Severe Hyperhomocysteinemia Decreases Creatine Kinase Activity and Causes Memory Impairment: Neuroprotective Role of Creatine

Caffeic acid protects against l-methionine induced reduction in neurogenesis and cognitive impairment in a rat model

l-methionine (L-met) is a substantial non-polar amino acid for normal development. L-met is converted to homocysteine that leads to hyperhomocysteinemia and subsequent excessive homocysteine in serum resulting in stimulating oxidative stress and vascular dementia. Several studies have found that hyperhomocysteine causes neuronal cell damage, which leads to memory impairment. Caffeic acid is a substrate in phenolic compound discovered in plant biosynthesis. Caffeic acid contains biological antioxidant and neuroprotective properties. The neuroprotective reaction of caffeic acid can protect against the brain disruption from hydrogen peroxide produced by oxidative stress. It also enhances GSH and superoxide dismutase activities, which protect against neuron cell loss caused by oxidative stress in the hippocampus. Hence, we investigated the protective role of caffeic acid in hippocampal neurogenesis and cognitive impairment induced by L-met in rats. Six groups of Sprague Dawley rats were assigned including control, L-met (1.7 g/kg/day), caffeic acid (20, 40 mg/kg), and L-met + caffeic acid (20, 40 mg/kg) groups. Spatial and recognition memories were subsequently examined using novel object location (NOL) and novel object recognition (NOR) tests. Moreover, the immunofluorescence technique was performed to detect Ki-67/RECA-1, bromodeoxyuridine (BrdU)/NeuN and p21 markers to represent hippocampal neurogenesis changes. The results revealed decreases in vasculature related cell proliferation and neuronal cell survival. By contrast, cell cycle arrest was increased in the L-met group. These results showed the association of the spatial and recognition memory impairments. However, the deterioration can be restored by co-administration with caffeic acid.

The potential role of creatine supplementation in neurodegenerative diseases

PURPOSE

The maintenance of energy balance in the body, especially in energy-demanding tissues like the muscles and the central nervous system, depends on creatine (Cr). In addition to improving muscle function, Cr is necessary for the bioenergetics of the central nervous system because it replenishes adenosine triphosphate without needing oxygen. Furthermore, Cr possesses anti-oxidant, anti-apoptotic, and anti-excitotoxic properties. Clinical research on neurodegenerative illnesses has shown that Cr supplementation results in less effective outcomes. With a brief update on the possible role of Cr in human, animal, and in vitro experiments, this review seeks to offer insights into the ideal dosage regimen.

METHODS

Using specified search phrases, such as "creatine and neurological disorder," "creatine supplementation and neurodegenerative disorders," and "creatine and brain," we searched articles in the PubMed database and Google Scholar. We investigated the association between creatine supplementation and neurodegenerative illnesses by examining references.

RESULTS

The neuroprotective effects of Cr were observed in in vitro and animal models of certain neurodegenerative diseases, while clinical trials failed to reproduce favorable outcomes.

CONCLUSION

Determining the optimal creatinine regime for increasing brain creatinine levels is essential for maintaining brain health and treating neurodegeneration.

Comparative study of aluminum speciation on brain-type creatine kinase: Enzyme kinetic, molecular docking, cellular experiment, and mouse model study

Brain-type Creatine kinase (CK-BB), which has a high affinity for Aluminum (Al), and its abnormality is closely related to neurodegenerative diseases. In this study, the comparative effect of Al speciation on the bioactivity of CK-BB has been studied by the inhibition kinetics method, molecular docking, cellular experiment, and mouse model study. Results showed that the half-inhibitory concentration of AlCl₃ was 0.67 mM, while Al(mal)₃ was 3.81 mM. Fluorescence spectra showed that Al(mal)₃ had a more substantial effect on the endogenous fluorescence of CK-BB than AlCl₃. Molecular docking showed that AlCl₃ was closer to the active site of CK-BB. C6 cells were used to explore the enzyme activity and intracellular distribution of CK-BB by AlCl₃ or Al(mal)₃. AlCl₃ treatment may directly affect CK-BB activity and cause insufficient local ATP supply in cells which affected the formation of F-actin and cell morphology. The change in the hydrophobicity of CK-BB induced by Al(mal)₃ affected the movement of CK-BB, which subsequently activated thecytochrome C (Cyt C)/Caspase 9/Caspase 3 pathway. Similar results have been found in vivo experiments. This study demonstrated that interaction between Al and CK-BB might be related to the process of Al-induced energy metabolism disorders, in which the Al speciation revealed differentiated toxicity mechanisms.

