Increased turnover of Na-K ATPase molecules in rat brain after rapid eye movement sleep deprivation

Rapid eye movement sleep loss associated cytomorphometric changes and neurodegeneration

Rapid eye movement sleep (REMS) is essential for leading normal healthy living at least in higher-order mammals, including humans. In this review, we briefly survey the available literature for evidence linking cytomorphometric changes in the brain due to loss of REMS. As a mechanism of action, we add evidence that REMS loss elevates noradrenaline (NA) levels in the brain, which affects neuronal cytomorphology. These changes may be a compensatory mechanism as the changes return to normal after the subjects recover from the loss of REMS or if during REMS deprivation, the subjects are treated with NA-adrenoceptor antagonist prazosin (PRZ). We had proposed earlier that one of the fundamental functions of REMS is to maintain the level of NA in the brain. We elaborate on this idea to propose that if REMS loss continues without recovery, the sustained level of NA breaks down neurophysiologically active compensatory mechanism/s starting with changes in the neuronal cytomorphology, followed by their degeneration, leading to acute and chronic pathological conditions. Identification of neuronal cytomorphological changes could prove to be of significance for predicting future neuronal (brain) damage as well as an indicator for REMS health. Although current brain imaging techniques may not enable us to visualize changes in neuronal cytomorphology, given the rapid technological progress including use of artificial intelligence, we are optimistic that it may be a reality soon. Finally, we propose that maintenance of optimum REMS must be considered a criterion for leading a healthy life.

Na+/K+-ATPase and lipid peroxidation in forebrain cortex and hippocampus of sleep-deprived rats treated with therapeutic lithium concentration for different periods of time

Lithium (Li) is a typical mood stabilizer and the first choice for treatment of bipolar disorder (BD). Despite an extensive clinical use of Li, its mechanisms of action remain widely different and debated. In this work, we studied the time-course of the therapeutic Li effects on ouabain-sensitive Na⁺/K⁺-ATPase in forebrain cortex and hippocampus of rats exposed to 3-day sleep deprivation (SD). We also monitored lipid peroxidation as malondialdehyde (MDA) production. In samples of plasma collected from all experimental groups of animals, Li concentrations were followed by ICP-MS. The acute (1 day), short-term (7 days) and chronic (28 days) treatment of rats with Li resulted in large decrease of Na⁺/K⁺-ATPase activity in both brain parts. At the same time, SD of control, Li-untreated rats increased Na⁺/K⁺-ATPase along with increased production of MDA. The SD-induced increase of Na⁺/K⁺-ATPase and MDA was attenuated in Li-treated rats. While SD results in a positive change of Na⁺/K⁺-ATPase, the inhibitory effect of Li treatment may be interpreted as a pharmacological mechanism causing a normalization of the stress-induced shift and return the Na⁺/K⁺-ATPase back to control level. We conclude that SD alone up-regulates Na⁺/K⁺-ATPase together with increased peroxidative damage of lipids. Chronic treatment of rats with Li before SD, protects the brain tissue against this type of damage and decreases Na⁺/K⁺-ATPase level back to control level.

Changes in Body Water Caused by Sleep Deprivation in Taeeum and Soyang Types in Sasang Medicine: Prospective Intervention Study

Background

There is a negative relationship between sleep deprivation and health. However, no study has investigated the effect of sleep deprivation on individuals with different body composition. The aim of this study was to determine the differential effect of sleep deprivation in individuals with different body compositions (fluid) according to Soyang type (SY) and Taeeum type (TE).

Methods

Sixty-two cognitively normal, middle-aged people with normal sleep patterns were recruited from the local population. The duration of participants' sleep was restricted to 4 h/day during the intervention phase. To examine the physiological changes brought on by sleep deprivation and recovery, 10 ml of venous blood was obtained.

Results

Total Body Water (TBW) and Extracellular Water (ECW) were significantly different between the groups in the intervention phase. Physiological parameters also varied from the beginning of the resting phase to the end of the experiment. Potassium levels changed more in SY than TE individuals.

Conclusion

Participants responded differently to the same amount of sleep deprivation depending on their Sasang constitution types. This study indicated that SY individuals were more sensitive to sleep deprivation and were slower to recover from the effects of sleep deprivation than TE individuals.

