Neuronal Damage In Rats Research Articles

The Activation of GABAAR Alleviated Cerebral Ischemic Injury via the Suppression of Oxidative Stress, Autophagy, and Apoptosis Pathways.

Ischemic stroke is a devastating disease leading to neurologic impairment. Compounding the issue is the very limited array of available interventions. The activation of a γ-aminobutyric acid (GABA) type A receptor (GABAAR) has been reported to produce neuroprotective properties during cerebral ischemia, but its mechanism of action is not yet fully understood. Here, in a rat model of photochemically induced cerebral ischemia, we found that muscimol, a GABAAR agonist, modulated GABAergic signaling, ameliorated anxiety-like behaviors, and attenuated neuronal damage in rats suffering cerebral ischemia. Moreover, GABAAR activation improved brain antioxidant levels, reducing the accumulation of oxidative products, which was closely associated with the NO/NOS pathway. Notably, the inhibition of autophagy markedly relieved the neuronal insult caused by cerebral ischemia. We further established an oxygen-glucose deprivation (OGD)-induced PC12 cell injury model. Both in vivo and in vitro experiments demonstrated that GABAAR activation obviously suppressed autophagy by regulating the AMPK-mTOR pathway. Additionally, GABAAR activation inhibited apoptosis through inhibiting the Bax/Bcl-2 pathway. These data suggest that GABAAR activation exerts neuroprotective effects during cerebral ischemia through improving oxidative stress and inhibiting autophagy and apoptosis. Our findings indicate that GABAAR serves as a target for treating cerebral ischemia and highlight the GABAAR-mediated autophagy signaling pathway.

Electroacupuncture inhibits the expression of HMGB1/RAGE and alleviates injury to the primary motor cortex in rats with cerebral ischemia.

The high-mobility group box 1 (HMGB1)/receptor for advanced glycation end products (RAGE) signaling pathway holds promise as a potential therapeutic target for ischemic brain injury. The effects of FPS-ZM1 and electroacupuncture (EA) on activation of the HMGB1/RAGE signaling pathway after cerebral ischemia remain uncertain. Middle cerebral artery occlusion (MCAO) model was established. Neurological function was assessed using Longa scores. Nissl staining was used to observe the morphology of neurons. The expression levels of HMGB1 and RAGE were assayed with immunofluorescence staining and western blot. The results showed that EA and FPS-ZM1 could reduce the neural function score and neurons cell injury in cerebral ischemia rats by inhibiting the expression of HMGB1 and RAGE in primary motor cortex (M1) region. In addition, EA combined with FPS-ZM1 had a better therapeutic effect. The HMGB1/RAGE pathway could be activated after cerebral ischemia. Both EA and FPS-ZM1 improved neurological deficits and attenuated neuronal damage in rats. They had synergistic effects. These interventions were observed to mitigate brain damage by suppressing the activation of HMGB1/RAGE.

Investigation of Myelin Basic Protein Activity in Determining Neuronal Damage in Rats with Experimental Head Trauma

Amaç: Çalışmamızda deneysel olarak oluşturulan kafa travması sonrası sıçanlarda hafif travmatik beyin hasarı meydana getirilmiştir. Amacımız alınan serum örneklerinde myelin basic protein (MBP) düzeyinin akut dönemde travmatik beyin hasarını göstermede tanısal değerini araştırmaktır.
 
 Gereç ve Yöntemler: Çalışmamızda toplam 40 adet erişkin Spraque-Dawley cinsi sıçan kullanılmıştır. Denekler kontrol grubu (n=8) ve 4 ayrı deney grubu (n=8) olarak 5 gruba ayrıldılar. Travma mekanizması oluşturulurken Marmarou ve ark.’nın tanımladığı model modifiye edilerek uygulandı. Yaptığımız modelde ağırlıkları ve yükseklikleri farklı olan bilyeler serbest düşme yöntemiyle bırakıldı. Sırasıyla 0.05, 0.1, 0.2, 0,4 newton şiddetinde travma oluşturulması hedeflendi ve sırasıyla A, B, C, D grubu olarak adlandırıldı. Travma gerçekleştirildikten 2 saat sonra sıçanlardan alınan kanlarda MBP düzeyi araştırıldı.
 
