This study investigates audiogenic epilepsy in Krushinsky-Molodkina (KM) rats, questioning the efficacy of conventional EEG techniques in capturing seizures during animal restraint. Using a wireless EEG system that allows unrestricted movement, our aim was to gather ecologically valid data. Nine male KM rats, prone to audiogenic seizures, received implants of wireless EEG transmitters that target specific seizure-related brain regions. These regions included the inferior colliculus (IC), pontine reticular nucleus, oral part (PnO), ventrolateral periaqueductal gray (VLPAG), dorsal area of the secondary auditory cortex (AuD), and motor cortex (M1), facilitating seizure observation without movement constraints. Our findings indicate that targeted neural intervention via electrode implantation significantly reduced convulsive seizures in approximately half of the subjects, suggesting therapeutic potential. Furthermore, the amplitude of brain activity in the IC, PnO, and AuD upon audiogenic stimulus onset significantly influenced seizure severity and nature, highlighting these areas as pivotal for epileptic propagation. Severe cases exhibited dual waves of seizure generalization, indicative of intricate neural network interactions. Distinctive interplay between specific brain regions, disrupted during convulsive activity, suggests neural circuit reconfiguration in response to escalating seizure intensity. These discoveries challenge conventional methodologies, opening avenues for novel approaches in epilepsy research and therapeutic interventions.

Vagus nerve stimulation (VNS) is an adjuvant neuromodulation therapy for the treatment of refractory epilepsy. However, the mechanisms behind its effectiveness are not fully understood. Our aim was to develop a VNS protocol for the Genetic Audiogenic Seizure Hamster from Salamanca (GASH/Sal) in order to evaluate the mechanisms of action of the therapy. The rodents were subject to VNS for 14 days using clinical stimulation parameters by implanting a clinically available neurostimulation device or our own prototype for laboratory animals. The neuroethological assessment of seizures and general behavior were performed before surgery, and after 7, 10, and 14 days of VNS. Moreover, potential side effects were examined. Finally, the expression of 23 inflammatory markers in plasma and the left-brain hemisphere was evaluated. VNS significantly reduced seizure severity in GASH/Sal without side effects. No differences were observed between the neurostimulation devices. GASH/Sal treated with VNS showed statistically significant reduced levels of interleukin IL-1β, monocyte chemoattractant protein MCP-1, matrix metalloproteinases (MMP-2, MMP-3), and tumor necrosis factor TNF-α in the brain. The described experimental design allows for the study of VNS effects and mechanisms of action using an implantable device. This was achieved in a model of convulsive seizures in which VNS is effective and shows an anti-inflammatory effect.

Research into genetic and physiological mechanisms of widespread disorders such as arterial hypertension as well as neuropsychiatric and other human diseases is urgently needed in academic and practical medicine and in the field of biology. Nevertheless, such studies have many limitations and pose difficulties that can be overcome by using animal models. To date, for the purposes of creating animal models of human pathologies, several approaches have been used: pharmacological/chemical intervention; surgical procedures; genetic technologies for creating transgenic animals, knockouts, or knockdowns; and breeding. Although some of these approaches are good for certain research aims, they have many drawbacks, the greatest being a strong perturbation (in a biological system) that, along with the expected effect, exerts side effects in the study. Therefore, for investigating the pathogenesis of a disease, models obtained using genetic selection for a target trait are of high value as this approach allows for the creation of a model with a \"natural\" manifestation of the pathology. In this review, three rat models are described: ISIAH rats (arterial hypertension), GC rats (catatonia), and PM rats (audiogenic epilepsy), which are developed by breeding in the Laboratory of Evolutionary Genetics at the Institute of Cytology and Genetics (the Siberian Branch of the Russian Academy of Sciences).

