Activities of monoamine oxidase (MAO) A and B in discrete regions of rat brain after rapid eye movement (REM) sleep deprivation

Acute 2-phenyl-3-(phenylselanyl)benzofuran treatment reverses the neurobehavioral alterations induced by sleep deprivation in mice

Sleep is a fundamental state for maintaining the organism homeostasis. Disruptions in sleep patterns predispose to the appearance of memory impairments and mental disorders, including depression. Recent pre-clinical studies have highlighted the antidepressant-like properties of the synthetic compound 2-phenyl-3-(phenylselanyl)benzofuran (SeBZF1). To further investigate the neuromodulatory effects of SeBZF1, this study aimed to assess its therapeutic efficacy in ameliorating neurobehavioral impairments induced by sleep deprivation (SD) in mice. For this purpose, a method known as multiple platforms over water was used to induce rapid eye movement (REM) SD. Two hours after acute SD (24 h), male Swiss mice received a single treatment of SeBZF1 (5 mg/kg, intragastric route) or fluoxetine (a positive control, 20 mg/kg, intraperitoneal route). Subsequently, behavioral tests were conducted to assess spontaneous motor function (open-field test), depressive-like behavior (tail suspension test), and memory deficits (Y-maze test). Brain structures were utilized to evaluate oxidative stress markers, monoamine oxidase (MAO) and acetylcholinesterase (AChE) activities. Our findings revealed that SD animals displayed depressive-like behavior and memory impairments, which were reverted by SeBZF1 and fluoxetine treatments. SeBZF1 also reverted the increase in lipoperoxidation levels and glutathione peroxidase activity in the pre-frontal cortex in mice exposed to SD. Besides, the increase in hippocampal AChE activity induced by SD was overturned by SeBZF1. Lastly, cortical MAO-B activity was reestablished by SeBZF1 in mice that underwent SD. Based on the main findings of this study, it can be inferred that the compound SeBZF1 reverses the neurobehavioral alterations induced by sleep deprivation in male Swiss mice.

Comparison between sub-chronic and chronic sleep deprivation-induced behavioral and neuroimmunological abnormalities in mice: Focusing on glial cell phenotype polarization

BACKGROUND

Sleep disorders, depression, and Alzheimer's disease (AD) are extensively reported as comorbidity. Although neuroinflammation triggered by microglial phenotype M1 activation, leading to neurotransmitter dysfunction and Aβ aggregation, is considered as the leading cause of depression and AD, whether and how sub-chronic or chronic sleep deprivation (SD) contribute to the onset and development of these diseases remains unclear.

METHODS

Memory and depression-like behaviors were evaluated in both SDs, and then circadian markers, glial cell phenotype polarization, cytokines, depression-related neurotransmitters, and AD-related gene/protein expressions were measured by qRT-PCR, enzyme-linked immunosorbent assay, high-performance liquid chromatography, and western-blotting respectively.

RESULTS

Both SDs induced give-up behavior and anhedonia and increased circadian marker period circadian regulator 2 (PER2) expression, which were much worse in chronic than in the sub-chronic SD group, while brain and muscle ARNT-like protein-1 only decreased in the chronic-SD. Furthermore, increased microglial M1 and astrocyte A1 expression and proinflammatory cytokines, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α was observed in both SDs, which were more significant in chronic SD. Similarly, decreased norepinephrine and 5-hydroxytryptamine/5-hydroxyindoleacetic acid ratio were more significant, which corresponds to the worse depression-like behavior in chronic than sub-chronic-SD. With regard to AD, increased amyloid precursor protein (APP) and soluble (s)-APPβ and decreased sAPPα in both SDs were more significant in the chronic. However, sAPPα/sAPPβ ratio was only decreased in chronic SD.

CONCLUSION

These findings suggest that both SDs induce depression-like changes by increasing PER2, leading to neuroinflammation and neurotransmitter dysfunction. However, only chronic SD induced memory impairment likely due to severer circadian disruption, higher neuroinflammation, and dysregulation of APP metabolism.

