Paradoxical Sleep Deprivation Causes Cardiac Dysfunction and the Impairment Is Attenuated by Resistance Training

Sleep deprivation modulates APOE and LDL receptor-related protein 1 through thyroid hormone T4 and impairs Aβ clearance in hippocampus of rats

Alzheimer's disease is the most common form of dementia. One of its pathological hallmarks is Aβ accumulation, which is influenced by APOE genotype and expression, as well as by sleep homeostasis. However, conflicting mechanisms for APOE roles in Aβ clearance have been reported, and the relationship between APOE and sleep also remains unclear. In this study, we aimed to investigate how hormonal alteration caused by sleep deprivation affects APOE and its receptors in rats, and to evaluate the role of different cell types in Aβ clearance. Paradoxical sleep deprivation for 96 h increased Aβ level in hippocampus with concomitant reduction of APOE and LRP1 at the time point within the resting period. Sleep deprivation also significantly reduced T4 levels in both active and resting times. To evaluate the effect of T4 variation, C6 glial cells and primary brain endothelial cells were treated with T4. High T4 level (300 ng/mL) increased APOE, but reduced LRP1 and LDL-R in C6 cells, while in primary endothelial cells, LDL-R levels were increased. Treatment of C6 cells with exogenous APOE reduced LRP1 and Aβ uptake. These results suggest that T4 modulates LRP1 and LDL-R in both cell types, but in the opposite manner, thus, sleep deprivation might modify the ratio of the receptors in blood-brain barrier and glial cells by altering T4 levels. Considering that LRP1 and LDL-R are important for Aβ clearance, sleep deprivation might also affect the degree of participation of glia in Aβ clearance, and consequently, turnover of Aβ in the brain.

Therapeutic effects of growth hormone in a rat model of total sleep deprivation: Evaluating behavioral, hormonal, biochemical and electrophysiological parameters

OBJECTIVE

Total sleep deprivation (TSD) causes several harmful changes in the brain, including memory impairment, increased stress and depression levels, as well as reduced antioxidant activity. Growth hormone (GH) has been shown to boost antioxidant levels while improving memory and depression. The present study was conducted to explain the possible effects of exogenous GH against behavioral and biochemical disorders caused by TSD and the possible mechanisms involved.

MAIN METHODS

To induce TSD, rats were housed in homemade special cages equipped with stainless steel wire conductors to induce general and inconsistent TSD. They received a mild repetitive electric shock to their paws every 10 min for 21 days. GH (1 ml/kg, sc) was administered to rats during induction of TSD for 21 days. Memory retrieval, anxiety, depression-like behaviors, pain behaviors, antioxidant activity, hippocampal level of BDNF, and simultaneously brain electrical activity were measured at scheduled times after TSD.

KEY FINDINGS

The results showed that GH treatment improved memory (p < 0.001) in the PAT test of rats exposed to TSD. These beneficial effects were associated with lowering the level of anxiety and depression-like behavior (p < 0.001), rising the pain threshold (p < 0.01), increasing the activity of antioxidants (p < 0.01), hippocampal BDNF (p < 0.001), and regular brain electrical activity.

SIGNIFICANCE

Our findings show that GH plays a key role in modulating memory, anxiety and depression behaviors, as well as reducing oxidative stress and improve hippocampal single-unit activity in the brain during TSD.

Acute sleep deprivation increases inflammation and aggravates heart failure after myocardial infarction

Sleep disorders have been observed among patients with heart failure. The aim of this study was to investigate whether acute sleep deprivation (SD) aggravates left heart function. Male C57B/L6 mice were assigned to four experimental groups. Ligation of the left anterior descending branch (LAD) caused myocardial infarction (MI) in mice in the LAD group and the LAD+SD group, while mice in the sham and sham+SD groups underwent the same surgery without ligation. Echocardiography was performed before and 8 weeks after ligation of the LAD to evaluate the left ventricular internal diameter at diastole (LVIDd), left ventricular internal diameter at systole (LVIDs), ejection fraction (EF), and fractional shortening (FS). Seven days of sleep deprivation induced using the modified single platform method resulted in a lower EF and FS and a higher LVIDd and LVIDs, as well as increased expression of the IL-1β, IL-18, and IL-10 mRNAs in the left ventricular tissue of MI mice. ELISA also indicated higher levels of IL-1β and IL-10 in the LAD+SD group. It was concluded that acute sleep deprivation induced cardiovascular alterations in cardiac structure and function in HF mice, accompanied by increased levels of inflammatory cytokines.

