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

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.

Efficacy of bumetanide in animal models of ischemic stroke: a systematic review and meta-analysis

This meta-analysis aimed to describe the efficacy of bumetanide in improving infarct volume, brain edema, and behavioral outcomes in animal models of cerebral ischemia. Embase, PubMed and Web of Science databases were searched from their inception to February 2024 (INPLASY:202430023). Data on the animal species, stroke model, drug dose, time of treatment, method of administration, study quality, and outcomes were extracted and pooled in a meta-analysis. The combined standardized mean difference (SMD) or mean difference (MD) estimates and 95% confidence intervals (CIs) were calculated using random- or fixed-effects models. Thirteen eligible studies involving >200 animals fulfilled the inclusion criteria and were included in this meta-analysis. Meta-analyses demonstrated that bumetanide treatment significantly reduced cerebral infarct volume (SMD: -0.42; 95% CI: -0.75, -0.09; p < 0.01; n = 186 animals) and consistently relieved brain edema (SMD: -1.39; 95% CI: -2.06, -0.72; p < 0.01; n = 64 animals). Subgroup analyses demonstrated that bumetanide treatment reduced infarct volume in transient but not permanent cerebral ischemia models. When administered after the stroke, it was more effective than treatment initiation before the stroke. Eight studies assessed the effect of bumetanide on behavioral function and the results showed that bumetanide treatment significantly improved neurobehavioral deficits (SMD: -2.35; 95% CI: -2.72, -1.97; p < 0.01; n = 250 animals). We conclude that bumetanide appears to be effective in reducing infarct volume and brain edema and improving behavioral recovery in animal models of cerebral ischemia. This mechanism needs to be confirmed through further investigation.

Dietary Trace Elements and the Pathogenesis of Neurodegenerative Diseases

Trace elements such as iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) are absorbed from food via the gastrointestinal tract, transported into the brain, and play central roles in normal brain functions. An excess of these trace elements often produces reactive oxygen species and damages the brain. Moreover, increasing evidence suggests that the dyshomeostasis of these metals is involved in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease, prion diseases, and Lewy body diseases. The disease-related amyloidogenic proteins can regulate metal homeostasis at the synapses, and thus loss of the protective functions of these amyloidogenic proteins causes neurodegeneration. Meanwhile, metal-induced conformational changes of the amyloidogenic proteins contribute to enhancing their neurotoxicity. Moreover, excess Zn and Cu play central roles in the pathogenesis of vascular-type senile dementia. Here, we present an overview of the intake, absorption, and transport of four essential elements (Fe, Zn, Cu, Mn) and one non-essential element (aluminum: Al) in food and their connections with the pathogenesis of neurodegenerative diseases based on metal-protein, and metal-metal cross-talk.

Exosomes-based therapy of stroke, an emerging approach toward recovery

Based on clinical observations, stroke is touted as one of the specific pathological conditions, affecting an individual’s life worldwide. So far, no effective treatment has been introduced to deal with stroke post-complications. Production and release of several neurotrophic factors by different cells exert positive effects on ischemic areas following stroke. As a correlate, basic and clinical studies have focused on the development and discovery of de novo modalities to introduce these factors timely and in appropriate doses into the affected areas. Exosomes (Exo) are non-sized vesicles released from many cells during pathological and physiological conditions and participate in intercellular communication. These particles transfer several arrays of signaling molecules, like several neurotrophic factors into the acceptor cells and induce specific signaling cascades in the favor of cell bioactivity. This review aimed to highlight the emerging role of exosomes as a therapeutic approach in the regeneration of ischemic areas.

Study on the mechanism of Tong-Qiao-Huo-Xue decoction regulating apoptosis via ASK1/MKK4/JNK pathway in MCAO/R rats

BACKGROUND

Activation of blood stasis is a crucial aspect of stroke treatment, and the Tong-Qiao-Huo-Xue-Decoction (TQHXD) formula is commonly utilized for this purpose. However, the mechanism underlying the protective effects of TQHXD against cerebral ischemia-reperfusion (I/R) injury is unclear.

PURPOSE

Identification of the TQHXD components responsible for its protective effects and determination of their mode of action against cerebral I/R injury.

