All living organisms exhibit circadian rhythms. Humans show circadian rhythm of the different physiological functions such as sleep-wake cycle, core body temperature, feeding behavior, metabolic activity, heart rate variability, hormone secretion, and others. The hypothalamic suprachiasmatic nucleus (SCN) acts as a primary circadian pacemaker. Peripheral tissues have an endogenous circadian clock; however, SCN synchronizes the circadian activity of the peripheral clocks. The retinohypothalamic tract (RHT) from retinal ganglionic cells carries the photic signal into the SCN that regulates the rhythmic expression of the core clock genes through the feedback loop. At the output level, the SCN connects with the pineal gland and the peripheral tissues with the help of neuroendocrine mediators. Disruption of circadian clock functions is detrimental to health. Shift work, night work, chronic or acute jet lag, and light-at-night have adverse effects on circadian functions. Misalignment of circadian rhythm alters the expression of core clock genes, leading to deregulation of cellular activity and metabolic functions. Circadian rhythm dysfunction causes many pathologic conditions, including sleep disorders, cardiovascular problems, metabolic dysfunction, infertility, poor physical performance, as well as cancer. The present work has reviewed the relationship between circadian clock dysfunction and impaired physiological activities.

Full Text

PDF

Viewed:31175

Downloaded:322

Cited: 15

Neuregulins (NRGs) and their cognate ErbB receptors (ErbB2–ErbB4) constitute a vast group of proteins encoded by six different genes (NRG1–6) and many isoforms with critical roles in the development and functioning of the nervous system. NRGs are known to regulate important processes in the nervous system like neural development, neuronal differentiation, neurite outgrowth, and specification. These factors are involved in the regulation of neurotransmission pathways and the modulation of several forms of synaptic plasticity. Due to NRGs’ role in synaptic plasticity, defects in their normal functioning are translated into altered signaling networks, which have been linked to susceptibility to developing psychiatric disorders like schizophrenia (SZ), autism, depression, and bipolar disorders. Additionally, deviation of the NRG normal functioning is involved in neurological diseases like Alzheimer’s and Parkinson’s disease. Contrastingly, NRG/ErbB signaling is also involved in the recovery after traumatic brain injuries (e.g., ischemic stroke). The NRG/ErbB signaling complex is highly unusual because the ligands (mainly NRG1–NRG3, with their multiple isoforms) and receptors (ErbB2–ErbB4) can orchestrate vast signaling complexes, with a wide reach within the processes that govern the development and appropriate function of the nervous system. This may explain why NRGs and ErbB receptor genes have been linked to complex brain disorders, like SZ. This review, are discussed important aspects of NRG and their relevance for nervous system functioning, including 1) subcellular localization, 2) signaling pathways involved in neuronal functions, 3) effect on neurite development and synapse formation, 4) modulation of some mechanisms of synaptic plasticity [long-term potentiation (LTP), depotentiation, long-term depression (LTD)] and 5) roles of NRGs in some neurological diseases. This review intends to present a summary of the main findings about this family of proteins, which might position them as one of the master regulators of brain functioning.

Full Text

PDF

Viewed:7882

Downloaded:92

Cited: 4

This brief statement describes some recent achievements of neuropathological research, with the focus on Alzheimer’s and other age-related diseases, neurodegenerative disorders (tauopathies, synucleinopathies), multimorbidity of the aged brain, multiple sclerosis (MS), and other neuroinflammatory disorders, including central nervous system involvement by coronavirus disease 2019 (COVID-19), as well as new developments in neurovascular diseases, neurooncology, and myopathies. Although neuropathology, using modern technologies, such as cryo-electron microscopy, proteomic and experimental methods, has helped to increase diagnostic accuracy and provided insight into the pathogenesis of many neurological disorders, future studies in co-operation with clinical and other neurosciences should overcome the challenges of disease-influencing therapeutic approaches.

Full Text

PDF

Viewed:5969

Downloaded:64

Cited: 1

Ischemic stroke is a highly prevalent condition that frequently results in life-long disability and death. Considerable efforts have been made to establish treatments that prevent secondary ischemic damage and promote stroke recovery. Until now, the recanalization of occluded blood vessels via thrombolysis and thrombectomy, although highly potent, remains the only treatment in humans that enhances stroke outcome. Small extracellular vesicles are non-replicating, nano-sized (70–150 nm) lipid bilayer-enclosed vesicles, which have shown remarkable biological activities in various physiological and pathophysiological contexts. When administered post-stroke, mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) induce neuroprotection, promote brain remodeling and plasticity, and enhance neurological recovery in rodents and non-human primates via mechanisms that involve immunomodulation and anti-inflammation. In this review, experimental studies on the therapeutic actions of MSC-EVs in animal stroke models are summarized and perspectives for clinical translation are outlined.