Targeting modulation of noradrenalin release in the brain for amelioration of REMS loss-associated effects

Rapid eye movement sleep (REMS) loss affects most of the physiological processes, and it has been proposed that REMS maintains normal physiological processes. Changes in cultural, social, personal traits and life-style severely affect the amount and pattern of sleep, including REMS, which then manifests symptoms in animals, including humans. The effects may vary from simple fatigue and irritability to severe patho-physiological and behavioral deficits such as cognitive and behavioral dysfunctions. It has been a challenge to identify a molecule(s) that may have a potential for treating REMS loss-associated symptoms, which are very diverse. For decades, the critical role of locus coeruleus neurons in regulating REMS has been known, which has further been supported by the fact that the noradrenalin (NA) level is elevated in the brain after REMS loss. In this review, we have collected evidence from the published literature, including those from this laboratory, and argue that factors that affect REMS and vice versa modulate the level of a common molecule, the NA. Further, NA is known to affect the physiological processes affected by REMS loss. Therefore, we propose that modulation of the level of NA in the brain may be targeted for treating REMS loss-related symptoms. Further, we also argue that among the various ways to affect the release of NA-level, targeting α₂ adrenoceptor autoreceptor on the pre-synaptic terminal may be the better option for ameliorating REMS loss-associated symptoms.

Protective role of noradrenaline in benzo[a]pyrene-induced learning impairment in developing rat

Benzo[a]pyrene (B[a]P), a carcinogen, affects brain development, learning, and memory. Isolated studies have reported that B[a]P elevates noradrenaline (NA) level that may modulate neuronal growth, learning, and memory. Therefore, we investigated in vivo and in vitro the effects of B[a]P on learning and memory and its possible mechanism of action. Intracisternal administration of B[a]P on postnatal day 5 significantly reduced learning and memory in adolescent rats as observed by probe test using the Morris water maze. The density of both the subunits of the N-methyl-D-aspartate (NMDA) receptor, NMDAR1 and NMDAR2B, significantly increased in the hippocampus. In vitro, B[a]P significantly increased NMDAR1 in both C6 and Neuro2a cell lines, whereas NMDAR2B was significantly increased in C6 but was significantly decreased in Neuro2a. Pretreatment with NA prevented the B[a]P-induced effect on NMDAR1 expression in both cell lines. However, although NA prevented the B[a]P-mediated increase in NMDAR2B expression in C6, it further potentiated the decrease of NMDAR2B in Neuro2a cells. Also, NA prevented the B[a]P-induced increase in intracellular Ca(2+) both in C6 and in Neuro2a. Our findings show that postnatal exposure of developing rats to B[a]P impairs learning and memory even when the rats became adolescent. We also observed that the effects were mediated by elevated intracellular Ca(2+) levels and increased expression of NMDAR; furthermore, NA exerted a protective effect by modulating those factors. NA differentially affects neurons and glia, which may have a compensatory role during toxic insults, especially from B[a]P.

REM sleep loss increases brain excitability: role of noradrenaline and its mechanism of action

Ever since the discovery of rapid eye movement sleep (REMS), studies have been undertaken to understand its necessity, function and mechanism of action on normal physiological processes as well as in pathological conditions. In this review, first, we briefly surveyed the literature which led us to hypothesise REMS maintains brain excitability. Thereafter, we present evidence from in vivo and in vitro studies tracing behavioural to cellular to molecular pathways showing REMS deprivation (REMSD) increases noradrenaline level in the brain, which stimulates neuronal Na-K ATPase, the key factor for maintaining neuronal excitability, the fundamental property of a neuron for executing brain functions; we also show for the first time the role of glia in maintaining ionic homeostasis in the brain. As REMSD exerts a global effect on most of the physiological processes regulated by the brain, we propose that REMS possibly serves a housekeeping function in the brain. Finally, subject to confirmation from clinical studies, based on the results reviewed here, it is being proposed that the subjects suffering from REMS loss may be effectively treated by reducing either noradrenaline level or Na-K ATPase activity in the brain.