METHODS

Gas chromatography (GC) and high-performance liquid chromatography (HPLC) were carried out to determine the active aspects of TQHXD. The active components and targets of TQHXD were looked up in the TCMSP and HERB databases; the Genecards, OMIM, TTD, and DrugBank databases were used to identify targets related to cerebral infarction; and the intersecting targets were obtained. The drug-ingredient-target-disease network and PPI network were subsequently built using Cytoscape 3.7.1 and STRING websites. Autodock VINA was used to perform molecular docking between the core target ASK1 and the active components of TQHXD detected by HPLC and GC. After successfully creating a rat model of middle cerebral artery occlusion (MCAO), the therapeutic effect of TQHXD was observed using triphenyltetrazolium and hematoxylin-eosin staining. We used Tunel-NeuN staining and transmission electron microscopy (TEM) to quantify hippocampal apoptosis. RT-qPCR and western blotting were used to detect protein and mRNA expression, respectively.

RESULTS

HPLC and GC identified six active ingredients. Network pharmacology analyses were performed to test 66 intersection targets, including ASK1, MKK4, and JNK. Ferulic acid, HSYA, ligustilide, paeoniflorin, and muscone all displayed high binding affinity with ASK1 in molecular docking studies. The neuroprotective effects of TQHXD in I/R rats were demonstrated in the experimental models. In comparison with the model group, TQHXD decreased the apoptosis rate and reduced the protein levels of p-ASK1, caspase 3, p-MKK4, CytC, p-c-Jun, Bax/Bcl-2, and p-JNK, while considerably increasing the mRNA levels of Bcl-2 and decreasing those of Bax.

CONCLUSION

By controlling the ASK1/MKK4/JNK pathway, TQHXD protects neurons from I/R damage and prevents apoptosis. Thus, TQHXD may be effective for the treatment of ischemic stroke. And the mechanism behind these therapeutic actions of TQHXD is supported by this research.

Carnosine as a potential therapeutic for the management of peripheral vascular disease

AIMS

To evaluate the potential role of carnosine in the management of peripheral vascular disease.

DATA SYNTHESIS

Peripheral vascular disease is growing in its burden and impact; however it is currently under researched, and there are a lack of strong, non-invasive therapeutic options for the clinicians. Carnosine is a dipeptide stored particularly in muscle and brain tissue, which exhibits a wide range of physiological activities, which may be beneficial as an adjunct treatment for peripheral vascular disease. Carnosine's strong anti-inflammatory, antioxidant and antiglycating actions may aid in the prevention of plaque formation, through protective actions on the vascular endothelium, and the inhibition of foam cells. Carnosine may also improve angiogenesis, exercise performance and vasodilatory response, while protecting from ischemic tissue injury.

CONCLUSIONS

Carnosine may have a role as an adjunct treatment for peripheral vascular disease alongside typical exercise and surgical interventions, and may be used in high risk individuals to aid in the prevention of atherogenesis.

CLINICAL RECOMMENDATION

This review identifies a beneficial role for carnosine supplementation in the management of patients with peripheral vascular disease, in conjunction with exercise and revascularization. Carnosine as a supplement is safe, and associated with a host of beneficial effects in peripheral vascular disease and its key risk factors.

Zinc Accumulation Aggravates Cerebral Ischemia/Reperfusion Injury Through Inducing Endoplasmic Reticulum Stress

