Ketogenic Diet Alleviates Hippocampal Neurodegeneration Possibly via ASIC1a and the Mitochondria-Mediated Apoptotic Pathway in a Rat Model of Temporal Lobe Epilepsy

Acidosis induces autophagic cell death through ASIC1-mediated Akt/mTOR signaling in HT22 neurons

Although it has been confirmed that acid-sensing ion channel 1 (ASIC1) plays a critical role in acidosis-induced neuronal injury and death, its underlying mechanisms remain largely unclear. In the present study, we investigated the involvement of ASIC1 in acidosis-induced neuronal death and its underlying mechanisms in HT22 neurons. The neurons were cultured in acidic medium to mimic extracellular acidosis. Cell viability and death, autophagy, ASIC1 expression, and the phosphorylation of Akt and mTOR were evaluated. Our results demonstrated that acidosis markedly increased the cell death rate, which was profoundly reversed by 3-MA (an autophagy inhibitor) but exacerbated by rapamycin (an autophagy activator). Moreover, our results indicated that acidosis induced excessive autophagy by increasing the expression and translocation of ASIC1, and decreasing the phosphorylation of the Akt and mTOR proteins. Intriguingly, inhibiting the activation of ASIC1 with its blocker PcTx-1 not only significantly decreased acidosis-induced neurotoxicity but also markedly compromised acidosis-induced autophagy and Akt/mTOR signaling inactivation, as evidenced by a decrease in the neuronal death rate, LC3Ⅱ/LC3Ⅰ ratio, and autophagosome number as well as p62 degradation and an increase in the phosphorylation of Akt and mTOR. Collectively, these results indicate that acidosis exerts its cytotoxic effects on HT22 neurons by inducing autophagic cell death through the ASIC1-related Akt/mTOR signaling pathway.

ASIC1a regulates ferroptosis in hepatic stellate cells via the Hippo/Yap-1 pathway in liver fibrosis

BACKGROUND

Liver fibrosis is a sustained process of liver tissue damage and repair caused by various physiological and pathological factors, with the activation and proliferation of hepatic stellate cells being central. Therefore, understanding and clarifying the relevant mechanisms of hepatic stellate cell activation and death is of great clinical significance for the treatment of liver fibrosis diseases.

METHODS

In vivo, recombinant adeno-associated virus was used to infect the liver of experimental mice, overexpressing ASIC1a, and based on this, a liver fibrosis model treated with sorafenib was constructed. In vitro, using RNA plasmid technology to transfect HSC-T6 cells, ASIC1a was overexpressed or silenced in the cells, and on this basis, PDGF-BB and Sorafenib were used to stimulate HSC-T6 cells, causing activated HSC-T6 to undergo ferroptosis.

RESULTS

The ferroptosis inducers Sorafenib and erastin can induce ferroptosis in HSCs, effectively inhibiting or reversing the progression of liver fibrosis. We found that the expression level of ASIC1a was significantly reduced in the livers of mice with liver fibrosis treated with Sorafenib. After treatment with an adeno-associated virus overexpressing ASIC1a, the therapeutic effect of Sorafenib was inhibited, and the level of ferroptosis induced by Sorafenib was also inhibited. The induction of ferroptosis in hepatic stellate cells in vitro depends on the presence of ASIC1a. By further exploring the potential mechanism, we observed that the overexpression of ASIC1a can promote an increase in YAP nuclear translocation, thereby regulating the activity of Hippo/YAP pathway signaling. After treatment with Sorafenib, the influx of Ca2+ significantly increased when ASIC1a was overexpressed, and BAPTA-AM intervention eliminated the intracellular Ca2+ accumulation induced by ASIC1a overexpression.

CONCLUSIONS

This indicated that the activation of YAP depends on the calcium ion influx induced by ASIC1a, which regulates ferroptosis in hepatic stellate cells by regulating the calcium ion-dependent Hippo/YAP pathway.

