Neuro-Behavioral Status and the Hippocampal Expression of Metabolic Associated Genes in Wild-Type Rat Following a Ketogenic Diet

Plasma exosomes proteome profiling discovers protein markers associated with the therapeutic effect of Chaihu-Longgu-Muli decoction on temporal lobe epilepsy

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine (TCM) uses Chaihu-Longgu-Muli decoction (CLMD) to alleviate disease, clear away heat, calm the mind, and temper excitation. It has been widely used for the therapy of neuropsychiatric disorders including epilepsy, dementia, anxiety, insomnia, and depression for several centuries in China.

AIM OF THE STUDY

This study aims to analyze differentially expressed proteins (DEPs) in the plasma exosomes of patients with temporal lobe epilepsy (TLE) and after the Chaihu-Longgu-Muli Decoction (CLMD) therapy and to explore the biomarkers of TLE and the potential targets of CLMD in treating TLE.

MATERIALS AND METHODS

The plasma exosomes of normal people and patients with TLE before the treatment of oxcarbazepine (OXC) and combined treatment of OXC and CLMD (OXC.CLMD) were harvested. The exosomes were separated from plasma through ultracentrifugation and then identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and flow cytometry. The DEPs were analyzed by proteomics and then subjected to gene ontology (GO) functional enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. The protein level of key genes was detected using Western blot. A lithium chloride-pilocarpine-induced epilepsy rat model was established and treated with OXC alone, OXC. CLMD, and CLMD alone (low dose and high dose). Neuronal injury in the hippocampal dentate gyrus and ribosomal protein L6 (RPL6) expression in the brain tissues were detected using H&E staining, Nissl staining, and Western blot.

RESULTS

The proteomic analysis showed several DEPs were present among plasma exosomes in the four groups; DEPs were enriched in epilepsy-related function and pathway. Four key proteins were screened, including RPL6, Nucleolin (NCL), Apolipoprotein A1 (APOA1), and Lactate Dehydrogenase A (LDHA). Among them, RPL6, NCL, and LDHA protein levels were downregulated and APOA1 protein level was upregulated in the plasma exosomes of TLE patients. After OXC and OXC. CLMD treatment, the protein level of RPL6, NCL, and LDHA was increased, and the APOA1 protein level was decreased. Moreover, the RPL6 protein level was further elevated after OXC. CLMD treatment than that after OXC treatment. In the TLE rat model, neuronal degeneration and necrosis in the hippocampal dentate gyrus increased and RPL6 expression level decreased. After the treatment with OXC, OXC. CLMD, and CLMD alone, the degeneration and necrosis of neurons decreased, and the RPL6 expression level was increased; RPL6 upregulation was remarkably obvious after CLMD treatment.

CONCLUSIONS

RPL6, NCL, LDHA and APOA1 are the DEPs in the plasma exosomes of patients with TLE before and after therapy. RPL6 might be a potential biomarker of CLMD in treating TLE.

Ketogenic diet for mood disorders from animal models to clinical application

Mood disorders such as major depressive disorder (MDD) and bipolar disorder (BD) are often resistant to current pharmacological treatment. Therefore, various alternative therapeutic approaches including diets are, therefore, under investigation. Ketogenic diet (KD) is effective for treatment-resistant epilepsy and metabolic diseases, however, only a few clinical studies suggest its beneficial effect also for mental disorders. Animal models are a useful tool to uncover the underlying mechanisms of therapeutic effects. Women have a twice-higher prevalence of mood disorders but very little is known about sex differences in nutritional psychiatry. In this review, we aim to summarize current knowledge of the sex-specific effects of KD in mood disorders. Ketone bodies improve mitochondrial functions and suppress oxidative stress, inducing neuroprotective and anti-inflammatory effects which are both beneficial for mental health. Limited data also suggest KD-induced improvement of monoaminergic circuits and hypothalamus-pituitary-adrenal axis-the key pathophysiological pathways of mood disorders. Gut microbiome is an important mediator of the beneficial and detrimental effects of diet on brain functioning and mental health. Gut microbiota composition is affected in mood disorders but its role in the therapeutic effects of different diets, including KD, remains poorly understood. Still little is known about sex differences in the effects of KD on mental health as well as on metabolism and body weight. Some animal studies used both sexes but did not find differences in behavior, body weight loss or gut microbiota composition. More studies, both on a preclinical and clinical level, are needed to better understand sex-specific effects of KD on mental health.

