generation of monoamine oxidase inhibitors

Irreversible and unspecific inhibitors of MAO were the first modern antidepressants, but after an initial success they fell into discredit due to adverse side effects. In the past two decades interest in MAO inhibitors has been renewed because of progress in basic research, a milestone being the finding that there are two subtypes of MAO, MAO-A and MAO-B. These are distinct proteins with high amino acid homology, coded by separate genes both located on the short arm of the human chromosome X. The enzyme subforms show different substrate specificities in vitro and different distributions within the central nervous system and in peripheral organs. In the central nervous system of man MAO-A seems to be mainly involved in the metabolism of 5 HT and noradrenaline, whereas 2-phenylethylamine and probably dopamine are predominantly deaminated by MAO-B. In the intestinal tract tyramine is mainly metabolized by MAO-A. These characteristics indicate distinct physiological functions of the two MAO-subforms. Several irreversible and reversible non-hydrazine inhibitors with relative selectivities for one of the MAO-subforms have been developed. They belong to various chemical classes with different modes of enzyme inhibition. These range from covalent mechanism based interaction (e.g. by propargyl- and allylamine derivatives) to pseudosubstrate inhibition (e.g. by 2-aminoethyl-carboxamides) and non-covalent interaction (e.g. by brofaromine, toloxatone and possibly moclobemide). The most important pharmacological effects of the new types of MAO inhibitors are those observed in neuropsychiatric disorders. The inhibitors of MAO-A show a favorable action in various forms of mental depression. The drugs seem to have about the same activity as other types of antidepressants, including tricyclic and related compounds as well as classical MAO inhibitors. The onset of action of the MAO-A inhibitors is claimed to be relatively fast. Other possible indications of these drugs include disorders with cognitive impairment, e.g. dementia of the Alzheimer type. In subjects with Parkinson's disease the MAO-B inhibitor L-deprenyl exerts a L-dopa-sparing effect, prolongs L-dopa action and seems to have a favorable influence regarding on-off disabilities. The action is in general transitory (months to several years). In addition L-deprenyl has been shown to delay the necessity for L-dopa treatment in patients with early parkinsonism. Whether the drug influence the progression of the disease is still a matter of debate. L-deprenyl also appears to have some antidepressant effect (especially in higher doses) and to exert a beneficial influence in other disorders, e.g. dementia of the Alzheimer type.(ABSTRACT TRUNCATED AT 400 WORDS)

The effects of moclobemide on nocturnal sleep of depressed patients

The effect of moclobemide, a short-acting, reversible, preferential type-A MAO inhibitor (300 mg daily in three divided doses), on the sleep of eight depressed patients was assessed by polysomnographic recordings in a 4-week therapeutic trial. Six patients showed an improvement greater than 50% on the Hamilton Depression Rating Scale. Compared to placebo, patients receiving moclobemide showed improved sleep continuity as judged by the decrease in wake time after sleep onset and total wake time, particularly during the intermediate and late stages of drug administration. Total sleep time increase was comprised of larger amounts of stage 2 NREM sleep. REM sleep latency was significantly increased and REM sleep % decreased during the drug administration period. However, in contrast to the older, non-selective and selective MAOIs, moclobemide had a mild REM sleep suppressant effect.