Brain Microdialysate Monoamines in Relation to Circadian Rhythms, Sleep, and Sleep Deprivation - a Systematic Review, Network Meta-analysis, and New Primary Data

Disruption of the monoaminergic system, e.g. by sleep deprivation (SD), seems to promote certain diseases. Assessment of monoamine levels over the circadian cycle, during different sleep stages and during SD is instrumental to understand the molecular dynamics during and after SD. To provide a complete overview of all available evidence, we performed a systematic review. A comprehensive search was performed for microdialysis and certain monoamines (dopamine, serotonin, noradrenaline, adrenaline), certain monoamine metabolites (3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA)) and a precursor (5-hydroxytryptophan (5-HTP)) in PubMed and EMBASE. After screening of the search results by two independent reviewers, 94 publications were included. All results were tabulated and described qualitatively. Network-meta analyses (NMAs) were performed to compare noradrenaline and serotonin concentrations between sleep stages. We further present experimental monoamine data from the medial prefrontal cortical (mPFC). Monoamine levels varied with brain region and circadian cycle. During sleep, monoamine levels generally decreased compared to wake. These qualitative observations were supported by the NMAs: noradrenaline and serotonin levels decreased from wakefulness to slow wave sleep and decreased further during Rapid Eye Movement sleep. In contrast, monoamine levels generally increased during SD, and sometimes remained high even during subsequent recovery. Decreases during or after SD were only reported for serotonin. In our experiment, SD did not affect any of the mPFC monoamine levels. Concluding, monoamine levels vary over the light-dark cycle and between sleep stages. SD modifies the patterns, with effects sometimes lasting beyond the SD period.

Control of sleep and wakefulness

This review summarizes the brain mechanisms controlling sleep and wakefulness. Wakefulness promoting systems cause low-voltage, fast activity in the electroencephalogram (EEG). Multiple interacting neurotransmitter systems in the brain stem, hypothalamus, and basal forebrain converge onto common effector systems in the thalamus and cortex. Sleep results from the inhibition of wake-promoting systems by homeostatic sleep factors such as adenosine and nitric oxide and GABAergic neurons in the preoptic area of the hypothalamus, resulting in large-amplitude, slow EEG oscillations. Local, activity-dependent factors modulate the amplitude and frequency of cortical slow oscillations. Non-rapid-eye-movement (NREM) sleep results in conservation of brain energy and facilitates memory consolidation through the modulation of synaptic weights. Rapid-eye-movement (REM) sleep results from the interaction of brain stem cholinergic, aminergic, and GABAergic neurons which control the activity of glutamatergic reticular formation neurons leading to REM sleep phenomena such as muscle atonia, REMs, dreaming, and cortical activation. Strong activation of limbic regions during REM sleep suggests a role in regulation of emotion. Genetic studies suggest that brain mechanisms controlling waking and NREM sleep are strongly conserved throughout evolution, underscoring their enormous importance for brain function. Sleep disruption interferes with the normal restorative functions of NREM and REM sleep, resulting in disruptions of breathing and cardiovascular function, changes in emotional reactivity, and cognitive impairments in attention, memory, and decision making.

REM sleep deprivation of rats induces acute phase response in liver

REM sleep is essential for maintenance of body physiology and its deprivation is fatal. We observed that the levels of ALT and AST enzymes and pro-inflammatory cytokines like IL-1 β, IL-6 and IL-12 circulating in the blood of REM sleep deprived rats increased in proportion to the extent of sleep loss. But in contrast the levels of IFN-γ and a ∼200 kDa protein, identified by N-terminal sequencing to be alpha-1-inhibitor-3(A1I3), decreased significantly. Quantitative PCR analysis confirmed that REM sleep deprivation down regulates AII3 gene and up regulates IL1 β, IL6 and their respective receptors gene expression in the liver initiating its inflammation.

