Modulation of epileptic activity induced by homocysteinethiolactone in rats: the role of hypermethionine diet, sleep, physical activity and nitric oxide

Epilepsija nastaje kao rezultat prevage ekscitatornih nad inhibitornim fenomenima u centralnom nervnom sistemu i jedno je od vodećih neuroloških oboljenja (1-2% u opštoj populaciji). Homocistein, zajedno sa svojim metabolitom homocistein tiolaktonom, je značajan faktor rizika za razvoj kardiovaskularnih i neuroloških oboljenja, uključujući epilepsiju. Jedini put produkcije tioaminokiseline homocisteina u organizmu je metabolizam metionina. Akutna administracija homocistein tiolaktona adultnim pacovima dovodi do elektroencefalogramske (EEG) epileptogene aktivnosti, konvulzivnog ponašanja, te predstavlja pogodan eksperimentalni model generalizovane epilepsije. Epilepsija je često praćena anksioznošću, koja je u pozitivnoj korelaciji sanivoom homocisteina prema rezultatima ATTICA studije, dok rezultati Hordaland studije negiraju ovu povezanost. Zbog dramatičnog toka epileptičnih napada i mogućnosti povređivanja, sedentaran način života je čest kod bolesnika sa epilepsijom. Poslednjih godina pojavili su se dokazi da fizička aktivnost može smanjiti intenzitet nekih tipova konvulzivnih napada, mada postoje rezultati koji ukazuju na pojačanje epileptiformne EEG aktivnosti nakon fizičke aktivnosti. Istraživanja ukazuju da se selektivnom deprivacijom REM (eng. rapid eye movement) spavanja redukuje nivo homocisteina kod pacova. Međutim, spavanje je fiziološki proces koji čini jednu trećinu ljudskog života i njegov nedostatak je povezan sa hiperekscitabilnošću. Azot monoksid (NO) pripada grupi gasnih neurotransmitera. Neuralna NO sintaza (nNOS) je prisutna u strukturama CNS u kojima NO kao neuromodulator reguliše ekscitabilnost. Međutim, povišena ekspresija inducibilne NOS (iNOS) pronađena je kod pacijenata sa epilepsijom...Epilepsy is a result of an imbalance between inhibitory and excitatory phenomena in the central nervous system. It is one of the leading neurological disorders and affects 1-2% of the world's population. Homocysteine, together with its metabolite homocysteine thiolactone is a risk factor for numerous cardiovascular and neurological disorders, including epilepsy. Homocysteine is produced by metabolism of methionine. Systemic administration of homocysteine to adult rats significantly alters neuronal circuits, leading to specific epileptogenic activity in the electroencephalogram (EEG) with convulsive episodes in animal behavior. Therefore, it represents suitable experimental model of generalized epilepsy. Anxiety is а common comorbidity among epileptic patients. Results of ATTICA study showed positive correlation between homocysteine and anxiety, while results of Hordaland study did not show the existence of this relationship. Increased sedentary lifestyle among epileptic patients is observed in populationbased studies Physical activity can play a favorable role in reducing the frequency and intensity of some seizures. However, an exercise – induced increase of epileptiform EEG activity has been also reported. Recent studies have shown that REM sleep deprivation can lower plasma homocysteine levels. On the other hand, sleep is a cyclic and vital physiological process that constitutes one-third of human life and deprivation of sleep is associated with hyperexcitability. Nitric oxide (NO) is a member of gasotransmitter family. Neuronal NO synthase (nNOS) is expressed in various brain regions in which NO acts as modulator of excitability. However, inducible NOS (iNOS) is found to be overexpressed in brains of humans with epilepsy..