Effects of moclobemide on sleep in healthy human subjects

Ten healthy, normal subjects (5 male and 5 female) aged 20-28 years participated in this experimental study of the effect of moclobemide on sleep. The design consisted of 2 sessions of 5 nights each, comprising 1 adaptation night, 2 nights on placebo and 2 inputs of moclobemide 4 mg/kg (session B). The 2 sessions were separated by at least 15 days and their order was balanced and randomized. During the last 4 nights of each session, sleep parameters were recorded throughout the night according to standard procedures. Moclobemide at a dose of 4 mg/kg induced moderate changes in the sleep-wake balance: a significant increase in stage 1 on the second drug night, a slight increase in stage 2 and a significant decrease in paradoxical sleep on the 2 drug nights. There was also a moderate reduction in the number of rapid eye movements (REM) during paradoxical sleep, but the number of cycles and latency to paradoxical sleep were unchanged, as well as all other sleep parameters measured. With 6.5 mg/kg, the changes were more pronounced: total sleep time was diminished, but this was significant only on the second and third nights. Transient awakenings increased significantly on the first drug night, and wakening latency decreased. The only modification of orthodox sleep was an increase in the percentage of stage 2 on the first drug night, whereas slow-wave sleep was unchanged. Paradoxical sleep was reduced on the first 2 drug nights, but tolerance appeared on the third night. The decrease in paradoxical sleep was exacerbated in the last part of the night. REM were decreased during paradoxical sleep.(ABSTRACT TRUNCATED AT 250 WORDS)

Drug effects on REM sleep and on endogenous depression

In earlier work REM sleep deprivation (RSD) by arousals improved endogenous depression. This suggested that drugs producing a similar RSD would have antidepressant activity. The arousal RSD was large, persisted for weeks, and was followed by a REM rebound. We call RSD with these properties arousal-type RSD. The present study reviewed literature from 1962 to 1989 on drug REM sleep effects to examine the hypothesis that drugs producing arousal-type RSD improve endogenous depression. The literature reviewed concerned the REM sleep effects of amine precursors, antidepressants, antihistamines, antipsychotics, barbiturates, benzodiazepines, other hypnotics, drugs affecting cholinergic and noradrenergic neurotransmission, ethanol, lithium and narcotics. Four hundred and sixty-eight relevant papers were read and 215 contributed information that could be used in the review. The findings indicated that all drugs producing arousal-type RSD improved endogenous depression. Four drugs that improved endogenous depression did not produce arousal-type RSD.

Marked amine and amine metabolite changes in Norrie disease patients with an X-chromosomal deletion affecting monoamine oxidase

Urinary and plasma amines and amine metabolites were quantified in two individuals with Norrie disease resulting from a deletion in chromosomal region Xp11.3, recently reported to be associated with absence of the gene encoding monoamine oxidase (MAO)-A and nondetectable MAO-A activity in fibroblasts and MAO-B activity in platelets. Marked (four-to 100-fold) elevations in levels of urinary phenylethylamine, o-tyramine, and m-tyramine (which are preferential substrates for MAO-B) and marked reductions (90%) in levels of 3-methoxy-4-hydroxyphenylglycol (a deaminated metabolite of norepinephrine, a preferential substrate for MAO-A) in urine and plasma confirmed the presence of a systemic, functionally significant reduction in the activities of both MAO isozymes. The magnitude of these changes, which are equivalent to those found in subjects taking MAO-inhibiting antidepressants, suggests that early initiation of dietary and drug restrictions may be clinically important in these and other patients with X-chromosomal mutations involving MAO. These findings further support the proposition that the MAOA and MAOB genes are located in close proximity on the X chromosome. Negligible changes in the metabolites of dopamine and serotonin raise the possibility that other metabolic pathways are of importance for their production, that dietary or intestinal bacterial sources contribute substantially to the presence of these amine metabolites in urine, or both.

Effects of brofaremine (CGP 11 305A), a short-acting, reversible, and selective inhibitor of MAO-A on sleep, nocturnal penile tumescence and nocturnal hormonal secretion in three healthy volunteers