The Role of Ketogenic Diet in the Treatment of Neurological Diseases

Over a hundred years of study on the favourable effect of ketogenic diets in the treatment of epilepsy have contributed to a long-lasting discussion on its potential influence on other neurological diseases. A significant increase in the number of scientific studies in that field has been currently observed. The aim of this paper is a widespread, thorough analysis of the available scientific evidence in respect of the role of the ketogenic diet in the therapy of neurological diseases such as: epilepsy, Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS) and migraine. A wide range of the mechanisms of action of the ketogenic diet has been demonstrated in neurological diseases, including, among other effects, its influence on the reduction in inflammatory conditions and the amount of reactive oxygen species (ROS), the restoration of the myelin sheath of the neurons, the formation and regeneration of mitochondria, neuronal metabolism, the provision of an alternative source of energy for neurons (ketone bodies), the reduction in glucose and insulin concentrations, the reduction in amyloid plaques, the induction of autophagy, the alleviation of microglia activation, the reduction in excessive neuronal activation, the modulation of intestinal microbiota, the expression of genes, dopamine production and the increase in glutamine conversion into GABA. The studies discussed (including randomised controlled studies), conducted in neurological patients, have stressed the effectiveness of the ketogenic diet in the treatment of epilepsy and have demonstrated its promising therapeutic potential in Alzheimer's disease (AD), Parkinson's disease (PD), multiple sclerosis (MS) and migraine. A frequent advantage of the diet was demonstrated over non-ketogenic diets (in the control groups) in the therapy of neurological diseases, with simultaneous safety and feasibility when conducting the nutritional model.

Potential for Ketotherapies as Amyloid-Regulating Treatment in Individuals at Risk for Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive neurodegenerative condition characterized by clinical decline in memory and other cognitive functions. A classic AD neuropathological hallmark includes the accumulation of amyloid-β (Aβ) plaques, which may precede onset of clinical symptoms by over a decade. Efforts to prevent or treat AD frequently emphasize decreasing Aβ through various mechanisms, but such approaches have yet to establish compelling interventions. It is still not understood exactly why Aβ accumulates in AD, but it is hypothesized that Aβ and other downstream pathological events are a result of impaired bioenergetics, which can also manifest prior to cognitive decline. Evidence suggests that individuals with AD and at high risk for AD have functional brain ketone metabolism and ketotherapies (KTs), dietary approaches that produce ketone bodies for energy metabolism, may affect AD pathology by targeting impaired brain bioenergetics. Cognitively normal individuals with elevated brain Aβ, deemed “preclinical AD,” and older adults with peripheral metabolic impairments are ideal candidates to test whether KTs modulate AD biology as they have impaired mitochondrial function, perturbed brain glucose metabolism, and elevated risk for rapid Aβ accumulation and symptomatic AD. Here, we discuss the link between brain bioenergetics and Aβ, as well as the potential for KTs to influence AD risk and progression.

