The neuroprotective effects of carnosine in early stage of focal ischemia rodent model

The Role of Zinc in the Development of Vascular Dementia and Parkinson's Disease and the Potential of Carnosine as Their Therapeutic Agent

Synaptic zinc ions (Zn2+) play an important role in the development of vascular dementia (VD) and Parkinson's disease (PD). In this article, we reviewed the current comprehension of the Zn2+-induced neurotoxicity that leads to the pathogenesis of these neuronal diseases. Zn2+-induced neurotoxicity was investigated by using immortalised hypothalamic neurons (GT1-7 cells). This cell line is useful for the development of a rapid and convenient screening system for investigating Zn2+-induced neurotoxicity. GT1-7 cells were also used to search for substances that prevent Zn2+-induced neurotoxicity. Among the tested substances was a protective substance in the extract of Japanese eel (Anguilla japonica), and we determined its structure to be like carnosine (β-alanylhistidine). Carnosine may be a therapeutic drug for VD and PD. Furthermore, we reviewed the molecular mechanisms that involve the role of carnosine as an endogenous protector and its protective effect against Zn2+-induced cytotoxicity and discussed the prospects for the future therapeutic applications of this dipeptide for neurodegenerative diseases and dementia.

Promising Strategies for the Development of Advanced In Vitro Models with High Predictive Power in Ischaemic Stroke Research

Although stroke is one of the world’s leading causes of death and disability, and more than a thousand candidate neuroprotective drugs have been proposed based on extensive in vitro and animal-based research, an effective neuroprotective/restorative therapy for ischaemic stroke patients is still missing. In particular, the high attrition rate of neuroprotective compounds in clinical studies should make us question the ability of in vitro models currently used for ischaemic stroke research to recapitulate human ischaemic responses with sufficient fidelity. The ischaemic stroke field would greatly benefit from the implementation of more complex in vitro models with improved physiological relevance, next to traditional in vitro and in vivo models in preclinical studies, to more accurately predict clinical outcomes. In this review, we discuss current in vitro models used in ischaemic stroke research and describe the main factors determining the predictive value of in vitro models for modelling human ischaemic stroke. In light of this, human-based 3D models consisting of multiple cell types, either with or without the use of microfluidics technology, may better recapitulate human ischaemic responses and possess the potential to bridge the translational gap between animal-based in vitro and in vivo models, and human patients in clinical trials.

An assessment of the transport mechanism and intraneuronal stability of L-carnosine

L-Carnosine (β-alanyl-L-histidine) is a well-known antioxidant and neuroprotector in various models on animals and cell cultures. However, while there is a plethora of data demonstrating its efficiency as a neuroprotector, there is a distinct lack of data regarding the mechanism of its take up by neurons. According to literature, cultures of rat astrocytes, SKPT cells and rat choroid plexus epithelial cells take up carnosine via the H⁺-coupled PEPT2 membrane transporter. We've assessed the effectiveness and mechanism of carnosine transport, and its stability in primary rat cortical culture neurons. We demonstrated that neurons take up carnosine via active transport with Km = 119 μM and a maximum velocity of 0.289 nmol/mg (prot)/min. Passive transport speed constituted 0.21∙10^-4 nmol/mg (prot)/min (with 119 μM concentration in the medium)-significantly less than active transport speed. However, carnosine concentrations over 12.5 mM led to passive transport speed becoming greater than active transport speed. Using PEPT2 inhibitor zofenopril, we demonstrated that PEPT2-dependent transport is one of the main modes of carnosine take up by neurons. Our experiments demonstrated that incubation with carnosine does not affect PEPT2 amount present in culture. At the same time, after removing carnosine from the medium, its elimination speed by culture cells reached 0.035 nmol/mg (prot)/min, which led to a decrease in carnosine quantity to control levels in culture within 1 h. Thus, carnosine is taken up by neurons with an effectiveness comparable to that of other PEPT2 substrates, but its elimination rate suggests that for effective use as a neuroprotector it's necessary to either maintain a high concentration in brain tissue, or increase the effectiveness of glial cell synthesis of endogenous carnosine and its shuttling into neurons, or use more stable chemical modifications of carnosine.

