High-fat diet-induced obesity exacerbates kainic acid-induced hippocampal cell death

Hippocampal and gut AMPK activation attenuates enterocolitis-like symptoms and co-occurring depressive-like behavior in ulcerative colitis model mice: Involvement of brain-gut autophagy

Patients with inflammatory bowel disease, including ulcerative colitis (UC) and Crohn's disease, have a high incidence of psychiatric disorders, including depression and anxiety. However, the underlying pathogenic mechanism remains unknown. Dextran sulfate sodium (DSS)-treated mice, a model of UC, exhibit depressive-like behavior and reduced adenosine monophosphate-activated protein kinase (AMPK) activity, which regulates various physiological functions in the brain and gut. However, comprehensive studies on UC pathophysiology with co-occurring depression focused on brain-gut AMPK activity are lacking. Therefore, we aimed to investigate whether resveratrol (RES), an AMPK activator, prevented DSS-induced UC-like symptoms and depressive-like behavior. DSS treatment induced UC-like pathology and depressive-like behavior, as assessed via the tail suspension test. Moreover, western blotting and immunohistochemical studies revealed that DSS increased p-p70S6 kinase (Thr389), p62, tumor necrosis factor-α, interleukin (IL)-1β, IL-18, NLR family pyrin domain containing 3 (NLRP3), cleaved caspase-1, cleaved Gasdermin-D (GSDMD), and cleaved caspase-3 expression levels in the rectum and hippocampus, and increased CD40, iNOS, and Kelch-like ECH-associated protein 1 expression levels, and the number of Iba1-positive cells in the hippocampus, and decreased p-AMPK and LC3II/I expression levels, and the number of NF-E2-related factor 2 (Nrf2)-positive cells, and reduced neurogenesis in the hippocampus. These changes were reversed by the RES administration. RES also enhanced PGC1α and SOD1 expression in the hippocampus of DSS-treated male mice. Moreover, NLRP3 staining was observed in the neurons and microglia, and cleaved GSDMD staining in neurons in the hippocampus of DSS-treated mice. Notably, RES prevented UC-like pathology and depressive-like behavior and enhancement of autophagy, decreased rectal and hippocampal inflammatory cytokines and inflammasome, and induced the Nrf2-PGC1α-SOD1 pathway in the hippocampus, resulting in neurogenesis in the hippocampal dentate gyrus. Our findings suggest that brain-gut AMPK activation may be an important therapeutic strategy in patients with UC and depression.

Causal relationship among obesity and body fat distribution and epilepsy subtypes

Objective

The observational studies indicate an association between obesity and epilepsy, but it is unclear whether such an association responds to causality. The objective of this study was to determine the causal relationship between obesity and fat distribution and epilepsy subtypes based on waist circumference, hip circumference (HP), waist-hip ratio (WHR), and body mass index (BMI).

Methods

A two-sample Mendelian randomization study was conducted separately for the four indicators of obesity and epilepsy and its seven subtypes, with reverse Mendelian randomization and multivariate Mendelian randomization for significant outcomes.

Results

A two-sample Mendelian randomized analysis informed us that waist circumference was a risk factor for juvenile myoclonic epilepsy (beta = 0.0299, P = 4.60 × 10−3). The increase in hip circumference increased the risk of juvenile myoclonic epilepsy and epilepsy, with effect values of 0.0283 (P = 2.01 × 10−3) and 0.0928 (P = 1.40 × 10−2), respectively. Furthermore, children with a higher BMI exhibit a higher risk of epilepsy (beta = 0.0148 P = 1.05 × 10−3). The reverse Mendelian randomization study revealed that childhood absence epilepsy increased its BMI (beta = 0.8980, P = 7.52 × 10−7), and juvenile myoclonic epilepsy increased its waist circumference (beta = 0.7322, P = 3.26 × 10−2). Multivariate Mendelian randomization revealed that an increase in hip circumference and waist-hip ratio increased the risk of juvenile myoclonic epilepsy, with an effect value of 0.1051 (P = 9.75 × 10−4) and 0.1430 (P = 3.99 × 10−3), respectively, while an increase in BMI and waist circumference instead decreased their risk, with effect values of −0.0951 (P = 3.14 × 10−2) and−0.0541 (P = 1.71 × 10−2). In contrast, multivariate Mendelian randomization for childhood absence epilepsy and epilepsy did not identify any independent risk factors.

