Noradrenaline Acting on Alpha1 Adrenoceptor as well as by Chelating Iron Reduces Oxidative Burden on the Brain: Implications With Rapid Eye Movement Sleep

REM Sleep Loss-Induced Elevated Noradrenaline Plays a Significant Role in Neurodegeneration: Synthesis of Findings to Propose a Possible Mechanism of Action from Molecule to Patho-Physiological Changes

Wear and tear are natural processes for all living and non-living bodies. All living cells and organisms are metabolically active to generate energy for their routine needs, including for survival. In the process, the cells are exposed to oxidative load, metabolic waste, and bye-products. In an organ, the living non-neuronal cells divide and replenish the lost or damaged cells; however, as neuronal cells normally do not divide, they need special feature(s) for their protection, survival, and sustenance for normal functioning of the brain. The neurons grow and branch as axons and dendrites, which contribute to the formation of synapses with near and far neurons, the basic scaffold for complex brain functions. It is necessary that one or more basic and instinct physiological process(es) (functions) is likely to contribute to the protection of the neurons and maintenance of the synapses. It is known that rapid eye movement sleep (REMS), an autonomic instinct behavior, maintains brain functioning including learning and memory and its loss causes dysfunctions. In this review we correlate the role of REMS and its loss in synaptogenesis, memory consolidation, and neuronal degeneration. Further, as a mechanism of action, we will show that REMS maintains noradrenaline (NA) at a low level, which protects neurons from oxidative damage and maintains neuronal growth and synaptogenesis. However, upon REMS loss, the level of NA increases, which withdraws protection and causes apoptosis and loss of synapses and neurons. We propose that the latter possibly causes REMS loss associated neurodegenerative diseases and associated symptoms.

Locus coeruleus and the defensive activation theory of rapid eye movement sleep: A mechanistic perspective

The defensive activation theory (DAT) was recently proposed to explain the biological function of dreaming. Briefly, DAT states that dreams are primarily visual to prevent plastic take-over of an otherwise inactive visual cortex during sleep. Evidence to support the DAT revolve around the interplay between dream activity (REM%) and cortical plasticity found in evolutionary history, primate studies, and coinciding decline in human cortical plasticity and REM% with age. As the DAT may prove difficult to test experimentally, we investigate whether further support for the DAT can be found in the literature. Plasticity and REM sleep are closely linked to functions of the Locus Coeruleus (LC). We therefore review existing knowledge about the LC covering LC stability with age, and the role of the LC in the plasticity of the visual cortex. Recent studies show the LC to be more stable than previously believed and therefore, the LC likely supports the REM% and plasticity in the same manner throughout life. Based on this finding, we review the effect of aging on REM% and visual cortex plasticity. Here, we find that recent, weighty studies are not in complete agreement with the data originally provided as support for DAT. Results from these studies, however, are not in themselves irreconcilable with the DAT. Our findings therefore do not disprove the DAT. Importantly, we show that the LC is involved in all mechanisms central to the DAT. The LC may therefore provide an experimental window to further explore and test the DAT.

Sleep and Neuroimmunomodulation for Maintenance of Optimum Brain Function: Role of Noradrenaline

Immune function and sleep are two normal physiological processes to protect the living organism from falling sick. There is hardly any disease in which they remain unaffected, though the quantum of effect may differ. Therefore, we propose the existence of a strong correlation between sleep (quality or quantity) and immune response. This may be supported by the fact that sleep loss modulates many of the immunological molecules, which includes interferons; however, not much is known about their mechanism of action. Sleep is divided into rapid eye movement sleep (REMS) and non-REMS. For practical reasons, experimental studies have been conducted mostly by inducing loss of REMS. It has been shown that withdrawal of noradrenaline (NA) is a necessity for generation of REMS. Moreover, NA level increases in the brain upon REMS loss and the elevated NA is responsible for many of the sleep loss-associated symptoms. In this review, we describe how sleep (and its disturbance/loss) modulates the immune system by modulating the NA level in the brain or vice versa to maintain immune functions, physiological homeostasis, and normal healthy living. The increased levels of NA during REMS loss may cause neuroinflammation possibly by glial activation (as NA is a key modulator of microglia). Therefore, maintaining sleep hygiene plays a crucial role for a normal healthy living.