Effect of L-Carnosine in children with autism spectrum disorders: a systematic review and meta-analysis of randomised controlled trials

Autism spectrum disorders (ASD) are an emerging health problem worldwide. So far, no definite cure for ASD exists. L-Carnosine is an amino acid containing β-alanine and L-histidine which has been proposed to have neuroprotective, antioxidant and anti-convulsive properties that may benefit affected children with this disorder. This review aimed to assess the effect of L-Carnosine in the management of ASD in children. We systematically reviewed randomised controlled trials (RCTs) which documented the effect of L-Carnosine in children with ASD. A literature search was performed in PubMed, Cochrane Library, Google Scholar, ClinicalTrials.gov, Clinical Trial Registry-India databases from inception to December 20, 2020. Articles were selected based on pre-set inclusion/exclusion criteria. The primary outcomes were changes in social, communication and behavioural responses and the secondary outcomes were improvement in sleep disorders, gastrointestinal problems, oxidative stress markers and adverse effects. Jadad scale was used to assess the quality of RCTs and modified Cochrane risk of bias tool was used to check the risk of bias of the included studies. The meta-analysis was reported based on the fixed-effects model. Four double-blinded, placebo-controlled, RCTs and one open label trial with a total of 215 participants were selected for the review. All the trials were methodological of high quality according to the Jadad scale. The modified Cochrane risk of bias tool showed a low to high risk of bias. Results from the meta-analysis of three studies showed no significant difference between L-Carnosine and placebo groups in the Gilliam autism rating scale (GARS) (MD = - 2.57; 95% CI - 10.30, 5.16, p = 0.52) and in its socialisation (MD = - 1.51; 95% CI - 6.16, 3.14, p = 0.53), behaviour (MD = - 0.48; 95% CI - 4.82, 3.87, p = 0.83) and communication (MD = - 3.94; 95% CI - 10.00, 2.11, p = 0.20) subscales as well as the childhood autism rating scale (CARS) (MD = - 0.88; 95% CI - 6.96, 5.20; p = 0.78). Current data do not support the use of L-Carnosine in the management of children with ASD due to a low number of studies and sample size available. Further studies are warranted to know the effect of L-Carnosine for ASD management.

Effect of L-Carnosine as adjunctive therapy in the management of children with autism spectrum disorder: a randomized controlled study

L-Carnosine is an amino acid that acts as an anti-oxidant, anti-toxic and neuroprotective agent. There is a paucity of data about the effectiveness of L-Carnosine in the management of autism spectrum disorder (ASD) in children. This study aimed at investigating the effectiveness of L-Carnosine as adjunctive therapy in the management of ASD. This was a randomized controlled trial. Children aged 3-6 years with a diagnosis of mild to moderate ASD were assigned to standard care arm (occupational and speech therapy) and intervention care arm (L-Carnosine, 10-15 mg/kg in 2 divided doses) plus standard care treatment. The children were assessed at the baseline and the end of 2 months for the scores of Childhood Autism Rating Scale, Second Edition-Standard Version (CARS2-ST), Autism Treatment Evaluation Checklist (ATEC), BEARS sleep screening tool and 6-item Gastrointestinal Severity Index (6-GSI). Of the sixty-seven children enrolled, sixty-three children had completed the study. No statistically significant difference (p > 0.05) was observed for any of the outcome measures assessed. Supplementation of L-Carnosine did not improve the total score of CARS2-ST, ATEC, BEARS sleep screening tool and 6-GSI scores of children with ASD. Further investigations are needed with more objective assessments to critically validate the effectiveness of L-Carnosine on ASD children for more decisive results.

Mechanisms of Neuroprotective Action of Hesperetin and Carnosine in Focal Ischemia of the Brain in Rats

We compared the direct neuroprotective effect of minor food components, antioxidants hesperetin and carnosine, and analyzed their influence on the parameters of the oxidative status of the penumbra zones in the cerebral cortex during focal ischemia (1 h) of with reperfusion in Wistar rats. The animals received hesperetin and carnosine included in the diet in daily doses of 50 and 150 mg/kg, respectively, for 7 days before ischemia induction. The neuroprotective effect of hesperetin manifested in reduction of the ischemic lesion size by 30%, which was comparable with the effect of carnosine. Both hesperetin and carnosine reduced the level of MDA in the penumbra zone of the cerebral cortex and increased the total antioxidant activity of the brain tissue. Hesperetin also increased SOD activity to a level observed in the sham-operated control group.