Zinc is highly enriched in the central nervous system. Numerous evidences suggest that high concentration of zinc acts as a critical mediator of neuronal death in the ischemic brain, however, the possible mechanisms of neurotoxicity of zinc during cerebral ischemia/reperfusion (I/R) remain elusive. Endoplasmic reticulum (ER) is a storage location of intracellular zinc. ER stress related genes were up-regulated during zinc-induced neuronal death in vascular-type senile dementia. In the present study, we investigated whether intracellular accumulated zinc aggravates I/R injury through ER stress and ER stress-associated apoptosis. Male Sprague-Dawley rats were subjected to 90 min middle cerebral artery occlusion (MCAO) and received either vehicle or zinc chelator TPEN 15 mg/kg. The expression of ER stress related factors glucose-regulated protein 78 (GRP78) and phosphorylated eukaryotic initiation factor 2α (p-eIF2α), ER stress related apoptotic proteins CCAAT-enhancer-binding protein homologous protein (CHOP) and caspase-12, as well as anti-apoptotic factor B-cell lymphoma-2 (Bcl-2) were assessed 24 h after reperfusion. Our results showed that the levels of GRP78 and p-eIF2α, as well as CHOP and caspase-12, were increased in ischemic brain, indicating that cerebral I/R triggers ER stress. Furthermore, GRP78, CHOP and caspase-12 were all colocalized with the zinc-specific dyes NG, suggesting that there is certain relationship between cytosolic labile zinc and ER stress following cerebral ischemia. Chelating zinc with TPEN reversed the expression of GRP78, p-eIF2α in ischemic rats. Moreover, CHOP and NeuN double staining positive cells, as well as caspase-12 and TUNEL double staining positive cells were also decreased after TPEN treatment, indicating that chelating zinc might inhibit ER stress and decreased ER stress associated neuronal apoptosis. In addition, TPEN treatment reversed the downregulated level of Bcl-2, which localized in the ER membrane and involved in the dysfunction of ER, confirming that the anti-apoptosis effects of chelating zinc following I/R are exerted via inhibition of the ER stress. Taken together, this study demonstrated that excessive zinc activates ER stress and zinc induced neuronal cell death is at least partially due to ER stress specific neuronal apoptosis in ischemic penumbra, which may provide an important mechanism of cerebral I/R injury.

Characterizing the spatial distribution of dipeptides in rodent tissue using MALDI MS imaging with on-tissue derivatization

A highly efficient on-tissue derivatization method for the matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) of dipeptides in tissues has been developed via a combination of a home-built laser-assisted chemical transfer (LACT) technique and hexafluoroisopropanol (HFIP).

Copper as a Collaborative Partner of Zinc-Induced Neurotoxicity in the Pathogenesis of Vascular Dementia

Copper is an essential trace element and possesses critical roles in various brain functions. A considerable amount of copper accumulates in the synapse and is secreted in neuronal firings in a manner similar to zinc. Synaptic copper and zinc modulate neuronal transmission and contribute to information processing. It has been established that excess zinc secreted during transient global ischemia plays central roles in ischemia-induced neuronal death and the pathogenesis of vascular dementia. We found that a low concentration of copper exacerbates zinc-induced neurotoxicity, and we have demonstrated the involvement of the endoplasmic reticulum (ER) stress pathway, the stress-activated protein kinases/c-Jun amino-terminal kinases (SAPK/JNK) signaling pathway, and copper-induced reactive oxygen species (ROS) production. On the basis of our results and other studies, we discuss the collaborative roles of copper in zinc-induced neurotoxicity in the synapse and the contribution of copper to the pathogenesis of vascular dementia.

Carnosine, Small but Mighty-Prospect of Use as Functional Ingredient for Functional Food Formulation

Carnosine is a dipeptide synthesized in the body from β-alanine and L-histidine. It is found in high concentrations in the brain, muscle, and gastrointestinal tissues of humans and is present in all vertebrates. Carnosine has a number of beneficial antioxidant properties. For example, carnosine scavenges reactive oxygen species (ROS) as well as alpha-beta unsaturated aldehydes created by peroxidation of fatty acid cell membranes during oxidative stress. Carnosine can oppose glycation, and it can chelate divalent metal ions. Carnosine alleviates diabetic nephropathy by protecting podocyte and mesangial cells, and can slow down aging. Its component, the amino acid beta-alanine, is particularly interesting as a dietary supplement for athletes because it increases muscle carnosine, and improves effectiveness of exercise and stimulation and contraction in muscles. Carnosine is widely used among athletes in the form of supplements, but rarely in the population of cardiovascular or diabetic patients. Much less is known, if any, about its potential use in enriched food. In the present review, we aimed to provide recent knowledge on carnosine properties and distribution, its metabolism (synthesis and degradation), and analytical methods for carnosine determination, since one of the difficulties is the measurement of carnosine concentration in human samples. Furthermore, the potential mechanisms of carnosine's biological effects in musculature, metabolism and on immunomodulation are discussed. Finally, this review provides a section on carnosine supplementation in the form of functional food and potential health benefits and up to the present, neglected clinical use of carnosine.