TBC1D15-regulated mitochondria-lysosome membrane contact exerts neuroprotective effects by alleviating mitochondrial calcium overload in seizure

Mitochondrial calcium overload plays an important role in the neurological insults in seizure. The Rab7 GTPase-activating protein, Tre-2/Bub2/Cdc16 domain family member 15 (TBC1D15), is involved in the regulation of mitochondrial calcium dynamics by mediating mitochondria-lysosome membrane contact. However, whether TBC1D15-regulated mitochondria-lysosome membrane contact and mitochondrial calcium participate in neuronal injury in seizure is unclear. We aimed to investigate the effect of TBC1D15-regulated mitochondria-lysosome membrane contact on epileptiform discharge-induced neuronal damage and further explore the underlying mechanism. Lentiviral vectors (Lv) infection and stereotaxic adeno-associated virus (AAV) injection were used to regulate TBC1D15 expression before establishing in vitro epileptiform discharge and in vivo status epilepticus (SE) models. TBC1D15's effect on inter-organellar interactions, mitochondrial calcium levels and neuronal injury in seizure was evaluated. The results showed that abnormalities in mitochondria-lysosome membrane contact, mitochondrial calcium overload, mitochondrial dysfunction, increased levels of reactive oxygen species, and prominent neuronal damage were partly relieved by TBC1D15 overexpression, whereas TBC1D15 knockdown markedly deteriorated these phenomena. Further examination revealed that epileptiform discharge-induced mitochondrial calcium overload in primary hippocampal neurons was closely associated with abnormal mitochondria-lysosome membrane contact. This study highlights the crucial role played by TBC1D15-regulated mitochondria-lysosome membrane contact in epileptiform discharge-induced neuronal injury by alleviating mitochondrial calcium overload.

Take the bull by the horns and tackle the potential downsides of the ketogenic diet

The ketogenic diet (KD) is a distinctive dietary regimen known for its low-carbohydrate and high-fat composition. Recently, it has garnered considerable interest from the scientific community and the general population because of its claimed efficacy in facilitating weight reduction, improving the management of glucose levels, and raising overall energy levels. The core principle of the KD is the substantial decrease in carbohydrate consumption, which is subsequently substituted by ingesting nourishing fats. While the KD has promising advantages and is gaining popularity, it must be acknowledged that this dietary method may not be appropriate for all individuals. The dietary regimen may give rise to adverse effects, including constipation, halitosis, and imbalances in electrolyte levels, which may pose a potential risk if not adequately supervised. Hence, thorough and meticulous inquiry is needed to better comprehend the possible hazards and advantages linked to the KD over prolonged durations. By obtaining a more comprehensive perspective, we can enhance our ability to make well-informed judgments and suggestions as to implementation of this specific dietary regimen.

A Ketogenic Diet may Improve Cognitive Function in Rats with Temporal Lobe Epilepsy by Regulating Endoplasmic Reticulum Stress and Synaptic Plasticity

A ketogenic diet (KD) is often used in the treatment of refractory epilepsy. Many studies have found that it also has a positive impact on cognitive comorbidities, but the specific mechanism remains unclear. In many disease models, endoplasmic reticulum stress (ERS) and synaptic plasticity is considered a new therapeutic target for improving cognitive impairment, and it has become a research focus in recent years. Recently, studies have found that a KD has a certain regulatory effect on both ERS and synaptic plasticity, but this result has not been confirmed in epilepsy. To investigate the effect of a KD on ERS and synaptic plasticity. In this study, a rat model of temporal lobe epilepsy (TLE) induced by lithium chloride-pilocarpine was used. After the model was successfully established, the rats in each group were fed a normal diet or a KD for 28 days, and the effect of a KD on the latency and seizure frequency of spontaneous recurrent seizures (SRSs) was observed via video monitoring. Subsequently, a Morris water maze was used to evaluate the spatial learning and memory abilities of the rats in each group; the ultrastructure of the ER and the synapses of the hippocampus were observed by transmission electron microscopy, and the dendritic spine density of the hippocampus was analysed by Golgi staining. Long-term potentiation (LTP) was used to detect the synaptic plasticity of the rats' hippocampi, and the expression of ERS-related proteins and synapse-related proteins was detected by Western blotting. A KD effectively reduced the frequency of SRSs in rats with TLE and improved their learning and memory impairment. Further investigations found that a KD inhibited the up-regulation of glucose-regulated protein 78, phospho-protein kinase-like ER kinase, phosphorylated α subunit of eukaryotic initiation factor 2, activating transcription factor 4 and C/EBP homologous protein expression in the hippocampi of rats with TLE and protected the ultrastructure of the neuronal ER, suggesting that a KD suppressed excessive ERS induced by epilepsy. Concurrently, we also found that a KD not only improved the synaptic ultrastructure and increased the density of dendritic spines in rats with TLE but also reversed the epilepsy-induced LTP deficit to some extent. More importantly, the expression of postsynaptic density protein 95, synaptotagmin-1 and synaptosomal-associated protein 25 in the hippocampi of rats with epilepsy was significantly increased after KD intervention. The study findings indicate that a KD improves learning and memory impairment in rats with epilepsy, possibly by regulating ERS and synaptic plasticity.