The distribution of the D2-like dopamine receptor (D2DR) in the cortex and striatum was compared between rats with absence, audiogenic, or combined genetically determined epilepsy and normal Wistar rats by autoradiography. A significantly lower D2DR binding density was observed in the dorsal and ventrolateral aspects of the nucleus accumbens in epileptic vs. non-epileptic rats. Rats with audiogenic epilepsy additionally showed a higher D2DR density in the dorsal striatum and motor and somatosensory cortex and a lower D2DR density in the ventrolateral part of the nucleus accumbens. The findings indicated that a common neuronal circuit is involved in the pathogenesis of both convulsive and nonconvulsive forms of generalized epilepsy.

Neuroinflammation plays an important role in epileptogenesis, however, most studies are performed using pharmacological models of epilepsy, while there are only few data available for non-invasive, including genetic, models. The levels of a number of pro-inflammatory cytokines were examined in the Krushinsky-Molodkina (KM) rat strain with high audiogenic epilepsy (AE) proneness (intense tonic seizure fit in response to loud sound) and in the control strain \"0\" (not predisposed to AE) using multiplex immunofluorescence magnetic assay (MILLIPLEX map Kit). Cytokine levels were determined in the dorsal striatum tissue and in the brain stem. Background levels of IL-1β, IL-6, and TNF-α in the dorsal striatum of the KM rats were significantly lower than in the rats \"0\" (by 32.31, 27.84, and 38.87%, respectively, p < 0.05, 0.05, and 0.01), whereas no inter-strain differences in the levels of these metabolites were detected in the brain stem in the \"background\" state. Four hours after sound exposure, the TNF-α level in the dorsal striatum of the KM rats was significantly lower (by 38.34%, p < 0.01) than in the \"0\" rats. In the KM rats, the dorsal striatal levels of IL-1β and IL-6 were significantly higher after the sound exposure and subsequent seizure fit, compared to the background (35.29 and 50.21% increase, p < 0.05, 0.01, respectively). In the background state the IL-2 level in the KM rats was not detected, whereas after audiogenic seizures its level was 14.01 pg/ml (significant difference, p < 0.01). In the KM rats the brain stem levels of IL-1β and TNF-α after audiogenic seizures were significantly lower than in the background (13.23 and 23.44% decrease, respectively, p < 0.05). In the rats of the \"0\" strain, the levels of cytokines in the dorsal striatum after the action of sound (which did not induce AE seizures) were not different from those of the background, while in the brain stem of the \"0\" strain the levels of IL-1β were lower than in the background (40.28%, p < 0.01). Thus, the differences between the background levels of cytokines and those after the action of sound were different in the rats with different proneness to AE. These data suggest involvement of the analyzed cytokines in pathophysiology of the seizure state, namely in AE seizures.

Binding densities to dopamine D1-like and D2-like receptors (D1DR and D2DR) were studied in brain regions of animals with genetic generalized audiogenic (AGS) and/or absence (AbS) epilepsy (KM, WAG/Rij-AGS, and WAG/Rij rats, respectively) as compared to non-epileptic Wistar (WS) rats. Convulsive epilepsy (AGS) exerted a major effect on the striatal subregional binding densities for D1DR and D2DR. An increased binding density to D1DR was found in the dorsal striatal subregions of AGS-prone rats. Similar changes were seen for D2DR in the central and dorsal striatal territories. Subregions of the nucleus accumbens demonstrated consistent subregional decreases in the binding densities of D1DR and D2DR in epileptic animals, irrespective of epilepsy types. This was seen for D1DR in the dorsal core, dorsal, and ventrolateral shell; and for D2DR in the dorsal, dorsolateral, and ventrolateral shell. An increased density of D2DR was found in the motor cortex of AGS-prone rats. An AGS-related increase in binding densities to D1DR and D2DR in the dorsal striatum and motor cortex, areas responsible for motor activity, possibly reflects the activation of brain anticonvulsive loops. General epilepsy-related decreases in binding densities to D1DR and D2DR in the accumbal subregions might contribute to behavioral comorbidities of epilepsy.