 Bulgular: Kontrol grubu ile karşılaştırıldığında kan MBP seviyeleri A ve B grubunda anlamlı yüksek saptandı. Gruplar kendi arasında karşılaştırıldığında ise B ve C grup arasında anlamlı farklılık vardır. Aynı şekilde A ve C ile A ve D grubu arasında da anlamlı fark saptanmıştır. Dört grup kendi arasında karşılaştırıldığında travma şiddetiyle MBP’nin kandaki düzeyi arasında korelasyon görülmemiştir.
 
 Sonuç: Travma şiddetinin farklı olduğu gruplarda değerlerin farklı olması MBP artışının sekonder sebeplere de bağlı olma ihtimalini güçlendirmektedir. MBP kafa travmasında TBH’yı değerlendirmek açısından değerli bir biyobelirteç olabilir ancak günümüzde MBP için yapılan çalışmalar yeterli değildir.

Synergistic effects of lipopolysaccharide and rotenone on dopamine neuronal damage in rats.

The etiology of Parkinson's disease (PD) is still unknown. Until now, oxidative stress and neuroinflammation play a crucial role in the pathogenesis of PD. However, the specific synergistic role of oxidative stress and neuroinflammation in the occurrence and development of PD remains unclear. The changes in motor behavior, dopamine (DA) neurons quantification and their mitochondrial respiratory chain, glial cells activation and secreted cytokines, Nrf2 signaling pathway, and redox balance in the brain of rats were evaluated. Lipopolysaccharide (LPS)-induced neuroinflammation and rotenone (ROT)-induced oxidative stress synergistically aggravated motor dysfunction, DA neuron damage, activation of glial cells, and release of related mediators, activation of Nrf2 signaling and destruction of oxidative balance. In addition, further studies indicated that after ROT-induced oxidative stress caused direct damage to DA neurons, LPS-induced inflammatory effects had stronger promoting neurotoxic effects on the above aspects. Neuroinflammation and oxidative stress synergistically aggravated DA neuronal loss. Furtherly, oxidative stress followed by neuroinflammation caused more DA neuronal loss than neuroinflammation followed by oxidative stress.

Heat-killed Lactobacillus murinus confers neuroprotection against dopamine neuronal loss by targeting NLRP3 inflammasome.

The intestinal flora has become very active in studies related to Parkinson's disease (PD) in recent years. The microbe-gut-brain axis is closely related to the maintenance of brain homeostasis as well as PD pathogenesis. Alterations in gut bacteria can contribute to neuroinflammation and dopamine (DA) neurodegeneration. Lactobacillus murinus, a gram-positive bacterium, is a commensal gut bacteria present in the mammalian gut and considered as a potential probiotic due to its beneficial effects, including anti-inflammatory and antibacterial actions. In this study, the effects of live L. murinus and heat-killed L. murinus on DA neuronal damage in rats and the underlying mechanisms were investigated. Data showed that heat-killed L. murinus ameliorated 6-hydroxydopamine-induced motor dysfunctions and loss of substantia nigra DA neurons, while no protection was shown in live L. murinus treatment. At the same time, heat-killed L. murinus reduced the activation of NLRP3 inflammasome in microglia and the secretion of pro-inflammatory factors, thus inhibiting the development of neuroinflammation. Furthermore, heat-killed L. murinus failed to display its original neuroprotective properties in NLRP3 inflammasome knockout mice. Together, heat-killed L. murinus conferred neuroprotection against DA neuronal loss via the inhibition of microglial NLRP3 inflammasome activation. These findings provide a promising potential for future applications of L. murinus, and also beneficial strategy for PD treatment.