Effect of uric acid in animal models of ischemic stroke: A systematic review and meta-analysis

Addition of uric acid (UA) to thrombolytic therapy, although safe, showed limited efficacy in improving patients' stroke outcome, despite alleged neuroprotective effects of UA in preclinical research. This systematic review assessed the effects of UA on brain structural and functional outcomes in animal models of ischemic stroke. We searched Medline, Embase and Web of Science to identify 16 and 14 eligible rodent studies for qualitative and quantitative synthesis, respectively. Range of evidence met 10 of a possible 13 STAIR criteria. Median (Q1, Q3) quality score was 7.5 (6, 10) on the CAMARADES 15-item checklist. For each outcome, we used standardised mean difference (SMD) as effect size and random-effects modelling. Meta-analysis showed that UA significantly reduced infarct size (SMD: -1.18; 95% CI [-1.47, -0.88]; p < 0.001), blood-brain barrier (BBB) impairment/oedema (SMD: -0.72; 95% CI [-0.97, -0.48]; p < 0.001) and neurofunctional deficit (SMD: -0.98; 95% CI [-1.32, -0.63]; p < 0.001). Overall, there was low to moderate between-study heterogeneity and sizeable publication bias. In conclusion, published rodent data suggest that UA improves outcome following ischemic stroke by reducing infarct size, improving BBB integrity and ameliorating neurofunctional condition. Specific recommendations are given for further high-quality preclinical research required to better inform clinical research.

Neuroprotection by cattle encephalon glycoside and ignotin beyond the time window of thrombolysis in ischemic stroke

Cattle encephalon glycoside and ignotin (CEGI) injection is known as a multi-target neuroprotective drug that contains numerous liposoluble molecules, such as polypeptides, monosialotetrahexosyl ganglioside (GM-1), free amino acids, hypoxanthine and carnosine. CEGI has been approved by the Chinese State Food and Drug Administration and widely used in the treatments of various diseases, such as stroke and Alzheimer's disease. However, the neuroprotective effects of CEGI beyond the time window of thrombolysis (within 4.5 hours) on acute ischemic stroke remain unclear. This study constructed a rat middle cerebral artery occlusion model by suture-occluded method to simulate ischemic stroke. The first daily dose was intraperitoneally injected at 8 hours post-surgery and the CEGI treatments continued for 14 days. Results of the modified five-point Bederson scale, beam balance test and rotameric test showed the neurological function of ischemic stroke rats treated with 4 mL/kg/d CEGI improved significantly, but the mortality within 14 days did not change significantly. Brain MRI and 2,3,5-triphenyltetrazolium chloride staining confirmed that the infarct size in the 4 mL/kg/d CEGI-treated rats was significantly reduced compared with ischemic insult only. The results of transmission electron microscopy and double immunofluorescence staining showed that the hippocampal neuronal necrosis in the ischemic penumbra decreased whereas the immunopositivity of new neuronal-specific protein doublecortin and the percentage of Ki67/doublecortin positive cells increased in CEGI-treated rats compared with untreated rats. Our results suggest that CEGI has an effective neuroprotective effect on ischemic stroke when administered after the time window of thrombolysis. The study was approved by the Animal Ethics Committee of The Third Military Medical University, China.

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.

LRP-1 functionalized polymersomes enhance the efficacy of carnosine in experimental stroke

Stroke is one of the commonest causes of death with limited treatment options. L-Carnosine has shown great promise as a neuroprotective agent in experimental stroke, but translation to the clinic is impeded by the large doses needed. We developed and evaluated the therapeutic potential of a novel delivery vehicle which encapsulated carnosine in lipoprotein receptor related protein-1 (LRP-1)-targeted functionalized polymersomes in experimental ischemic stroke. We found that following ischemic stroke, polymersomes encapsulating carnosine exhibited remarkable neuroprotective effects with a dose of carnosine 3 orders of magnitude lower than free carnosine. The LRP-1-targeted functionalization was essential for delivery of carnosine to the brain, as non-targeted carnosine polymersomes did not exhibit neuroprotection. Using Cy3 fluorescence in vivo imaging, we showed that unlike non-targeted carnosine polymersomes, LRP-1-targeted carriers accumulated in brain in a time dependent manner. Our findings suggest that these novel carriers have the ability to deliver neuroprotective cargo effectively to the brain.