Animal models of epilepsy are of great importance in epileptology. They are used to study the mechanisms of epileptogenesis, and search for new genes and regulatory pathways involved in the development of epilepsy as well as screening new antiepileptic drugs. Today, many methods of modeling epilepsy in animals are used, including electroconvulsive, pharmacological in intact animals, and genetic, with the predisposition for spontaneous or refractory epileptic seizures. Due to the simplicity of manipulation and universality, genetic models of audiogenic epilepsy in rodents stand out among this diversity. We tried to combine data on the genetics of audiogenic epilepsy in rodents, the relevance of various models of audiogenic epilepsy to certain epileptic syndromes in humans, and the advantages of using of rodent strains predisposed to audiogenic epilepsy in current epileptology.

The review presents data which provides evidence for the internal relationship between the stages of rodent audiogenic seizures and post-ictal catalepsy with the general pattern of animal reaction to the dangerous stimuli and/or situation. The wild run stage of audiogenic seizure fit could be regarded as an intense panic reaction, and this view found support in numerous experimental data. The phenomenon of audiogenic epilepsy probably attracted the attention of physiologists as rodents are extremely sensitive to dangerous sound stimuli. The seizure proneness in this group shares common physiological characteristics and depends on animal genotype. This concept could be the new platform for the study of epileptogenesis mechanisms.

Audiogenic epilepsy (AE), inherent to several rodent strains is widely studied as a model of generalized convulsive epilepsy. The molecular mechanisms that determine the manifestation of AE are not well understood. In the present work, we compared transcriptomes from the corpora quadrigemina in the midbrain zone, which are crucial for AE development, to identify genes associated with the AE phenotype. Three rat strains without sound exposure were compared: Krushinsky-Molodkina (KM) strain (100% AE-prone); Wistar outbred rat strain (non-AE prone) and \"0\" strain (partially AE-prone), selected from F2 KM × Wistar hybrids for their lack of AE. The findings showed that the KM strain gene expression profile exhibited a number of characteristics that differed from those of the Wistar and \"0\" strain profiles. In particular, the KM rats showed increased expression of a number of genes involved in the positive regulation of the MAPK signaling cascade and genes involved in the positive regulation of apoptotic processes. Another characteristic of the KM strain which differed from that of the Wistar and \"0\" rats was a multi-fold increase in the expression level of the Ttr gene and a significant decrease in the expression of the Msh3 gene. Decreased expression of a number of oxidative phosphorylation-related genes and a few other genes was also identified in the KM strain. Our data confirm the complex multigenic nature of AE inheritance in rodents. A comparison with data obtained from other independently selected AE-prone rodent strains suggests some common causes for the formation of the audiogenic phenotype.