Multi-target strategies for the improved treatment of depressive states: Conceptual foundations and neuronal substrates, drug discovery and therapeutic application

Major depression is a debilitating and recurrent disorder with a substantial lifetime risk and a high social cost. Depressed patients generally display co-morbid symptoms, and depression frequently accompanies other serious disorders. Currently available drugs display limited efficacy and a pronounced delay to onset of action, and all provoke distressing side effects. Cloning of the human genome has fuelled expectations that symptomatic treatment may soon become more rapid and effective, and that depressive states may ultimately be "prevented" or "cured". In pursuing these objectives, in particular for genome-derived, non-monoaminergic targets, "specificity" of drug actions is often emphasized. That is, priority is afforded to agents that interact exclusively with a single site hypothesized as critically involved in the pathogenesis and/or control of depression. Certain highly selective drugs may prove effective, and they remain indispensable in the experimental (and clinical) evaluation of the significance of novel mechanisms. However, by analogy to other multifactorial disorders, "multi-target" agents may be better adapted to the improved treatment of depressive states. Support for this contention is garnered from a broad palette of observations, ranging from mechanisms of action of adjunctive drug combinations and electroconvulsive therapy to "network theory" analysis of the etiology and management of depressive states. The review also outlines opportunities to be exploited, and challenges to be addressed, in the discovery and characterization of drugs recognizing multiple targets. Finally, a diversity of multi-target strategies is proposed for the more efficacious and rapid control of core and co-morbid symptoms of depression, together with improved tolerance relative to currently available agents.

Involvement of active oxygen species in protein and oligonucleotide degradation induced by nitrofurans

It is of great interest to know how nitrofurans are mutagenic and clastogenic. In particular, the 3-amino-2-oxazolidone (AOZ) ring, deriving from a cleavage of furazolidone, is not further metabolized and has been found to be part of protein-bound residues in edible tissues of farm animals and these might be released in the stomach of the consumer. The data in this paper show that isoniazide as well as AOZ and 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ), the latter deriving from furaltadone, cause irreversible damage to the prosthetic group of enzymes as well as degrade their polypeptide chain and cause fragmentation of the backbone chain of cellular or isolated DNA and RNA. Cellular DNA was degraded into small fragments of 2000 Mb, while rRNA was completely destroyed. Nitrofuran derivatives and hydrazides, in fact, share an N–N moiety, which is assumed to play an essential role in the irreversible damage observed. The key to the molecular mechanisms by which these compounds cause their irreversible effects may lie in oxygen consumption and electron spin resonance measurements, which reveal that both nitrofurans and isoniazide produce oxygen radicals at various degrees of efficiency. AOZ and AMOZ are not metabolized into more reactive metabolites, being themselves able to react with atmospheric oxygen and induce protein and oligonucleotide damage. The reaction does not require metal ions, although their presence will accelerate it.Key words: nitrofurans, active oxygen, furazolidone, DNA degradation, protein fragmentation.

Rapid eye movement sleep deprivation induces an increase in acetylcholinesterase activity in discrete rat brain regions