Combined exposure of heat stress and ozone enhanced cognitive impairment via neuroinflammation and blood brain barrier disruption in male rats

BackgroundHeat stress (HS) exposure has been linked to cognitive dysfunction. In reality, high temperature does not occur alone in environment, and ozone (O3) and heatwaves usually co-exist in atmospheric environment. However, whether O3 exposure exacerbates HS-induced cognitive impairment and the potential underlying mechanisms have not been explored experimentally. The aim of this study was to determine the co-effects and mechanisms of HS and O3 on the cognitive dysfunction. Methods48 Sprague Dawley male rats were randomly divided into 4 groups: control, HS, O3 and HS plus O3 (HO3) groups. Rats in HS and HO3 group were exposed to 40 °C every morning from 9:00 to 12:00 for 15 consecutive days. While rats in O3 and HO3 groups were exposed to 0.7 ppm O3 the same day from 14:00 to 17:00 for 15 days. Cognitive performance was examined with Morris water maze test. Neurodegeneration, glial activation, neuroinflammation, blood brain barrier (BBB) disruption and apoptosis were evaluated by Western blot, Elisa, immunohistochemistry and immunofluorescence staining. ResultsHS induced cognitive decline and neuronal damage in rats. Further studies showed that exposure of rats to HS could also induce glial activation, neuroinflammation and neuronal apoptosis in hippocampus, and decrease in the expressions of ZO-1, claudin-5 and occluding, indicative of BBB disruption. Impressively, the neuronal effects induced by HS, as depicted above, could be worsened by co-exposure to O3 in rats. ConclusionsCo-exposure to O3 promotes HS-induced cognitive impairment in rats possibly through glial-mediated neuroinflammation and BBB disruption.

Neuroprotective potential of ocimum sanctum (Linn) leaf extract in preventing and attenuating stress induced substantia nigral neuronal damage in rats

BackgroundIn Ayurveda; an Indian system of traditional medicine, Ocimum sanctum is said to have remedial effect on hriddaurbalya (problems affecting the mind), aakshepayukta vikara (nervous disorders) and shiroroga (diseases of head). Hence, in Ayurvedic practice, it is profoundly used as an antistress medicine. Stress is known to affect neurons of functionally significant brain regions like substantia nigra. However, experimental evidence showing its effect on morphology of substantia nigral neurons is lacking. In addition, whether the O. sanctum treatment attenuates stress induced substantia nigral neuronal structural changes is not known. ObjectivesTo know the effect of stress on morphology of substantia nigral neurons and the effect of O. sanctum fresh leaf extract (OSE) on substantia nigral neurons of stressed rats. Material and methodsPresent study included three experiments. Experiment I: To study the effect of 3 and 6 weeks of foot shock stress in rats; Experiment II- To study the effect of 3 weeks of OSE treatment on 3 week-stress undergoing rats and on 3 week-stressed rats; Experiment III- To study the effect of 6 weeks of OSE treatment in 6 week-stress undergoing rats and in 6 week-stressed rats. ResultsIn experiment I, stress had significant deleterious effect on dendritic arborization of substantia nigral neurons. Experiments II and III showed prevention and attenuation of the stress induced dendritic atrophy of substantia nigral neurons in both 2 ml and 4 ml OSE treatment groups. Protective effect of OSE was more pronounced in rats which are treated for a longer duration. ConclusionsFoot shock stress induces neuronal damage in the substantia nigra of rats. Treatment with fresh leaf extract of O. sanctum could prevent and attenuate the foot shock stress induced behavioral deficit and substantia nigral neuronal damage.

Parthanatos participates in glutamate-mediated HT22 cell injury and hippocampal neuronal death in kainic acid-induced status epilepticus rats.

Epileptic seizures or status epilepticus (SE) can cause hippocampal neuronal death, which has detrimental effects. Parthanatos, a new form of programmed cell death, is characterized by hyperactivation of poly (ADP-ribose) polymerase-1 (PARP-1), excessive synthesis of poly ADP-ribose polymer, mitochondrial depolarization, and nuclear translocation of apoptosis-inducing factor, observed in various neurodegenerative disorders but rarely reported in epilepsy. We aimed to investigate whether parthanatos participates in the mechanism of seizure-induced hippocampal neuronal death. Glutamate-mediated excitotoxicity cell model was used to study the mechanism of seizure-induced cell injury. Injection of kainic acid into the amygdala was used to establish the epileptic rat model. Corresponding biochemical tests were carried out on hippocampal tissues and HT22 cells following indicated treatments. In vitro, glutamate time-dependently induced HT22 cell death, accompanied by parthanatos-related biochemical events. Pretreatment with PJ34 (PARP-1 inhibitor) or small interfering RNA-mediated PARP-1 knockdown effectively protected HT22 cells against glutamate-induced toxic effects and attenuated parthanatos-related biochemical events. Application of the antioxidant N-acetylcysteine (NAC) rescued HT22 cell death and reversed parthanatos-related biochemical events. In vivo, PJ34 and NAC afforded protection against SE-induced hippocampal neuronal damage and inhibited parthanatos-related biochemical events. Parthanatos participates in glutamate-induced HT22 cell injury and hippocampal neuronal damage in rats following epileptic seizures. ROS might be the initiating factor during parthanatos.