The study of the role of neurotransmitter systems in the pathogenesis of epilepsy is one of the priorities of epileptology. New data on the functions of free neurotransmitter-like amino acid in the central nervous system are of the greatest importance and determine the prospects for the development of novel effective anticonvulsants. It is widely believed in clinical medicine that epilepsy has distinct gender characteristics. The aim of this study was to investigate the gender peculiarities in the content of neurotransmitter amino acids in the brain of Krushinsky-Molodkina (KM) rats, which were used as model organisms for the study of genetically induced audiogenic epilepsy. The content of Asp, Glu, GABA, Gly, and Tau of the medulla oblongata, hippocampus and cerebral cortex were determined using high-performance liquid chromatography (HPLC) in intact KM rats, KM rats exposed to a series of epileptiform seizures, and Wistar rats (control group). Both the Wistar and KM rats had gender distinctions in the distribution of free amino acids among the investigated brain parts. The audiogenic epilepsy was characterized by smoothing gender differences as well as differences between the concentrations of free amino acids in the cortex and medulla oblongata, specific for Wistar rats. The changes observed in male rats after the set of seizures included the increase in GABA concentration and a decrease in the Gly level in all investigated brain parts, as well as the decrease of the Tau content in the cortex and hippocampus. At the same time, the Glu content in cortex increased, while the Asp level decreased. After 6 days of audiogenic stimulations the female KM rats demonstrated the increase in the Glu level in all investigated brain parts, the increase in Gly and Asp levels in hippocampus, and no changes in the GABA content. Thus, after the set of epileptiform seizures the KM rats achieved a new steady state of the studied amino acids pool, which differed in males and females. In this case, gender differences significantly changed after the seizures.
Izuchenie roli neĭromediatornykh sistem v patogeneze épilepsii – odno iz prioritetnykh napravleniĭ épileptologii. Novye dannye o funktsiiakh svobodnykh aminokislot-neĭromediatorov v tsentral\'noĭ nervnoĭ sisteme imeiut naibol\'shuiu znachimost\' i opredeliaiut perspektivy sozdaniia novykh éffektivnykh protivosudorozhnykh sredstv. V klinicheskoĭ meditsine uzhe ustoialos\' mnenie o tom, chto épilepsiia imeet otchetlivye polovye osobennosti. Odnako na segodniashniĭ den\' eshche ne nakopleno dostatochno dannykh, podvodiashchikh pod éto predstavlenie biokhimicheskuiu osnovu. Tsel\'iu nastoiashchikh issledovaniĭ bylo izuchenie polovykh otlichiĭ v soderzhanii aminokislot-neĭromediatorov golovnogo mozga u krys linii Krushinskogo-Molodkinoĭ (KM) – modeli vrozhdennoĭ audiogennoĭ épilepsii. Kontsentratsii Asp, Glu, GAMK, Gly i Tau opredeleny metodom vysokoéffektivnoĭ zhidkostnoĭ khromatografii v prodolgovatom mozge, gippokampe i kore bol\'shikh polushariĭ. Biokhimicheskiĭ analiz proveden dlia intaktnykh krys KM – zhivotnykh posle serii épileptiformnykh pripadkov – i kontrol\'noĭ gruppy linii Vistar. Rezul\'taty biokhimicheskogo analiza svidetel\'stvuiut o tom, chto nariadu s obshchimi zakonomernostiami raspredeleniia svobodnykh aminokislot-neĭromediatorov v golovnom mozge, ne zavisiashchimi ni ot pola, ni ot predraspolozhennosti k sudorogam, sushchestvuiut otchetlivye polovye razlichiia kak u krys Vistar, tak i u KM. Audiogennaia épilepsiia krys KM kharakterizuetsia sglazhivaniem kak polovykh otlichiĭ, tak i kharakternoĭ dlia linii Vistar raznitsy mezhdu koroĭ i prodolgovatym mozgom v soderzhanii svobodnykh aminokislot. Seriia iz shesti ezhednevnykh audiostimuliatsiĭ vyzyvaet u samtsov i samok KM razlichnye izmeneniia kontsentratsiĭ svobodnykh aminokislot v golovnom mozge. Izmeneniia, nabliudaemye u samtsov posle pripadkov, nosiat obshchemozgovoĭ kharakter i proiavliaiutsia v povyshenii kontsentratsii GAMK i padenii urovnia Gly (vo vsekh otdelakh), snizhenii soderzhaniia Tau (v kore i gippokampe). Pri étom v kore vozrastaet kontsentratsiia Glu i snizhaetsia uroven\' Asp. U samok zhe nabliudaetsia povyshenie urovnia Glu (vo vsekh otdelakh), v gippokampe vozrastaiut kontsentratsii Gly i Asp, pri étom soderzhanie GAMK ne izmeniaetsia. Takim obrazom, posle serii épileptiformnykh pripadkov u krys KM ustanavlivaetsia novoe ustoĭchivoe sostoianie pula issleduemykh aminokislot, razlichnoe u samtsov i samok. Pri étom kharakter polovykh otlichiĭ posle perenesennykh pristupov sushchestvenno izmeniaetsia.