Strategy for the Biosynthesis of Short Oligopeptides: Green and Sustainable Chemistry

Short oligopeptides are some of the most promising and functionally important amide bond-containing components, with widespread applications. Biosynthesis of these oligopeptides may potentially become the ultimate strategy because it has better cost efficiency and environmental-friendliness than conventional solid phase peptide synthesis and chemo-enzymatic synthesis. To successfully apply this strategy for the biosynthesis of structurally diverse amide bond-containing components, the identification and selection of specific biocatalysts is extremely important. Given that perspective, this review focuses on the current knowledge about the typical enzymes that might be potentially used for the synthesis of short oligopeptides. Moreover, novel enzymatic methods of producing desired peptides via metabolic engineering are highlighted. It is believed that this review will be helpful for technological innovation in the production of desired peptides.

The Potential of Carnosine in Brain-Related Disorders: A Comprehensive Review of Current Evidence

Neurological, neurodegenerative, and psychiatric disorders represent a serious burden because of their increasing prevalence, risk of disability, and the lack of effective causal/disease-modifying treatments. There is a growing body of evidence indicating potentially favourable effects of carnosine, which is an over-the-counter food supplement, in peripheral tissues. Although most studies to date have focused on the role of carnosine in metabolic and cardiovascular disorders, the physiological presence of this di-peptide and its analogues in the brain together with their ability to cross the blood-brain barrier as well as evidence from in vitro, animal, and human studies suggest carnosine as a promising therapeutic target in brain disorders. In this review, we aim to provide a comprehensive overview of the role of carnosine in neurological, neurodevelopmental, neurodegenerative, and psychiatric disorders, summarizing current evidence from cell, animal, and human cross-sectional, longitudinal studies, and randomized controlled trials.

The Role of Mast Cells in Stroke

Mast cells (MCs) are densely granulated perivascular resident cells of hematopoietic origin. Through the release of preformed mediators stored in their granules and newly synthesized molecules, they are able to initiate, modulate, and prolong the immune response upon activation. Their presence in the central nervous system (CNS) has been documented for more than a century. Over the years, MCs have been associated with various neuroinflammatory conditions of CNS, including stroke. They can exacerbate CNS damage in models of ischemic and hemorrhagic stroke by amplifying the inflammatory responses and promoting brain–blood barrier disruption, brain edema, extravasation, and hemorrhage. Here, we review the role of these peculiar cells in the pathophysiology of stroke, in both immature and adult brain. Further, we discuss the role of MCs as potential targets for the treatment of stroke and the compounds potentially active as MCs modulators.

[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.

Effects of different interventions on animal models of ischemic stroke: Protocol for an overview and a network meta-analysis

BACKGROUND

Ischemic stroke often leads to lifelong disability or death in stroke patients. It is one of the most common causes of death and disability worldwide, so it is a global health problem. The objective of this protocol is to provide the methods for using overview and network meta-analysis to identify the more effective intervention for infarct volume and neurobehavioral score in animal models of ischemic stroke.

METHODS

A systematic literature search will be conducted in PubMed and Embase to obtain relevant systematic reviews on December 11, 2018. Assessing the Methodological Quality of Systematic Reviews (AMSTAR2) and SYRCLE's risk of bias tool will be used to assess quality of the included reviews and risk of bias of randomized controlled trials (RCTs) for animal studies. Infarct volume and neurobehavioral score will be chosen as primary and secondary outcomes. The relative effect size of the treatment will be calculated using the standardized mean difference (SMD) and 95% confidence interval (CI). R 3.5.1 through the GEMTC package will be used to perform a network meta-analysis to synthesize direct and indirect evidence.

RESULTS

The results of this paper will be submitted to a peer-reviewed journal for publication.

CONCLUSION

Our study can provide a reference for further clinical practice and can be compared with clinical trial results to obtain a more credible therapeutic effect of this intervention.

ETHICS AND COMMUNICATION

Formal ethical approval is unnecessary, because this study is based on published researches.

PROSPERO REGISTRATION NUMBER

CRD42019126811.

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.