Therapeutic Effect of Buyang Huanwu Decoction on the Gut Microbiota and Hippocampal Metabolism in a Rat Model of Cerebral Ischemia.

Buyang Huanwu decoction (BHD) is a well-known Chinese herbal prescription. It has been widely used in the clinical treatment of cerebral ischemia (CI) in China. However, the mechanism underlying the treatment of CI with BHD remains to be elucidated. In this study, we combined microbiomic and metabolomic strategies to explore the therapeutic effects of BHD on middle cerebral artery occlusion (MCAO) in rats. Our results showed that BHD could effectively improve neurological severity scores and alleviate neuronal damage in rats with MCAO. BHD could also reduce the level of peripheral proinflammatory cytokines and inhibit neuroinflammation. 16S rRNA sequencing showed that BHD could increase the relative abundances of the genera Lactobacillus, Faecalibacterium, Ruminococcaceae_UCG-002, etc., while decreasing the relative abundances of the genera Escherichia-Shigella, Klebsiella, Streptococcus, Coprococcus_2, Enterococcus, etc. Untargeted metabolomic analysis of hippocampal samples showed that 17 significantly differentially abundant metabolites and 9 enriched metabolic pathways were linked with BHD treatment. We also found that the regulatory effects of BHD on metabolites were correlated with the differentially abundant microbial taxa. The predicted function of the gut microbiota and the metabolic pathway enrichment results showed that purine metabolism, glutamatergic synapses, arginine and proline metabolism, and alanine, aspartic acid and glutamate metabolism were involved in the effects of BHD. These pathways may be related to pathological processes such as excitotoxicity, neuroinflammation, and energy metabolism disorder in CI. In summary, these findings suggest that regulation of hippocampal metabolism and of the composition and function of the gut microbiota may be important mechanisms underlying the effect of BHD in the treatment of CI.

Protective role of activating transcription factor 3 against neuronal damage in rats with cerebral ischemia.

BackgroundThe participation of activating transcription factor 3 (ATF3) in transient middle cerebral artery occlusion and reperfusion injury has been reported. However, the precise mechanism of ATF3 in cerebral ischemia is little known so far. Thus, the study examines the mechanism of action underlying the protective role of ATF3 following middle cerebral artery occlusion (MCAO) in rats.Methods and resultsThe MCAO rats exhibited reduced body weight and motor ability, while increased neurological deficits and brain infarct volume. Gene ontology (GO) enrichment and KEGG pathway analyses revealed that differentially expressed genes were mainly enriched in the TLR4/NF‐κB signaling. Moreover, ATF3 was the most differentially expressed gene in brain tissues of MCAO rats versus sham‐operated rats, which could bind to CCL2. ATF3 was reduced in MCAO rats, and ATF3 inhibited CCL2 expression to mediate the TLR4/NF‐κB signaling. Functionally, ATF3 inhibited neuronal apoptosis, microglia activation, and pro‐inflammatory cytokine production to alleviate brain injury in rats. By contrast, CCL2 was overexpressed in neurons and microglia, and CCL2 mitigated the effects of ATF3 to exacerbate brain injury in rats.ConclusionOur findings suggested that ATF3 repressed neuronal apoptosis and microglia activation caused by cerebral ischemia via targeting CCL2 and mediating the TLR4/NF‐κB signaling.

The Protective Effects of Hydrogen Sulfide New Donor Methyl S-(4-Fluorobenzyl)-N-(3,4,5-Trimethoxybenzoyl)-l-Cysteinate on the Ischemic Stroke.