The Unconventional Effects of the Ketogenic Diet (KD) in Preclinical Epilepsy

The integration of metabolic therapeutics in the available clinical armory is becoming more commonplace in health care as our understanding about the dependence of disease on metabolism continues to deepen and evolve. In the epilepsy field, we often think about the ketogenic diet (KD, high fat: carbohydrate ratio) in terms of its anti-seizure efficacy. The aim of this article is to review what we've learned from preclinical studies about the KD's more unconventional effects, including its neuroprotective effects, anti-epileptogenic and disease-modifying effects, and how the KD influences comorbidities associated with epilepsy. As time moves us into the future and metabolic therapies become more common place, the effects of the KD considered unconventional herein, may end up being referred to as traditional.

Ketogenic diet and behavior: insights from experimental studies

As a journal page for full details. The ketogenic diet (KD) has been established as a treatment for epilepsy, but more recently it has been explored as an alternative or add-on therapy for many other diseases ranging from weight loss to neurological disorders. Animal models are widely used in studies investigating the therapeutic effects of the KD as well as underlying mechanisms. Especially in the context of neurological, psychiatric, and neurodevelopmental disorders essential endpoints are assessed by behavioral and motor tests. Here we summarized research evaluating the influence of the KD on cognition, depressive and anxiety-related behaviors, and social and nutritional behaviors of laboratory rodents. Each section contains a brief description of commonly used behavioral tests highlighting their limitations. Ninety original research articles, written in English, performed on mice or rats, providing measurement of blood beta-hydroxybutyrate (BHB) levels and behavioral evaluation were selected for the review. The majority of research performed in various disease models shows that the KD positively impacts cognition. Almost an equal number of studies report a reduction or no effect of the KD on depressive-related behaviors. For anxiety-related behaviors, the majority of studies show no effect. Despite the increasing use of the KD in weight loss and its appetite-reducing properties the behavioral evaluation of appetite regulation has not been addressed in preclinical studies. This review provides an overview of the behavioral effects of nutritional ketosis addressed to a broad audience of scientists interested in the KD field but not necessarily specializing in behavioral tests.

The many "Neurofaces" of Prohibitins 1 and 2: Crucial for the healthy brain, dysregulated in numerous brain disorders

Prohibitin 1 (PHB1) and prohibitin 2 (PHB2) are proteins that are nearly ubiquitously expressed. They are localized in mitochondria, cytosol and cell nuclei. In the healthy CNS, they occur in neurons and non-neuronal cells (oligodendrocytes, astrocytes, microglia, and endothelial cells) and fulfill pivotal functions in brain development and aging, the regulation of brain metabolism, maintenance of structural integrity, synapse formation, aminoacidergic neurotransmission and, probably, regulation of brain action of certain hypothalamic-pituitary hormones.With regard to the diseased brain there is increasing evidence that prohibitins are prominently involved in numerous major diseases of the CNS, which are summarized and discussed in the present review (brain tumors, neurotropic viruses, Alzheimer disease, Down syndrome, Fronto-temporal and vascular dementia, dementia with Lewy bodies, Parkinson disease, Huntington disease, Multiple sclerosis, Amyotrophic lateral sclerosis, stroke, alcohol use disorder, schizophrenia and autism). Unfortunately, there is no PHB-targeted therapy available for any of these diseases.

Acid-sensing ion channel 1a modulation of apoptosis in acidosis-related diseases: implications for therapeutic intervention

Acid-sensing ion channel 1a (ASIC1a), a prominent member of the acid-sensing ion channel (ASIC) superfamily activated by extracellular protons, is ubiquitously expressed throughout the human body, including the nervous system and peripheral tissues. Excessive accumulation of Ca2+ ions via ASIC1a activation may occur in the acidified microenvironment of blood or local tissues. ASIC1a-mediated Ca2+‑induced apoptosis has been implicated in numerous pathologies, including neurological disorders, cancer, and rheumatoid arthritis. This review summarizes the role of ASIC1a in the modulation of apoptosis via various signaling pathways across different disease states to provide insights for future studies on the underlying mechanisms and development of therapeutic strategies.

Why Is Iron Deficiency/Anemia Linked to Alzheimer's Disease and Its Comorbidities, and How Is It Prevented?