Oxidative Status in Different Areas of the Cerebral Cortex of Wistar Rats during Focal Ischemia and Its Modulation with Carnosine

Oxidative status was assessed in different areas of the cerebral cortex of male Wistar rats under normal condition and during permanent 24-h focal ischemia. In intact animals, the level of lipid hydroperoxides in the frontal lobes of both hemispheres was by 36% higher than in other cortical areas, while total antioxidant activity was by 25% higher than in other areas. During ischemia, changes in oxidative status were localized only in the ischemic focus and penumbra zone and did not involve other cortical areas. We demonstrated for the first time a neuroprotective effect of therapeutic administration of carnosine in low doses (50 mg/kg) on parameters of the oxidative status under conditions of focal ischemia comparable to its effect of high doses (500 mg/kg) as well as its local effect in the penumbra zone. A dose-dependent effect of carnosine on antioxidant activity in the penumbra zone during ischemia was also demonstrated. These findings confirm effectiveness of not only preventive carnosine administration, but also its application in the postischemic period of the stroke.

His-Leu, an angiotensin I-derived peptide, does not affect haemodynamics in rats

INTRODUCTION:

The dipeptide histidine-leucine (His-Leu) is formed in the process of converting angiotensin I into angiotensin II. Several studies show that short peptides containing His-Leu may produce significant haemodynamic effects; however, to the best of our knowledge, data on haemodynamic effects of His-Leu are not available in medical databases.

MATERIALS AND METHODS:

We evaluated acute haemodynamic effects of intravenous administration of either 0.9% NaCl (vehicle) or His-Leu at a dose of 3-15 mg/kg body weight in anaesthetized 15-16-week-old, male, normotensive Wistar Kyoto and spontaneously hypertensive rats. Chronic effects of treatment with either the vehicle or His-Leu at a dose of 15 mg/kg body weight given subcutaneously daily were determined during continuous telemetry recordings in freely moving rats.

RESULTS:

In anaesthetized rats both the vehicle and His-Leu produced a mild and transient increase in blood pressure and no change in plasma renin activity. There was no significant difference in haemodynamics between the rats infused with the vehicle and the rats infused with His-Leu. In chronic studies, seven-day treatment with vehicle and with His-Leu did not affect arterial blood pressure in freely moving rats.

CONCLUSION:

His-Leu does not produce either acute or chronic changes in arterial blood pressure in normotensive and hypertensive rats.

Protective effect of carnosine on white matter damage in corpus striatum induced by chronic cerebral hypoperfusion

Subcortical ischemic vascular dementia caused by chronic cerebral hypoperfusion due to small-artery disease is a common subtype of vascular dementia, which is recognized as the second most prevalent type of dementia. The aim of this study was to determine the effect of carnosine on white matter damage in corpus striatum. Adult male mice (C57BL/6 strain) were subjected to right unilateral common carotid arteries occlusion (rUCCAO), and treated with carnosine or saline. Klüver-Barrera staining, immunohistochemical analyses, Western blots and neurochemical analysis were performed after rUCCAO. The white matter in corpus striatum was damaged at day 37 after rUCCAO, which was largely rescued by carnosine (200, 500 mg/kg). Carnosine (200, 500 mg/kg) significantly recovered the expression of myelin basic protein, suppressed the activation of microglia and reversed the decrease of 5-hydroxytryptamine and dopamine levels in corpus striatum. Moreover, carnosine (200, 500 mg/kg) significantly inhibited the apoptosis in corpus striatum. These data suggest that carnosine has the neuroprotective effect in corpus striatum on rUCCAO in mice, may be due to its protection of neurotransmitters and inhibition of apoptosis.

Zinc, Carnosine, and Neurodegenerative Diseases

Zinc (Zn) is abundantly present in the brain, and accumulates in the synaptic vesicles. Synaptic Zn is released with neuronal excitation, and plays essential roles in learning and memory. Increasing evidence suggests that the disruption of Zn homeostasis is involved in various neurodegenerative diseases including Alzheimer's disease, a vascular type of dementia, and prion diseases. Our and other numerous studies suggest that carnosine (β-alanyl histidine) is protective against these neurodegenerative diseases. Carnosine is an endogenous dipeptide abundantly present in the skeletal muscles and in the brain, and has numerous beneficial effects such as antioxidant, metal chelating, anti-crosslinking, and anti-glycation activities. The complex of carnosine and Zn, termed polaprezinc, is widely used for Zn supplementation therapy and for the treatment of ulcers. Here, we review the link between Zn and these neurodegenerative diseases, and focus on the neuroprotective effects of carnosine. We also discuss the carnosine level in various foodstuffs and beneficial effects of dietary supplementation of carnosine.