Carnosine as a Possible Drug for Zinc-Induced Neurotoxicity and Vascular Dementia

Increasing evidence suggests that the metal homeostasis is involved in the pathogenesis of various neurodegenerative diseases including senile type of dementia such as Alzheimer’s disease, dementia with Lewy bodies, and vascular dementia. In particular, synaptic Zn²⁺ is known to play critical roles in the pathogenesis of vascular dementia. In this article, we review the molecular pathways of Zn²⁺-induced neurotoxicity based on our and numerous other findings, and demonstrated the implications of the energy production pathway, the disruption of calcium homeostasis, the production of reactive oxygen species (ROS), the endoplasmic reticulum (ER)-stress pathway, and the stress-activated protein kinases/c-Jun amino-terminal kinases (SAPK/JNK) pathway. Furthermore, we have searched for substances that protect neurons from Zn²⁺-induced neurotoxicity among various agricultural products and determined carnosine (β-alanyl histidine) as a possible therapeutic agent for vascular dementia.

Endogenous BMP-4/ROS/COX-2 Mediated IPC and Resveratrol Alleviated Brain Damage

The objective of the study was to examine the therapeutic role of combined ischemic preconditioning (IPC) and resveratrol (RES) on brain ischemia/reperfusion injury (BI/RI) by modulating endogenous bone morphogenetic protein-4 (BMP-4)/reactive oxygen species (ROS)/cyclooxygenase-2 (COX-2) in rats. Sprague Dawley (SD) rats were pretreated with 20 mg/kg RES (20 mg/kg RES was administered once a day via intraperitoneal injection 7 days prior to the I/R procedure) and IPC (equal volumes of saline were administered once a day by intraperitoneal injection over 7 days, and the bilateral common carotid arteries were separated for clamp 5 minutes followed by 5 minutes of reperfusion prior to the I/R procedure), and then subjected to 2 hours of ischemia and 22 hours of reperfusion. Blood and cerebral tissues were collected, cerebral pathological injuries and infarct sizes were investigated, serum interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) levels were measured, the activities of superoxide dismutase (SOD) and ROS were calculated, the contents of methane dicarboxylic aldehyde (MDA), IL-6, TNF-α and hemodynamic change were estimated, and expression levels of b-cell lymphoma-2 (Bcl-2), bcl-2-associated x (Bax), BMP-4 and COX-2 were assessed in cerebral tissues. IPC, RES and a combination of IPC and RES preconditioning ameliorated the pathological damage and infarct sizes, reduced cerebral oxidative stress damage, alleviated inflammatory damage, restrained apoptosis, and downregulated the expression levels of BMP-4 and COX-2 compared with those of the ischemia/reperfusion (I/R) group. This study suggested a combined strategy that could enhance protection against BI/RI in clinical brain disease.

[Study of the neuroprotective effects of carnosine in an experimental model of focal cerebral ischemia/reperfusion]

Oxidative stress is one of the key factors in brain tissue damage in ischemia, which indicates the appropriateness of using antioxidants under these conditions. One of the promising antioxidants for the therapy of ischemic stroke is the natural dipeptide carnosine. The neuroprotective effect of dietary carnosine administration was investigated in an experimental model of focal cerebral ischemia/reperfusion in Wistar rats. Animals received carnosine with a diet at a daily dose of 150 mg/kg for 7 days before temporary occlusion of the middle cerebral artery (MCA), performed for 60 min. At 24 h after the onset of ischemia the effect of carnosine on the area of the necrotic core was evaluated in animals. In brain tissue of animals the content of malondialdehyde (MDA), protein carbonyls (PC), total antioxidant capacity (TAC), total activity of superoxide dismutase (SOD), glutathione peroxidase (GP), catalase (CAT) and glutathione transferase (GT), content of isoprostanes and cytokines were measured. Carnosine significantly reduced the infarct size. Carnosine also increased TAC and reduced the level of MDA and isoprostanes in brain tissue. Influence of carnosine on other parameters was not detected. Thus carnosine consumed prophylactically with the diet for 7 days before the induction of ischemia by means of MCA occlusion in rats provides the direct neuroprotective effect, retains high antioxidant activity of brain tissue, reduces the level of oxidative damage markers (MDA and isoprostanes) but does not have any effect on the activity of antioxidant enzyme systems and production of cytokines in brain tissue.

