Stabilization of mitochondrial function by chlorogenic acid protects against kainic acid-induced seizures and neuronal cell death in rats

Epigoitrin decreases synaptosomal glutamate release and protects neurons from glutamate excitotoxicity in rats

Excessive synaptic glutamate levels can lead to excitotoxicity, which is implicated in various neuropathologies. This study investigates whether epigoitrin, an alkaloid abundantly found in Radix isatidis, affects glutamate release in rat cortical nerve terminals (synaptosomes) and its impact on excitotoxicity induced by the glutamate analogue kainic acid in rats. In rat cortical synaptosomes, epigoitrin reduced glutamate release induced by 4-aminopyridine in a dose-dependent manner, with an IC50 value of 3 μM. Removal of extracellular Ca2+ or blockade of P/Q-type Ca2+ channels prevented epigoitrin's effect on synaptosomal glutamate release, while the N-type Ca2+ channel inhibitor did not. In an in vivo rat model of glutamate excitotoxicity induced by kainic acid, epigoitrin pretreatment significantly mitigated neuronal injury, glutamate elevation, and the upregulation of excitotoxicity-related proteins (DAPK1 and NMDA receptor subunit GluN2B) in the cortex of kainic acid-treated rats. Additionally, epigoitrin pretreatment reduced reactive oxygen species (ROS) production, glial activation, and levels of inflammatory cytokines (tumor necrosis factor-α, interleukin-1β, and interleukin-6), while increasing the anti-inflammatory cytokine interleutin-10 in the cortex of kainic acid-treated rats. These results suggest that epigoitrin inhibits glutamate release from cortical synaptosomes by reducing P/Q-type Ca2+ channel activity and provides neuroprotection against kainic acid-induced neurotoxicity by preventing oxidative stress, neuroinflammation, and glutamate elevation. This study is the first to reveal the impact of epigoitrin on the glutamatergic system.

Azilsartan Confers Protection Against Kainic Acid-Induced Hippocampal Neuron Damage by Upregulating Sirt3/Sod2 Pathway

Epilepsy refers to a diverse group of neurological pathologies, coupled with a significant worldwide impact. Azilsartan, an angiotensin receptor blocker, is broadly applied as an antihypertensive medication. Considering that the neuroprotective potential of Azilsartan has been newly documented, our work was committed to characterizing the association of Azilsartan with epilepsy and its possible mechanism. First, mice hippocampal neuron (HT-22) cells were exposed to kainic acid (KA) with or without Azilsartan treatment. Cell Counting Kit 8 (CCK8) method assessed the viability of KA-treated HT-22 cells. Flow cytometry assay was employed to detect cellular apoptotic capacity. DCF-DA fluorescent staining, JC-1 probe, and related assay kits were used to estimate mitochondrial oxidative stress. Western blotting examined the expression of Sirtuin 3 (Sirt3), superoxide dismutase 2 (Sod2), and apoptosis-related proteins. Additionally, Sirt3 was silenced to analyze whether the protective effect of Azilsartan on KA-induced damage of HT-22 cell damage was achieved by regulating Sirt3. Results indicated that KA intervention concentration-dependently triggered the viability loss, apoptosis, and mitochondrial damage in HT-22 cells. Azilsartan treatment protected against KA-induced HT-22 cell injury by elevating the viability, reducing the apoptosis, and attenuating mitochondrial damage. Besides, Azilsartan administration activated Sirt3 and Sod2 expression in KA-stimulated HT-22 cells, and Sirt3 depletion partially blocked the impacts of Azilsartan on Sirt3/Sod2 pathway, mitochondrial damage, viability, and apoptosis in HT-22 cells exposed to KA. Collectively, Azilsartan might act as a neuroprotective agent in treating epilepsy through the activation of Sirt3/Sod2 pathway.

Role and therapeutic considerations of SIRT1 in epilepsy

Epilepsy is a primary study focus for scientists worldwide due to its prevalence and poor prognosis. Silent information regulator 1 (SIRT1), a nicotinamide adenine dinucleotide-dependent deacetylase, is becoming increasingly recognized for its critical role in the pathophysiology and progression of epilepsy. The treatment of epilepsy remains challenging despite the discovery of numerous factors that contribute to the development of several beneficial medications. In recent years, many microRNAs have been linked to the progression of epilepsy because they target SIRT1 mRNA. SIRT1, which protects from epilepsy, has been reported to be upregulated by several natural compounds and their derivatives. This review will summarize the latest findings about SIRT1's role in epilepsy. Results from the literature indicate that SIRT1 is a promising target for epilepsy therapy.

