Locus Coeruleus Acid-Sensing Ion Channels Modulate Sleep-Wakefulness and State Transition from NREM to REM Sleep in the Rat

Deciphering Post-Stroke Sleep Disorders: Unveiling Neurological Mechanisms in the Realm of Brain Science

Sleep disorders are the most widespread mental disorders after stroke and hurt survivors' functional prognosis, response to restoration, and quality of life. This review will address an overview of the progress of research on the biological mechanisms associated with stroke-complicating sleep disorders. Extensive research has investigated the negative impact of stroke on sleep. However, a bidirectional association between sleep disorders and stroke exists; while stroke elevates the risk of sleep disorders, these disorders also independently contribute as a risk factor for stroke. This review aims to elucidate the mechanisms of stroke-induced sleep disorders. Possible influences were examined, including functional changes in brain regions, cerebrovascular hemodynamics, neurological deficits, sleep ion regulation, neurotransmitters, and inflammation. The results provide valuable insights into the mechanisms of stroke complicating sleep disorders.

ROS: Executioner of regulating cell death in spinal cord injury

The damage to the central nervous system and dysfunction of the body caused by spinal cord injury (SCI) are extremely severe. The pathological process of SCI is accompanied by inflammation and injury to nerve cells. Current evidence suggests that oxidative stress, resulting from an increase in the production of reactive oxygen species (ROS) and an imbalance in its clearance, plays a significant role in the secondary damage during SCI. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) is a crucial regulatory molecule for cellular redox. This review summarizes recent advancements in the regulation of ROS-Nrf2 signaling and focuses on the interaction between ROS and the regulation of different modes of neuronal cell death after SCI, such as apoptosis, autophagy, pyroptosis, and ferroptosis. Furthermore, we highlight the pathways through which materials science, including exosomes, hydrogels, and nanomaterials, can alleviate SCI by modulating ROS production and clearance. This review provides valuable insights and directions for reducing neuronal cell death and alleviating SCI through the regulation of ROS and oxidative stress.

Neuroepigenetics of ageing and neurodegeneration-associated dementia: An updated review

Gene expression is tremendously altered in the brain during memory acquisition, recall, and forgetfulness. However, non-genetic factors, including environmental elements, epigenetic changes, and lifestyle, have grabbed significant attention in recent years regarding the etiology of neurodegenerative diseases (NDD) and age-associated dementia. Epigenetic modifications are essential in regulating gene expression in all living organisms in a DNA sequence-independent manner. The genes implicated in ageing and NDD-related memory disorders are epigenetically regulated by processes such as DNA methylation, histone acetylation as well as messenger RNA editing machinery. The physiological and optimal state of the epigenome, especially within the CNS of humans, plays an intricate role in helping us adjust to the changing environment, and alterations in it cause many brain disorders, but the mechanisms behind it still need to be well understood. When fully understood, these epigenetic landscapes could act as vital targets for pharmacogenetic rescue strategies for treating several diseases, including neurodegeneration- and age-induced dementia. Keeping this objective in mind, this updated review summarises the epigenetic changes associated with age and neurodegeneration-associated dementia.

Molecular profiling of CO2/pH-sensitive neurons in the locus coeruleus of bullfrogs reveals overlapping noradrenergic and glutamatergic cell identity

Locus coeruleus (LC) neurons regulate breathing by sensing CO2/pH. Neurons within the vertebrate LC are the main source of norepinephrine within the brain. However, they also use glutamate and GABA for fast neurotransmission. Although the amphibian LC is recognized as a site involved in central chemoreception for the control of breathing, the neurotransmitter phenotype of these neurons is unknown. To address this question, we combined electrophysiology and single-cell quantitative PCR to detect mRNA transcripts that define norepinephrinergic, glutamatergic, and GABAergic phenotypes in LC neurons activated by hypercapnic acidosis (HA) in American bullfrogs. Most LC neurons activated by HA had overlapping expression of noradrenergic and glutamatergic markers but did not show strong support for GABAergic transmission. Genes that encode the pH-sensitive K+ channel, TASK2, and acid-sensing cation channel, ASIC2, were most abundant, while Kir5.1 was present in 1/3 of LC neurons. The abundance of transcripts related to norepinephrine biosynthesis linearly correlated with those involved in pH sensing. These results suggest that noradrenergic neurons in the amphibian LC also use glutamate as a neurotransmitter and that CO2/pH sensitivity may be linkedto the noradrenergic cell identity.

Triggering of Major Brain Disorders by Protons and ATP: The Role of ASICs and P2X Receptors

Adenosine triphosphate (ATP) is well-known as a universal source of energy in living cells. Less known is that this molecule has a variety of important signaling functions: it activates a variety of specific metabotropic (P2Y) and ionotropic (P2X) receptors in neuronal and non-neuronal cell membranes. So, a wide variety of signaling functions well fits the ubiquitous presence of ATP in the tissues. Even more ubiquitous are protons. Apart from the unspecific interaction of protons with any protein, many physiological processes are affected by protons acting on specific ionotropic receptors-acid-sensing ion channels (ASICs). Both protons (acidification) and ATP are locally elevated in various pathological states. Using these fundamentally important molecules as agonists, ASICs and P2X receptors signal a variety of major brain pathologies. Here we briefly outline the physiological roles of ASICs and P2X receptors, focusing on the brain pathologies involving these receptors.