The neuroprotective properties of carnosine in a mouse model of manganism is mediated via mitochondria regulating and antioxidative mechanisms

Objective(s): Manganese (Mn) is an essential trace element physiologically incorporated in the structure of several vital enzymes. Despite its essentiality, excessive Mn exposure is toxic with brain tissue as the primary target organ. There is no specific and clinically available therapeutic/preventive option against Mn neurotoxicity. Carnosine is a neuropeptide with several physiological roles. The neuroprotective properties of this peptide have been evaluated in different experimental models. The current study was designed to investigate the effect of carnosine supplementation and its potential mechanisms of action in an animal model of Mn-induced neurotoxicity. Materials and Methods: Male C57BL/6 mice received Mn (100 mg/kg, s.c) alone and/or in combination with carnosine (10, 50, and 100 mg/kg, i.p). Several locomotor activity indices were monitored. Moreover, biomarkers of oxidative stress and mitochondrial function were assessed in the brain tissue of Mn-exposed animals. Results: Significant locomotor dysfunction was revealed in Mn-exposed animals. Furthermore, brain tissue biomarkers of oxidative stress were significantly increased, and mitochondrial indices of functionality were impaired in Mn-treated animals. It was found that carnosine supplementation (10, 50, and 100 mg/kg, i.p) alleviated the Mn-induced locomotor deficit. Moreover, this peptide mitigated oxidative stress biomarkers and preserved brain tissue mitochondrial functionality in the animal model of manganism. Conclusion: These data indicate that carnosine is a potential neuroprotective agent against Mn neurotoxicity. Antioxidative and mitochondria protecting effects of carnosine might play a fundamental role in its neuroprotective properties against Mn toxicity.

Carnosine as an effective neuroprotector in brain pathology and potential neuromodulator in normal conditions

Carnosine (b-alanyl-L-histidine) is an endogenous dipeptide widely distributed in excitable tissues, such as muscle and neural tissues-though in minor concentrations in the latter. Multiple benefits have been attributed to carnosine: direct and indirect antioxidant effect, antiglycating, metal-chelating, chaperone and pH-buffering activity. Thus, carnosine turns out to be a multipotent protector against oxidative damage. However, the role of carnosine in the brain remains unclear. The key aspects concerning carnosine in the brain reviewed are as follows: its concentration and bioavailability, mechanisms of action in neuronal and glial cells, beneficial effects in human studies. Recent literature data and the results of our own research are summarized here. This review covers studies of carnosine effects on both in vitro and in vivo models of cerebral damage, such as neurodegenerative disorders and ischemic injuries and the data on its physiological actions on neuronal signaling and cerebral functions. Besides its antioxidant and homeostatic properties, new potential roles of carnosine in the brain are discussed.

Structure of the mouse acidic amino acid decarboxylase GADL1

Pyridoxal 5'-phosphate (PLP) is a ubiquitous cofactor in various enzyme classes, including PLP-dependent decarboxylases. A recently discovered member of this class is glutamic acid decarboxylase-like protein 1 (GADL1), which lacks the activity to decarboxylate glutamate to γ-aminobutyrate, despite its homology to glutamic acid decarboxylase. Among the acidic amino acid decarboxylases, GADL1 is most similar to cysteine sulfinic acid decarboxylase (CSAD), but the physiological function of GADL1 is unclear, although its expression pattern and activity suggest a role in neurotransmitter and neuroprotectant metabolism. The crystal structure of mouse GADL1 is described, together with a solution model based on small-angle X-ray scattering data. While the overall fold and the conformation of the bound PLP are similar to those in other PLP-dependent decarboxylases, GADL1 adopts a more loose conformation in solution, which might have functional relevance in ligand binding and catalysis. The structural data raise new questions about the compactness, flexibility and conformational dynamics of PLP-dependent decarboxylases, including GADL1.