In this paper, we report the design, synthesis and biological evaluation of a novel S-allyl-l-cysteine (SAC) and gallic acid conjugate S-(4-fluorobenzyl)-N-(3,4,5-trimethoxybenzoyl)-l-cysteinate (MTC). We evaluate the effects on ischemia-reperfusion-induced PC12 cells, primary neurons in neonatal rats, and cerebral ischemic neuronal damage in rats, and the results showed that MTC increased SOD, CAT, GPx activity and decreased LDH release. PI3K and p-AKT protein levels were significantly increased by activating PI3K/AKT pathway. Mitochondrial pro-apoptotic proteins Bax and Bim levels were reduced while anti-apoptotic protein Bcl-2 levels were increased. The levels of cleaved caspase-9 and cleaved caspase-3 were also reduced in the plasma. The endoplasmic reticulum stress (ERS) was decreased, which in turns the survival rate of nerve cells was increased, so that the ischemic injury of neurons was protected accordingly. MTC activated the MEK-ERK signaling pathway and promoted axonal regeneration in primary neurons of the neonatal rat. The pretreatment of MEK-ERK pathway inhibitor PD98059 and PI3K/AKT pathway inhibitor LY294002 partially attenuated the protective effect of MTC. Using a MCAO rat model indicated that MTC could reduce cerebral ischemia-reperfusion injury and decrease the expression of proinflammatory factors. The neuroprotective effect of MTC may be due to inhibition of the over-activation of the TREK-1 channel and reduction of the current density of the TREK1 channel. These results suggested that MTC has a protective effect on neuronal injury induced by ischemia reperfusion, so it may have the potential to become a new type of neuro-ischemic drug candidate.

The neuroprotective mechanism of sevoflurane in rats with traumatic brain injury via FGF2

BackgroundTraumatic brain injury (TBI) is a kind of acquired brain injury, which is caused by external mechanical forces. Moreover, the neuroprotective role of sevoflurane (Sevo) has been identified in TBI. Therefore, this research was conducted to figure out the mechanism of Sevo in TBI via FGF2.MethodsThe key factors of neuroprotective effects of Sevo in TBI rats were predicted by bioinformatics analysis. A TBI model was induced on rats that then inhaled Sevo for 1 h and grouped via lentivirus injection. Modified Neurological Severity Score was adopted to evaluate neuronal damage in rats, followed by motor function and brain water content measurement. FGF2, EZH2, and HES1 expression in brain tissues was evaluated by immunofluorescence staining, and expression of related genes and autophagy factors by RT-qPCR and Western blot analysis. Methylation-specific PCR was performed to assess HES1 promoter methylation level, and ChIP assay to detect the enrichment of EZH2 in the HES1 promoter. Neuronal damage was assessed by cell immunofluorescence staining, and neuronal apoptosis by Nissl staining, TUNEL staining, and flow cytometry.ResultsSevo diminished brain edema, improved neurological scores, and decreased neuronal apoptosis and autophagy in TBI rats. Sevo preconditioning could upregulate FGF2 that elevated EZH2 expression, and EZH2 bound to the HES1 promoter to downregulate HES1 in TBI rats. Also, FGF2 or EZH2 overexpression or HES silencing decreased brain edema, neurological deficits, and neuronal autophagy and apoptosis in Sevo-treated TBI rats.ConclusionsOur results provided a novel insight to the neuroprotective mechanism of Sevo in TBI rats by downregulating HES1 via FGF2/EZH2 axis activation.

Investigating the Activity of Alpha-synuclein Protein in Determining Neuronal Damage in Rats with Experimental Head Trauma

