Molecular mechanism and potential therapeutic targets of necroptosis and ferroptosis in Alzheimer's disease.

Alzheimer's disease (AD), a neurodegenerative condition, is defined by neurofibrillary tangles, amyloid plaques, and gradual cognitive decline. Regardless of the advances in understanding AD's pathogenesis and progression, its causes are still contested, and there are currently no efficient therapies for the illness. The post-mortem analyses revealed widespread neuronal loss in multiple brain regions in AD, evidenced by a decrease in neuronal density and correlated with the disease's progression and cognitive deterioration. AD's neurodegeneration is complicated, and different types of neuronal cell death, alone or in combination, play crucial roles in this process. Recently, the involvement of non-apoptotic programmed cell death in the neurodegenerative mechanisms of AD has received a lot of attention. Aberrant activation of necroptosis and ferroptosis, two newly discovered forms of regulated non-apoptotic cell death, is thought to contribute to neuronal cell death in AD. In this review, we first address the main features of necroptosis and ferroptosis, cellular signaling cascades, and the mechanisms involved in AD pathology. Then, we discuss the latest therapies targeting necroptosis and ferroptosis in AD animal/cell models and human research to provide vital information for AD treatment.

Neuroinflammatory Response in Reward-Associated Psychostimulants and Opioids: A Review.

Substance abuse is one of the significant problems in social and public health worldwide. Vast numbers of evidence illustrate that motivational and reinforcing impacts of addictive drugs are primarily attributed to their ability to change dopamine signaling in the reward circuit. However, the roles of classic neurotransmitters, especially dopamine and neuromodulators, monoamines, and neuropeptides, in reinforcing characteristics of abused drugs have been extensively investigated. It has recently been revealed that central immune signaling includes cascades of chemokines and proinflammatory cytokines released by neurons and glia via downstream intracellular signaling pathways that play a crucial role in mediating rewarding behavioral effects of drugs. More interestingly, inflammatory responses in the central nervous system modulate the mesolimbic dopamine signaling and glutamate-dependent currents induced by addictive drugs. This review summarized researches in the alterations of inflammatory responses accompanied by rewarding and reinforcing properties of addictive drugs, including cocaine, methamphetamine, and opioids that were evaluated by conditioned place preference and self-administration procedures as highly common behavioral tests to investigate the motivational and reinforcing impacts of addictive drugs. The neuroinflammatory responses affect the rewarding properties of psychostimulants and opioids.

Intranasal interferon-beta alleviates anxiety and depressive-like behaviors by modulating microglia polarization in an Alzheimer's disease model.

Alzheimer's disease (AD) patients frequently experience neuropsychiatric symptoms (NPS), which are linked to a lower quality of life and a faster rate of disease progression. A growing body of research indicates that several microglial phenotypes control the inflammatory response and are crucial in the pathophysiology of AD-related NPS. Given the crucial role played by inflammatory mediators produced by microglia in developing of NPS, interferon-beta (IFNß), a cytokine with anti-inflammatory capabilities, maybe a successful treatment for NPS caused by AD. In this investigation, using a rat model of AD, we examined the impact of intranasal treatment of IFNß on anxious/depressive-like behavior and microglial M1/M2 polarization. The rat hippocampus was bilaterally injected with lentiviruses harboring mutant human amyloid precursor protein. Rats were given recombinant IFNß1a (68,000 IU/rat) via the intranasal route, starting on day 23 following viral infection and continuing until day 49. On days 47-49, the elevated plus maze, forced swim, and tail suspension tests were applied to measure anxiety- and depressive-like behavior. Additionally, qPCR was utilized to quantify the expression of M1 markers (CD68, CD86, and CD40) and M2 markers (Ym1, CD206, Arg1, GDNF, BDNF, and SOCS1). Our findings demonstrated that decreased M2 marker expression is accompanied by anxious/depressive-like behavior when the mutant human APP gene is overexpressed in the hippocampus. In the rat model of AD, IFNß therapy reduces anxious/depressive-like behaviors, at least in part by polarizing microglia towards M2. Therefore, IFNß may be a viable therapeutic drug for reducing NPS in the context of AD.