Dysregulation of iron metabolism in cardiovascular diseases: From iron deficiency to iron overload

Iron deficiency and iron overload are the most prevalent and opposite forms of dysregulated iron metabolism that affect approximately 30 percent of the world population, in particularly, elderly and patients with chronic diseases. Both iron deficiency and overload are frequently observed in a wide range of cardiovascular diseases, contributing to the onset and progression of these diseases. One of the devastating seqeulae for iron overload is the induction of ferroptosis, a newly defined form of regulated cell death which heavily impacts cardiac function through ferroptotic cell death in cardiomyocytes. In this review, we will aim to evaluate iron deficiency and iron overload in cardiovascular diseases. We will summarize current therapeutic strategies to tackle iron deficiency and iron overload, major pitfalls of current studies, and future perspectives.

Rapid eye movement sleep deprivation impairs neuronal plasticity and reduces hippocampal neuronal arborization in male albino rats: Noradrenaline is involved in the process

Rapid eye movement sleep (REMS) favors brain development and memory, while it is decreased in neurodegenerative diseases. REMS deprivation (REMSD) affects several physiological processes including memory consolidation; however, its detailed mechanism(s) of action was unknown. REMS reduces, while REMSD elevates noradrenaline (NA) level in the brain; the latter induces several deficiencies and disorders, including changes in neuronal cytomorphology and apoptosis. Therefore, we proposed that REMS- and REMSD-associated modulation of NA level might affect neuronal plasticity and affect brain functions. Male albino rats were REMS deprived by flower-pot method for 6 days, and its effects were compared with home cage and large platform controls as well as post-REMSD recovered and REMS-deprived prazosin (α1-adrenoceptor antagonist)-treated rats. We observed that REMSD reduced CA1 and CA3 neuronal dendritic length, branching, arborization, and spine density, while length of active zone and expressions of pre- as well as post-synaptic proteins were increased as compared to controls; interestingly, prazosin prevented most of the effects in vivo. Studies on primary culture of neurons from chick embryo brain confirmed that NA at lower concentration(s) induced neuronal branching and arborization, while higher doses were destructive. The findings support our contention that REMSD adversely affects neuronal plasticity, branching, and synaptic scaffold, which explain the underlying cytoarchitectural basis of REMSD-associated patho-physio-behavioral changes. Consolidation of findings of this study along with that of our previous reports suggest that the neuronal disintegration could be due to either withdrawal of direct protective and proliferative role of low dose of NA or indirect effect of high dose of NA or both.

Autophagy status as a gateway for stress-induced catecholamine interplay in neurodegeneration

The catecholamine-containing brainstem nuclei locus coeruleus (LC) and ventral tegmental area (VTA) are critically involved in stress responses. Alterations of catecholamine systems during chronic stress may contribute to neurodegeneration, including cognitive decline. Stress-related catecholamine alterations, while contributing to anxiety and depression, might accelerate neuronal degeneration by increasing the formation of toxic dopamine and norepinephrine by-products. These, in turn, may impair proteostasis within a variety of cortical and subcortical areas. In particular, the molecular events governing neurotransmission, neuroplasticity, and proteostasis within LC and VTA affect a variety of brain areas. Therefore, we focus on alterations of autophagy machinery in these nuclei as a relevant trigger in this chain of events. In fact, these catecholamine-containing areas are mostly prone to autophagy-dependent neurodegeneration. Thus, we propose a dynamic hypothesis according to which stress-induced autophagy alterations within the LC-VTA network foster a cascade towards early neurodegeneration within these nuclei.

