Neuroprotective properties of l-carnosine in the brain slices exposed to autoblood in the hemorrhagic stroke model in vitro

Comparative Cerebroprotective Potential of d- and l-Carnosine Following Ischemic Stroke in Mice

l-carnosine is an attractive therapeutic agent for acute ischemic stroke based on its robust preclinical cerebroprotective properties and wide therapeutic time window. However, large doses are needed for efficacy because carnosine is rapidly degraded in serum by carnosinases. The need for large doses could be particularly problematic when translating to human studies, as humans have much higher levels of serum carnosinases. We hypothesized that d-carnosine, which is not a substrate for carnosinases, may have a better pharmacological profile and may be more efficacious at lower doses than l-carnosine. To test our hypothesis, we explored the comparative pharmacokinetics and neuroprotective properties of d- and L-carnosine in acute ischaemic stroke in mice. We initially investigated the pharmacokinetics of d- and L-carnosine in serum and brain after intravenous (IV) injection in mice. We then investigated the comparative efficacy of d- and l-carnosine in a mouse model of transient focal cerebral ischemia followed by in vitro testing against excitotoxicity and free radical generation using primary neuronal cultures. The pharmacokinetics of d- and l-carnosine were similar in serum and brain after IV injection in mice. Both d- and l-carnosine exhibited similar efficacy against mouse focal cerebral ischemia. In vitro studies in neurons showed protection against excitotoxicity and the accumulation of free radicals. d- and l-carnosine exhibit similar pharmacokinetics and have similar efficacy against experimental stroke in mice. Since humans have far higher levels of carnosinases, d-carnosine may have more favorable pharmacokinetics in future human studies.

Carnosine and L-arginine attenuate the downregulation of brain monoamines and gamma aminobutyric acid; reverse apoptosis and upregulate the expression of angiogenic factors in a model of hemic hypoxia in rats

PURPOSE

The purpose of the present study was to investigate the preventive effect of L-arginine (ARG) and carnosine (CAR) on hypoxia-induced neurotoxicity in rats. The impact on neuro-inflammation, apoptosis, angiogenesis, and the brain levels of monoamines and GABA were investigated.

METHODS

Rats were divided into the following: normal control, hypoxia model induced by sodium nitrite (75 mg/kg s.c), and hypoxic rats pre-treated with CAR (250 mg/kg), ARG (200 mg/kg), and their combination.

RESULTS

Data revealed that hypoxia induced significant elevation of hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and its receptor reflecting the stimulation of angiogenesis. Hypoxia also resulted in increased inflammatory mediators-including nuclear factor kappa B (NF-κB), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). In addition, hypoxia initiates cerebral apoptosis as revealed by increased caspase-3 and BAX with reduced Bcl-2. These changes were associated with reduced brain levels of GABA and monoamines including noradrenaline (NADR), dopamine (DOP), and serotonin (SER). Pre-treatment with ARG and/or CAR significantly mitigated the neural changes induced by hypoxia and attenuated the elevated levels of NF-κB, TNF-α, IL-6, caspase-3, and BAX, while ameliorated the reduced levels of Bcl-2, NADR, DOP, SER, and GABA, with the best improvement observed with the combination. Further elevation of the angiogenic markers was observed indicating their role in boosting oxygen delivery to brain.

CONCLUSION

CAR, ARG, and, importantly, their combination could effectively protect against hypoxia-induced neurotoxicity, via their angiogenic, anti-inflammatory, and anti-apoptotic properties in addition to reversing the effect on GABA and monoamines.

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.

Mystixin-7 Peptide Protects Ionotropic Glutamatergic Mechanisms against Glutamate-Induced Excitotoxicity In Vitro

Hyperactivation of the N-methyl-D-aspartic acid type glutamate receptors (NMDARs) causes glutamate excitotoxicity, a process potentially important for many neurological diseases. This study aims to investigate protective effects of the synthetic corticotrophin-releasing factor-like peptide, mystixin-7 (MTX), on model glutamate-induced excitotoxicity in vitro. The technique online monitoring of electrophysiological parameters (excitatory glutamatergic alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic (AMPAR) and NMDAR-dependent postsynaptic mechanisms) in the olfactory cortex slices was used. Application of L-glutamate in toxic concentration (20 mM) on slices evoked hyperactivation of NMDARs and weaker activation of the AMPARs. Upon further action agonist, the excessive activation of glutamate receptors was replaced by their irreversible blockade. Pretreatment of the slices using MTX in different concentrations (50 and 100 mg/mL) protected both NMDARs and AMPARs from glutamate-induced damage. An enzymatic treatment of MTX reduced hyperactivation of both NMDARs and AMPARs. The present study demonstrated that MTX minipeptide protected the functioning of both NMDARs and AMPARs against glutamate-induced damage. The MTX peptide is a prospective candidate for elaborated medication in treatment of neurological diseases.