Decreased cpg15 augments oxidative stress in sleep deprived mouse brain

Understanding neuron-glia crosstalk and biological clocks in insomnia

According to the World Health Organization, about one-third of the population experiences insomnia symptoms, and about 10-15% suffer from chronic insomnia, the most common sleep disorder. Sleeping difficulties associated with insomnia are often linked to chronic sleep deprivation, which has a negative health impact partly due to disruption in the internal synchronisation of biological clocks. These are regulated by clock genes and modulate most biological processes. Most studies addressing circadian rhythm regulation have focused on the role of neurons, yet glial cells also impact circadian rhythms and sleep regulation. Chronic insomnia and sleep loss have been associated with glial cell activation, exacerbated neuroinflammation, oxidative stress, altered neuronal metabolism and synaptic plasticity, accelerated age-related processes and decreased lifespan. It is, therefore, essential to highlight the importance of glia-neuron interplay on sleep/circadian regulation and overall healthy brain function. Hence, in this review, we aim to address the main neurobiological mechanisms involved in neuron-glia crosstalk, with an emphasis on microglia and astrocytes, in both healthy sleep, chronic sleep deprivation and chronic insomnia.

Overexpression of Cpg15 Alleviates the Oxidative Stress in Neuronal Cells Via Regulating Redox Enzymes and Nrf2 Antioxidative Pathway

Oxidative stress is becoming increasingly implicated in the development of a variety of neurological disorders. However, the underlying mechanism remains elusive. In the present study, we investigated the function and related signal pathway which Cpg15, a neuronal-specific expressed neurotrophic factor, plays in the oxidative stress of neurons using a H₂O₂-treated N2a cell model. The results showed that the Cpg15 expression was decreased under oxidative stress, and overexpression of Cpg15 increased the activity of antioxidative SOD enzymes and decreased the expression level of prooxidative COX2 enzyme, and the level of oxidative products malondialdehyde (MDA), indicating its function and potential mechanism in alleviating the oxidative stress of cells. The results also indicated that the Nrf2/HO-1 antioxidative pathway was involved in the Cpg15-mediated alleviation of oxidative stress. Also, overexpression of Cpg15 activated the Nrf2 antioxidative pathway in the thalamus of the REM sleep-deprived mice. In conclusion, our results implied that supplemental expression of Cpg15 may alleviate oxidative stress in neuronal cells via regulating the redox enzymes or activating the Nrf2 antioxidant pathway.

Endothelial Function and Arterial Stiffness Should Be Measured to Comprehensively Assess Obstructive Sleep Apnea in Clinical Practice

Objective: An effective clinical tool to assess endothelial function and arterial stiffness in patients with obstructive sleep apnea (OSA) is lacking. This study evaluated the clinical significance of subclinical markers for OSA management in males without serious complications.

Patients/Methods: Males without serious complications were consecutively recruited. Clinical data, biomarker tests, reactive hyperemia index (RHI), and augmentation index at 75 beats/min (AIx75) measured by peripheral arterial tonometry were collected. An apnea hypopnea index (AHI) cutoff of ≥15 events/h divided the patients into two groups.

Results: Of the 75 subjects, 42 had an AHI ≥15 events/h. Patients with an AHI ≥15 events/h had higher high-sensitivity C-reactive protein, tumor necrosis factor-alpha (TNF-α), vascular endothelial growth factor, and AIx75 values than the control group but no statistical difference in RHI was observed. After controlling for confounders, TNF-α was negatively correlated with the average oxygen saturation (r = −0.258, P = 0.043). RHI was correlated with the rapid eye movement (REM) stage percentage (r = 0.306, P = 0.016) but not with AHI (P > 0.05). AIx75 was positively correlated with the arousal index (r = 0.289, P = 0.023) but not with AHI (r = 0.248, P = 0.052).

Conclusions: In males with OSA without severe complications, TNF-α and AIx75 are independently related to OSA. The role of RHI in OSA management requires further elucidation. These markers combined can comprehensively evaluate OSA patients to provide more evidence for the primary prevention of coronary heart disease and treatment response assessment.

Sleep Deprivation Aggravates Cognitive Impairment by the Alteration of Hippocampal Neuronal Activity and the Density of Dendritic Spine in Isoflurane-Exposed Mice

Isoflurane contributes to cognitive deficits when used as a general anesthetic, and so does sleep deprivation (SD). Patients usually suffer from insomnia before an operation due to anxiety, fear, and other factors. It remains unclear whether preoperative SD exacerbates cognitive impairment induced by isoflurane. In this study, we observed the effects of pretreated 24-h SD in adult isoflurane-exposed mice on the cognitive behaviors, the Ca²⁺ signals of dorsal hippocampal CA1 (dCA1) neurons in vivo with fiber photometry, and the density of dendritic spines in hippocampal neurons. Our results showed that in cognitive behavior tasks, short-term memory damages were more severe with SD followed by isoflurane exposure than that with SD or isoflurane exposure separately, and interestingly, severe long-term memory deficits were induced only by SD followed by isoflurane exposure. Only the treatment of SD followed by isoflurane exposure could reversibly decrease the amplitude of Ca²⁺ signals when mice were freely moving and increase the duration of Ca²⁺ signals during the long-term memory behavior test. The density of dendritic spines with both SD and isoflurane exposure was lower than that with SD alone. This study suggests that SD should be avoided preoperatively in patients undergoing elective surgery under isoflurane anesthesia.