Role of anti-diabetic drugs as therapeutic agents in Alzheimer's disease

Exploring the Potential of Antidiabetic Agents as Therapeutic Approaches for Alzheimer's and Parkinson's Diseases: A Comprehensive Review

Alzheimer's and Parkinson's are two prevalent neurodegenerative disorders with significant societal and healthcare burdens. The search for effective therapeutic approaches to combat these diseases has led to growing interest in exploring the potential of antidiabetic agents. This comprehensive review aims to provide a detailed overview of the current literature on using antidiabetic agents as therapeutic interventions for Alzheimer's and Parkinson's diseases. We discuss the underlying pathological mechanisms of these neurodegenerative diseases, including protein misfolding, inflammation, oxidative stress, and mitochondrial dysfunction. We then delve into the potential mechanisms by which antidiabetic agents may exert neuroprotective effects, including regulation of glucose metabolism and insulin signaling, anti-inflammatory effects, modulation of oxidative stress, and improvement of mitochondrial function and bioenergetics. We highlight in vitro, animal, and clinical studies that support the potential benefits of antidiabetic agents in reducing disease pathology and improving clinical outcomes. However, we also acknowledge these agents' limitations, variability in treatment response, and potential side effects. Furthermore, we explore emerging therapeutic targets and novel approaches, such as glucagon-like peptide-1 receptor (GLP-1R) agonists, insulin sensitizer drugs, neuroinflammation-targeted therapies, and precision medicine approaches. The review concludes by emphasizing the need for further research, including large-scale clinical trials, to validate the efficacy and safety of antidiabetic agents in treating Alzheimer's and Parkinson's disease. The collaboration between researchers, clinicians, and pharmaceutical companies is essential in advancing the field and effectively treating patients affected by these debilitating neurodegenerative disorders.

Rosiglitazone Ameliorates Cardiac and Skeletal Muscle Dysfunction by Correction of Energetics in Huntington’s Disease

Huntington’s disease (HD) is a rare neurodegenerative disease that is accompanied by skeletal muscle atrophy and cardiomyopathy. Tissues affected by HD (central nervous system [CNS], skeletal muscle, and heart) are known to suffer from deteriorated cellular energy metabolism that manifests already at presymptomatic stages. This work aimed to test the effects of peroxisome proliferator-activated receptor (PPAR)-γ agonist—rosiglitazone on grip strength and heart function in an experimental HD model—on R6/1 mice and to address the mechanisms. We noted that rosiglitazone treatment lead to improvement of R6/1 mice grip strength and cardiac mechanical function. It was accompanied by an enhancement of the total adenine nucleotides pool, increased glucose oxidation, changes in mitochondrial number (indicated as increased citric synthase activity), and reduction in mitochondrial complex I activity. These metabolic changes were supported by increased total antioxidant status in HD mice injected with rosiglitazone. Correction of energy deficits with rosiglitazone was further indicated by decreased accumulation of nucleotide catabolites in HD mice serum. Thus, rosiglitazone treatment may not only delay neurodegeneration but also may ameliorate cardio- and myopathy linked to HD by improvement of cellular energetics.

Glimepiride mitigates tauopathy and neuroinflammation in P301S transgenic mice: role of AKT/GSK3β signaling

BACKGROUND AND OBJECTIVE

Tauopathy is a group of neurodegenerative diseases in which the pathogenesis processes are related to tau protein. The imbalances between the activities of kinases and phosphatases of tau protein lead to tau hyperphosphorylation and subsequent neurodegeneration. Numerous studies suggest a strong linkage between type 2 diabetes mellitus (T2D) and neurodegenerative diseases. Therefore, finding a drug with a dual therapeutic activity against T2D and neuroprotective will be a promising idea. Hence, the potential neuroprotective effect of Glimepiride (GPD) against tauopathy was evaluated in the current study.

METHODS

P301S mice model was employed for tauopathy and C57BL/6 wild type mice (WT) was used as control. Phosphorylated and acetylated tau protein levels was assessed in cortex and hippocampus by western blot. Effect of GPD on tauopathy related enzymes, neuroinflammation, apoptotic markers were evaluated. Furthermore, the neuroprotective effects against anxiety like behavior and motor impairment was analyzed using Parallel rod floor and Open field tests.

