The association between seizure predisposition and inflammation in a rat model of fatty liver disease

Long-Term High-Fat Diet Aggravates Absence Seizures and Neurobehavioral Disorders Without Inducing Metabolic Disorders in WAG/Rij Rats: Involvement of Systemic and Central Inflammation

The consumption of a high-fat diet (HFD) represents a risk factor for diseases such as obesity, diabetes, insulin resistance (IR), and different brain disorders. HFD-induced obesity is linked with systemic and neuroinflammation implicated in the pathogenesis of metabolic impairment and epilepsy. In this study, we studied the negative effects of HFD consumption (16 weeks) on absence epilepsy and behavior comorbidities in WAG/Rij rats, a well-validated idiopathic model of absence epilepsy and comorbidities. Moreover, we investigated how, by restoring a normocaloric diet (NCD; 12 weeks), epileptic seizures and neuropsychiatric comorbidities could improve. We found that the HFD group showed a worsening of absence seizures, aggravation of depressive-like behavior, and performance in learning and memory than the NCD group even in the absence of hyperglycemia and/or obesity. In addition, intestinal villus rupture, inflammatory infiltrate, and intestinal permeability alteration increased after prolonged HFD intake, which could prevent weight gain. Inflammatory protein levels were found higher in the colon of the HFD group than in the NCD group, and also in the cortex and hippocampus, regions involved in absence seizures and behavioral alterations. After replacing HFD with NCD, a reduction in absence seizures and behavioral alterations was observed, and this decrease was well correlated with an improvement in inflammatory pathways. In conclusion, HFD consumption is sufficient to disrupt gut integrity resulting in systemic and brain inflammation contributing to the worsening of absence epilepsy and its comorbidities also without obesity development. These alterations can be improved by switching back the diet to NCD.

Sex Differences in Hepatic Inflammation, Lipid Metabolism, and Mitochondrial Function Following Early Lipopolysaccharide Exposure in Epileptic WAG/Rij Rats

Among the non-communicable neurological diseases, epilepsy is characterized by abnormal brain activity with several peripheral implications. The role of peripheral inflammation in the relationship between seizure development and nonalcoholic fatty liver disease based on sex difference remains still overlooked. Severe early-life infections lead to increased inflammation that can aggravate epilepsy and hepatic damage progression, both related to increased odds of hospitalization for epileptic patients with liver diseases. Here, we induced a post-natal-day 3 (PND3) infection by LPS (1 mg/kg, i.p.) to determine the hepatic damage in a genetic model of young epileptic WAG/Rij rats (PND45). We evaluated intra- and inter-gender differences in systemic and liver inflammation, hepatic lipid dysmetabolism, and oxidative damage related to mitochondrial functional impairment. First, epileptic rats exposed to LPS, regardless of gender, displayed increased serum hepatic enzymes and altered lipid profile. Endotoxin challenge triggered a more severe inflammatory and immune response in male epileptic rats, compared to females in both serum and liver, increasing pro-inflammatory cytokines and hepatic immune cell recruitment. Conversely, LPS-treated female rats showed significant alterations in systemic and hepatic lipid profiles and reduced mitochondrial fatty acid oxidation. The two different sex-dependent mechanisms of LPS-induced liver injury converge in increased ROS production and related mitochondrial oxidative damage in both sexes. Notably, a compensatory increase in antioxidant defense was evidenced only in female rats. Our study with a translational potential demonstrates, for the first time, that early post-natal infections in epileptic rats induced or worsened hepatic disorders in a sex-dependent manner, amplifying inflammation, lipid dysmetabolism, and mitochondrial impairment.

Prospects of Electrocorticography in Neuropharmacological Studies in Small Laboratory Animals

Electrophysiological methods of research are widely used in neurobiology. To assess the bioelectrical activity of the brain in small laboratory animals, electrocorticography (ECoG) is most often used, which allows the recording of signals directly from the cerebral cortex. To date, a number of methodological approaches to the manufacture and implantation of ECoG electrodes have been proposed, the complexity of which is determined by experimental tasks and logistical capabilities. Existing methods for analyzing bioelectrical signals are used to assess the functional state of the nervous system in test animals, as well as to identify correlates of pathological changes or pharmacological effects. The review presents current areas of applications of ECoG in neuropharmacological studies in small laboratory animals. Traditionally, this method is actively used to study the antiepileptic activity of new molecules. However, the possibility of using ECoG to assess the neuroprotective activity of drugs in models of traumatic, vascular, metabolic, or neurodegenerative CNS damage remains clearly underestimated. Despite the fact that ECoG has a number of disadvantages and methodological difficulties, the recorded data can be a useful addition to traditional molecular and behavioral research methods. An analysis of the works in recent years indicates a growing interest in the method as a tool for assessing the pharmacological activity of psychoactive drugs, especially in combination with classification and prediction algorithms.

A forebrain-hypothalamic ER stress driven circuit mediates hepatic steatosis during obesity

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) affects 1 in 3 adults and contributes to advanced liver injury and cardiometabolic disease. While recent evidence points to involvement of the brain in NAFLD, the downstream neural circuits and neuronal molecular mechanisms involved in this response, remain unclear. Here, we investigated the role of a unique forebrain-hypothalamic circuit in NAFLD.