The impacts of anesthetic regimens on the middle cerebral artery occlusion outcomes in male rats.

The middle cerebral artery occlusion (MCAO) model was introduced more than 3 decades ago to simulate human stroke. Till now, it is the most common platform to investigate stroke-induced pathological changes as well as to discover new drugs and treatments. Induction of general anesthesia is mandatory to induce this model, and different laboratories are using various anesthetic drugs, which might affect MCAO results. Therefore, the present study was designed to compare the impacts of several widely used anesthetic regimens on the MCAO outcomes. Here, adult male rats were anesthetized by isoflurane inhalation, intraperitoneal injection of chloral hydrate (CH), intraperitoneal injection of ketamine-xylazine, or subcutaneous administration of ketamine-xylazine, then subjected to 30 min MCAO. Survival rate, body weight change, infarct size, as well as cognitive and neurological performance were evaluated up to 3 days after the surgery. Our findings revealed CH caused the highest, whereas subcutaneous ketamine-xylazine led to the lowest mortality. Meanwhile, there were no significant differences in the body weight loss, infarct size, cognitive impairments, and neurological deficits among the experimental groups. Based on the current results, we proposed that subcutaneous injection of ketamine-xylazine could be an effective anesthetic regimen in the rat model of MCAO with several advantages such as low mortality, cost-effectiveness, safety, ease of administration, and not requiring specialized equipment.

Interferon beta attenuates recognition memory impairment and improves brain glucose uptake in a rat model of Alzheimer's disease: Involvement of mitochondrial biogenesis and PI3K pathway.

Interferon beta (IFNß) is a cytokine with anti-apoptotic and anti-inflammatory properties, and its beneficial effects on Alzheimer's disease (AD) have been recently shown. The alterations in cerebral glucose uptake are closely linked to memory deficit and AD progression. The current study was designed to determine if IFNß can improve recognition memory and brain glucose uptake in a rat model of AD. The lentiviruses expressing mutant human amyloid precursor protein were injected bilaterally to the rat hippocampus. From day 23 after virus injection, rats were intranasally treated with recombinant IFNß protein (68,000 IU/rat) every other day until day 50. Recognition memory performance was evaluated by novel object recognition test on days 46-49. The 18F-2- fluoro-deoxy-d-glucose positron emission tomography (18F-FDG-PET) was used to determine changes in brain glucose metabolism on day 50. The expression of the PI3K/Akt pathway components, neurotrophins and mitochondrial biogenesis factors were also measured by qPCR in the hippocampus. Our results showed that IFNß treatment improves recognition memory performance in parallel with increased glucose uptake and neuronal survival in the hippocampus of the AD rats. The neuroprotective effect of IFNß could be attributed, at least partly, to activation of PI3K-Akt-mTOR signaling pathway, increased expression of NGF, and mitochondrial biogenesis. Taken together, our findings suggest the therapeutic potential of IFNß for AD.

Preconditioning with secretome of neural crest-derived stem cells enhanced neurotrophic expression in mesenchymal stem cells.

During the last 20 years, stem cell therapy has been considered as an effective approach for regenerative medicine. Due to poor ability of stem cells to survive following transplantation, it has been proposed that beneficial effects of stem cells mainly depend on paracrine function. Therefore, the present study was designed to reinforce mesenchymal stem cells (MSCs) to express higher levels of trophic factors especially the ones with the neurotrophic properties. Here, bone marrow (BM)-MSCs and adipose-MSCs were treated with conditioned medium (CM) of dental pulp stem cells (DPSCs) or hair follicle stem cells (HFSCs) for up to three days. The relative expression of five key trophic factors that have critical effects on the central nervous system regeneration were evaluated using qRT-PCR technique. Furthermore, to assess the impacts of conditioned mediums on the fate of MSCs, expression of seven neuronal/glial markers were evaluated 3 days after the treatments. The obtained data revealed priming of BM-MSCs with HFSC-CM or DPSC-CM increases the BDNF expression over time. Such effect was also observed in adipose-MSCs following DPSC-CM treatment. Secretome preconditioning remarkably increased NGF expression in the adipose-MSCs. In addition, although priming of adipose-MSCs with HFSC-CM increased GDNF expression one day after the treatment, DPSC-CM enhanced GDNF mRNA in BM-MSCs at a later time point. It seemed priming of BM-MSCs with HFSC-CM, promoted differentiation into the glial lineage. Our findings showed that MSCs preconditioning with secretome of neural crest-derived stem cells could be a promising approach to enhance the neurotrophic potential of these stem cells.