Harmine-induced disruption of the blood-brain barrier via excessive mitophagy in zebrafish

Stroke is a serious condition with sudden onset, high severity, and significant rates of mortality and disability, ranking as the second leading cause of death globally at 11.6%. Hemorrhagic stroke, characterized by non-traumatic rupture of cerebral vessels, can cause secondary brain injury such as neurotoxicity, inflammation, reactive oxygen species, and blood-brain barrier (BBB) damage. The integrity of the BBB plays a crucial role in stroke outcomes, as its disruption can exacerbate injury. Harmine, a natural β-carboline alkaloid, has been studied for various pharmacological effects, including its potential benefits in protecting cardiac and cognitive functions. However, its impact on cerebrovascular conditions, particularly in the context of stroke, remains underexplored. This study investigates harmine's effects on BBB integrity and its role in inducing cerebral hemorrhage in zebrafish. We found that harmine disrupts BBB permeability, leading to cerebral hemorrhage through modulation of tight junction protein Claudin-5 and cytoskeletal protein F-actin expression. Furthermore, harmine altered mitochondrial morphology, causing structural imbalance, excessive mitophagy, and cell death. Together, these data indicate that harmine can induce BBB damage and intracerebral hemorrhage in zebrafish, and provide a possible mechanism and explanation for this effect.

NRICM101 prevents kainic acid-induced seizures in rats by modulating neuroinflammation and the glutamatergic system

Taiwan Chingguan Yihau (NRICM101) is a Traditional Chinese medicine (TCM) formula used to treat coronavirus disease 2019; however, its impact on epilepsy has not been revealed. Therefore, the present study evaluated the anti-epileptogenic effect of orally administered NRICM101 on kainic acid (KA)-induced seizures in rats and investigated its possible mechanisms of action. Sprague-Dawley rats were administered NRICM101 (300 mg/kg) by oral gavage for 7 consecutive days before receiving an intraperitoneal injection of KA (15 mg/kg). NRICM101 considerably reduced the seizure behavior and electroencephalographic seizures induced by KA in rats. NRICM101 also significantly decreased the neuronal loss and glutamate increase and increased GLAST, GLT-1, GAD67, GDH and GS levels in the cortex and hippocampus of KA-treated rats. In addition, NRICM101 significantly suppressed astrogliosis (as determined by decreased GFAP expression); neuroinflammatory signaling (as determined by reduced HMGB1, TLR-4, IL-1β, IL-1R, IL-6, p-JAK2, p-STAT3, TNF-α, TNFR1 and p-IκB levels, and increased cytosolic p65-NFκB levels); and necroptosis (as determined by decreased p-RIPK3 and p-MLKL levels) in the cortex and hippocampus of KA-treated rats. The effects of NRICM101 were similar to those of carbamazepine, a well-recognized antiseizure drug. Furthermore, no toxic effects of NRICM101 on the liver and kidney were observed in NRICM101-treated rats. The results indicate that NRICM101 has antiepileptogenic and neuroprotective effects through the suppression of the inflammatory cues (HMGB1/TLR4, Il-1β/IL-1R1, IL-6/p-JAK2/p-STAT3, and TNF-α/TNFR1/NF-κB) and necroptosis signaling pathways (TNF-α/TNFR1/RIP3/MLKL) associated with glutamate level regulation in the brain and is innocuous. Our findings highlight the promising role of NRICM101 in the management of epilepsy.

Neuroprotective effects of chlorogenic acid against oxidative stress in rats subjected to lithium-pilocarpine-induced status epilepticus

Epilepsy is a condition marked by sudden, self-sustained, and recurring brain events, showcasing unique electro-clinical and neuropathological phenomena that can alter the structure and functioning of the brain, resulting in diverse manifestations. Antiepileptic drugs (AEDs) can be very effective in 30% of patients in controlling seizures. Several factors contribute to this: drug resistance, individual variability, side effects, complexity of epilepsy, incomplete understanding, comorbidities, drug interactions, and no adherence to treatment. Therefore, research into new AEDs is important for several reasons such as improved efficacy, reduced side effects, expanded treatment options, treatment for drug-resistant epilepsy, improved safety profiles, targeted therapies, and innovation and progress. Animal models serve as crucial biological tools for comprehending neuronal damage and aiding in the discovery of more effective new AEDs. The utilization of antioxidant agents that act on the central nervous system may serve as a supplementary approach in the secondary prevention of epilepsy, both in laboratory animals and potentially in humans. Chlorogenic acid (CGA) is a significant compound, widely prevalent in numerous medicinal and food plants, exhibiting an extensive spectrum of biological activities such as neuroprotection, antioxidant, anti-inflammatory, and analgesic effects, among others. In this research, we assessed the neuroprotective effects of commercially available CGA in Wistar rats submitted to lithium-pilocarpine-induced status epilepticus (SE) model. After 72-h induction of SE, rats received thiopental and were treated for three consecutive days (1st, 2nd, and 3rd doses). Next, brains were collected and studied histologically for viable cells in the hippocampus with staining for cresyl-violet (Nissl staining) and for degenerating cells with Fluoro-Jade C (FJC) staining. Moreover, to evaluate oxidative stress, the presence of malondialdehyde (MDA) and superoxide dismutase (SOD) was quantified. Rats administered with CGA (30 mg/kg) demonstrated a significant decrease of 59% in the number of hippocampal cell loss in the CA3, and of 48% in the hilus layers after SE. A significant reduction of 75% in the cell loss in the CA3, shown by FJC+ staining, was also observed with the administration of CGA (30 mg/kg). Furthermore, significant decreases of 49% in MDA production and 72% in the activity of SOD were seen, when compared to animals subjected to SE that received vehicle. This study introduces a novel finding: the administration of CGA at a dosage of 30 mg/kg effectively reduced oxidative stress induced by lithium-pilocarpine, with its effects lasting until the peak of neural damage 72 h following the onset of SE. Overall, the research and development of new AEDs are essential for advancing epilepsy treatment, improving patient outcomes, and ultimately enhancing the quality of life for individuals living with epilepsy.