Alpha-7 Nicotinic Receptor Signaling Pathway Participates in the Neurogenesis Induced by ChAT-Positive Neurons in the Subventricular Zone

Choline acetyltransferase-positive (ChAT+) neurons within the subventricular zone (SVZ) have been shown to promote neurogenesis after stroke in mice by secreting acetylcholine (ACh); however, the mechanisms remain unclear. Receptors known to bind ACh include the nicotinic ACh receptors (nAChRs), which are present in the SVZ and have been shown to be important for cell proliferation, differentiation, and survival. In this study, we investigated the neurogenic role of the alpha-7 nAChR (α7 nAChR) in a mouse model of middle cerebral artery occlusion (MCAO) by using α7 nAChR inhibitor methyllycaconitine. Mice subjected to MCAO exhibited elevated expression of cytomembrane and nuclear fibroblast growth factor receptor 1 (FGFR1), as well as increased expression of PI3K, pAkt, doublecortin (DCX), polysialylated - neuronal cell adhesion molecule (PSA-NCAM), and mammalian achaete-scute homolog 1 (Mash1). MCAO mice also had more glial fibrillary acidic protein (GFAP)/5-bromo-2'-deoxyuridine (BrdU)-positive cells and DCX-positive cells in the SVZ than did the sham-operated group. Methyllycaconitine treatment increased cytomembrane FGFR1 expression and GFAP/BrdU-positive cells, upregulated the levels of phosphoinositide 3-kinase (PI3K) and phospho-Akt (pAkt), decreased nuclear FGFR1 expression, decreased the number of DCX-positive cells, and reduced the levels of DCX, PSA-NCAM, and Mash1 in the SVZ of MCAO mice compared with levels in vehicle-treated MCAO mice. MCAO mice treated with α7 nAChR agonist PNU-282987 exhibited the opposite effects. Our data show that α7 nAChR may decrease the proliferation of neural stem cells and promote differentiation of existing neural stem cells after stroke. These results identify a new mechanism of SVZ ChAT+ neuron-induced neurogenesis.

Reactive Carbonyl Species Scavengers-Novel Therapeutic Approaches for Chronic Diseases

PURPOSE OF THE REVIEW

To summarize recent evidence supporting the use of reactive carbonyl species scavengers in the prevention and treatment of disease.

RECENT FINDINGS

The newly developed 2-aminomethylphenol class of scavengers shows great promise in preclinical trials for a number of diverse conditions including neurodegenerative diseases and cardiovascular disease. In addition, new studies with the thiol-based and imidazole-based scavengers have found new applications outside of adjunctive therapy for chemotherapeutics.

SUMMARY

Reactive oxygen species (ROS) generated by cells and tissues act as signaling molecules and as cytotoxic agents to defend against pathogens, but ROS also cause collateral damage to vital cellular components. The polyunsaturated fatty acyl chains of phospholipids in the cell membranes are particularly vulnerable to damaging peroxidation by ROS. Evidence suggests that the breakdown of these peroxidized lipids to reactive carbonyls species plays a critical role in many chronic diseases. Antioxidants that abrogate ROS-induced formation of reactive carbonyl species also abrogate normal ROS signaling and thus exert both beneficial and adverse functional effects. The use of scavengers of reactive dicarbonyl species represent an alternative therapeutic strategy to potentially mitigate the adverse effects of ROS without abrogating normal signaling by ROS. In this review, we focus on three classes of reactive carbonyl species scavengers: thiol-based scavengers (2-mercaptoethanesulfonate and amifostine), imidazole-based scavengers (carnosine and its analogs), and 2-aminomethylphenols-based scavengers (pyridoxamine, 2-hydroxybenzylamine, and 5'-O-pentyl-pyridoxamine) that are either undergoing pre-clinical studies, advancing to clinical trials, or are already in clinical use.

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.