- Dopamine loss alters the hippocampus-nucleus accumbens synaptic transmission in the Tg2576 mouse model of Alzheimer's disease. [Journal Article]
- NDNeurobiol Dis 2018 May 17
- The functional loop involving the ventral tegmental area (VTA), dorsal hippocampus and nucleus accumbens (NAc) plays a pivotal role in the formation of spatial memory and persistent memory traces. In...
The functional loop involving the ventral tegmental area (VTA), dorsal hippocampus and nucleus accumbens (NAc) plays a pivotal role in the formation of spatial memory and persistent memory traces. In particular, the dopaminergic innervation from the VTA to the hippocampus is critical for hippocampal-related memory function and alterations in the midbrain dopaminergic system are frequently reported in Alzheimer's disease (AD), contributing to age-related decline in memory and non-cognitive functions. However, much less is known about the hippocampus-NAc connectivity in AD. Here, we evaluated the functioning of the hippocampus-to-NAc core connectivity in the Tg2576 mouse model of AD that shows a selective and progressive degeneration of VTA dopaminergic neurons. We show that reduced dopaminergic innervation in the Tg2576 hippocampus results in reduced synaptic plasticity and excitability of dorsal subiculum pyramidal neurons. Importantly, the glutamatergic transmission from the hippocampus to the NAc core is also impaired. Chemogenetic depolarisation of Tg2576 subicular pyramidal neurons with an excitatory Designer Receptor Exclusively Activated by Designer Drugs, or systemic administration of the DA precursor levodopa, can both rescue the deficits in Tg2576 mice. Our data suggest that the dopaminergic signalling in the hippocampus is essential for the proper functioning of the hippocampus-NAc excitatory synaptic transmission.
- Aberrant working memory processing in major depression: evidence from multivoxel pattern classification. [Journal Article]
- NNeuropsychopharmacology 2018 May 02
- Major depressive disorder (MDD) is often accompanied by severe impairments in working memory (WM). Neuroimaging studies investigating the mechanisms underlying these impairments have produced conflic...
Major depressive disorder (MDD) is often accompanied by severe impairments in working memory (WM). Neuroimaging studies investigating the mechanisms underlying these impairments have produced conflicting results. It remains unclear whether MDD patients show hyper- or hypoactivity in WM-related brain regions and how potential aberrations in WM processing may contribute to the characteristic dysregulation of cognition-emotion interactions implicated in the maintenance of the disorder. In order to shed light on these questions and to overcome limitations of previous studies, we applied a multivoxel pattern classification approach to investigate brain activity in large samples of MDD patients (N = 57) and matched healthy controls (N = 61) during a WM task that incorporated positive, negative, and neutral stimuli. Results showed that patients can be distinguished from healthy controls with good classification accuracy based on functional activation patterns. ROI analyses based on the classification weight maps showed that during WM, patients had higher activity in the left DLPFC and the dorsal ACC. Furthermore, regions of the default-mode network (DMN) were less deactivated in patients. As no performance differences were observed, we conclude that patients required more effort, indexed by more activity in WM-related regions, to successfully perform the task. This increased effort might be related to difficulties in suppressing task-irrelevant information reflected by reduced deactivation of regions within the DMN. Effects were most pronounced for negative and neutral stimuli, thus pointing toward important implications of aberrations in WM processes in cognition-emotion interactions in MDD.
- Amyloid PET in neurodegenerative diseases with dementia. [Journal Article]
- RERev Esp Med Nucl Imagen Mol 2018 May 15
- Alzheimer's disease (AD) is a neurodegenerative condition characterized by progressive cognitive decline and memory loss, and is the most common form of dementia. Amyloid plaques with neurofibrillary...
Alzheimer's disease (AD) is a neurodegenerative condition characterized by progressive cognitive decline and memory loss, and is the most common form of dementia. Amyloid plaques with neurofibrillary tangles are a neuropathological hallmark of AD that produces synaptic dysfunction and culminates later in neuronal loss. Amyloid PET is a useful, available and non-invasive technique that provides in vivo information about the cortical amyloid burden. In the latest revised criteria for the diagnosis of AD biomarkers were defined and integrated: pathological and diagnostic biomarkers (increased retention on fibrillar amyloid PET or decreased Aβ1-42 and increased T-Tau or P-Tau in CSF) and neurodegeneration or topographical biomarkers (temporoparietal hypometabolism on 18F-FDG PET and temporal atrophy on MRI). Recently specific recommendations have been created as a consensus statement on the appropriate use of the imaging biomarkers, including amyloid PET: early-onset cognitive impairment/dementia, atypical forms of AD, mild cognitive impairment with early age of onset, and to differentiate between AD and other neurodegenerative diseases that occur with dementia. Amyloid PET is also contributing to the development of new therapies for AD, as well as in research studies for the study of other neurodegenerative diseases that occur with dementia where the deposition of Aβ amyloid is involved in its pathogenesis. In this paper, we review some general concepts and study the use of amyloid PET in depth and its relationship with neurodegenerative diseases and other diagnostic techniques.