Significance

Our findings provide novel evidence in favor of obesity as a risk factor for epilepsy and waist circumference as a risk factor for juvenile myoclonic epilepsy. Increased hip circumference confers an elevated risk of juvenile myoclonic epilepsy and epilepsy (all documented cases), and a high BMI increases the risk of childhood absence epilepsy. With this, new insights are provided into the energy metabolism of epilepsy, which supports further nutritional interventions and the search for new therapeutic targets.

Cognitive impairment in obese rat model: role of glial cells

BACKGROUND

Obesity is a worldwide problem. Some studies revealed that it leads to deterioration of the cognitive function, regardless of age.

AIM OF THE STUDY

explore the effect of obesity on cognitive function in a rat model of obesity highlighting the role of glial cells.

MATERIALS AND METHODS

twenty adult male albino rats were assigned to two groups: group I: consumed normal diet, group II: consumed high-fat diet. Body Mass Index (BMI), serum glucose, insulin, HOMA IR and lipid profile were measured. Also, hippocampal expression of Brain derived neurotrophic factor (Bdnf), synapsin, Ionized calcium binding adaptor molecule 1 (Iba), nuclear factor erythroid -related factor 2 (Nrf2), Myelin basic protein (Mbp) were measured by real-time polymerase chain reaction. The Morris Water Maze is a test used to assess spatial learning and memory capacities of rats.

RESULTS

There was a high significant increase in lipid profile, serum glucose, insulin serum levels and HOMA-IR in obese groups with impaired Morris water maze performance compared to control group. There was a significant downregulation in hippocampal Bdnf and synapsin mRNA expression. In addition to decrease in Mbp mRNA expression (P < 0.001). This could be explained by oxidative stress through significant downregulation of Nrf2 mRNA, and inflammation observed in significant upregulation Iba mRNA gene expression in the obese group.

CONCLUSION

Many factors contribute to obesity associated cognitive impairment. In our study, we figured out the crucial roles of glial cells including microglial activation and oligodendrocytes affection with other underlying mechanisms including oxidative stress and hippocampal inflammation.

Exendin-4 Pretreatment Attenuates Kainic Acid-Induced Hippocampal Neuronal Death

Exendin-4 (Ex-4) is a glucagon-like peptide-1 receptor (GLP-1R) agonist that protects against brain injury. However, little is known about the effect of Ex-4 on kainic acid (KA)-induced seizures and hippocampal cell death. Therefore, this study evaluated the neuroprotective effects of Ex-4 pretreatment in a mouse model of KA-induced seizures. Three days before KA treatment, mice were intraperitoneally injected with Ex-4. We found that Ex-4 pretreatment reversed KA-induced reduction of GLP-1R expression in the hippocampus and attenuated KA-induced seizure score, hippocampal neuronal death, and neuroinflammation. Ex-4 pretreatment also dramatically reduced hippocampal lipocalin-2 protein in KA-treated mice. Furthermore, immunohistochemical studies showed that Ex-4 pretreatment significantly alleviated blood–brain barrier leakage. Finally, Ex-4 pretreatment stimulated hippocampal expression of phosphorylated cyclic adenosine monophosphate (cAMP) response element-binding protein (p-CREB), a known target of GLP-1/GLP-1R signaling. These findings indicate that Ex-4 pretreatment may protect against KA-induced neuronal damage by regulating GLP-1R/CREB-mediated signaling pathways.

Associations of overweight and obesity with drug-resistant epilepsy

BACKGROUND

Obesity and overweight have been well established as comorbidities of epilepsy in adults. However, the effects of overweight and obesity on the risk of adult drug-resistant epilepsy (DRE) has not been fully assessed. Thus, the objective of this study was to investigate the relationships between categories of body mass index (BMI) and DRE.