Çalışmamızın amacı deneysel olarak hafif travmatik beyin hasarı oluşturulan kafa travması modelinde sıçanlardan alınan serum örneklerinde alfa-sinüklein (α-syn) düzeyinin akut dönemde travmatik beyin hasarını göstermede tanısal değerini araştırmaktır. Çalışmamızda toplam 40 adet erişkin Spraque-Dawley cinsi sıçan kullanılmıştır. Denekler kontrol grubu (n=8) ve 4 ayrı deney grubu (n=8) olarak 5 gruba ayrıldılar. Çalışmamızda Marmarou ve ark.’nın tanımladığı model modifiye edilerek uygulandı. Bu modelde farklı yüksekliklerden farklı ağırlıklarda bilyeler serbest düşme yöntemiyle bırakılarak sırayla 0,05, 0,1, 0.2 ve 0,4 Newton şiddetinde travma oluşturulması hedeflendi. Travmanın indüksiyonundan 2 saat sonra sıçanların kalbinden alınan kanlarda α-syn düzeyi araştırıldı. Kontrol grubuna göre kan α-syn düzeyleri ölçüldüğünde, 0,05 ve 0,2 Newton şiddetinde travma oluşturduğumuz gruplarda düşüş görülmüştür. Daha şiddetli travma oluşturduğumuz (0,2 Newton) grup, az şiddetli oluşturduğumuz gruba (0,05 Newton) göre anlamlı olarak daha düşük bulunmuştur. Sonuç olarak farklı şiddetlerde kafa travması oluşturduğumuz sıçanlardan ikinci saatte alınan kan örneklerinden α-syn düzeylerinde anlamlı bir yükselme görülmemiştir. Aksine iki travma grubunda kontrol grubu ile kıyaslandığında düşme görülmüştür. Bu sonuçlar kafa travması sonrası ikinci saatte alınan kanlardan bakılan α-syn düzeyinin TBY için erken dönemde tanısal olarak etkin olmadığını düşündürmektedir.

Buyang Huanwu Decoction promotes neurogenesis via sirtuin1/autophagy pathway in a cerebral ischemia model.

Stroke is one of the main causes of disease-related mortality worldwide. Buyang Huanwu Decoction (BHD) has been used to protect against stroke and stroke-induced disability for several years in China. Studies have shown that BHD can relieve neuronal damage in rats with cerebral ischemia/reperfusion (I/R) injury. However, the mechanism remains unclear. A middle cerebral artery occlusion and reperfusion (MCAO-R) model was used in the present study. The animals were treated with BHD (5, 10 and 20 g/kg) or rapamycin. Infarct size and modified neurological severity score were calculated on day 5 following MCAO-R surgery. Cellular changes around the ischemic penumbra were revealed by hematoxylin and eosin and Nissl staining. The protein expression levels of nestin, brain-derived neurotrophic factor (BDNF), doublecortin on the X chromosome (DCX) and autophagy-related proteins (beclin 1, LC3-II and p62) in the peri-ischemic area of the brain were detected. The results demonstrated that post-surgical treatment with BHD reduced the brain infarct size and improved neurological deficits in MCAO-R rats. BHD protected against MCAO-R-induced neuronal impairment and promoted neurogenesis, increased the protein expression of nestin, BDNF and DCX and markedly enhanced autophagy by increasing beclin 1 and LC3-II and decreasing p62. Meanwhile, BHD promoted the expression of sirtuin 1 (SIRT1), an important regulator of autophagy. In conclusion, the present study suggested that post-surgical treatment with BHD could protect rat brains from I/R injury, potentially through the SIRT1/autophagy pathway.

Effects of amantadine and topiramate on neuronal damage in rats with experimental cerebral ischemia-reperfusion.

Ischemia-reperfusion models are used to evaluate treatment options that may minimize cellular damage after ischemia. To investigate the effects of amantadine and topiramate on apoptosis and cellular oxidative damage. This experiment was performed using 30 male Wistar albino rats. The right internal carotid artery was identified and clamped with an aneurysm clip under general anesthesia, except for animals in the control group. After 10 min of occlusion, the aneurysm clip was removed, allowing reperfusion. After reperfusion and a waiting period of 12 h, the test and control groups were intraperitoneally administered the following solutions: the sham group received 10 mg/kg of isotonic solution, the amantadine group received 20 mg/kg of amantadine, the topiramate group received 40 mg/kg of topiramate, and the amantadine-topiramate group received 20 mg/kg of amantadine and 40 mg/kg of topiramate. After 24 h, the rats were euthanized. Apoptosis was evaluated using the TUNEL method. Total antioxidant status (TAS), total oxidant status (TOS), total thiol, and ischemia-modified albumin (IMA) levels were measured in both brain tissue and serum samples. The rate of apoptosis in the sham and amantadine groups increased significantly compared to the control group and the non-ischemic counter hemisphere. In the amantadine-topiramate group, both serum TAS and tissue thiol levels decreased. Tissue TOS levels were significantly higher in the topiramate group compared to all other test groups. Tissue TAS levels were significantly higher in the amantadine group compared to all other test groups. This experimental ischemia-reperfusion model revealed that topiramate reduces apoptosis in the early period after ischemia and that its combination with amantadine does not provide additional benefits against cell death. However, topiramate did not have an inhibitory effect on the oxidative stress biomarkers used in our study (TAS, TOS, IMA, and thiol). Studies that reveal the neuroprotective mechanism of action and long-term effects of topiramate are needed to complement this study.