Cytomorphometric changes in the dorsal raphe neurons after rapid eye movement sleep deprivation are mediated by noradrenalin in rats

OBJECTIVES

This study was carried out to investigate the effect of rapid eye movement sleep (REMS) deprivation (REMSD) on the cytomorphology of the dorsal raphe (DR) neurons and to evaluate the possible role of REMSD-induced increased noradrenalin (NA) in mediating such effects.

METHODS

Rats were REMS deprived by the flowerpot method; free moving normal home cage rats, large platform and post REMS-deprived recovered rats were used as controls. Further, to evaluate if the effects were induced by NA, separate sets of experimental rats were treated (i.p.) with α1-adrenoceptor antagonist, prazosin (PRZ). Histomorphometric analysis of DR neurons in stained brain sections were performed in experimental and control rats; neurons in inferior colliculus (IC) served as anatomical control.

RESULTS

The mean size of DR neurons was larger in REMSD group compared to controls, whereas, neurons in the recovered group of rats did not significantly differ than those in the control animals. Further, mean cell size in the post-REMSD PRZ-treated animals was comparable to those in the control groups. IC neurons were not affected by REMSD.

CONCLUSIONS

REMS loss has been reported to impair several physiological, behavioral and cellular processes. The mean size of the DR neurons was larger in the REMS deprived group of rats than those in the control groups; however, in the REMS deprived and prazosin treated rats the size was comparable to the normal rats. These results showed that REMSD induced increase in DR neuronal size was mediated by NA acting on α1-adrenoceptor. The findings suggest that the sizes of DR neurons are sensitive to REMSD, which if not compensated could lead to neurodegeneration and associated disorders including memory loss and Alzheimer's disease.

Capillary endothelial Na(+), K(+), ATPase transporter homeostasis and a new theory for migraine pathophysiology

BACKGROUND

Cerebrospinal fluid sodium concentration ([Na(+)](csf)) increases during migraine, but the cause of the increase is not known.

OBJECTIVE

Analyze biochemical pathways that influence [Na(+)](csf) to identify mechanisms that are consistent with migraine.

METHOD

We reviewed sodium physiology and biochemistry publications for links to migraine and pain.

RESULTS

Increased capillary endothelial cell (CEC) Na(+), K(+), -ATPase transporter (NKAT) activity is probably the primary cause of increased [Na(+)](csf). Physiological fluctuations of all NKAT regulators in blood, many known to be involved in migraine, are monitored by receptors on the luminal wall of brain CECs; signals are then transduced to their abluminal NKATs that alter brain extracellular sodium ([Na(+)](e)) and potassium ([K(+)](e)).

CONCLUSIONS

We propose a theoretical mechanism for aura and migraine when NKAT activity shifts outside normal limits: (1) CEC NKAT activity below a lower limit increases [K(+)](e), facilitates cortical spreading depression, and causes aura; (2) CEC NKAT activity above an upper limit elevates [Na(+)](e), increases neuronal excitability, and causes migraine; (3) migraine-without-aura may arise from CEC NKAT over-activity without requiring a prior decrease in activity and its consequent spreading depression; (4) migraine triggers disturb, and treatments improve, CEC NKAT homeostasis; (5) CEC NKAT-induced regulation of neural and vasomotor excitability coordinates vascular and neuronal activities, and includes occasional pathology from CEC NKAT-induced apoptosis or cerebral infarction.

Increased apoptosis in rat brain after rapid eye movement sleep loss

Rapid eye movement (REM) sleep loss impairs several physiological, behavioral and cellular processes; however, the mechanism of action was unknown. To understand the effects of REM sleep deprivation on neuronal damage and apoptosis, studies were conducted using multiple apoptosis markers in control and experimental rat brain neurons located in areas either related to or unrelated to REM sleep regulation. Furthermore, the effects of REM sleep deprivation were also studied on neuronal cytoskeletal proteins, actin and tubulin. It was observed that after REM sleep deprivation a significantly increased number of neurons in the rat brain were positive to apoptotic markers, which however, tended to recover after the rats were allowed to undergo REM sleep; the control rats were not affected. Further, it was also observed that REM sleep deprivation decreased amounts of actin and tubulin in neurons confirming our previous reports of changes in neuronal size and shape after such deprivation. These findings suggest that one of the possible functions of REM sleep is to protect neurons from damage and apoptosis.