METHODS

This was a case-control study. Patients with epilepsy hospitalized for Video electroencephalogram were included in the study from 2015 to 2020. Low/normal weight, overweight, and obesity were defined as BMI<23 and 23-24.9 and ≥25 kg/m², respectively. The proportions of patients diagnosed with DRE in each category were calculated.

RESULTS

A total of 1272 patients with drug-responsive epilepsy and 345 patients with DRE were included in this study. More men than women had DRE (P=0.012). Higher proportions of patients with DRE had a history of status epilepticus (P<0.001), CNS infection (P=0.027), developmental delay (P=0.001), and comorbidity (P<0.001). Obesity (BMI≥25 kg/m²) was associated with an increased risk of DRE (adjusted OR, 2.339; 95% CI, 1.724-3.171). No significant increase in the risk of DRE was found to be associated with overweight. Further stratified analyses by valproic acid (VPA) treatment attenuated the obesity-DRE relationship, but the associations remained statistically significant (adjusted OR, 1.79; 95% CI, 1.15-2.80).

CONCLUSION

Obesity, but not overweight, potentially plays a role in DRE, although confounders, such as antiseizure medications (ASMs) use, need to be explored. In the future, well-designed trials are needed to elucidate this issue.

Lipocalin-2 Deficiency Reduces Oxidative Stress and Neuroinflammation and Results in Attenuation of Kainic Acid-Induced Hippocampal Cell Death

The hippocampal cell death that follows kainic acid (KA)-induced seizures is associated with blood–brain barrier (BBB) leakage and oxidative stress. Lipocalin-2 (LCN2) is an iron-trafficking protein which contributes to both oxidative stress and inflammation. However, LCN2′s role in KA-induced hippocampal cell death is not clear. Here, we examine the effect of blocking LCN2 genetically on neuroinflammation and oxidative stress in KA-induced neuronal death. LCN2 deficiency reduced neuronal cell death and BBB leakage in the KA-treated hippocampus. In addition to LCN2 upregulation in the KA-treated hippocampus, circulating LCN2 levels were significantly increased in KA-treated wild-type (WT) mice. In LCN2 knockout mice, we found that the expressions of neutrophil markers myeloperoxidase and neutrophil elastase were decreased compared to their expressions in WT mice following KA treatment. Furthermore, LCN2 deficiency also attenuated KA-induced iron overload and oxidative stress in the hippocampus. These findings indicate that LCN2 may play an important role in iron-related oxidative stress and neuroinflammation in KA-induced hippocampal cell death.

Date seeds alleviate behavioural and neuronal complications of metabolic syndrome in rats

Unhealthy dietary habits can play a crucial role in metabolic damages, promoting alteration of neural functions through the lifespan. Recently, dietary change has been perceived as the first line intervention in prevention and/or treatment of metabolic damages and related diseases. In this context, our study was designed to assess the eventual therapeutic effect of date seeds administration on memory and learning and on neuronal markers in a rat Metabolic Syndrome model. For this purpose, 32 adult male Wistar rats were fed with standard diet or high-fat high-sugar diet during ten weeks. After this, 16 rats were sacrified and the remaining rats received an oral administration of 300 mg of date seeds/kg of body weight during four supplementary weeks. Before sacrifice, we evaluate cognitive performances by the Barnes maze test. Afterwards, neuronal, astrocytic, microtubular and oxidative markers were investigated by immunoblotting methods. In Metabolic syndrome rats, results showed impairment of spatial memory and histological alterations. We identified neuronal damages in hippocampus, marked by a decrease of NeuN and an increase of GFAP and pTau396. Finally, we recorded an increase in protein oxidation and lipid peroxidation, respectively identified by an up-regulation of protein carbonyls and 4-HNe. Interestingly, date seeds administration improved these behavioural, histological, neuronal and oxidative damages highlighting the neuroprotective effect of this natural compound. Liquid Chromatography-Mass Spectrometry (LC-MS) identified, in date seeds, protocatechuic acid, caffeoylshikimic acid and vanillic acid, that could potentially prevent the progression of neurodegenerative diseases, acting through their antioxidant properties.