Some upper brainstem cholinergic neurons (pedunculopontine and laterodorsal tegmental nuclei) are involved in the generation of rapid eye movement (REM) sleep and project rostrally to the thalamus and caudally to the medulla oblongata. A previous report showed that 96 h of REM sleep deprivation in rats induced an increase in the activity of brainstem acetylcholinesterase (Achase), the enzyme which inactivates acetylcholine (Ach) in the synaptic cleft. There was no change in the enzyme's activity in the whole brain and cerebrum. The components of the cholinergic synaptic endings (for example, Achase) are not uniformly distributed throughout the discrete regions of the brain. In order to detect possible regional changes we measured Achase activity in several discrete rat brain regions (medulla oblongata, pons, thalamus, striatum, hippocampus and cerebral cortex) after 96 h of REM sleep deprivation. Naive adult male Wistar rats were deprived of REM sleep using the flower-pot technique, while control rats were left in their home cages. Total, membrane-bound and soluble Achase activities (nmol of thiocholine formed min(-1) mg protein(-1)) were assayed photometrically. The results (mean +/- SD) obtained showed a statistically significant (Student t-test) increase in total Achase activity in the pons (control: 147.8 +/- 12.8, REM sleep-deprived: 169.3 +/- 17.4, N = 6 for both groups, P<0.025) and thalamus (control: 167.4 +/- 29.0, REM sleep-deprived: 191.9 +/- 15.4, N = 6 for both groups, P<0.05). Increases in membrane-bound Achase activity in the pons (control: 171.0 +/- 14.7, REM sleep-deprived: 189.5 +/- 19.5, N = 6 for both groups, P<0.05) and soluble enzyme activity in the medulla oblongata (control: 147.6 +/- 16.3, REM sleep-deprived: 163.8 +/- 8.3, N = 6 for both groups, P<0.05) were also observed. There were no statistically significant differences in the enzyme's activity in the other brain regions assayed. The present findings show that the increase in Achase activity induced by REM sleep deprivation was specific to the pons, a brain region where cholinergic neurons involved in REM generation are located, and also to brain regions which receive cholinergic input from the pons (the thalamus and medulla oblongata). During REM sleep extracellular levels of Ach are higher in the pons, medulla oblongata and thalamus. The increase in Achase activity in these brain areas after REM sleep deprivation suggests a higher rate of Ach turnover.

The neurophysiology of sleep and waking: intracerebral connections, functioning and ascending influences of the medulla oblongata

This paper focuses on the successive historical papers related to medulla oblongata (M.O.) intracerebral connections, its activities and ascending influences regulating sleep waking behavior. The M.O. certainly influences the quantitative and qualitative processes of waking. However, its neurophysiological properties are often concealed by those of the upper-situated brain stem structures. The M.O., particularly the solitary tract nucleus, is involved in sleep-inducing processes. This nucleus seem to act as a deactivating system of the above situated reticular formation, but it also impacts directly on the thalamocortical slow wave and spindle-inducing processes. The M.O. is significantly involved in paradoxical sleep mechanisms. Indeed, the mesopontine executive centers are unable to induce paradoxical sleep without the M.O. Moreover, stimulation of the solitary tract nucleus afferents can induce paradoxical sleep, and the M.O. metabolic functioning is specifically disturbed by paradoxical sleep deprivation. Finally. there seems to be a paradoxical sleep Zeitgeber. Our current knowledge shows that this lowest brain stem level is crucial for sleep waking mechanisms. It will undoubtedly be further highlighted by future electrophysiologial and neurochemical studies.

Decreased activity of striatal monoamine oxidase B after rapid eye movement (REM) sleep deprivation in rats

The striatum seems to be the main brain region involved in stereotyped behavior induced by dopaminergic agonists. Rapid eye movement (REM) sleep deprivation increases dopaminergic agonist-induced stereotypy and produces biochemical changes in striatal dopaminergic neurotransmission. However, the mechanism underlying the increased dopaminergic sensitivity induced by REM sleep deprivation has not been elucidated. In an attempt to determine some of the biochemical changes in striatal dopaminergic neurotransmission that could contribute to REM sleep deprivation effects, we measured the activity of monoamine oxidase (MAO) A and B, the enzymes responsible for dopamine and beta-phenylethylamine (beta-PEA) deamination in striatum. Male adult rats were deprived of REM sleep for 96 h by the flower-pot technique. MAO A and B were assayed radioisotopically in the mitochondrial fraction by standard laboratory procedures, using [14C]-5-hydroxytryptamine (5-HT) and [14C]-beta-phenylethylamine (beta-PEA), as substrates for MAO A and MAO B, respectively. The results showed no significant statistical differences in striatal MAO A activity, whereas a significant decrease in MAO B activity was observed. The results are discussed in terms of the possible involvement of beta-PEA, a striatal endogenous trace amine, which potentiates dopaminergic neurotransmission and may participate in the increased dopaminergic sensitivity observed after REM sleep deprivation.