A Review on the Alzheimer Disease Animal Models and Retinal Degeneration

Alzheimer’s disease (AD) is a chronic neurodegen- erative disease, serving as the most common form of dementia among the elderly population. AD targets various neurological processes in humans such as the visual pathway and hence resulting in various forms of visual abnormalities. Several studies have reported the loss of retinal ganglion cells, reduced thickness of nerve fibre layers (NFL) and damage of the optic nerve head and fiber layers. These findings suggest a putative link between AD and visual function deficits. As genetic defects have been found to be associated with AD, it is possible to experimentally mimic this condition in animal models. AD gene mutations discovered in human amyloid pre- cursor protein (APP), presenilin 1/2 (PS1/PS2) and microtubule- associated tau protein have been used to engineer AD animal models. In this review, we discuss the underlying molecular mecha- nisms of AD in terms of amyloidogenesis and tauopathies, as well as explain the pathological changes leading to vision loss in AD patients. Subsequently, the biology of the genes/proteins which have a causative link to AD, including APP, PS1 and PS2 will be discussed. Several recent reports of retinal degeneration in AD transgenic mouse models are selected to examine the relationship between AD and visual disturbance. We believe that a well- established method to generate transgenic mice will enhance our understanding of AD pathology and its correlation with retinal degeneration, leading to possible detection and treatment methods for AD

Drug discovery from Chinese medicine against neurodegeneration in Alzheimer's and vascular dementia

Alzheimer's disease and vascular dementia are two major diseases associated with dementia, which is common among the elderly. While the etiology of dementia is multi-factorial and complex, neurodegeneration may be the major cause of these two diseases. Effective drugs for treating dementia are still to be discovered. Current western pharmacological approaches against neurodegeneration in dementia develop symptom-relieving and disease-modifying drugs. Current integrative and holistic approaches of Chinese medicine to discovering drugs for neurodegeneration in dementia include (1) single molecules from the herbs, (2) standardized extracts from a single herb, and (3) herbal formula with definite composition. This article not only reviews the concept of dementia in western medicine and Chinese medicine but also evaluates the advantages and disadvantages of these approaches

Lycium barbarum Extracts Protect the Brain from Blood-Brain Barrier Disruption and Cerebral Edema in Experimental Stroke

BACKGROUND AND PURPOSE: Ischemic stroke is a destructive cerebrovascular disease and a leading cause of death. Yet, no ideal neuroprotective agents are available, leaving prevention an attractive alternative. The extracts from the fruits of Lycium barbarum (LBP), a Chinese anti-aging medicine and food supplement, showed neuroprotective function in the retina when given prophylactically. We aim to evaluate the protective effects of LBP pre-treatment in an experimental stroke model. METHODS: C57BL/6N male mice were first fed with either vehicle (PBS) or LBP (1 or 10 mg/kg) daily for 7 days. Mice were then subjected to 2-hour transient middle cerebral artery occlusion (MCAO) by the intraluminal method followed by 22-hour reperfusion upon filament removal. Mice were evaluated for neurological deficits just before sacrifice. Brains were harvested for infarct size estimation, water content measurement, immunohistochemical analysis, and Western blot experiments. Evans blue (EB) extravasation was determined to assess blood-brain barrier (BBB) disruption after MCAO. RESULTS: LBP pre-treatment significantly improved neurological deficits as well as decreased infarct size, hemispheric swelling, and water content. Fewer apoptotic cells were identified in LBP-treated brains by TUNEL assay. Reduced EB extravasation, fewer IgG-leaky vessels, and up-regulation of occludin expression were also observed in LBP-treated brains. Moreover, immunoreactivity for aquaporin-4 and glial fibrillary acidic protein were significantly decreased in LBP-treated brains. CONCLUSIONS: Seven-day oral LBP pre-treatment effectively improved neurological deficits, decreased infarct size and cerebral edema as well as protected the brain from BBB disruption, aquaporin-4 up-regulation, and glial activation. The present study suggests that LBP may be used as a prophylactic neuroprotectant in patients at high risk for ischemic stroke.published_or_final_versio

PKR deficiency alters E. coli-induced sickness behaviors but does not exacerbate neuroimmune responses or bacterial load

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Cigarette Smoking Accelerated Brain Aging and Induced Pre-Alzheimer-Like Neuropathology in Rats

Cigarette smoking has been proposed as a major risk factor for aging-related pathological changes and Alzheimer's disease (AD). To date, little is known for how smoking can predispose our brains to dementia or cognitive impairment. This study aimed to investigate the cigarette smoke-induced pathological changes in brains. Male Sprague-Dawley (SD) rats were exposed to either sham air or 4% cigarette smoke 1 hour per day for 8 weeks in a ventilated smoking chamber to mimic the situation of chronic passive smoking. We found that the levels of oxidative stress were significantly increased in the hippocampus of the smoking group. Smoking also affected the synapse through reducing the expression of pre-synaptic proteins including synaptophysin and synapsin-1, while there were no changes in the expression of postsynaptic protein PSD95. Decreased levels of acetylated-tubulin and increased levels of phosphorylated-tau at 231, 205 and 404 epitopes were also observed in the hippocampus of the smoking rats. These results suggested that axonal transport machinery might be impaired, and the stability of cytoskeleton might be affected by smoking. Moreover, smoking affected amyloid precursor protein (APP) processing by increasing the production of sAPPβ and accumulation of β–amyloid peptide in the CA3 and dentate gyrus region. In summary, our data suggested that chronic cigarette smoking could induce synaptic changes and other neuropathological alterations. These changes might serve as evidence of early phases of neurodegeneration and may explain why smoking can predispose brains to AD and dementia