Full Text

PDF

Viewed:5382

Downloaded:68

Cited: 2

The therapy of many neurological disorders has advanced markedly during recent decades. Not so for neurodegenerative disorders. Early detection, deep individual genotyping and phenotyping, and personalized therapies have been suggested as the way forward. However, we still do not know enough about the aetiology and molecular basics of these diseases. In fact, the term neurodegenerative disorder may be a misleading categorization that constitutes a major cognitive barrier against better characterization and understanding of these disorders. Therefore, we need to go back to the basics and employ novel, open-minded observational study protocols that combine very extensive and robust clinical, molecular and epidemiological data collection methods. Moreover, we need to reconsider our basic orientation towards these diseases to increase our chances of finding out what we are actually trying to care for and cure.

Full Text

PDF

Viewed:2988

Downloaded:29

Cited: 0

Stroke is a leading cause of morbidity and mortality. The advent of mechanical thrombectomy has largely improved patient outcomes. This article reviews the features and outcomes associated with aspiration, stent retrievers, and combination catheters used in current practice. There is also a discussion on clinical considerations based on anatomical features and clot composition. The reperfusion grading scale and outcome metrics commonly used following thrombectomy when a patient is still in the hospital are reviewed. Lastly, there are proposed discharge and outpatient follow-up goals in caring for patients hospitalized for a stroke.

Full Text

PDF

Viewed:11993

Downloaded:118

Cited: 6

Exposure to stressful conditions plays a critical role in brain processes, including neural plasticity, synaptic transmission, and cognitive functions. Since memory-related brain regions, the hippocampus (Hip), the amygdala, and the prefrontal cortex, express high glucocorticoid receptors (GRs), these areas are the potential targets of stress hormones. Stress affects memory encoding, consolidation, and retrieval, which may depend on many factors such as the type, duration, the intensity of the stressor or the brain region. Here, this review mainly focused on the mechanisms involved in stress-induced memory impairment. Acute/chronic stress induces structural and functional changes in neurons and glial cells. Dendritic arborization, reduction of dendritic spine density, and alteration in glutamatergic-mediated synaptic transmission via N-methyl-D-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors are mechanisms that stress affect long-term memory formation. Exposure to acute or chronic stress could interplay with multiple neurotransmitter signaling, modulating the neuronal circuits involved in memory impairment or state-dependent learning. Stress hormones also modulate the expression of microRNAs in the specific brain regions responsible for stress-induced behaviors. Because of expressing GRs in astrocytes and microglial cells, stress could affect the morphology, structure, and functions of these glial cells in memory-related brain regions. Astrocytes play a crucial role in stress-induced aversive or fear memory formation. Over-activation of the microglial cells enhances the release of inflammatory cytokines, which results in neuronal injury. Stress has a prominent role in cognitive decline to induces memory problems, particularly in older adults. Due to the issue’s importance, here the provided overview attempted to address the question of how stress alters neuronal epigenetic regulators, synaptic transmissions, and glial activity in the brain.

Full Text

PDF

Viewed:21661

Downloaded:205

Cited: 3

Astrocytomas include a wide range of tumors with unique mutations and varying grades of malignancy. These tumors all originate from the astrocyte, a star-shaped glial cell that plays a major role in supporting functions of the central nervous system (CNS), including blood-brain barrier (BBB) development and maintenance, water and ion regulation, influencing neuronal synaptogenesis, and stimulating the immunological response. In terms of epidemiology, glioblastoma (GB), the most common and malignant astrocytoma, generally occur with higher rates in Australia, Western Europe, and Canada, with the lowest rates in Southeast Asia. Additionally, significantly higher rates of GB are observed in males and non-Hispanic whites. It has been suggested that higher levels of testosterone observed in biological males may account for the increased rates of GB. Hereditary syndromes such as Cowden, Lynch, Turcot, Li-Fraumeni, and neurofibromatosis type 1 have been linked to increased rates of astrocytoma development. While there are a number of specific gene mutations that may influence malignancy or be targeted in astrocytoma treatment, O⁶-methylguanine-DNA methyltransferase (MGMT) gene function is an important predictor of astrocytoma response to chemotherapeutic agent temozolomide (TMZ). TMZ for primary and bevacizumab in the setting of recurrent tumor formation are two of the main chemotherapeutic agents currently approved in the treatment of astrocytomas. While stereotactic radiosurgery (SRS) has debatable implications for increased survival in comparison to whole-brain radiotherapy (WBRT), SRS demonstrates increased precision with reduced radiation toxicity. When considering surgical resection of astrocytoma, the extent of resection (EoR) is taken into consideration. Subtotal resection (STR) spares the margins of the T1 enhanced magnetic resonance imaging (MRI) region, gross total resection (GTR) includes the margins, and supramaximal resection (SMR) extends beyond the margin of the T1 and into the T2 region. Surgical resection, radiation, and chemotherapy are integral components of astrocytoma treatment.

