Amyloid ß lowering and cognition enhancing effects of ghrelin receptor analog [D-Lys (3)] GHRP-6 in rat model of obesity.

Obesity arising due to the dietary and life style changes is fast reaching epidemic proportions all over the world. There is increasing evidence that the incidence of Alzheimer disease (AD) is significantly influenced by a cluster of metabolic diseases, including diabetes and obesity. This study was aimed to test the suitability of experimentally-induced obesity in rats as an experimental animal model of AD. We used the procedure of neonatal administration of rats with monosodium L-glutamate (MSG), which generates adult obese animals as our study design and assessed the AD-like changes by measuring amyloid ß (1-42) and acetylcholinesterase (AChE) levels in the hippocampal extracts and cognitive impairments by Barnes maze task. Further, we investigated the influence of anti-obesity substance [D-Lys (3)] GHRP-6 on blood glucose, hippocampal Aß, AChE levels and restoration of cognitive deficits. Results revealed that administration of MSG to neonatal rats exhibited increased body mass index and serum glucose levels over the controls. Measurement of markers for AD-like molecular changes i.e. amyloid ß (Aß) and AChE levels showed marked elevation in these two parameters in the hippocampus of MSG-treated rats. Assessment of cognitive abilities by Barnes maze revealed spatial disorientation characteristic of AD. Administration of ghrelin receptor analog [D-Lys (3)] GHRP-6 to obese rats resulted in significant restoration of serum cholesterol, glucose, leptin and ghrelin levels to that of control with concomitant reduction in hippocampal Aß and AChE levels. In addition, the treated animals exhibited marked improvement in Barne’s maze task. These findings suggest that MSG-induced obese rats may serve as non-transgenic animal model for AD research. Further, the results indicate the potential of [D-Lys (3)] GHRP-6 as a promising anti-Alzheimer candidate.

In vitro evaluation of anti-Alzheimer effects of dry ginger (Zingiber officinale Roscoe) extract.

As the disease modifying therapies against Alzheimer’s disease (AD) continue to exist as a major challenge of this century, the search for newer drug leads with lesser side effects is on the rise. A large number of plant extracts and phytocompounds are being actively pursued for their anti-Alzheimer effects. In the present study, the antioxidant activity, cholinesterase inhibition, anti-amyloidogenic potential and neuroprotective properties of methanolic extract of dry ginger (GE) have been evaluated. The extract contained 18±0.6 mg/g gallic acid equivalents of total phenolic content and 4.18±0.69 mg quercetin equivalents/g of dry material. GE expressed high antioxidant activity with an IC50 value of 70±0.304 µg/mL in DPPH assay and 845.4±56.62 μM Fe(II) equivalents/g dry weight in FRAP assay respectively. In Ellman’s assay for the cholinesterase inhibitory activity, GE had an IC50 value of 41±1.2 µg/mL and 52±2 µg/mL for inhibition of acetyl- and butyrylcholinesterase respectively. Also, GE increased the cell survival against amyloid β (Aβ) induced toxicity in primary adult rat hippocampal cell culture. Aggregation experiments with the thioflavin T binding studies showed that GE effectively prevented the formation of Aβ oligomers and dissociated the preformed oligomers. These findings suggest that methanolic GE influences multiple therapeutic molecular targets of AD and can be considered as an effective nontoxic neutraceutical supplement for AD.

Intranasal administration of insulin lowers amyloid- levels in rat model of diabetes.

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by abnormal accumulation of amyloid (A) peptide in brain regions subserving memory and other cognitive functions. Hyperglycemia and perturbed insulin signaling have been proposed as pathogenic factors contributing to AD. The aim of the present study is to validate the use of streptozotocin (STZ) injected rats as an experimental model of AD. Using this model, the effect of intranasal administration of insulin on reduction of Aß levels was measured. The current findings strengthen the case for insulin as therapy for AD afflicted individuals with or without diabetes.

I32E and V36K double mutation in ß2-sheet abrogates amyloid ß peptide toxicity.

Alzheimer’s disease (AD) is the most common cause of dementia in the elderly, wherein, the accumulation of amyloid ß(Aß) peptide as cytotoxic oligomers leads to neuropathologic changes. Transgenic mice with brain Aß plaques immunizedwith aggregated Aß have reduced amyloid burden and improved cognitive functions. However, such active immunization inhumans led to a small but significant occurrence of meningoencephalitis in 6% AD volunteers due to Aß induced toxicity. Inan attempt to develop safer alternative vaccines, the design of a highly soluble peptide homologous to Aß (Aß-EK), that hasa reduced amyloidogenic potential while maintaining the major immunogenic epitopes of Aß is reported. More importantly,this homologue has been shown to be non-toxic, as this peptide failed to exert any observable effect on erythrocytes. Theresults of the present study suggests that immunization with non-toxic Aß derivative may offer a safer therapeutic approachto AD, instead of using toxic Aß fibrils.

Expression, purification and characterization of a synthetic gene encoding human amyloid beta (Abeta1-42) in Escherichia coli.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by a progressive loss of cognitive function. Existing evidence indicates that abnormal processing and extracellular deposition of the longer form of the amyloid peptide Abeta(1-42), a proteolytic derivative of the amyloid precursor protein (APP), is a key step in the pathogenesis of AD. Active immunization with Abeta(1-42) has been shown to decrease brain beta deposition and improve cognitive performance in mouse models of AD. In the present study, we sought to express the synthetic gene encoding AB in Escherichia coli to enable rapid production of the antigen and its purification. The synthetic gene has been constructed from six oligonucleotides by employing overlapping PCR strategy and expressed in E. coli using the T7 promoter system. The recombinant peptide has been purified to homogeneity by a single step Ni+2 affinity chromatography. Enzyme-linked immunosorbent assay (ELISA) using polyclonal anti-Abeta(1-42) sera confirms that the corresponding linear B-cell epitopic sequences are available for immunorecognition in the recombinant peptide. This methodology enables rapid, continuous production and purification in bulk amounts of human Abeta sequence by employing bacterial expression system