A ketogenic diet affects brain volume and metabolome in juvenile mice

Ketogenic diet (KD) is a high-fat and low-carbohydrate therapy for medically intractable epilepsy, and its applications in other neurological conditions, including those occurring in children, have been increasingly tested. However, how KD affects childhood neurodevelopment, a highly sensitive and plastic process, is not clear. In this study, we explored structural, metabolic, and functional consequences of a brief treatment of a strict KD (weight ratio of fat to carbohydrate plus protein is approximately 6.3:1) in naive juvenile mice of different inbred strains, using a multidisciplinary approach. Systemic measurements using magnetic resonance imaging revealed that unexpectedly, the volumes of most brain structures in KD-fed mice were about 90% of those in mice of the same strain but fed a standard diet. The reductions in volumes were nonselective, including different regions throughout the brain, the ventricles, and the white matter. The relative volumes of different brain structures were unaltered. Additionally, as KD is a metabolism-based treatment, we performed untargeted metabolomic profiling to explore potential means by which KD affected brain growth and to identify metabolic changes in the brain. We found that brain metabolomic profile was significantly impacted by KD, through both distinct and common pathways in different mouse strains. To explore whether the volumetric and metabolic changes induced by this KD treatment were associated with functional consequences, we recorded spontaneous EEG to measure brain network activity. Results demonstrated limited alterations in EEG patterns in KD-fed animals. In addition, we observed that cortical levels of brain-derived neurotrophic factor (BDNF), a critical molecule in neurodevelopment, did not change in KD-fed animals. Together, these findings indicate that a strict KD could affect volumetric development and metabolic profile of the brain in inbred juvenile mice, while global network activities and BDNF signaling in the brain were mostly preserved. Whether the volumetric and metabolic changes are related to any core functional consequences during neurodevelopment and whether they are also observed in humans need to be further investigated. In addition, our results indicate that certain outcomes of KD are specific to the individual mouse strains tested, suggesting that the physiological profiles of individuals may need to be examined to maximize the clinical benefit of KD.

PRG5 Knockout Precipitates Late-Onset Hypersusceptibility to Pilocarpine-Induced Juvenile Seizures by Exacerbating Hippocampal Zinc Signaling-Mediated Mitochondrial Damage

Introduction

Epileptogenesis is understood as the plastic process that produces a persistent reorganization of the brain’s neural network after a precipitating injury (recurrent neonatal seizures, for instance) with a latent period, finally leading to neuronal hyperexcitability. Plasticity-related genes (PRGs), also known as lipid phosphate phosphatase-related proteins (PLPPRs), are regulators of mitochondrial membrane integrity and energy metabolism. This study was undertaken to determine whether PRG5 gene knockout contributes to the delayed hypersensitivity induced by developmental seizures and the aberrant sprouting of hippocampal mossy fibers, and to determine whether it is achieved through the mitochondrial pathway. Here, we developed a “twist” seizure model by coupling pilocarpine-induced juvenile seizures with later exposure to penicillin to test the long-term effects of PRG5 knockout on seizure latency through comparison with wild-type (WT) mice. Hippocampal mossy fiber sprouting (MFS) was detected by Timm staining. In order to clarify the mechanism of the adverse reactions triggered by PRG5 knockout, hippocampal HT22 neuronal cultures were exposed to glutamate, with or without PRG5 interference. Mitochondrial function, oxidative stress indicators and zinc ion content were detected.

Results

PRG5 gene knockout significantly reduced the seizure latency, and aggravated the lowered seizure threshold induced by developmental seizures. Besides, knockout of the PRG5 gene reduced the MFS scores to a certain extent. Furthermore, PRG5 gene silencing significantly increases the zinc ion content in hippocampal neurons, impairs neuronal activity and mitochondrial function, and exacerbates glutamate-induced oxidative stress damage.

Conclusion

In summary, PRG5 KO is associated with significantly greater hypersusceptibility to juvenile seizures in PRG5^(–/–) mice compared with WT mice. These effects may be related to the hippocampal zinc signaling. The effects do not appear to be related to changes in MFS because KO mice with juvenile seizures had the shortest seizure latencies but exhibited less MFS than WT mice with juvenile seizures.