Full Text

PDF

Viewed:22157

Downloaded:160

Cited: 8

Despite decades of intensive research, effective treatment and prevention strategies for neurodegenerative diseases (NDDs) remain elusive. This review focuses on Alzheimer’s and Parkinson’s diseases and acquired epilepsy suggesting that in their early phase, these progressive pathologies share common or interacting molecular pathways. Indeed, oxidative stress associated with disrupted glucose metabolism is the expected end state of most, if not all, risk factors preceding the onset of major NDDs. This review proposes that the initial oxidative stress in the brain resulting specifically from the hyperactivation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) causes a decline in glucose utilization and is the primary initiating factor of major NDDs. The existing clinical and experimental evidence points to NOX as the primary initiating mechanism shared within the major NDDs. During early oxidative stress, NOX activation is triggered in variable brain cells via multiple pathways, from beta-amyloid to alpha-synuclein, fibrin to glutamate and seizures. Therefore, the treatment strategy should have targeted the activation of NOX, wouldn’t there be a lack of clinically approved selective NOX antagonists? On the other hand, there are promising metabolism-altering approaches via dietary means able to switch energy intake from glucose to ketones, which influences both oxidative stress and glucose utilization and could ameliorate disease progression. The regimen of time-restricted eating appears to be the most feasible, nutritious, and palatable one providing the essential benefits of a ketogenic diet without adverse effects.

Full Text

PDF

Viewed:5860

Downloaded:68

Cited: 0

Neuroinflammation plays a key role in the pathogenesis of post-cardiac arrest (CA) brain injury. Innate immune cells sense a variety of danger signals through pattern-recognition receptors and evoke rapidly after ischemic challenge, triggering inflammatory responses and amplifying brain damage. A programmed cell death (PCD) pathway is activated after ischemic and/or inflammatory stimuli, leading to the elimination of the damaged cells. However, PCD also regulates inflammatory responses flexibly. The present review aimed to summarize the mechanisms of inflammatory responses, including the biology of immune cells, the innate immune recognition that initiates the inflammation, and the immunomodulatory effects of PCD following CA. Promising therapeutic approaches of targeting inflammatory responses to alleviate brain injury and improve neurological outcomes after CA are also reviewed.

Full Text

PDF

Viewed:6960

Downloaded:115

Cited: 2

For more than a decade now, research studies, proof of concept work, and clinical trials have endeavored to understand how mesenchymal stem cells might be used to help protect, repair, and/or regenerate damaged brain tissue following stroke. To date, the majority of studies have not demonstrated significant improvements in either morbidity or medium-long-term outcome, although safety has been relatively well proven. Limitations are likely to be linked to the pathobiological complexity and seriousness of stroke tissue damage, low efficacy of treatment, and short half-life of bio-active proteins released by stem cells. This article will highlight the heterogeneity and limitation of completed studies and the current status of ongoing work. At the same time, the potential of other combinational type treatments, such as drug-loading and targeting, and the use of hydrogels is discussed.

Full Text

PDF

Viewed:6116

Downloaded:66

Cited: 1

Globally, the incidence of Parkinson’s disease (PD) is increasing faster than other neurodegenerative disorders. Neuropathologically, PD is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta due to the accumulation of aggregates of misfolded α-synuclein (α-Syn) in the cytoplasm of these neurons, forming Lewy bodies. Extracellular vesicles (EVs) are associated with the spread of α-Syn to different brain areas. However, at the same time that these EVs contribute to the pathophysiology of PD, they can also be explored as therapeutic, serving as a vehicle to deliver specific molecules, since these vesicles can easily cross the blood-brain barrier. Thus, this review summarizes the recent progress in EVs as a therapeutic strategy for PD, focusing on their delivery to the brain, and discusses the potential challenges and future directions in this field.