Impaired iron metabolism has been increasingly observed in many diseases, but a deeper, mechanistic understanding of the cellular impact of altered iron metabolism is still lacking. In addition, deficits in neuronal energy metabolism due to reduced glucose import were described for Alzheimer's disease (AD) and its comorbidities like obesity, depression, cardiovascular disease, and type 2 diabetes mellitus. The aim of this review is to present the molecular link between both observations. Insufficient cellular glucose uptake triggers increased ferritin expression, leading to depletion of the cellular free iron pool and stabilization of the hypoxia-induced factor (HIF) 1α. This transcription factor induces the expression of the glucose transporters (Glut) 1 and 3 and shifts the cellular metabolism towards glycolysis. If this first line of defense is not adequate for sufficient glucose supply, further reduction of the intracellular iron pool affects the enzymes of the mitochondrial electron transport chain and activates the AMP-activated kinase (AMPK). This enzyme triggers the translocation of Glut4 to the plasma membrane as well as the autophagic recycling of cell components in order to mobilize energy resources. Moreover, AMPK activates the autophagic process of ferritinophagy, which provides free iron urgently needed as a cofactor for the synthesis of heme- and iron-sulfur proteins. Excessive activation of this pathway ends in ferroptosis, a special iron-dependent form of cell death, while hampered AMPK activation steadily reduces the iron pools, leading to hypoferremia with iron sequestration in the spleen and liver. Long-lasting iron depletion affects erythropoiesis and results in anemia of chronic disease, a common condition in patients with AD and its comorbidities. Instead of iron supplementation, drugs, diet, or phytochemicals that improve energy supply and cellular glucose uptake should be administered to counteract hypoferremia and anemia of chronic disease.

Research progress on correlations between trace element levels and epilepsy

Research investigating the correlation between human trace element levels and disease alterations is growing. Epilepsy, a common nervous system disease, has also been found to be closely related to abnormal levels of trace elements. Studies continue to explore mechanisms of various trace elements involved in epileptic seizures through experimental animal models of epilepsy. Thus, we reviewed the research progress on the correlation between trace element levels and epilepsy in recent years and found that the trace elements most closely related to epilepsy are mainly metal ions such as selenium, iron, copper, zinc, and manganese. These results indicate that the changes in some trace elements are closely related to the increase in epilepsy susceptibility. In addition, after treatment with drugs and a ketogenic diet, the concentration of trace elements in the serum of patients with epilepsy changes. In other words, the abnormality of trace element concentrations is of great significance in the occurrence and development of epilepsy. This article is a literature update on the potential role of trace element imbalance in the development of epilepsy, providing new references for the subsequent prevention and treatment of epilepsy.

The Relationship of Ketogenic Diet with Neurodegenerative and Psychiatric Diseases: A Scoping Review from Basic Research to Clinical Practice

BACKGROUND

The ketogenic diet (KD) has become widespread for the therapy of epileptic pathology in childhood and adulthood. In the last few decades, the current re-emergence of its popularity has focused on the treatment of obesity and diabetes mellitus. KD also exerts anti-inflammatory and neuroprotective properties, which could be utilized for the therapy of neurodegenerative and psychiatric disorders.

PURPOSE

This is a thorough, scoping review that aims to summarize and scrutinize the currently available basic research performed in in vitro and in vivo settings, as well as the clinical evidence of the potential beneficial effects of KD against neurodegenerative and psychiatric diseases. This review was conducted to systematically map the research performed in this area as well as identify gaps in knowledge.

METHODS

We thoroughly explored the most accurate scientific web databases, e.g., PubMed, Scopus, Web of Science, and Google Scholar, to obtain the most recent in vitro and in vivo data from animal studies as well as clinical human surveys from the last twenty years, applying effective and characteristic keywords.

RESULTS

Basic research has revealed multiple molecular mechanisms through which KD can exert neuroprotective effects, such as neuroinflammation inhibition, decreased reactive oxygen species (ROS) production, decreased amyloid plaque deposition and microglial activation, protection in dopaminergic neurons, tau hyper-phosphorylation suppression, stimulating mitochondrial biogenesis, enhancing gut microbial diversity, restoration of histone acetylation, and neuron repair promotion. On the other hand, clinical evidence remains scarce. Most existing clinical studies are modest, frequently uncontrolled, and merely assess the short-term impacts of KD. Moreover, several clinical studies had large dropout rates and a considerable lack of compliance assessment, as well as an increased level of heterogeneity in the study design and methodology.

CONCLUSIONS

KD can exert substantial neuroprotective effects via multiple molecular mechanisms in various neurodegenerative and psychiatric pathological states. Large, long-term, randomized, double-blind, controlled clinical trials with a prospective design are strongly recommended to delineate whether KD may attenuate or even treat neurodegenerative and psychiatric disease development, progression, and symptomatology.