On the Relationship between Energy Metabolism, Proteostasis, Aging and Parkinson's Disease: Possible Causative Role of Methylglyoxal and Alleviative Potential of Carnosine

Recent research shows that energy metabolism can strongly influence proteostasis and thereby affect onset of aging and related disease such as Parkinson's disease (PD). Changes in glycolytic and proteolytic activities (influenced by diet and development) are suggested to synergistically create a self-reinforcing deleterious cycle via enhanced formation of triose phosphates (dihydroxyacetone-phosphate and glyceraldehyde-3-phosphate) and their decomposition product methylglyoxal (MG). It is proposed that triose phosphates and/or MG contribute to the development of PD and its attendant pathophysiological symptoms. MG can induce many of the macromolecular modifications (e.g. protein glycation) which characterise the aged-phenotype. MG can also react with dopamine to generate a salsolinol-like product, 1-acetyl-6,7-dihydroxy-1,2,3,4-tetrahydroisoquinaline (ADTIQ), which accumulates in the Parkinson's disease (PD) brain and whose effects on mitochondria, analogous to MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), closely resemble changes associated with PD. MG can directly damage the intracellular proteolytic apparatus and modify proteins into non-degradable (cross-linked) forms. It is suggested that increased endogenous MG formation may result from either, or both, enhanced glycolytic activity and decreased proteolytic activity and contribute to the macromolecular changes associated with PD. Carnosine, a naturally-occurring dipeptide, may ameliorate MG-induced effects due, in part, to its carbonyl-scavenging activity. The possibility that ingestion of highly glycated proteins could also contribute to age-related brain dysfunction is briefly discussed.

Carnosine modulates glutamine synthetase expression in senescent astrocytes exposed to oxygen-glucose deprivation/recovery

Carnosine is believed to be neuroprotective in cerebral ischemia. However, few reports concern its function on senescent astrocytes during cerebral ischemia. The aim of this study was to investigate the effects of carnosine on cell damage and glutamine synthetase (GS) expression in D-galactose-induced senescent astrocytes exposed to oxygen-glucose deprivation/recovery (OGD/R). The results showed that OGD/R caused massive cell damage and a significant decrease in GS expression both in the young and senescent astrocytes. The GS expression level was partly recovered whereas it continued to decline in the recovery stage in the young and senescent astrocytes, respectively. Decreased GS expression significantly inhibited glutamate uptake and glutamine production and release. Carnosine prevented the cell damage, rescued the expression of GS and reversed the glutamate uptake activity and glutamine production in the senescent astrocytes exposed to OGD/R. The modulatory effect of carnosine on GS expression was partly antagonized by pyrilamine, a selective histamine H₁ receptors antagonist, but not bestatin. Bisindolylmaleimide II, a broad-spectrum inhibitor of PKC could also reverse the action of carnosine on GS expression. Thus, histamine H₁ receptors and PKC pathway may be involved in the modulatory action of carnosine in GS expression in the senescent astrocytes exposed to OGD/R.

Compound porcine cerebroside and ganglioside injection attenuates cerebral ischemia-reperfusion injury in rats by targeting multiple cellular processes

BACKGROUND

Compound porcine cerebroside and ganglioside injection (CPCGI) is a neurotrophic drug used clinically to treat certain functional disorders of brain. Despite its extensive usage throughout China, the exact mechanistic targets of CPCGI are unknown. This study was carried out to investigate the protective effect of CPCGI against ischemic neuronal damage in rats with middle cerebral artery occlusion (MCAO) reperfusion injury and to investigate the neuroprotective mechanisms of CPCGI.

MATERIALS AND METHODS

Adult male Sprague-Dawley rats were subjected to MCAO surgery for 2 hours followed by reperfusion. The rats were administered CPCGI once a day for 14 days after reperfusion, and behavioral tests were performed 1, 3, 7, and 14 days post MCAO. Hematoxylin-eosin staining was used to measure infarct volume, and immunohistochemical analysis was performed to determine the number of NeuN-positive neurons in the ischemic cortex penumbra. Finally, the relative expression levels of proteins associated with apoptosis (Bcl-2, Bax, and GADD45α), synaptic function (Synaptophysin, SNAP25, Syntaxin, and Complexin-1/2), and mitochondrial function (KIFC2 and UCP3) were determined by Western blot.

RESULTS

CPCGI treatment reduced infarct size, decreased neurological deficit scores, and accelerated the recovery of somatosensory function 14 days after MCAO. In addition, CPCGI reduced the loss of NeuN-positive cells in the ischemic cortex penumbra. In the ischemic cortex, CPCGI treatment decreased GADD45α expression, increased the Bcl-2/Bax ratio, augmented Synaptophysin, SNAP25, and Complexin-1/2 expression, and increased the expression of KIFC2 and UCP3 compared with sham rats 14 days after MCAO reperfusion injury.