Priorities for research on neuromodulatory subcortical systems in Alzheimer's disease: Position paper from the NSS PIA of ISTAART

The neuromodulatory subcortical system (NSS) nuclei are critical hubs for survival, hedonic tone, and homeostasis. Tau-associated NSS degeneration occurs early in Alzheimer's disease (AD) pathogenesis, long before the emergence of pathognomonic memory dysfunction and cortical lesions. Accumulating evidence supports the role of NSS dysfunction and degeneration in the behavioral and neuropsychiatric manifestations featured early in AD. Experimental studies even suggest that AD-associated NSS degeneration drives brain neuroinflammatory status and contributes to disease progression, including the exacerbation of cortical lesions. Given the important pathophysiologic and etiologic roles that involve the NSS in early AD stages, there is an urgent need to expand our understanding of the mechanisms underlying NSS vulnerability and more precisely detail the clinical progression of NSS changes in AD. Here, the NSS Professional Interest Area of the International Society to Advance Alzheimer's Research and Treatment highlights knowledge gaps about NSS within AD and provides recommendations for priorities specific to clinical research, biomarker development, modeling, and intervention. HIGHLIGHTS: Neuromodulatory nuclei degenerate in early Alzheimer's disease pathological stages. Alzheimer's pathophysiology is exacerbated by neuromodulatory nuclei degeneration. Neuromodulatory nuclei degeneration drives neuropsychiatric symptoms in dementia. Biomarkers of neuromodulatory integrity would be value-creating for dementia care. Neuromodulatory nuclei present strategic prospects for disease-modifying therapies.

Role of the Voltage-Gated Proton Channel Hv1 in Nervous Systems

Hv1 is the only voltage-gated proton-selective channel in mammalian cells. It contains a conserved voltage-sensor domain, shared by a large class of voltage-gated ion channels, but lacks a pore domain. Its primary role is to extrude protons from the cytoplasm upon pH reduction and membrane depolarization. The best-known function of Hv1 is the regulation of cytosolic pH and the nicotinamide adenine dinucleotide phosphate oxidase-dependent production of reactive oxygen species. Accumulating evidence indicates that Hv1 is expressed in nervous systems, in addition to immune cells and others. Here, we summarize the molecular properties, distribution, and physiological functions of Hv1 in the peripheral and central nervous systems. We describe the recently discovered functions of Hv1 in various neurological diseases, including brain or spinal cord injury, ischemic stroke, demyelinating diseases, and pain. We also summarize the current advances in the discovery and application of Hv1-targeted small molecules in neurological diseases. Finally, we discuss the current limitations of our understanding of Hv1 and suggest future research directions.

Proton Pump Inhibitor "Lansoprazole" Inhibits Locus Coeruleus's Neuronal Activity and Increases Rapid Eye Movement Sleep

Alteration of the bodily CO₂ concentration and proton pump activity affects the sleep architecture. The brainstem locus coeruleus (LC) area plays an essential role in rapid eye movement (REM) sleep generation and chemoregulation. Previously, we reported that lansoprazole injections (intraperitoneal) increased REM sleep in the rats. However, it is not known if proton pumps in the LC influence REM sleep. Here, we studied the effects of lansoprazole in the LC on the neuronal activity and REM sleep expression. Male Wistar rats (250-300 g) were surgically prepared for sleep recording and drug microinjections into the LC. We determined the localization of proton pumps and expression levels of cFOS in the LC neurons immunohistochemically. Sleep-wake was recorded before and after the microinjections of drugs/vehicles. Our results demonstrate (i) the presence of proton pumps in the LC neurons, (ii) that the microinjection of lansoprazole into the LC reduced the number of cFOS^+ve-TH^+ve double-labeled neurons in the LC by 52.6% (p < 0.001) compared to the vehicle and (iii) that low and high doses of lansoprazole significantly increased REM sleep by 32% (p < 0.001) and 60% (p < 0.001), respectively, compared to the vehicle. Our results suggest that the proton pumps modulate the LC's noradrenergic (NE-ergic) neuronal activity and REM sleep. The increased amount of REM sleep can be attributed to the inhibition of the LC NE-ergic activity. Further, the REM sleep amount increased after the lansoprazole microinjections into the LC with a significant increase in the REM sleep episode numbers. Overall, our results suggest that proton pumps in the LC may be involved in REM sleep generation.

Metformin Attenuates Bone Cancer Pain by Reducing TRPV1 and ASIC3 Expression

Bone cancer pain (BCP) is a common pathologic pain associated with destruction of bone and pathological reconstruction of nervous system. Current treatment strategies in clinical is inadequate and have unacceptable side effects due to the unclear pathology mechanism. In the present study, we showed that transplantation of Walker 256 cells aggravated mechanical allodynia of BCP rats (**p < 0.01 vs. Sham), and the expression of ASIC3 (Acid-sensitive ion channel 3) and TRPV1 was obviously enhanced in L4-6 dorsal root ganglions (DRGs) of BCP rats (**p < 0.01 vs. Sham). ASIC3 and TRPV1 was mainly expressed in CGRP and IB4 positive neurons of L4-6 DRGs. While, TRPV1 but not ASIC3 was markedly upregulated in L4-6 spinal dorsal horn (SDH) of BCP rats (**p < 0.01 vs. Sham). Importantly, intrathecal injection of CPZ (a TRPV1 inhibitor) or Amiloride (an ASICs antagonist) markedly increased the paw withdraw threshold (PWT) of BCP rats response to Von Frey filaments (**p < 0.01 vs. BCP + NS). What’s more, intraperitoneally injection of Metformin or Vinorelbine markedly elevated the PWT of BCP rats, but reduced the expression of TRPV1 and ASIC3 in L4-6 DRGs and decreased the TRPV1 expression in SDH (*p < 0.05, **p < 0.01 vs. BCP + NS). Collectively, these results suggest an effective analgesic effect of Metformin on mechanical allodynia of BCP rats, which may be mediated by the downregulation of ASIC3 and TRPV1.