- Cognition and objectively measured sleep duration in children: a systematic review and meta-analysis. [Journal Article]
- SHSleep Health 2018; 4(3):292-300
- CONCLUSIONS: Future research using more rigorous experimental methodologies is needed to properly elucidate the relationship between sleep duration and cognition in this age group.
- Zika Virus Baculovirus-Expressed Virus-Like Particles Induce Neutralizing Antibodies in Mice. [Journal Article]
- VSVirol Sin 2018 May 17
- The newly emerged mosquito-borne Zika virus (ZIKV) strains pose a global challenge owing to its ability to cause microcephaly and neurological disorders. Several ZIKV vaccine candidates have been pro...
The newly emerged mosquito-borne Zika virus (ZIKV) strains pose a global challenge owing to its ability to cause microcephaly and neurological disorders. Several ZIKV vaccine candidates have been proposed, including inactivated and live attenuated virus vaccines, vector-based vaccines, DNA and RNA vaccines. These have been shown to be efficacious in preclinical studies in mice and nonhuman primates, but their use will potentially be a threat to immunocompromised individuals and pregnant women. Virus-like particles (VLPs) are empty particles composed merely of viral proteins, which can serve as a safe and valuable tool for clinical prevention and treatment strategies. In this study, we used a new strategy to produce ZIKV VLPs based on the baculovirus expression system and demonstrated the feasibility of their use as a vaccine candidate. The pre-membrane (prM) and envelope (E) proteins were co-expressed in insect cells and self-assembled into particles similar to ZIKV. We found that the ZIKV VLPs could be quickly and easily prepared in large quantities using this system. The VLPs were shown to have good immunogenicity in immunized mice, as they stimulated high levels of virus neutralizing antibody titers, ZIKV-specific IgG titers and potent memory T cell responses. Thus, the baculovirus-based ZIKV VLP vaccine is a safe, effective and economical vaccine candidate for use against ZIKV.
- Orexin A Differentially Influences the Extinction Retention of Recent and Remote Fear Memory. [Journal Article]
- FNFront Neurosci 2018; 12:295
- Recently the role of the orexin system in the learning and memory, especially orexin A, which could enhance fear memory through regulating the activity of amygdala, has drawn considerable attention. ...
Recently the role of the orexin system in the learning and memory, especially orexin A, which could enhance fear memory through regulating the activity of amygdala, has drawn considerable attention. However, the relationship between orexin A and extinction memory remains unclear. To investigate the effect of orexin A on extinction memory in humans, we recruited 43 male subjects and divided them into a recent group and remote group. After acquiring Pavlovian fear conditioning, individuals in recent group experienced fear extinction 24 h after acquisition, and remote group underwent extinction 2 weeks later. Meanwhile, plasma orexin A levels before extinction were measured by enzyme-linked immunosorbent assay. Both groups received memory test 24 h after fear extinction. The results showed that both recent and remote groups successfully acquired fear conditioning and had spontaneous recovery at test. In particular, the correlational analysis indicated that orexin A levels before extinction were negatively associated with fear responses during test only in recent group, but not in remote group. Moreover, individuals with high orexin A levels still kept low fear responses after extinction in recent group by subgroup analyses. The results suggest that orexin A could influence the retention of recent fear memory extinction, without affecting remote fear extinction. These findings remind us the orexin system can be a potential treatment target for fear-related disorders, and the mechanisms of recent and remote fear extinction may be different.
- Combined Administration of Monosodium Glutamate and High Sucrose Diet Accelerates the Induction of Type 2 Diabetes, Vascular Dysfunction, and Memory Impairment in Rats. [Journal Article]
- JEJ Environ Pathol Toxicol Oncol 2018; 37(1):63-80
- In this study, we aimed to develop an experimental animal model for type 2 diabetes mellitus (T2DM) using a combination of monosodium glutamate (MSG) and high sucrose diet (HSD). Young male Wistar ra...
In this study, we aimed to develop an experimental animal model for type 2 diabetes mellitus (T2DM) using a combination of monosodium glutamate (MSG) and high sucrose diet (HSD). Young male Wistar rats (20-30 g) were injected with MSG (2 or 4 mg/g, i.p. for 4 days). These rats were also fed an HSD, while the control group was fed a starch diet (SFD) for 150 days. Parameters assessed periodically were body weight, feed intake, blood glucose level, and oral glucose tolerance test (OGTT), lipid profile, liver and kidney function tests, skeletal muscle glucose uptake, cognitive function tests, and microvascular changes using isolated rat aorta. Histological changes in pancreas, liver, and kidney tissue were assessed using hematoxylin and eosin staining, whereas brain tissue was assessed using cresyl violet stain. Feeding MSG in combination with HSD in rats significantly increased body weight, and produced hyperglycemia, dyslipidemia, and hyperinsulinemia. Animals developed frank diabetic complications, which included insulin resistance in skeletal muscle, hypertension, vascular dysfunction, nephropathy, and dementia. Histological studies revealed neuronal loss with necrotic bodies in the brain, reduction in glomerular count in kidney, and severe hypertrophy and hyperplasia in the islets of Langerhans. These results indicate the successful induction of type-2 diabetes along with several diabetic complications by combining MSG with HSD.