CONCLUSION

CPCGI displays neuroprotective properties in rats subjected to MCAO injury by inhibiting apoptosis and improving synaptic and mitochondrial function.

Systematic review and stratified meta-analysis of the efficacy of carnosine in animal models of ischemic stroke

Carnosine is a naturally occurring pleotropic dipeptide which influences multiple deleterious mechanisms that are activated during stroke. Numerous published studies have reported that carnosine has robust efficacy in ischemic stroke models. To further evaluate these data, we have conducted a systematic review and meta-analysis of published studies. We included publications describing in vivo models of ischemic stroke where the neuroprotective efficacy of carnosine was being evaluated through the reporting of infarct volume and/or neurological score as outcomes. Overall efficacy was evaluated using weighted mean difference random effects meta-analysis. We also evaluated for study quality and publication bias. We identified eight publications that met our inclusion criteria describing a total of 29 comparisons and 454 animals. Overall methodological quality of studies was moderate (median = 4/9). Carnosine reduced infarct volume by 29.4% (95% confidence interval (CI), 24.0% to 34.9%; 29 comparisons). A clear dose-response effect was observed, and efficacy was reduced when carnosine was administered more than 6 h after ischemia. Our findings suggest that carnosine administered before or after the onset of ischemia exhibits robust efficacy in experimental ischemic stroke. However, the methodological quality of some of the studies was low and testing occurred only in healthy young male animals.

Neuroprotective Effect of Resveratrol on Acute Brain Ischemia Reperfusion Injury by Measuring Annexin V, p53, Bcl-2 Levels in Rats

Background

Cerebral ischemia is as a result of insufficient cerebral blood flow for cerebral metabolic functions. Resveratrol is a natural phytoalexin that can be extracted from grape's skin and had potent role in treating the cerebral ischemia. Apoptosis, a genetically programmed cellular event which occurs after ischemia and leads to biochemical and morphological changes in cells. There are some useful markers for apoptosis like Bcl-2, bax, and p53. The last reports, researchers verify the apoptosis with early markers like Annexin V.

Methods

We preferred in this experimental study a model of global cerebral infarction which was induced by bilateral common carotid artery occlusion method. Rats were randomly divided into 4 groups : sham, ischemia-reperfusion (I/R), I/R plus 20 mg/kg resveratrol and I/R plus 40 mg/kg resveratrol. Statistical analysis was performed using Sigmastat 3.5 ve IBM SPSS Statistics 20. We considered a result significant when p<0.001.

Results

After administration of resveratrol, Bcl-2 and Annexin levels were significantly increased (p<0.001). Depending on the dose of resveratrol, Bcl2 levels increased, p53 levels decreased but Annexin V did not effected. P53 levels were significantly increased in ishemia group, so apoptosis is higher compared to other groups.

Conclusion

In the acute period, Annexin V levels misleading us because the apoptotic cell counts could not reach a certain level. Therefore we should support our results with bcl-2 and p53.

Neuroprotective effect of humic Acid on focal cerebral ischemia injury: an experimental study in rats

Stroke is still a major cause of death and permanent neurological disability. As humic acids are well-known antioxidant molecules, the purpose of this study was to investigate the potential neuroprotective effects of humic acid in a focal cerebral ischemia model. Twenty-four rats were divided equally into three groups. A middle cerebral artery occlusion model was performed in this study where control (group II) and humic acid (group III) were administered intraperitoneally following an ischemic experimental procedure. Group I was evaluated as sham. Malondialdehyde (MDA), superoxide dismutase (SOD), and nuclear respiratory factor-1 (NRF-1) levels were analyzed biochemically on the right side of the ischemic cerebral hemisphere, while ischemic histopathological studies were completed on the left side to investigate the antioxidant status. Biochemical results showed that SOD and NRF-1 levels were significantly increased in the humic acid group (III) compared with the control group (II) while MDA levels were significantly decreased. On histopathological examination, cerebral edema, vacuolization, degeneration, and destruction of neural elements were decreased in the humic acid group (III) compared with the control group (II). Cerebral ischemia was attenuated by humic acid administration. These observations indicate that humic acid may have potential as a therapeutic agent in cerebral ischemia by preventing oxidative stress.