Lithium Treatment Improves Cardiac Dysfunction in Rats Deprived of Rapid Eye Movement Sleep

Rapid eye movement (REM) sleep deprivation triggers mania and induces cardiac fibrosis. Beyond neuroprotection, lithium has cardioprotective potential and antifibrotic activity. This study investigated whether lithium improved REM sleep deprivation-induced cardiac dysfunction and evaluated the potential mechanisms. Transthoracic echocardiography, histopathological analysis, and Western blot analysis were performed in control and REM sleep-deprived rats with or without lithium treatment (LiCl of 1 mmol/kg/day administered by oral gavage for 4 weeks) in vivo and in isolated ventricular preparations. The results revealed that REM sleep-deprived rats exhibited impaired contractility and greater fibrosis than control and lithium-treated REM sleep-deprived rats. Western blot analysis showed that REM sleep-deprived hearts had higher expression levels of transforming growth factor beta (TGF-β), phosphorylated Smad 2/3, and alpha-smooth muscle actin than lithium-treated REM sleep-deprived and control hearts. Moreover, lithium-treated REM sleep-deprived hearts had lower expression of angiotensin II type 1 receptor, phosphorylated nuclear factor kappa B p65, calcium release-activated calcium channel protein 1, transient receptor potential canonical (TRPC) 1, and TRPC3 than REM sleep-deprived hearts. The findings suggest that lithium attenuates REM sleep deprivation-induced cardiac fibrogenesis and dysfunction possibly through the downregulation of TGF-β, angiotensin II, and Ca²⁺ signaling.

Sleep debt induces skeletal muscle injuries in athletes: A promising hypothesis

Sleep is a physiological state and it is fundamental for physical and cognitive recovery of athletes. Due to strenuous training and competitions, athletes may present sleep complaints compromising good quality and quantity of sleep. Studies have related sleep debt to the occurrence of musculoskeletal injuries in athletes, but the mechanisms that can lead to this are not entirely clear. Studies involving animals and humans have shown that poor sleep quality can cause significant changes in hormones and cytokines. Demonstrating that this hormones changes lead to a decrease of testosterone and growth hormone levels and increased cortisol levels, important hormones in the process of protein synthesis and degradation. In athletes, the sport itself is a risk factor of injuries, and sleep debt may result in overtraining syndrome associated with inflammatory markers and ultimately to immune system dysfunction. Thus, we hypothesize that athletes who have sleep debt are more susceptible to musculoskeletal injuries due to increased catabolic pathway signaling, i.e. protein degradation and decreased anabolic pathway signaling, compromising muscle integrity. In this sense, we indicate the relationship between musculoskeletal injuries and sleep debt involving new targets for immunological signaling pathways that start the reduction of the muscle recovery process.

Sleep and the GH/IGF-1 axis: Consequences and countermeasures of sleep loss/disorders

This article presents an up-to-date review of the state-of-the-art knowledge regarding the effect of sleep on the anabolic growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis. This axis is involved in learning and memory and neuroprotection at the central level, and in the crosstalk between sleep and the immune system, with respect to its anti-inflammatory properties. We also aim to provide insight into the consequences of sleep loss on cognitive capacities in healthy individuals and patients with obstructive sleep apnea (OSA), regarding the mechanistic association with the GH/IGF-1 axis. Finally, this review examines the inflammatory/endocrine pathways that are affected by sleep loss, and which may consequently interact with the GH/IGF-1 axis. The deleterious effects of sleep loss include fatigue, and can cause several adverse age-dependent health outcomes. It is therefore important to improve our understanding of the fundamental physiology underlying these effects in order to better apply non-pharmacological countermeasures (e.g., sleep strategies, exercise training, continuous positive airway pressure therapy) as well as pharmacological solutions, so as to limit the deleterious consequences of sleep loss/disorders.

Roles of sleep deprivation in cardiovascular dysfunctions

It is widely recognized that inadequate sleep is associated with multiple acute and chronic diseases and results in increased mortality and morbidity for cardiovascular diseases. In recent years, there has been increasing interest in sleep related investigations. Emerging evidence indicates that sleep deprivation changes the biological phenotypes of DNA, RNA and protein levels, but the underlying mechanisms are not clear. We summarized the current research on the detrimental roles of sleep deprivation on the heart and elucidated the underlying mechanisms of sleep deficiency to improve our understanding of sleep deprivation and the emerging strategies to target this process for therapeutic benefit.