METHODS

Chemogenetic activation and inhibition of circumventricular subfornical organ (SFO) neurons that project to the paraventricular nucleus of the hypothalamus (PVN; SFO→PVN) in mice were used to study the role of SFO→PVN signaling in NAFLD. Novel scanning electron microscopy techniques, histological approaches, molecular biology techniques, and viral methodologies were further used to delineate the role of endoplasmic reticulum (ER) stress within this circuit in driving NAFLD.

RESULTS

In lean animals, acute chemogenetic activation of SFO→PVN neurons was sufficient to cause hepatic steatosis in a liver sympathetic nerve dependent manner. Conversely, inhibition of this forebrain-hypothalamic circuit rescued obesity-associated NAFLD. Furthermore, dietary NAFLD is associated with marked ER ultrastructural alterations and ER stress in the PVN, which was blunted following reductions in excitatory signaling from the SFO. Finally, selective inhibition of PVN ER stress reduced hepatic steatosis during obesity.

CONCLUSIONS

Collectively, these findings characterize a previously unrecognized forebrain-hypothalamic-ER stress circuit that is involved in hepatic steatosis, which may point to future therapeutic strategies for NAFLD.

Can the Gut Microbiota Serve as a Guide to the Diagnosis and Treatment of Childhood Epilepsy?

BACKGROUND

To investigate the activity of the gut-brain axis in the pathogenesis of childhood epilepsy and to define biomarkers capable of assisting with determining new strategies in that context.

METHODS

Twenty children with epilepsy of "unknown etiology" and seven healthy controls in the same age group were included in the study. The groups were compared using a questionnaire. Stool samples were stored in tubes containing DNA/RNA Shield (Zymo Research) with a sterile swab. Sequencing was carried out using the MiSeq System (Illumina). The 16S rRNA sequencing of samples using next-generation sequencing involved V4 variable region polymerase chain reaction amplification concluded by 2 × 250-bp paired-end sequencing of amplicons and at least 50,000 reads (>Q30) per sample. DNA sequences were classified at the genus level using the Kraken program. Bioinformatics and statistical analysis were then performed.

RESULTS

Individuals' gut microbiota relative abundance values differed between the groups at the genus, order, class, family, and phylum levels. Flavihumibacter, Niabella, Anoxybacillus, Brevundimonas, Devosia, and Delftia were seen only in the control group, whereas Megamonas and Coriobacterium were observed only in the epilepsy group. The linear discriminant analysis effect size method identified 33 taxa as important in differentiating the groups.

CONCLUSIONS

We think that bacterial varieties (such as Megamonas and Coriobacterium) that differ between the two groups can be employed as useful biomarkers in the diagnosis and follow-up of epileptic patients. We also predict that, in addition to epilepsy treatment protocols, the restoration of eubiotic microbiota may increase the success of treatment.

The potential effects of anticonvulsant drugs on neuropeptides and neurotrophins in pentylenetetrazol kindled seizures in the rat

Purpose: Neuropeptides and neurotrophic factors are thought to be involved in epileptogenesis. This study aims to investigate the potential effects of anticonvulsant drugs on neuropeptides (galanin and neuropeptide Y) and neurotrophic factors (BDNF and NGF) in pentylenetetrazol (PTZ)-kindled seizures in the rat.Methods: Forty-eight adult male Sprague-Dawley rats were included in the study. The animals were divided into 8 groups of six rats. Group 1 was defined as naïve control, and received no medication. Group 2 (PTZ + saline) was treated with sub-convulsive doses of PTZ (35 mg/kg) and saline i.p. for 14 days. For anticonvulsant treatments, Groups 3-8 were treated with 200 mg/kg levetiracetam (PTZ + LEV), 1 mg/kg midazolam (PTZ + MDZ), 80 mg/kg phenytoin (PTZ + PHT), 80 mg/kg topiramate (PTZ + TPR), 40 mg/kg lamotrigine (PTZ + LMT) and 50 mg/kg sodium valproate (PTZ + SV), respectively. All anticonvulsant drugs were injected 30 min prior to PTZ injection throughout 14 days. Following treatment period, behavioral, biochemical and immunohistochemical studies were performed.Results: PTZ + saline group revealed significantly decreased galanin, NPY, BDNF and NGF levels compared to control. PTZ + MDZ group had significantly increased galanin, BDNF and NGF levels compared to saline group. Also, PTZ + LEV group showed increased BDNF levels. PTZ + saline group revealed significantly lower neuron count and higher GFAP (+) cells in hippocampal CA1-CA3 regions. All anticonvulsants significantly reduced hippocampal astrogliosis whereas only midazolam, levetiracetam, sodium valproate and lamotrigine prevented neuronal loss.Conclusion: Our results suggested that anticonvulsant drugs may reduce the severity of seizures, and exert neuroprotective effects by altering the expression of neuropeptides and neurotrophins in the epileptogenic hippocampus.