Hippocampal Lipocalin 2 Is Associated With Neuroinflammation and Iron-Related Oxidative Stress in ob/ob Mice

Obesity causes brain injuries with inflammatory and structural changes, leading to neurodegeneration. Although increased circulating lipocalin 2 (LCN2) level has been implicated in neurodegenerative diseases, the precise mechanism of neurodegeneration in obesity is not clear. Here, we investigated whether LCN2-mediated signaling promotes neurodegeneration in the hippocampus of leptin-deficient ob/ob mice, which are characterized by obesity, insulin resistance, systemic inflammation, and neuroinflammation. In particular, there was significant upregulation of both LCN2 and matrix metalloproteinase 9 levels from serum and hippocampus in ob/ob mice. Using RNA-seq analysis, we found that neurodegeneration- sortilin-related receptor 1 (Sorl1) and brain-derived neurotrophic factor (Bdnf) genes were significantly reduced in the hippocampus of ob/ob mice. We additionally found that the endosome-related WD repeat and FYVE-domain-containing 1 (Wdfy1) gene were upregulated in ob/ob mice. In particular, iron overload-related mitochondrial ferritin and nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) proteins were increased in the hippocampus of ob/ob. Thus, these findings indicate that iron-binding protein LCN2-mediated oxidative stress promotes neurodegeneration in ob/ob mice.

Neuroimmune interaction in seizures and epilepsy: focusing on monocyte infiltration

Epilepsy is a major neurological condition that affects millions of people globally. While a number of interventions have been developed to mitigate this condition, a significant number of patients are refractory to these treatments. Consequently, other avenues of research are needed. One such avenue is modulation of the immune system response to this condition, which has mostly focused on microglia, the resident immune cells of the central nervous system (CNS). However, other immune cells can impact neurological conditions, principally blood-borne monocytes that can infiltrate into brain parenchyma after seizures. As such, this review will first discuss how monocytes can be recruited to the CNS and how they can be distinguished from there immunological cousins, microglia. Then, we will explore what is known about the role monocytes have within seizure pathogenesis and epilepsy. Considering how little is known about monocyte function in seizure- and epilepsy-related pathologies, further studies are warranted that investigate infiltrated blood-borne monocytes as a potential therapeutic target for epilepsy treatment.

Triglyceride is a Good Biomarker of Increased Injury Severity on a High Fat Diet Rat After Traumatic Brain Injury

Injury severity is correlated with poor prognosis after traumatic brain injury (TBI). It is not known whether triglycerides (TGs) or total cholesterol (TC) is good biomarker of increased injury of neuroinflammation and apoptosis in a high fat diet (HFD)-treated rat after TBI episodes. Five-week-old male Sprague-Dawley (SD) rats were fed a HFD for 8 weeks. The anesthetized male SD rats were divided into three sub-groups: sham-operated and TBI with 1.6 atm or with 2.4 atm fluid percussion injury (FPI). Cell infarction volume (triphenyltetrazolium chloride stain), tumor necrosis factor-alpha (TNF-α) expression in the microglia (OX42 marker) and astrocytes (Glial fibrillary acidic protein marker), TNF-α receptor expression in the neurons (TNFR1 and TNFR2 markers), and the extent of neuronal apoptosis (TUNEL marker) were evaluated by immunofluorescence, and the functional outcome was assessed by an inclined plane test. These tests were performed 72 h after TBI. Serum triglyceride and cholesterol levels were measured at 24, 48 and 72 h after TBI. The FPI with 2.4 atm significantly increased body weight loss, infarction volume, neuronal apoptosis and TNF-α expression in the microglia and astrocytes, and it decreased the maximum grasp degree and TNFR1 and TNFR2 expression in neurons at the 3rd day following TBI. The serum TG level was positively correlated with FPI force, infarction volume, Neu-N-TUNEL, GFAP-TNFα, and OX42-TNFα Simultaneously; the serum TG level was negatively correlated with Neu-N-TNFR1 and Neu-N-TNFR2. TG is a good biomarker of increased injury for neuroinflammation and apoptosis at the 3rd day after TBI in HFD rats.

