Inhibition of complex I-III activity of brain mitochondria after intracerebroventricular administration of streptozotocin in rats is possibly related to loss of body weight

Memantine/Rosuvastatin Therapy Abrogates Cognitive and Hippocampal Injury in an Experimental Model of Alzheimer's Disease in Rats: Role of TGF-β1/Smad Signaling Pathway and Amyloid-β Clearance

Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder of complex pathogenesis and multiple interacting signaling pathways where amyloidal-β protein (Aβ) clearance plays a crucial role in cognitive decline. Herein, the current study investigated the possible modulatory effects of memantine/ rosuvastatin therapy on TGF-β1/p-Smad/p21 signaling pathway and their correlation to the blood brain barrier transporters involved in Aβ-clearance and microRNAs as a novel molecular mechanism in AD treatment. AD was induced by a single intracerebroventricular streptozotocin injection (ICV-STZ, 3 mg/kg) in rats and drug therapy was continued for 28 days after AD induction. Efficacy was monitored by applying a battery of behavioral assessments, as well as biochemical, histopathological, molecular and gene expression techniques. The upregulated TGF-β1-signaling in the untreated rats was found to be highly correlated to transporters and microRNAs governing Aβ-efflux; ABCA1/miRNA-26 and LRP1/miRNA-205 expressions, rather than RAGE/miRNA-185 controlling Aβ-influx; an effect that was opposed by the tested drugs and was found to be correlated with the abolished TGF-β1-signaling as well. Combined memantine/rosuvastatin therapy ameliorated the STZ evoked decreases in escape latency and number of crossovers in the Morris water maze test, % spontaneous alternation in the Y-maze test, and discrimination and recognition indices in the object recognition test. The evoked behavioral responses were directly related to the β-amyloid accumulation and the alteration in its clearance. Additionally, drug treatment increased brain glutathione and decreased malondialdehyde levels. These findings were histopathologically confirmed by a marked reduction of gliosis and restoration of neuronal integrity in the CA1 region of the hippocampus of the AD rats. These findings implicated that the memantine/rosuvastatin combination could offer a new therapeutic potential for AD management by abrogating the TGF-β1/p-Smad2/p21 pathway and regulating Aβ-clearance.

Protective effects of cyclosporine A on neurodegeneration and motor impairment in rotenone-induced experimental models of Parkinson's disease

The development of neuroprotective drugs targeting mitochondria could be an important strategy in combating the progressive clinical course of Parkinson's disease. In the current study, we demonstrated that in SH-SY5Y cells (human dopaminergic neuroblastoma cell line), rotenone caused a dose-dependent (0.25-1 μM) and time-dependent (up to 48 h) loss of cell viability and a loss of cellular ATP content with mitochondrial membrane depolarization and an increased formation of reactive oxygen species; all these processes were markedly prevented by the mitochondrial permeability transition pore blocker cyclosporine A, which did not affect complex I inhibition by rotenone. The nuclear morphology of rotenone-treated cells for 48 h indicated the presence of both necrosis and apoptosis. We then examined the effects of cyclosporine A on the rotenone-induced model of Parkinson's disease in Wistar rats. Cyclosporine A significantly improved the motor deficits and prevented the loss of nigral dopaminergic neurons projecting into the striatum in rotenone-treated rats. Being a marketed immuno-suppressive drug, cyclosporine A should be further evaluated for its putative neuroprotective action in Parkinson's disease.

Cannabidiol Treatment Improves Glucose Metabolism and Memory in Streptozotocin-Induced Alzheimer’s Disease Rat Model: A Proof-of-Concept Study

An early and persistent sign of Alzheimer’s disease (AD) is glucose hypometabolism, which can be evaluated by positron emission tomography (PET) with ¹⁸F-2-fluoro-2-deoxy-D-glucose ([¹⁸F]FDG). Cannabidiol has demonstrated neuroprotective and anti-inflammatory properties but has not been evaluated by PET imaging in an AD model. Intracerebroventricular (icv) injection of streptozotocin (STZ) is a validated model for hypometabolism observed in AD. This proof-of-concept study evaluated the effect of cannabidiol treatment in the brain glucose metabolism of an icv-STZ AD model by PET imaging. Wistar male rats received 3 mg/kg of STZ and [¹⁸F]FDG PET images were acquired before and 7 days after STZ injection. Animals were treated with intraperitoneal cannabidiol (20 mg/kg—STZ–cannabidiol) or saline (STZ–saline) for one week. Novel object recognition was performed to evaluate short-term and long-term memory. [¹⁸F]FDG uptake in the whole brain was significantly lower in the STZ–saline group. Voxel-based analysis revealed a hypometabolism cluster close to the lateral ventricle, which was smaller in STZ–cannabidiol animals. The brain regions with more evident hypometabolism were the striatum, motor cortex, hippocampus, and thalamus, which was not observed in STZ–cannabidiol animals. In addition, STZ–cannabidiol animals revealed no changes in memory index. Thus, this study suggests that cannabidiol could be an early treatment for the neurodegenerative process observed in AD.