Neuroprotective effects of dexpanthenol on streptozotocin-induced neuronal damage in rats

Aim Although the most common age-related neurodegenerative disease defined by memory loss is Alzheimer's disease (AD), only symptomatic therapies are present. A complex pathway for the AD pathogenesis that includes an increase in inflammation has recently been suggested. Since in previous animal experiments dexpanthenol has anti-inflammatory and neuroprotective activities, effects and role of dexpanthenol in an intracerebroventricular (ICV)-streptozotocin (STZ) induced sporadic-AD(memory impairment) animal model have been examined. Design and methods In total, 18 adult sprague-dawley rats were classified into 3 groups; control (n = 6), STZ + Saline (n = 6) and STZ + Dexpanthenol (n = 6). Twelve AD-induced rats through STZ-injection (3 mg/kg) into both lateral ventricles via stereotaxy were separated into two groups five days after STZ administration: one of these groups was treated with dexpanthenol (1000 mg/kg/day, i.p.) for 3 weeks and the other with saline. A passive avoidance learning (PAL) test was used after treatment, followed by brain tissue extraction in all subjects. Brain levels of tumor necrosis factor-alpha (TNF-α) and choline acetyl transferase (ChAT) were measured and Cresyl violet staining was used to count neurons in cornu ammonis-1 (CA1) and cornu ammonis-3 (CA3). Results It was observed that ICV-STZ significantly shortened PAL latency, increased levels of TNF-α in brain, decreased activity of ChAT in brain, and number of hippocampal neurons. However, dexpanthenol significantly reduced all of those STZ-induced harmful effects. Conclusion Dexpanthenol significantly prevented the memory deficit induced by ICV-STZ through mitigating neuronal loss in hippocampus, cholinergic deficiency and neuroinflammation in rats. These findings suggest that dexpanthenol may be beneficial for treating memory impairment.

Effect of Piracetam on Brain Oxidative Stress and Tissue Damage Following Toluene Exposure in Rats

In this study, the effect of the nootropic drug piracetam on brain oxidative stress and histopathological changes in brain, liver and kidney following exposure to toluene in rats was examined. Piracetam (150 or 300 mg/kg, subcutaneously, daily) was given along with toluene (500 mg/kg, intraperitoneally, daily) for one week. The brain content of malondialdehyde (MDA), reduced glutathione (GSH) and the activity of paraoxonase-1 (PON-1), and butyrylcholinesterase (BChE) in brain homogenates were determined. Histopathology of the brain, liver and kidney and brain Bax immunohistochemistry were performed. Results showed that exposure to toluene resulted in increased brain lipid peroxidation (MDA) and NO along with decreased reduced glutathione. Toluene also inhibited PON-1, and BChE activities. The administration of piracetam had no significant effect on brain lipid peroxidation. The level of reduced glutathione was unchanged by piracetam but PON1 activity was increased by the lower dose of the drug. Piracetam showed no significant effect on BChE activity in toluene treated rats. Histopathological examination of the brain of toluene only treated rats showed degenerated neurons in cerebral cortex, marked neuronal vacuolation in hippocampus and focal hemorrhage. Bax 3 immunohistochemical staining showed cytoplasmic reactivity in degenerated neurons. Rats given piracetam showed decreased cortical cellularity, increased number of degenerated neurons and increased BAX staining. The higher dose of the drug caused sinusoidal hemorrhage and intertubular hemorrhage in kidney. Collectively, these results indicate that treatment with piracetam wan not able to decrease neuronal damage in rats exposed to toluene.