Alterations of medial prefrontal cortex bioelectrical activity in experimental model of isoprenaline-induced myocardial infarction

Background Clinical and animal studies have found that anxiety and depression are significantly more common after acute myocardial infarction (AMI). The medial prefrontal cortex (PFC) has a dual role: in higher brain functions and in cardiovascular control, making it a logical candidate for explaining the perceived bidirectional heart-brain connection. We used parallel Electrocardiography (ECG) and Electrocorticography (ECoG) registration to investigate AMI-induced changes in medial PFC bioelectrical activity in a rat model of AMI. Materials and methods Adult male Wistar albino rats were used in the study. Gold-plated recording electrodes were implanted over the frontal cortex for ECoG recording. ECG was recorded via two holter electrodes attached on the skin of the back fixed in place by a jacket. Induction of AMI was performed by isoprenaline (150 mg/kg, i.p.). ECoG and ECG signals were registered at baseline, during 3 hours after isoprenaline administration and at 24 hours after isoprenaline administration. Results Significant increases of theta, alpha, and beta electroencephalographic (EEG) band power were observed in different time intervals after isoprenaline administration. Significant increase of theta band peak frequency was also observed during the first hour after isoprenaline administration. No statistically significant differences in band-power activity were found between the pre-isoprenaline measurements and 24 hours after administration. Conclusion Our results demonstrate significant increases in EEG band power of alpha beta and theta bands during isoprenaline-induced AMI model. These are the first findings to connect heart damage during isoprenaline- induced AMI to disturbances in the cortical bioelectrical activity. © 2020 Vorkapić et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.The study was supported by Ministry of Science Education and Technological Development of Serbia, Grant No. 175032 and 175016. The TECNALIA provided support in the form of salary for author MI, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of this author are articulated in the ‘author contributions’ section. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Sleep disturbances and depression: Directions and mechanisms of interaction

Sleep represents physiological process which effects are crucial to maintain homeostasis. Sleep disturbances are widely spread within the population worldwide. The loss in quantity or quality of sleep is associated with numerous diseases. Also, sleep disturbances are highly connected to depressive disorders, but exact mechanism of this interaction still remains unknown. Understanding the underlying mechanisms could be the key for treatment of both disorders especially in patients with psychosomatic and psychiatric comorbidities. Therefore, in this article, we will summarize the most recent findings on the connection between sleep disturbances and depressive disorders, including the mechanisms of this interaction

Heart rate variability processing in epilepsy: The role in detection and prediction of seizures and SUDEP

Epilepsy is a very prevalent neurological disorder. The gold standard in diagnosis of epilepsy is the EEG signal recorded during a seizure with characteristic ictal pattern. Automated systems for detection of seizures are a field of intensive research, in an attempt to create a reproducible, observer-independent mechanism for epilepsy diagnosis. Chronic therapy is a cornerstone of the epilepsy treatment, but the possibility to predict seizure onset and, consequently, to act with medications right before the seizure, instead of relying on everyday medications, is considered the holy grail of epilepsy research. Significant element of morbidity and mortality in epilepsy is sudden unexpected death in epilepsy (SUDEP) that occurs in roughly 1% of patients. Signal analysis techniques for EEG have been a staple in epilepsy research, but recently, with the rise of telemetric systems, heart rate variability (HRV) analysis derived from the ECG signal has been gaining importance. It has been found that perturbations in autonomic nervous system (ANS) regulation occur during, and even up to several minutes before, seizure onset allowing for changes in HRV to act in prediction, as well as detection, of seizures. Also, there is a compelling research exploring the extent of autonomic disbalance during seizures, as well as in the interictal periods in patients at risk for or that have had SUDEP. The focus of this review is to give a short crossection of research involving the utility HRV has in prediction and detection of seizure onset, as well as determining etiology classification and risk evaluation in SUDEP

The effects of acutely and subchronically applied DL-methionine on plasma oxidative stress markers and activity of acetylcholinesterase in rat cardiac tissue