Sodium Houttuyfonate Prevents Seizures and Neuronal Cell Loss by Maintaining Glutamatergic System Stability in Male Rats with Kainic Acid-Induced Seizures

The present study evaluated the antiseizure and neuroprotective effects of sodium houttuyfonate (SH), a derivative of Houttuynia cordata Thunb. (H. cordata), in a kainic acid (KA)- induced seizure rat model and its underlying mechanism. Sprague Dawley rats were administered normal saline, SH (50 or 100 mg/kg), or carbamazepine (300 mg/kg) by oral gavage for seven consecutive days before the intraperitoneal administration of KA (15 mg/kg). SH showed antiseizure effects at a dose of 100 mg/kg; it prolonged seizure latency and decreased seizure scores. SH also significantly decreased neuronal loss in the hippocampi of KA-treated rats, which was associated with the prevention of glutamate level increase, the upregulation of glutamate reuptake-associated proteins (excitatory amino acid transporters 1-3), glutamate metabolism enzyme glutamine synthetase, the downregulation of the glutamate synthesis enzyme glutaminase, and significant alterations in the expression of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor) and NMDA (N-methyl-D-aspartic acid receptor) receptor subunits in the hippocampus. Furthermore, the effects of SH were similar to those of the antiseizure drug carbamazepine. Therefore, the results of the present study suggest that SH has antiseizure effects on KA-induced seizures, possibly through the prevention of glutamatergic alterations. Our findings suggest that SH is a potential alternative treatment that may prevent seizures by preserving the normal glutamatergic system.

Gypenoside XVII Reduces Synaptic Glutamate Release and Protects against Excitotoxic Injury in Rats

Excitotoxicity is a common pathological process in neurological diseases caused by excess glutamate. The purpose of this study was to evaluate the effect of gypenoside XVII (GP-17), a gypenoside monomer, on the glutamatergic system. In vitro, in rat cortical nerve terminals (synaptosomes), GP-17 dose-dependently decreased glutamate release with an IC50 value of 16 μM. The removal of extracellular Ca2+ or blockade of N-and P/Q-type Ca2+ channels and protein kinase A (PKA) abolished the inhibitory effect of GP-17 on glutamate release from cortical synaptosomes. GP-17 also significantly reduced the phosphorylation of PKA, SNAP-25, and synapsin I in cortical synaptosomes. In an in vivo rat model of glutamate excitotoxicity induced by kainic acid (KA), GP-17 pretreatment significantly prevented seizures and rescued neuronal cell injury and glutamate elevation in the cortex. GP-17 pretreatment decreased the expression levels of sodium-coupled neutral amino acid transporter 1, glutamate synthesis enzyme glutaminase and vesicular glutamate transporter 1 but increased the expression level of glutamate metabolism enzyme glutamate dehydrogenase in the cortex of KA-treated rats. In addition, the KA-induced alterations in the N-methyl-D-aspartate receptor subunits GluN2A and GluN2B in the cortex were prevented by GP-17 pretreatment. GP-17 also prevented the KA-induced decrease in cerebral blood flow and arginase II expression. These results suggest that (i) GP-17, through the suppression of N- and P/Q-type Ca2+ channels and consequent PKA-mediated SNAP-25 and synapsin I phosphorylation, reduces glutamate exocytosis from cortical synaptosomes; and (ii) GP-17 has a neuroprotective effect on KA-induced glutamate excitotoxicity in rats through regulating synaptic glutamate release and cerebral blood flow.