Hyperhomocysteinemia: Metabolic Role and Animal Studies with a Focus on Cognitive Performance and Decline-A Review

Disturbances in the one-carbon metabolism are often indicated by altered levels of the endogenous amino acid homocysteine (HCys), which is additionally discussed to causally contribute to diverse pathologies. In the first part of the present review, we profoundly and critically discuss the metabolic role and pathomechanisms of HCys, as well as its potential impact on different human disorders. The use of adequate animal models can aid in unravelling the complex pathological processes underlying the role of hyperhomocysteinemia (HHCys). Therefore, in the second part, we systematically searched PubMed/Medline for animal studies regarding HHCys and focused on the potential impact on cognitive performance and decline. The majority of reviewed studies reported a significant effect of HHCys on the investigated behavioral outcomes. Despite of persistent controversial discussions about equivocal findings, especially in clinical studies, the present evaluation of preclinical evidence indicates a causal link between HHCys and cognition-related- especially dementia-like disorders, and points out the further urge for large-scale, well-designed clinical studies in order to elucidate the normalization of HCys levels as a potential preventative or therapeutic approach in human pathologies.

Chronic mild hyperhomocysteinemia induces anxiety-like symptoms, aversive memory deficits and hippocampus atrophy in adult rats: New insights into physiopathological mechanisms

In the last decade, increased homocysteine levels have been implicated as a risk factor for neurodegenerative and psychiatric disorders. We have developed an experimental model of chronic mild hyperhomocysteinemia (HHcy) in order to observe metabolic impairments in the brain of adult rodents. Besides its known effects on brain metabolism, the present study sought to investigate whether chronic mild HHcy could induce learning/memory impairments associated with biochemical and histological damage to the hippocampus. Adult male Wistar rats received daily subcutaneous injections of homocysteine (0.03 μmol/g of body weight) twice a day, from the 30th to the 60th day of life or saline solution (Controls). After injections, anxiety-like and memory tests were performed. Following behavioral analyses, brains were sliced and hippocampal volumes assessed and homogenized for redox state assessment, antioxidant activity, mitochondrial functioning (chain respiratory enzymes and ATP levels) and DNA damage analyses. Behavioral analyses showed that chronic mild HHcy may induce anxiety-like behavior and impair long-term aversive memory (24 h) that was evaluated by inhibitory avoidance task. Mild HHcy decreased locomotor and/or exploratory activities in elevated plus maze test and caused hippocampal atrophy. Decrease in cytochrome c oxidase, DNA damage and redox state changes were also observed in hippocampus of adult rats subjected to mild HHcy. Our findings show that chronic mild HHcy alters biochemical and histological parameters in the hippocampus, leading to behavioral impairments. These findings might be considered in future studies aiming to search for alternative strategies for treating the behavioral impairments in patients with mild elevations in homocysteine levels.

Creatine as a Neuroprotector: an Actor that Can Play Many Parts

Creatine is a nitrogenous organic acid that plays a central role as an energy buffer in high energy demanding systems, including the muscular and the central nervous system. It can be acquired from diet or synthesized endogenously, and its main destination is the system creatine/phosphocreatine that strengthens cellular energetics via a temporal and spatial energy buffer that can restore cellular ATP without a reliance on oxygen. This compound has been proposed to possess secondary roles, such as direct and indirect antioxidant, immunomodulatory agent, and possible neuromodulator. However, these effects may be associated with its bioenergetic role in the mitochondria. Given the fundamental roles that creatine plays in the CNS, several preclinical and clinical studies have tested the potential that creatine has to treat degenerative disorders. However, although in vitro and in vivo animal models are highly encouraging, most clinical trials fail to reproduce positive results suggesting that the prophylactic use for neuroprotection in at-risk populations or patients is the most promising field. Nonetheless, the only clearly positive data of the creatine supplementation in human beings are related to the (rare) creatine deficiency syndromes. It seems critical that future studies must establish the best dosage regime to increase brain creatine in a way that can relate to animal studies, provide new ways for creatine to reach the brain, and seek larger experimental groups with biomarkers for prediction of efficacy.

Caffeine Prevents Memory Impairment Induced by Hyperhomocysteinemia

L-Methionine chronic administration leads to impairment of memory. This impairment is due to the increase in the body oxidative stress, which damages neurons and prevents their firing. On the other hand, caffeine has antioxidant and neuroprotective effects that could prevent impairment of memory induced by L-methionine chronic administration. In the current study, this hypothesis was evaluated. L-methionine (1.7 g/kg/day) was orally administered to animals for 4 weeks and caffeine (0.3 g/L) treatment was added to the drinking water. The radial arm water maze (RAWM) was used to test spatial learning and memory. Antioxidant biomarkers were assessed in the hippocampus tissues using biochemical assay methods. Chronic L-methionine administration induced (short- and long-) term memory impairment (P < 0.05), while caffeine treatment prevented such effect. Additionally, L-methionine treatment reduced catalase and glutathione peroxidase (GPx") enzymatic activities, and reduced glutathione (GSH) to oxidized glutathione (GSSG) ratio. These effects were normalized by caffeine treatment. Activity of superoxide dismutase (SOD) was unchanged by either L-methionine or caffeine treatments. In conclusion, L-methionine induces impairment of memory, and caffeine treatment prevented this impairment probably through affecting hippocampus antioxidant mechanisms.