The effects of brofaremine (CGP 11 305A), a short-acting, reversible and selective inhibitor of MAO-A, on sleep, nocturnal penile tumescence (NPT) and hormonal secretion during the night were studied during a long-term trial. Three healthy males underwent sleep-EEG and NPT recordings during consecutive nights (1) under placebo, (2) under stepwise increasing dosages of brofaremine and (3) under placebo after withdrawal. Hormone profiles were sampled during selected nights to analyze the plasma concentration of cortisol, HGH, prolactin, testosterone, LH and FSH. REM sleep was suppressed markedly under 150 mg brofaremine, while stages 1 and 2 increased. In comparison to the effect of irreversible MAOIs the REM suppression was shorter and did not persist after withdrawal. A decrease of the plasma concentration of the drug coincided with a return of sleep variables to baseline values. A REM rebound occurred after withdrawal of brofaremine. REM sleep and NPT showed a dissociation; NPT variables did not follow the decrease of REM sleep. The effects of REM parameters are correlated with the dosage and the plasma concentration of the substance. Intraindividually, a decrease in secretion of HGH was observed throughout the trial. No marked changes were found in the other endocrinological variables.

A life-sustaining function for REM sleep: a theory

A hypothesis has been advanced that the primary function of rapid eye movement (REM) sleep is to provide periodic endogenous stimulation to the brain which serves to maintain minimum requisite levels of CNS activity throughout sleep. REM, in effect, is the mechanism used by the brain to promote and ensure recovery from sleep. Failures of REM may hinder, or in extreme cases, prevent arousal from sleep. The possibility that two fatal sleep-associated syndromes (Sudden Infant Death Syndrome and the Oriental Nocturnal Death Syndrome) may involve deficits of REM was discussed.

Comparison of effects of desipramine and amitriptyline on EEG sleep of depressed patients

Despite their widespread use, there are few data concerning the effects of tricyclic antidepressants on EEG sleep in depression. The present study documented the effects of desipramine (DMI, n = 17) and amitriptyline (AT, n = 16) upon EEG sleep in hospitalized depressed patients as part of a double-blind protocol involving 28 days of active treatment. Compared to placebo, patients receiving DMI showed somewhat worsened sleep continuity, particularly after 1 week of administration when the dose was 150 mg/day. On the other hand, sleep architecture and REM measures showed a rapid suppression of REM sleep, and then partial tolerance for this effect was observed with continued administration of DMI for 3 weeks. DMI was a more potent suppressor of REM sleep, while AT was more sedative. Based on these differences in effects upon EEG sleep, a discriminant function was derived and resulted in a correct classification of 87.5% of AT cases and 76.5% of DMI cases. These results are discussed in terms of the differences in pharmacological profiles for uptake blockade and anticholinergic potency for these two compounds.

The effect of rapid eye movement sleep deprivation on cortical beta-adrenergic receptors

The relationship between rapid eye movement sleep deprivation (REMD) and rat beta-adrenergic receptors was evaluated. REMD was achieved using the platform method and verified by EEG and EMG recordings. Although the amount of REM sleep was diminished 90%, there was no alteration in either the number of binding sites or their affinity for [3H]-dihydroalprenolol. Periods of stress as well as recovery periods after REMD were also without effect on the cortical beta-adrenergic receptors. Thus no support is garnered for the interaction of REMD and the cortical beta-adrenergic receptor binding parameters, although REMD is sometimes used as a mode of therapy for depression and other antidepressives do in fact affect the beta-adrenergic system. The mechanism of REMD as a potential antidepressive therapy is yet to be elucidated.

Correlation of changes in alpha 2-adrenoceptor number and locomotor responses to clonidine following clorgyline discontinuation

[3H]-clonidine binding in vitro and the locomotor response to clonidine in vivo were studied over an eight week period following four weeks of treatment with the monoamine oxidase-inhibiting antidepressant, clorgyline (1 mg kg-1 day-1). Long-term clorgyline administration caused decreases in responsiveness to clonidine and in the number of alpha 2-adrenoceptors; these changes reverted towards pretreatment values very gradually over an eight week period following discontinuation of the drug. This study provides some of the first detailed evidence regarding the slow return of adaptional changes following discontinuation of an antidepressant drug in animals and has implications for understanding some delayed drug interactions associated with MAO-inhibiting antidepressants in man.