Background/Aim. Chronically induced hypermethioninemia leads to hyperhomocysteinemia which causes oxidative stress, atherogenesis, neurodegeneration and cancer. However, little is known about the acute and subchronic effects of DL-methionine (Met). The aim of study was to assess the effects of acutely and subchronically applied Met on oxidative stress parameters in rat plasma [enzymes: catalase (CAT), glutathione peroxidise (GPx), superoxide dismutase (SOD) and index of lipid peroxidation, malondialdehyde (MDA)], and acetylcholinesterase (AChE) activity in rat cardiac tissue. Methods. The enzymes activities, as well as MDA concentration were evaluated following acute (n = 8) and subchronic (n = 10) application of Met [i.p. 0.8 mmoL/kg body weight (b.w.) in a single dose in the acute overload or daily during three weeks in the subchronic overload]. The same was done in the control groups following application of physiological solution [i.p. 1 mL 0.9% NaCl (n = 8) in the acute overload and 0.1–0.2 mL 0.9% NaCl, daily during three weeks (n =10) in the subchronic overload]. Tested parameters were evaluated 60 minutes after application in acute experiments and after three weeks of treatment in subchronic experiments. Results. There were no difference in homocysteine values between the groups treated with Met for three weeks and the control group. Met administration significantly increased the activity of CAT and GPx after 1 h compared to the control group (p = 0.008 for both enzymes), whereas the activity of SOD and MDA concentrations were unchanged. Subchronically applied Met did not affect activity of antioxidant enzymes and MDA level. AChE activity did not show any change in rat cardiac tissue after 1 h, but it was significantly decreased after the subchronic treatment (p = 0.041). Conclusion. Results of present research indicate that Met differently affects estimated parameters during acute and subchronic application. In the acute treatment Met mobilizes the most part of antioxidant enzymes while during the subchronic treatment these changes seems to be lost. On the contrary, the acute Met overload was not sufficient to influence on the AChE activity, while longer duration of Met loading diminished function of the enzyme. These findings point out that methionine can interfere with antioxidant defense system and cholinergic control of the heart function

Glial cells, blood brain barrier and cytokines in seizures: Implications for therapeutic modalities

Epilepsy is a chronic, common, neurological disorder marked by transient, paroxysmal and hypersynchronous activity of the brain neurons, behaviorally manifested as seizures. It is developed through the process of epileptogenesis which alters neuronal excitability, establishes critical interconnections and develop neuronal hyperexcitability and degeneration, as well as the neuronal network reorganization as its main mechanisms. There are a number of different mechanisms of epileptogenesis, including neuroinflammation as a recently highlighted important novel mechanism. In this review paper, our focus will be to light up the latest findings about neuroinflammation as a pathogenic factor in epileptogenesis. Neuroinflammation is characterized by the structural and functional alteration of the CNS glial cells and peripherally derived immune cells with the presence of blood-brain barrier (BBB) dysfunction as main mechanisms. Disequilibrium in the CNS microenvironment is often followed by increased synthesis of proinflammatory cytokines (IL-6, IL-1β, TNF-α, IFN-γ) and chemokines. The interplay between glial alteration, BBB dysfunction, cytokines and chemokines establish a positive feedback cascade for further epileptogenesis. It is still unclear if neuroinflammation is causing epileptogenesis or whether in a consequence of that, but, there are clear findings about positive feedback between these two processes. This interconnection could be a helpful key to better target therapeutic treatment of neuroinflammation for providing beneficial effects for patients with epilepsy

Exploratory behavior alteration as an epileptic comorbidity in elevated plus maze test