Ketogenic diets and the nervous system: a scoping review of neurological outcomes from nutritional ketosis in animal studies

OBJECTIVES

Ketogenic diets have reported efficacy for neurological dysfunctions; however, there are limited published human clinical trials elucidating the mechanisms by which nutritional ketosis produces therapeutic effects. The purpose of this present study was to investigate animal models that report variations in nervous system function by changing from a standard animal diet to a ketogenic diet, synthesise these into broad themes, and compare these with mechanisms reported as targets in pain neuroscience to inform human chronic pain trials.

METHODS

An electronic search of seven databases was conducted in July 2020. Two independent reviewers screened studies for eligibility, and descriptive outcomes relating to nervous system function were extracted for a thematic analysis, then synthesised into broad themes.

RESULTS

In total, 170 studies from eighteen different disease models were identified and grouped into fourteen broad themes: alterations in cellular energetics and metabolism, biochemical, cortical excitability, epigenetic regulation, mitochondrial function, neuroinflammation, neuroplasticity, neuroprotection, neurotransmitter function, nociception, redox balance, signalling pathways, synaptic transmission and vascular supply.

DISCUSSION

The mechanisms presented centred around the reduction of inflammation and oxidative stress as well as a reduction in nervous system excitability. Given the multiple potential mechanisms presented, it is likely that many of these are involved synergistically and undergo adaptive processes within the human body, and controlled animal models that limit the investigation to a particular pathway in isolation may reach differing conclusions. Attention is required when translating this information to human chronic pain populations owing to the limitations outlined from the animal research.

Scopoletin Attenuates Intracerebral Hemorrhage-Induced Brain Injury and Improves Neurological Performance in Rats

BACKGROUND

Among the hypertension-related complications, the onset of intracerebral hemorrhage (ICH) is a destructive stage and is the most disabling type of stroke that has the highest death rate. At present, there is no promising treatment for ICH.

OBJECTIVES

The present investigation was aimed at evaluating the safeguarding effect of scopoletin against ICH-induced brain injury.

METHODS

We used Wistar male rats and divided them into 4 groups. Group 1 served as control, group 2 was induced with ICH, group 3 served as scopoletin-pretreated ICH rats, and group 4 as scopoletin drug control. During the experimental period, neurobehavioral outcome, cerebral edema, and neuroinflammation parameters were evaluated using RT-PCR and other biochemical analyses.

RESULTS

The rats that received scopoletin treatment demonstrated a significant attenuation in neurological deficits, neurodegeneration markers expression (TREM-1, SERPINE-1), and restored cerebral edema compared to ICH animals. On the other hand, an upsurge in inflammatory cytokines, for example, TNF-α, IL-13, IL-1β, and IL-17, was observed in ICH rats and was reduced to the level near normalcy in the scopoletin-treated groups.

CONCLUSION

Our investigations propose that the effectiveness of scopoletin in improving acute neurological function after ICH is promising, and this could be a lead molecule for the development of treatment plans in ICH treatment.

Dietary Neuroketotherapeutics for Alzheimer's Disease: An Evidence Update and the Potential Role for Diet Quality

Alzheimer’s disease (AD) is a devastating neurodegenerative disease with growing prevalence as the global population ages. Currently available treatments for AD have minimal efficacy and there are no proven treatments for its prodrome, mild cognitive impairment (MCI). AD etiology is not well understood and various hypotheses of disease pathogenesis are currently under investigation. A consistent hallmark in patients with AD is reduced brain glucose utilization; however, evidence suggests that brain ketone metabolism remains unimpaired, thus, there is a great deal of increased interest in the potential value of ketone-inducing therapies for the treatment of AD (neuroketotherapeutics; NKT). The goal of this review was to discuss dietary NKT approaches and mechanisms by which they exert a possible therapeutic benefit, update the evidence available on NKTs in AD and consider a potential role of diet quality in the clinical use of dietary NKTs. Whether NKTs affect AD symptoms through the restoration of bioenergetics, the direct and indirect modulation of antioxidant and inflammation pathways, or both, preliminary positive evidence suggests that further study of dietary NKTs as a disease-modifying treatment in AD is warranted.