RESULTS

GPD significantly ameliorates motor impairment, anxiety like behavior and neurodegeneration in P301S mice. Phosphorylated tau and acetylated tau were significantly decreased in both cortex and hippocampus of P301S mice via decreasing GSK3β, increasing ratio of phosphorylated-AKT to total-AKT, increasing PP2A and normalization of CDK5 levels. Furthermore, GPD treatment also decreased neuroinflammation and apoptosis by reducing NF-kB, TNF-α and caspase 3 levels.

CONCLUSION

The current data suggests that GPD exerts a protective effect against tauopathy, behavioural consequences, neurodegeneration, neuroinflammation and apoptosis. GPD is therefore a promising agent for the treatment of neurodegenerative diseases associated with tauopathy.

MicroRNA-29b Modulates β-Secretase Activity in SH-SY5Y Cell Line and Diabetic Mouse Brain

Hyperglycemia is one of the major risk factors responsible for memory impairment in diabetes which may lead to Alzheimer's disease (AD) at a later stage. MicroRNAs are a class of non-coding RNAs that are found to play a role in diabetes. Downregulation of microRNA-29b in diabetes is well reported. Moreover, microRNA-29b is also reported to target the 3' UTR of β-secretase (BACE-1) enzyme which is involved in the formation of amyloid-beta (Aβ) in AD via cleavage of amyloid precursor protein (APP). Therefore, the present study was designed to elucidate whether microRNA-29b could be a link between diabetes and dementia. In the in vitro and in vivo diabetic model, we found downregulation of microRNA-29b due to hyperglycemia. After human microRNA-29b treatment, there was a significant improvement in the short-term and spatial memory in diabetic mice. Also, the human microRNA-29b treatment decreased oxidative stress and BACE-1 activity in diabetes. The present findings revealed that the downregulation of microRNA-29b in diabetes could be associated with memory impairment and increased BACE-1 activity. These results would give a future direction to study the role played by microRNAs in diabetes-associated memory impairment and hence aid in the development of therapeutics to treat the same.

Sleep Disorders Associated With Alzheimer's Disease: A Perspective

Sleep disturbances, as well as sleep-wake rhythm disturbances, are typical symptoms of Alzheimer's disease (AD) that may precede the other clinical signs of this neurodegenerative disease. Here, we describe clinical features of sleep disorders in AD and the relation between sleep disorders and both cognitive impairment and poor prognosis of the disease. There are difficulties of the diagnosis of sleep disorders based on sleep questionnaires, polysomnography or actigraphy in the AD patients. Typical disturbances of the neurophysiological sleep architecture in the course of the AD include deep sleep and paradoxical sleep deprivation. Among sleep disorders occurring in patients with AD, the most frequent disorders are sleep breathing disorders and restless legs syndrome. Sleep disorders may influence circadian fluctuations of the concentrations of amyloid-β in the interstitial brain fluid and in the cerebrovascular fluid related to the glymphatic brain system and production of the amyloid-β. There is accumulating evidence suggesting that disordered sleep contributes to cognitive decline and the development of AD pathology. In this mini-review, we highlight and discuss the association between sleep disorders and AD.

Exosomes as Carriers of Alzheimer's Amyloid-ß

The intracerebral level of the aggregation-prone peptide, amyloid-ß (Aß), is constantly maintained by multiple clearance mechanisms, including several degradation enzymes, and brain efflux. Disruption of the clearance machinery and the resultant Aß accumulation gives rise to neurotoxic assemblies, leading to the pathogenesis of Alzheimer's disease (AD). In addition to the classic mechanisms of Aß clearance, the protein may be processed by secreted vesicles, although this possibility has not been extensively investigated. We showed that neuronal exosomes, a subtype of extracellular nanovesicles, enwrap, or trap Aß and transport it into microglia for degradation. Here, we review Aß sequestration and elimination by exosomes, and discuss how this clearance machinery might contribute to AD pathogenesis and how it might be exploited for effective AD therapy.