Optogenetic stimulation of entorhinal cortex reveals the implication of insulin signaling in adult rat's hippocampal neurogenesis.

Adult neurogenesis in the hippocampal dentate gyrus plays a critical role in learning and memory. Projections originating from entorhinal cortex, known as the perforant pathway, provide the main input to the dentate gyrus and promote neurogenesis. However, neuromodulators and molecular changes mediating neurogenic effects of this pathway are not yet fully understood. Here, by means of an optogenetic approach, we investigated neurogenesis and synaptic plasticity in the hippocampus of adult rats induced by stimulation of the perforant pathway. The lentiviruses carrying hChR2 (H134R)-mCherry gene under the control of the CaMKII promoter were injected into the medial entorhinal cortex region of adult rats. After 21 days, the entorhinal cortex region was exposed to the blue laser (473 nm) for five consecutive days (30 min/day). The expression of synaptic plasticity and neurogenesis markers in the hippocampus were evaluated using molecular and histological approaches. In parallel, the changes in the gene expression of insulin and its signaling pathway, trophic factors, and components of mitochondrial biogenesis were assessed. Our results showed that optogenetic stimulation of the entorhinal cortex promotes hippocampal neurogenesis and synaptic plasticity concomitant with the increased levels of insulin mRNA and its signaling markers, neurotrophic factors, and activation of mitochondrial biogenesis. These findings suggest that effects of perforant pathway stimulation on the hippocampus, at least in part, are mediated by insulin increase in the dentate gyrus and subsequently activation of its downstream signaling pathway.

Neurogenic differentiation of human dental pulp stem cells by optogenetics stimulation.

INTRODUCTION: Human dental pulp stem cells (hDPSCs), a promising source for autologous transplantation in regenerative medicine, have been shown to be able to differentiate into neural precursors. Optogenetics is considered as an advanced biological technique in neuroscience which is able to control the activity of genetically modified stem cells by light. The purpose of this study is to investigate the neurogenic differentiation of hDPSCs following optogenetic stimulation. METHODS: The hDPSCs were isolated by mechanical enzymatic digestion from an impacted third molar and cultured in DMEM/F12. The cells were infected with lentiviruses carrying CaMKIIa-hChR2 (H134R). Opsin-expressing hDPSCs were plated at the density of 5 × 104 cells/well in 6-well plates and optical stimulation was conducted with blue light (470 nm) pulsing at 15 Hz, 90 % Duty Cycle and 10 mW power for 10 s every 90 minutes, 6 times a day for 5 days. Two control groups including non-opsin-expressing hDPSCs and opsin-expressing hDPSCs with no optical stimulation were also included in the study. A day after last light stimulation, the viability of cells was analyzed by the MTT assay and the morphological changes were examined by phase contrast microscopy. The expression of Nestin, Microtubule-Associated protein 2 (MAP2) and Doublecortin (DCX) were examined by immunocytochemistry. RESULTS: Human DPSCs expressed the reporter gene, mCherry, 72 hours after lentiviral infection. The result of MTT assay revealed a significant more viability in optical stimulated opsin-expressing hDPSCs as compared with two control groups. Moreover, optical stimulation increased the expression of Nestin, Doublecortin and MAP2 along with morphological changes from spindle shape to neuron-like shape. CONCLUSION: Optogenetics stimulation through depolarizing the hDPSCs can increase the cells viability and/or proliferation and also promote the differentiation toward neuron-like cells.