Alterations in tanycytes and related cell populations of arcuate nucleus in streptozotocin-induced Alzheimer disease model

It is assumed that dysfunction of tanycytes could be one of the components of pathogenesis of both Alzheimer disease and type 2 diabetes mellitus. The study was aimed to assess alterations in the tanycyte morphology in the Alzheimer disease model. The 3 mg/kg streptozotocin dose was injected in the lateral ventricles of Wistar rats in order to model the Alzheimer disease. Alterations in hypothalamic tanycytes were assessed 2 weeks, 4 weeks, 3 months and 6 months after administration of the toxin. Immunohistochemistry was used to identify the protein markers of tanycytes (vimentin, nestin), astrocytes (GFAP, glutamine synthetase) and neurons (HuC/D), as well as to assess cell proliferation (with the use of Ki67 protein) and mitochondrial alterations (mitochondrial complex IV, PGC1a). Administration of streptozotocin lead to β-amyloid accumulation in hypothalamus and ventricular enlargement (p < 0.001). Streptozotocin damaged both α1/α2 tanycytes and β1 tanycytes. The intensity of vimentin staining in α1/α2 tanycytes decreased by week 4 (p = 0.003), and in β1 tanycytes it decreased in three months (p < 0.001). The same trend was observed for nestin. The number of Ki67+ nuclei decreased (p < 0.05), and the expression of proteins associated with mitochondria changed. The density of hypothalamic tanycytes decreased by week 4 after administration of the toxin. Moreover, astrocyte activation was revealed. However, no prominent damage to both astrocytes and neurons was observed within four weeks after administration of streptozotocin. The revealed high tanycyte vulnerability to streptozotocin is in line with the hypothesis of the role of damage to hypothalamic structures in both local and systemic metabolic disorders occurring in the Alzheimer disease models.

Protective Effect of Biobran/MGN-3 against Sporadic Alzheimer's Disease Mouse Model: Possible Role of Oxidative Stress and Apoptotic Pathways

Alzheimer's disease (AD) is a debilitating and irreversible brain disease that affects an increasing number of aged individuals, mandating the development of protective nutraceuticals. Biobran/MGN-3, an arabinoxylan from rice bran, has potent antioxidant, antiaging, and immunomodulatory effects. The aim of the present study was to investigate the protective effect of Biobran against sporadic Alzheimer's disease (SAD). SAD was induced in mice via intracerebroventricular injection of streptozotocin (STZ) (3 mg/kg). STZ-treated mice were administered with Biobran for 21 days. The effects of Biobran on memory and learning were measured via the Morris water maze, novel object recognition, and Y-maze tests. Biomarkers for apoptosis, oxidative stress, and amyloidogenesis were measured using ELISA and western blot analysis. Histopathological examination was performed to confirm neuronal damage and amyloid-beta deposition. Biobran reversed the spatial memory deficit in SAD-induced mice, and it increased the expression of glutathione, reduced malondialdehyde, decreased IL-6, decreased intercellular adhesion molecule-1 (ICAM-1), and significantly increased nuclear factor erythroid 2-related factor 2 (Nrf2) and antioxidant response element (ARE). Moreover, Biobran exerted a protective effect against amyloid-beta-induced apoptosis via the suppression of both cleaved caspase-3 and the proapoptotic protein Bax and via the upregulation of the antiapoptotic protein Bcl-2. Furthermore, it reduced the expression of forkhead box class O proteins. It could be concluded from this study that Biobran may be a useful nutritional antioxidant agent for protection against SAD through its activation of the gene expression of Nrf2/ARE, which in turn modulates the apoptotic and amyloidogenic pathways.

Naturally Inspired Pyrimidines Analogues for Alzheimer's Disease

Alzheimer's disease (AD) is a multifarious and developing neurodegenerative disorder. The treatment of AD is still a challenge and availability of drug therapy on the basis of symptoms is not up to the mark. In the context of existence, which is getting worse for the human brain, it is necessary to take care of all critical measures. The disease is caused due to multidirectional pathology of the body, which demands the multi-target-directed ligand (MTDL) approach. This gives hope for new drugs for AD, summarized here in with the pyrimidine based natural product inspired molecule as a lead. The review is sufficient in providing a list of chemical ingredients of the plant to cure AD and screen them against various potential targets of AD. The synthesis of a highly functionalized scaffold in one step in a single pot without isolating the intermediate is a challenging task. In few examples, we have highlighted the importance of this kind of reaction, generally known as multi-component reaction. Multi-component is a widely accepted technique by the drug discovery people due to its high atom economy. It reduces multi-step process to a one-step process, therefore the compounds library can be made in minimum time and cost. This review has highlighted the importance of multicomponent reactions by giving the example of active scaffolds of pyrimidine/fused pyrimidines. This would bring importance to the fast as well as smart synthesis of bio-relevant molecules.