- Ethyl Acetate Fraction from Persimmon (Diospyros kaki) Ameliorates Cerebral Neuronal Loss and Cognitive Deficit via the JNK/Akt Pathway in TMT-Induced Mice. [Journal Article]
- IJInt J Mol Sci 2018 May 17; 19(5)
- This study was conducted to assess the antioxidant capacity and protective effect of the ethyl acetate fraction from persimmon (Diospyros kaki) (EFDK) on H₂O₂-induced hippocampal HT22 cells and trime...
This study was conducted to assess the antioxidant capacity and protective effect of the ethyl acetate fraction from persimmon (Diospyros kaki) (EFDK) on H₂O₂-induced hippocampal HT22 cells and trimethyltin chloride (TMT)-induced Institute of Cancer Research (ICR) mice. EFDK had high antioxidant activities and neuroprotective effects in HT22 cells. EFDK ameliorated behavioral and memory deficits in Y-maze, passive avoidance and Morris water maze tests. Also, EFDK restored the antioxidant system by regulating malondialdehyde (MDA), superoxide dismutase (SOD) and reduced gluthathione (GSH), and the cholinergic system by controlling the acetylcholine (ACh) level and acetylcholinesterase (AChE) activity and expression. EFDK enhanced mitochondrial function by regulating reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP), and adenosine triphosphate (ATP). Ultimately, EFDK regulated the c-Jun N-terminal kinase (JNK)/protein kinase B (Akt) pathway and apoptotic pathway by suppressing the expression of tumor necrosis factor-alpha (TNF-α), phosphorylated insulin receptor substrate 1 (IRS-1pSer), phosphorylated JNK (p-JNK), phosphorylated tau (p-tau), phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells (p-NF-κB), Bcl-2-associated X protein (BAX) and cytosolic cytochrome c, and increasing the expression of phosphorylated Akt (p-Akt) and mitochondrial cytochrome c. This study suggested that EFDK had antioxidant activity and a neuroprotective effect, and ameliorated cognitive abnormalities in TMT-induced mice by regulating the JNK/Akt and apoptotic pathway.
- Marine derived bioactive compounds for treatment of Alzheimer's disease. [Journal Article]
- FBFront Biosci (Elite Ed) 2018 Jun 01; 10:537-548
- Alzheimer's disease (AD ) is mounting as social and economic encumbrance which are accompanied by deficits in cognition and memory. Over the past decades, Alzheimer's disease (AD) holds the frontline...
Alzheimer's disease (AD ) is mounting as social and economic encumbrance which are accompanied by deficits in cognition and memory. Over the past decades, Alzheimer's disease (AD) holds the frontline as one of the biggest healthcare issues in the world. AD is an age related neurodegenerative disorder marked by a decline in memory and an impairment of cognition. Inspite of tedious scientific effort, AD is still devoid of pharmacotherapeutic strategies for treatment as well as prevention. Current treatment strategies using drugs are symbolic in nature as they treat disease manifestation though are found effective in treating cognition. Inclination of science towards naturopathic treatments aiming at preventing the disease is highly vocal. Application of marine-derived bioactive compounds, has been gaining attention as mode of therapies against AD. Inspired by the vastness and biodiversity richness of the marine environment, role of marine metabolites in developing new therapies targeting brain with special emphasis to neurodegeneration is heading as an arable field. This review summarizes select-few examples highlighted as therapeutical applications for neurodegenerative disorders with special emphasis on AD.
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- Myricetin attenuates neurodegeneration and cognitive impairment in Parkinsonism. [Journal Article]
- FBFront Biosci (Elite Ed) 2018 Jun 01; 10:481-494
- Parkinson's disease (PD) is a progressive neurodegenerative disease due to dopaminergic neuron degeneration. It mostly affects the aged population, leads to memory decline and loss of motor coordinat...
Parkinson's disease (PD) is a progressive neurodegenerative disease due to dopaminergic neuron degeneration. It mostly affects the aged population, leads to memory decline and loss of motor coordination. The present study investigates the neuroprotective role of myricetin a flavonol isolated from the brown seaweed Turbinaria ornata in rotenone induced Drosophila model of PD. Rotenone administration led to dopaminergic neuronal degeneration, dopamine depletion, impaired muscular coordination, gait disturbances, memory decline oxidative stress and apoptosis. Ingestion of myricetin by Drosophila significantly prevented rotenone induced neuronal degeneration. These results confirm that myricetin exerts neuroprotective effect in experimental PD.