Sheng-jiang powder ameliorates obesity-induced pancreatic inflammatory injury via stimulating activation of the AMPK signalling pathway in rats

AIM

To investigate the mechanisms by which Sheng-jiang powder (SJP) ameliorates obesity-induced pancreatic inflammatory injury.

METHODS

Sprague-Dawley rats were randomized into three groups: normal group (NG), obese group (HLG), or SJP treatment group (HSG). Obesity was induced by feeding a high-fat diet in the HLG and HSG, while the NG received standard chow. Rats were euthanized after 12 wk, and blood and pancreatic tissues were collected for histopathological analyses. Nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and transforming growth factor beta (TGF-β) expression, serum triglyceride and adiponectin levels, and apoptosis in pancreatic acinar cells were assessed. A high-fat AR42J acinar cell injury model was established using very low-density lipoprotein (VLDL). AR42J acinar cell culture supernatant, treated with different interventions, was applied to seven groups of pancreatic stellate cells (PSCs). The proliferation of PSCs and the expression of fibronectin and type I collagenase were assessed.

RESULTS

Compared with the NG, we found higher pathological scores for pancreatic tissues, lower serum adiponectin levels, higher expression levels of NF-κB in pancreatic tissues and TGF-β in pancreatic inflammatory cells, and increased apoptosis among pancreatic acinar cells for the HLG (P < 0.05). Compared with the HLG, we found reduced body weight, Lee’s index scores, serum triglyceride levels, and pathological scores for pancreatic tissues; higher serum adiponectin levels; and lower expression levels of NF-κB, in pancreatic tissue and TGF-β in pancreatic inflammatory cells for the HSG (P < 0.05). The in vitro studies showed enhanced PSC activation and increased expression levels of fibronectin and type I collagenase after SJP treatment. An adenosine 5‘-monophosphate-activated protein kinase (AMPK) inhibitor inhibited PSC activation.

CONCLUSION

SJP may ameliorate obesity-induced pancreatic inflammatory injury in rats by regulating key molecules of the adiponectin-AMPK signalling pathway.

Atorvastatin pretreatment attenuates kainic acid-induced hippocampal neuronal death via regulation of lipocalin-2-associated neuroinflammation

Statins mediate vascular protection and reduce the prevalence of cardiovascular diseases. Recent work indicates that statins have anticonvulsive effects in the brain; however, little is known about the precise mechanism for its protective effect in kainic acid (KA)-induced seizures. Here, we investigated the protective effects of atorvastatin pretreatment on KA-induced neuroinflammation and hippocampal cell death. Mice were treated via intragastric administration of atorvastatin for 7 days, injected with KA, and then sacrificed after 24 h. We observed that atorvastatin pretreatment reduced KA-induced seizure activity, hippocampal cell death, and neuroinflammation. Atorvastatin pretreatment also inhibited KA-induced lipocalin-2 expression in the hippocampus and attenuated KA-induced hippocampal cyclooxygenase-2 expression and glial activation. Moreover, AKT phosphorylation in KA-treated hippocampus was inhibited by atorvastatin pretreatment. These findings suggest that atorvastatin pretreatment may protect hippocampal neurons during seizures by controlling lipocalin-2-associated neuroinflammation.

A High-fat and High-Cholesterol Diet Potentiates Oxidative Damage in Hippocampus of Mice Lacking Apolipoprotein E

Objective:

We examined genetic and dietary challenge on hippocampal oxidative damage. Mice expressing (ApoE+/+) or lacking apolipoprotein E (ApoE-/-) were maintained on a standard diet or a high fat /high cholesterol (challenge) diet for 11-31 weeks. Similar levels of oxidative species were observed for ApoE+/+ and -/- mice maintained on the basal diet.

Method:

However, treatment of ApoE-/- homogenates with hydrogen peroxide and iron increased oxidative species by >100%, indicating an equivalent amount of potential oxidative species in latent form. We observed a time- and region-specific induction of oxidative damage in the hippocampi of ApoE-/- but not +/+ mice while maintained on the challenge diet. Notably, however, additional significant latent oxidative products were detected during this time. After 31 weeks of dietary challenge, by which time hippocampal oxidative species had doubled, there was an additional 50% in the latent form.