Ephedrine alleviates middle cerebral artery occlusion-induced neurological deficits and hippocampal neuronal damage in rats by activating PI3K/AKT signaling pathway

ABSTRACT Inflammation and oxidative stress are crucial in ischemic stroke. Ephedrine (EPH) has been proven to have anti-inflammatory and anti-oxidative stress effects. The present study analyzes whether EPH possessed neuroprotective effects and explored the underlying mechanisms of EPH based on an experimental model of middle cerebral artery occlusion (MCAO). We found that intraperitoneal injection with EPH attenuated the neurological deficit, cerebral infarction, and cerebral edema induced by MCAO in rats. Besides, EPH treatment alleviated MCAO-induced brain tissue damage and morphological abnormality, as well as neuronal loss. Moreover, EPH treatment upregulated GPx and CAT activity and downregulated MDA and NO content. EPH also evidently decreased the levels of IL-6 and TNF-α but increased IL-4 and IL-10 levels. Of note, EPH treatment promoted the phosphorylation of PI3K and AKT proteins in MCAO rats. Furthermore, administration of PI3K/AKT pathway inhibitor LY294002 abolished the beneficial effects of EPH. These results confirmed that EPH alleviated brain injury induced by MCAO via activating PI3K/AKT signaling pathway.

Antiepileptic effects of exogenous β-hydroxybutyrate on kainic acid-induced epilepsy.

The aim of the present study was to explore the potential anticonvulsant effects of β-hydroxybutyrate (BHB) in a kainic acid (KA)-induced rat epilepsy model. The KA-induced rat seizure model was established and BHB was administrated intraperitoneally at a dose of 4 mmol/kg 30 min prior to KA injection. Hippocampal tissues were then obtained 1, 3 and 7 days following KA administration, following which the expression levels of neuron-specific enolase (NSE) and glial fibrillary acidic protein (GFAP) were measured using a double immunofluorescence labeling method. In addition, the contents of glutathione (GSH), γ-aminobutyric acid (GABA) and ATP were measured using ELISA. Pretreatment with BHB markedly increased the expression of NSE after KA injection compared with that in the normal saline (NS) + KA group, suggesting that the application of BHB could alleviate neuronal damage in rats. The protective effect of BHB may be associated with suppressed inflammatory responses, which was indicated by the observed inhibition of GFAP expression in rats in the BHB + KA group compared with that in the NS + KA group. It was also found that GSH and GABA contents were notably increased after the rats were pretreated with BHB compared with those in the NS + KA group. To conclude, the application of exogenous BHB can serve as a novel therapeutic agent for epilepsy.

Neuroprotective effect of low-intensity transcranial ultrasound stimulation in endothelin-1-induced middle cerebral artery occlusion in rats

BackgroundIschemic stroke is one of the leading causes of death and disability worldwide. Low-intensity transcranial ultrasound stimulation (LITUS) is a promising neuroprotective treatment for ischemic stroke. Diffusion-weighted imaging (DWI) can be highly sensitive in the detection of ischemic brain injury. Relative apparent diffusion coefficient (rADC) values can be used to evaluate the effect of LITUS on ischemic stroke. PurposeThe aim of this study was to determine the neuroprotective effect of LITUS at different time points using endothelin-1-induced middle cerebral artery occlusion in rats as a model of ischemic stroke. MethodsEndothelin-1 (ET-1) was injected into the cerebral parenchyma near the middle cerebral artery, which induced focal, reversible, low-flow ischemia in rats. After occlusion of the middle cerebral artery for 30 min, 120 min, and 240 min, LITUS stimulation was used respectively. DWI was performed at 1, 3, 6, 12, 18, 24, 48, and 72 h after ischemia using a 3 T scanner. The rADC values were calculated, and functional outcomes assessed using neurobehavioral scores after ischemia. Nissl staining and estimation of Na+–K+-ATPase activity were used to assess the neuropathology after completing the last Magnetic Resonance Imaging (MRI) examination. ResultsEndothelin-1-induced occlusion of the middle cerebral artery resulted in significant dysfunction and neuronal damage in rats. Rats that received LITUS exhibited reduced damage of the affected brain tissue after cerebral ischemia. The greatest protective effect was found when LITUS stimulation occurred 30 min after cerebral ischemia. ConclusionsImaging, behavioral, and histological results suggested that LITUS stimulation after an ischemic stroke produced significant neuroprotective effects.