Intrapartum Results on Differing Degrees of Ketonuria in Nulliparous Women with Gestational Diabetes Mellitus during Spontaneous Labor

To compare intrapartum results associated with differing degrees of ketonuria in nulliparous women with gestational diabetes mellitus (GDM), we implemented a retrospective cohort study comparing clinical characteristics among differing degrees of ketonuria and the duration and distribution of ketonuria at different stages of labor. We also analyzed adverse maternal and neonatal outcomes for each group. A total of 570 GDM deliveries were included; of these, 238 had negative ketonuria (41.8%), 180 had moderate ketonuria (31.6%), and 152 had ketosis (26.6%). The proportion of patients with a family history of diabetes significantly increased as the degree of ketonuria increased (P < 0.001). Moreover, a significantly lower level of HOMA-IR (the insulin resistance index) was observed for the Negative group (P < 0.001). The triglyceride (TG) level was significantly higher in the Ketosis group (P < 0.001), and the total cholesterol (TC) levels significantly increased as the degree of ketonuria progressed (P < 0.001). There were also higher maternal blood sugar levels and a significantly higher proportion of oxytocin augmentation in ketonuria cases (P < 0.001). Over three-fourths of patients (75.6%) had a ketonuria duration of ≤2 hours in the Moderate group, 61.2% had a ketonuria duration of between 3 and 4 h in the Ketosis group, and most of the ketonuria cases resolved in the first stage of labor. As the degree of ketonuria progressed, we observed a significantly higher number of cases with fetal heart rate pattern III (FHR pattern III), meconium-stained amniotic fluid III (MSAF III), postpartum hemorrhages, prolonged labor, neonatal hypoglycemia, an umbilical cord arterial pH of <7.2, low Apgar scores, increased neonatal intensive care admissions, augmented forceps-assisted deliveries, and conversions to cesarean sections. The results showed that ketonuria is common during the intrapartum period and that the risk of adverse maternal and neonatal outcomes may increase when complicated with ketonuria.

Reduction of Mitophagy-Related Oxidative Stress and Preservation of Mitochondria Function Using Melatonin Therapy in an HT22 Hippocampal Neuronal Cell Model of Glutamate-Induced Excitotoxicity

Recent evidence indicates that autophagy-mediated mitochondrial homeostasis is crucial for oxidative stress-related brain damage and repair. The highest concentration of melatonin is in the mitochondria of cells, and melatonin exhibits well-known antioxidant properties. We investigated the impact and mechanism involved in mitochondrial function and the mitochondrial oxidative stress/autophagy regulator parameters of glutamate cytotoxicity in mouse HT22 hippocampal neurons. We tested the hypothesis that melatonin confers neuroprotective effects via protecting against mitochondrial impairment and mitophagy. Cells were divided into four groups: the control group, melatonin alone group, glutamate injury group, and melatonin pretreatment group. We found that glutamate induced significant changes in mitochondrial function/oxidative stress-related parameters. Leptin administration preserved mitochondrial function, and this effect was associated with increased superoxide dismutase, glutathione (GSH), and mitochondrial membrane potential and decreased GSSG (oxidized glutathione) and mitochondrial reactive oxygen species. Melatonin significantly reduced the fluorescence intensity of mitophagy via the Beclin-1/Bcl-2 pathway, which involves Beclin-1 and Bcl-2 proteins. The mitophagy inhibitor CsA corrected these glutamate-induce changes, as measured by the fluorescence intensity of Mitophagy-Tracker Red CMXROS, mitochondrial ROS, and mitochondrial membrane potential changes. These findings indicate that melatonin exerts neuroprotective effects against glutamate-induced excitotoxicity by reducing mitophagy-related oxidative stress and maintaining mitochondrial function.