Intranasal interferon beta improves memory and modulates inflammatory responses in a mutant APP-overexpressing rat model of Alzheimer's disease.

Alzheimer's disease (AD) is the most common neurodegenerative disorder characterized by progressive cognitive decline. According to the critical role of inflammation in pathogenesis of AD and memory deficits, a cytokine with anti-inflammatory properties like interferon beta (IFNß), currently used to slow down disease progression and protect against cognitive disturbance in multiple sclerosis, might be also an effective treatment in AD condition. This study aimed to answer if the intranasal (IN) administration of IFNß with high CNS accessibility can alleviate memory impairments in a mutant APP-overexpressing rat model of AD through modulating inflammatory responses. To address this question, the lentiviruses carrying human amyloid protein precursor (APP) with the Swedish and Indiana mutations (LV-APPSw/Ind) were bilaterally injected in the hippocampus of adult rats. Memory performance was assessed using passive avoidance task on days 49 and 50 after injection. Moreover, the expression of glial markers (GFAP and Iba1) and pro-inflammatory (TNF-α, IL-1ß and IL-6) and anti-inflammatory cytokines (IL-10) were evaluated in the hippocampus. Therapeutic effects of IN-administered IFNß (0.5 µg/kg and 1 µg/kg doses, every other day from day 23 to 50 after lentivirus injection) were examined in the LV-APP-injected rats. Our results showed that over-expression of mutant human APP gene in the hippocampus led to learning and memory deficits concomitant with gliosis and pro-inflammatory responses. Interestingly, treatment of AD-modeled rats with IFNß ameliorated memory impairments possibly through suppressing gliosis and shifting from pro-inflammatory toward anti-inflammatory status, suggesting that IFNß may be a promising therapeutic agent to improve cognitive functions and modulate inflammatory responses in an AD-like neurodegenerative context.

Interferon beta ameliorates cognitive dysfunction in a rat model of Alzheimer's disease: Modulation of hippocampal neurogenesis and apoptosis as underlying mechanism.

Neuronal apoptosis and impaired hippocampal neurogenesis are major players in cognitive/memory dysfunctions including Alzheimer's disease (AD). Interferon beta (IFNß) is a cytokine with anti-apoptotic and neuroprotective properties on the central nervous system (CNS) cells which specifically affects neural progenitor cells (NPCs) even in the adult brain. In this study, we examined the effect of IFNß on memory impairment as well as hippocampal neurogenesis and apoptosis in a rat model of AD. AD model was induced by lentiviral-mediated overexpression of mutant APP in the hippocampus of adult rats. Intranasal (IN) administration of IFNß (0.5 µg/kg and 1 µg/kg doses) was started from day 23 after virus injection and continued every other day to the final day of experiments. The expression levels of APP, neurogenesis (Nestin, Ki67, DCX, and Reelin) and apoptosis (Bax/Bcl-2 ratio, cleaved-caspase-3 and seladin-1) markers were evaluated by immunohistochemistry, real-time PCR, immunofluorescence and western blotting. Moreover, thioflavin T and Nissl stainings were used to assess Aß plaque levels and neuronal degeneration in the hippocampus, respectively. Our results showed that IFNß treatment reduced APP expression and Aß plaque formation, and concomitantly ameliorated spatial learning and memory deficits examined in Y-maze and Morris water maze tests. Moreover, in parallel with reducing apoptosis and neural loss in the hippocampal subfields, IFNß decreased ectopic neurogenesis in the CA1 and CA3 regions of the AD rat hippocampus. However, IFNß increased neurogenesis in the dentate gyrus neurogenic niche. Our findings suggest that IFNß exerts neuroprotective effects at least partly by inhibition of apoptosis and modulation of neurogenesis. Taken together, IFNß can be a promising therapeutic approach to improve cognitive performance in AD-like neurodegenerative context.