Effect of Inducible Co-Stimulatory Molecule siRNA in Cerebral Infarction Rat Models

Background

T cell-induced inflammatory response and related cytokine secretion at the injury site may participate in the pathogenesis of cerebral infarction. Recent studies established inducible co-stimulatory molecule (ICOS) as a novel T cell-related factor for its activation and functions. We thus investigate the role of ICOS in cerebral infarction.

Material/Methods

The siRNA of ICOS was first used to suppress the gene expression in cultured lymphocytes. An in vivo study was then performed by intravenous application of ICOS siRNA in cerebral infarction rats. Survival rates, neurological scores, serum tumor necrosis factor (TNF)-α, interleukin (IL)-1, and IL-17 levels were observed.

Results

The expression of ICOS in cultured lymphocytes was significantly suppressed by siRNA. In the in vivo study, the application of siRNA effectively lowered mortality rates of rats, in addition to the improvement of neurological behaviors and amelioration of cerebral tissue damage. Serum levels of TNF-α, IL-1 and IL-17 were all significantly suppressed after siRNA injection.

Conclusions

ICOS siRNA can protect brain tissues from ischemia injuries after cerebral infarction, improve limb movement and coordination, lower the mortality rate of rats, and inhibit T cell-induced cytokines. These results collectively suggest the potential treatment efficacy of ICOS siRNA against cerebral infarction.

Dual effects of carnosine on energy metabolism of cultured cortical astrocytes under normal and ischemic conditions

OBJECTIVE

The aim of this study was to investigate the effects of carnosine on the bioenergetic profile of cultured cortical astrocytes under normal and ischemic conditions.

METHODS

The Seahorse Bioscience XF96 Extracellular Flux Analyzer was used to measure the oxygen consumption rates (OCRs) and extracellular acidification rates (ECARs) of cultured cortical astrocytes treated with and without carnosine under normal and ischemic conditions.

RESULTS

Under the normal growth condition, the basal OCRs and ECARs of astrocytes were 21.72±1.59 pmol/min/μg protein and 3.95±0.28 mpH/min/μg protein respectively. Mitochondrial respiration accounted for ~80% of the total cellular respiration and 85% of this coupled to ATP synthesis. Carnosine significantly reduced basal OCRs and ECARs and ATP-linked respiration, but it strikingly increased the spare respiratory capacity of astrocytes. The cellular ATP level in carnosine-treated astrocytes was reduced to ~42% of the control. However, under the ischemic condition, carnosine upregulated the mitochondrial respiratory and cellular ATP content of astrocytes exposed to 8h of oxygen-glucose deprivation (OGD) followed by 24 h of recovery under the normal growth condition.

CONCLUSIONS

Carnosine may be an endogenous regulator of astrocyte energy metabolism and a clinically safe therapeutic agent for promoting brain energy metabolism recovery after ischemia/reperfusion injury.

Carnosine attenuates early brain injury through its antioxidative and anti-apoptotic effects in a rat experimental subarachnoid hemorrhage model

Carnosine (β-alanyl-L-histidine) has been demonstrated to provide antioxidative and anti-apoptotic roles in the animal of ischemic brain injuries and neurodegenerative diseases. The aim of this study was to examine whether carnosine prevents subarachnoid hemorrhage (SAH)-induced early brain injury (EBI) in rats. We found that intraperitoneal administration of carnosine improved neurobehavioral deficits, attenuated brain edema and blood-brain barrier permeability, and decreased reactive oxygen species level at 48 h following SAH in rat models. Carnosine treatment increased tissue copper/zinc superoxide dismutase (CuZn-SOD) and glutathione peroxidase (GSH-Px) enzymatic activities, and reduced post-SAH elevated lactate dehydrogenase (LDH) activity, the concentration of malondialdehyde (MDA), 3-nitrotyrosine (3-NT), 8-hydroxydeoxyguanosine (8-OHDG), interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) in rats. Furthermore, carnosine treatment attenuated SAH-induced microglia activation and cortical neuron apoptosis. These results indicated that administration of carnosine may provide neuroprotection in EBI following SAH in rat models.