REM sleep loss-induced elevated noradrenaline could predispose an individual to psychosomatic disorders: a review focused on proposal for prediction, prevention, and personalized treatment

Historically and traditionally, it is known that sleep helps in maintaining healthy living. Its duration varies not only among individuals but also in the same individual depending on circumstances, suggesting it is a dynamic and personalized physiological process. It has been divided into rapid eye movement sleep (REMS) and non-REMS (NREMS). The former is unique that adult humans spend the least time in this stage, when although one is physically asleep, the brain behaves as if awake, the dream state. As NREMS is a pre-requisite for appearance of REMS, the latter can be considered a predictive readout of sleep quality and health. It plays a protective role against oxidative, stressful, and psychopathological insults. Several modern lifestyle activities compromise quality and quantity of sleep (including REMS) affecting fundamental physiological and psychopathosomatic processes in a personalized manner. REMS loss-induced elevated brain noradrenaline (NA) causes many associated symptoms, which are ameliorated by preventing NA action. Therefore, we propose that awareness about personalized sleep hygiene (including REMS) and maintaining optimum brain NA level should be of paramount significance for leading physical and mental well-being as well as healthy living. As sleep is a dynamic, multifactorial, homeostatically regulated process, for healthy living, we recommend addressing and treating sleep dysfunctions in a personalized manner by the health professionals, caregivers, family, and other supporting members in the society. We also recommend that maintaining sleep profile, optimum level of NA, and/or prevention of elevation of NA or its action in the brain must be seriously considered for ameliorating lifestyle and REMS disturbance-associated dysfunctions.

Impact of sleep disturbances on neurodegeneration: Insight from studies in animal models

Chronic short sleep or extended wake periods are commonly observed in most industrialized countries. Previously neurobehavioral impairment following sleep loss was considered to be a readily reversible occurrence, normalized upon recovery sleep. Recent clinical studies suggest that chronic short sleep and sleep disruption may be risk factors for neurodegeneration. Animal models have been instrumental in determining whether disturbed sleep can injure the brain. We now understand that repeated periods of extended wakefulness across the typical sleep period and/or sleep fragmentation can have lasting effects on neurogenesis and select populations of neurons and glia. Here we provide a comprehensive overview of the advancements made using animal models of sleep loss to understand the extent and mechanisms of chronic short sleep induced neural injury.

Autophagy-Based Hypothesis on the Role of Brain Catecholamine Response During Stress

Stressful events, similar to abused drugs, significantly affect the homeostatic balance of the catecholamine brain systems while activating compensation mechanisms to restore balance. In detail, norepinephrine (NE)- and dopamine (DA)-containing neurons within the locus coeruleus (LC) and ventral tegmental area (VTA), are readily and similarly activated by psychostimulants and stressful events involving neural processes related to perception, reward, cognitive evaluation, appraisal, and stress-dependent hormonal factors. Brain catecholamine response to stress results in time-dependent regulatory processes involving mesocorticolimbic circuits and networks, where LC-NE neurons respond more readily than VTA-DA neurons. LC-NE projections are dominant in controlling the forebrain DA-targeted areas, such as the nucleus accumbens (NAc) and medial pre-frontal cortex (mPFC). Heavy and persistent coping demand could lead to sustained LC-NE and VTA-DA neuronal activity, that, when persisting chronically, is supposed to alter LC-VTA synaptic connections. Increasing evidence has been provided indicating a role of autophagy in modulating DA neurotransmission and synaptic plasticity. This alters behavior, and emotional/cognitive experience in response to drug abuse and occasionally, to psychological stress. Thus, relevant information to address the role of stress and autophagy can be drawn from psychostimulants research. In the present mini-review we discuss the role of autophagy in brain catecholamine response to stress and its dysregulation. The findings here discussed suggest a crucial role of regulated autophagy in the response and adaptation of LC-NE and VTA-DA systems to stress.

Anesthesia and sleep disorders – a new problem in modern anesthesiology (literature review)

Sleep is an active state that is as complex as wakefulness. The main tasks of sleep are the adaptation and restoration of physical and mental strength. Sleep regulation is a complex multimodal process involving not only neurotransmitters, but also releasing­factors, hormones, cytokines, signaling molecules and metabolites. Having a lot of physiological effects, postoperative sleep plays a role not only in quality of life, but also in the recovery of the patient. The characteristics of the patient, the type of surgical intervention, the methods of anesthesia and their interaction affects postoperative sleep, but the relationship and the level of influence of these factors are not clear. Therefore, given the high prevalence of postoperative insomnia, this problem is relevant for modern anesthesiology.