Introduction: Epileptic seizure consists of preictal, ictal and postictal period. Postictal period is characterized by a variety of psychiatric phenomenon of which the most frequent ones are anxiety and depressive disorder. Anxiety in rodents can be assessed by measuring the exploratory behavior. Lindane evokes generalized tonic-clonic epileptic seizures in rats, when applied intraperitoneally, due to its lypophilic characteristics. Aim: The aim of this study was to assess exploratory behavior linked with anxiety level in the elevated plus maze test (EPM) upon generalized seizures, induced by lindane in male rats. Material and methods: The experiment was conducted on Wistar albino male rats that were randomly divided into: control group (DMSO, 0.5 ml/kg) and experimental group (lindane, 8 mg/kg) (n=8, each). After the drug injection, the assessment of the seizure intensity lasted for 30 minutes. Descriptive rating scale was used to describe the seizure severity. Subsequently, the EPM testing took place immediately after evoking the seizure (Test 1), after 1h (Test 2) and after 24h (Test 3). Time spent in open areas and number of transitions was further analyzed. Results: Experimental group of animals spent less time in open areas of EPM, when compared to controls in Test 1 and Test 2. The same holds true for the number of transitions to the open area, i.e. lindane-treated animals tend to stay in enclosed parts of the maze in Test1, Test 2. Finally, in Test 3 there was no significant difference between the groups, in any parameter of interest. Conclusion: Lindane-induced generalized epileptic seizures are accompanied by reduced exploratory behavior in the elevated plus maze test, up to 24h after the seizure ended. This finding can be a basis for the further translational research of anxiety as epileptic comorbidity in this experimental model of epilepsy

Acetylcholinesterase as a potential target of acute neurotoxic effects of lindane in rats

Abstract. The aim of our study was to investigate the possible involvement of acetylcholinesterase (AchE) in mediating the early phase of acute lindane neurotoxicity in rats. Male Wistar rats (n = 48) were divided into following groups: 1. control, saline-treated group; 2. dimethylsulfoxidetreated group; 3. group that received lindane dissolved in dimethylsulfoxide, in a dose of 8 mg/kg intraperitoneally. Eight animals from each group were sacrificed 0.5 and 4 h after treatment and brain samples were prepared for further analysis. AchE activity (mitochondrial and synaptosomal fraction) was determined in cerebral cortex, thalamus, hippocampus and nc. caudatus spectrophotometrically. A significant increase in mitochondrial AchE activity was detected in cortex and nc. caudatus of lindane-treated animals 0.5 h after administration (p < 0.05). This rise was sustained in nc. caudatus within 4 h after treatment (p < 0.05). In contrast, activity of synaptosomal AchE fraction was significantly increased only in thalamus 4 h after lindane administration (p < 0.05). An increase in AchE activity may be involved in mediating acute neurotoxic effects of lindane, at least in some brain structures in rats

Basic characteristics of epileptiform discharges triggered by lindane in rats

Introduction: EEG is a widely used method of epilepsy examination. In order to quantitatively inspect ictal EEG findings, a number of mathematical models have been developed over the years, one of them being the Fast Fourier Transform (FFT). It transforms the signal from time domain into frequency domain, giving information about their power spectral densities (PSD). Lindane is a well-established neurotoxic agent often used in experimental studies as a model of generalized epilepsy. This study aims to quantitatively examine the characteristics of ictal EEG activity in rats on model of generalized epilepsy induced by lindane. Materials and Methods: Wistar albino rats were used for the study. Electrodes were surgically implanted over the frontal, parietal and occipital cortices of each animal for EEG recording purposes prior to lindane administration in convulsive dose. An 8-channel EEG apparatus was used, combined with a software developed in the Laboratory (NeuroSciLaBG). Ictal EEG epochs were extracted from the original signal and FFT analysis performed to obtain information considering PSD in predefined frequency bands. Amplitude histogram feature of the software was used to differentiate ictal spikes based on their voltage. Results: FFT analysis has yielded important information regarding spectral powers in frequency domain. Ictal EEG showed considerable stratification, theta frequency band (4-7 Hz) being markedly dominant. Amplitude histogram showed the majority of spikes to be in the voltage ranges up to 250 μV, while higher voltage spikes were rarely observed. Conclusion: FFT is capable of giving important information about ictal period characteristics. Ictal periods induced by lindane are characterized by dominancy of theta rhythm and spiking activity mostly in amplitude bins up to 250 μV. FFT and amplitude histograms can be of critical importance in the future pharmacological and toxicity studies