Conclusion:

This highlights the degree to which ApoE deficiency places hippocampal tissue at risk for oxidative damage. Even a modest dietary deficiency may be sufficient to provoke oxidative damage to hippocampal tissue. These results highlight the combinatorial impact of genetic and dietary deficiencies on oxidative damage to hippocampal tissue.

Tannins Enriched Fraction of Emblica officinalis Fruits Alleviates High-Salt and Cholesterol Diet-Induced Cognitive Impairment in Rats via Nrf2-ARE Pathway

Modern diets containing high quantities of salt and cholesterol have exhibited to cause a considerable effect on our health. Such diets, when consumed in the long term, have also shown to be a precursor to several disorders such as the metabolic disorder and consequently, various other diseases, including cognitive deficits. In the present study, we used a high salt and cholesterol diet (HSCD) to induce cognitive impairment in rats and also investigated the pharmacological action of tannins enriched fractions of Emblica officinalis (EOT) – a fruit that has been traditionally used for the treatment of numerous disorders for centuries. Significant alterations in MDA, GSH, TBARS, GPx, mitochondrial ATP, and mitochondrial membrane potential levels were observed in rats fed HSCD, which indicated presence of oxidative stress. Moreover, classic signs of cognitive impairment and deficits in spatial learning and memory were observed in the neurobehavioral tests. E. officinalis tannins exhibited good affinity to Nrf2 receptors in in silico studies, significantly reversed the changes in the aforementioned biomarkers of oxidative stress which were altered in the model group, as well as improved the performance of rats in Morris water maze task. Our results also reflected that EOT supplementation significantly increased the expression of Nrf2 in the CA1 region of hippocampus and cortex. Additionally, TUNEL assay indicated that EOT supplementation led to reversal of DNA fragmentation and apoptosis caused by HSCD. Immunohistochemical analysis and western blot further revealed a surge in the nuclear location of Nrf2. Through our study, we have demonstrated that cognitive impairment can be caused in rats via HSCD as a result of the oxidative stress induced by the same. Additionally, we have investigated a novel mechanism of action for EOT (which strongly suggests to be via the Nrf2–ARE pathway) and demonstrated that it has the potential to be used in the treatment of cognitive impairment.

Purple sweet potato color attenuates high fat-induced neuroinflammation in mouse brain by inhibiting MAPK and NF-κB activation

Purple sweet potato color (PSPC) is a natural anthocyanin pigment that is derived from purple sweet potato storage roots. PSPC possesses a variety of biological activities, including antioxidant, anti‑inflammatory and neuroprotective effects; however, the detailed effects of PSPC on high‑fat diet (HFD)‑induced neuroinflammation remain to be determined. The aim of the present study was to investigate whether PSPC has a protective role in HFD‑associated neuroinflammation in the mouse brain and to provide novel insight into the mechanisms of the action. C57BL 6J mice were maintained on a normal diet (10 kcal% fat), a HFD (60 kcal% fat), a HFD with PSPC (700 mg/kg/day) or PSPC alone, which was administrated over 20 weeks. Open field and step‑through tests were used to evaluate the effects of HFD and PSPC on mouse behavior and memory function. Western blotting and ELISA analyses were used to assess the expression of inflammatory cytokines and the activation of mitogen‑activated protein kinase and nuclear factor‑κB (NF‑κB). The results demonstrated that PSPC treatment was able to significantly improve the HFD‑induced impairment of mouse behavior and memory function, and suppressed the increase in body weight, fat content, hyperlipemia and the level of endotoxin. PSPC treatment also markedly decreased the expression of cyclooxygenase‑2, inducible nitric oxide synthase, tumor necrosis factor‑α, interleukin (IL)‑1β and IL‑6, and increased the level of IL‑10 in the HFD‑treated mouse brain. In addition, PSPC inhibited the HFD‑induced phosphorylation of extracellular signal‑regulated kinase (ERK), c‑Jun N‑terminal kinase (JNK) and p38, and the activation of NF‑κB. These findings indicated that PSPC treatment may alleviate HFD‑induced neuroinflammation in the mouse brain by inhibiting ERK, JNK, p38 and NF-κB activation.