Full Text

PDF

Viewed:7442

Downloaded:85

Cited: 6

Earth’s rotation generates the basic circadian rhythm of day and night to which all living organisms must adapt to survive. In mammals, this happens thanks to a central clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus and to peripheral clock genes at the cellular level. The main environmental cue capable of synchronizing such clocks is light sensed by retinal ganglion cells signaling through a complex nervous pathway to the pineal gland which ultimately regulates melatonin synthesis that occurs during the night, darkness hours in all mammals. The central clock synchronized by melatonin drives the circadian oscillation of the sympathetic nervous system (SNS) adrenergic activity which in turn controls glucocorticoid production in the adrenal glands. These oscillations are integrated with peripheral cellular clocks by still not completely understood mechanisms and drive the homeostatic control of activity-rest (sleep) cycles, cardiovascular activity, body temperature, and immune-hematopoietic functions. The neuronal and hormonal mechanisms governing the circadian oscillation of hematopoiesis and immunity will be addressed in this review focusing on those offering therapeutic perspectives.

Full Text

PDF

Viewed:9464

Downloaded:100

Cited: 6

Hemangioblastoma are benign, vascularized cranial tumors caused by autosomal dominant inherited von Hippel-Lindau disease or can appear sporadically. This review will investigate current and emerging treatments for cerebral tumors. It will focus on the current and, more importantly, developing hemangioblastoma treatments. Surgical resectioning and radiotherapy are effective treatment options for cerebral tumors, whereas chemotherapies are not commonly used due to their limited ability to penetrate the blood-brain barrier. Recent chemotherapies have shown promise, but further research is needed to determine the efficacy as a treatment for hemangioblastomas. New advances in brachytherapy and immunotherapy are considered promising treatment options for hemangioblastoma. This review aims to offer valuable insights into the latest developments in hemangioblastoma treatments.

Full Text

PDF

Viewed:9449

Downloaded:82

Cited: 4

Bipolar disorder (BD) is a debilitating psychiatric disorder characterized by recurrent depression, mania, and hypomania episodes. The interaction of psychological, neuropsychological, and neurobiological factors (cognitive, behavioral, and emotional) is implicated in the development and persistence of BD. Accordingly, almost all investigators confirm that BD is the outcome of psychological and genetic interactions. Therefore, researchers should consider various factors in the psychopathology and psychotherapy of BD. This selective review first reviews research on these factors, then points to a variety of therapeutic methods for BD [interpersonal and social rhythm therapy (IPSRT), cognitive behavioral therapy (CBT), dialectical behavior therapy (DBT), mindfulness-based cognitive therapy (MBCT), and family-focused therapy (FFT)], and finally suggested a new comprehensive integrated model for the assessment and therapy of BD.

Full Text

PDF

Viewed:16703

Downloaded:130

Cited: 2

Receptor tyrosine kinases (RTKs) are known to perform versatile roles in disease landscapes, which determine the fate of the cell. Although much has been discussed from the perspective of proliferation, this review focuses on the impact of RTK-mediated signaling and its role in cytoskeletal degradation, the penultimate stage of cellular degeneration. In the case of degenerative diseases such as Alzheimer’s disease (AD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS), Parkinson’s disease (PD), age-related macular degeneration (AMD), and type 2 diabetes mellitus (T2DM), RTK signaling has been reported to be perturbed in several studies. The implications of downstream signaling via these receptors through canonical and noncanonical pathways alter the status of actin filaments that provide structural integrity to cells. Degenerative signaling leads to the altered status of rat sarcoma (Ras), Ras homologous (Rho), Ras-related C3 botulinum toxin substrate (Rac), and cell division control protein 42 (Cdc42), the best-characterized components of the cytoskeleton remodeling machinery. RTKs, along with their diverse adaptor partners and other membrane receptors, affect the functionality of Rho family guanosine triphosphate hydrolases (GTPases), which are discussed in this review. To conclude, this review focuses on therapeutic strategies targeting RTKs and Rho GTPase-mediated pathways that can be more effective due to their combined multifactorial impact on neurodegenerative cascades.

Full Text

PDF

Viewed:9131

Downloaded:100

Cited: 15