Proteomic identification of brain proteins in the canine model of human aging following a long-term treatment with antioxidants and a program of behavioral enrichment: Relevance to Alzheimer's disease

Abstract

Aging and age-related disorders such as Alzheimer's disease (AD) are usually accompanied by oxidative stress as one of the main mechanisms contributing to neurodegeneration and cognitive decline. Aging canines develop cognitive dysfunction and neuropathology similar to those seen in humans, and the use of antioxidants results in reductions in oxidative damage and in improvement in cognitive function in this canine model of human aging. In the present study, the effect of a longterm treatment with an antioxidant fortified diet and a program of behavioral enrichment on oxidative damage was studied in aged canines. To identify the neurobiological mechanisms underlying these treatment effects, the parietal cortex from 23 beagle dogs (8.1-12.4 years) were treated for 2.8 years in one of four treatment groups: i.e., control food-control behavioral enrichment (CC); control food -behavioral enrichment (CE); antioxidant food-control behavioral enrichment (CA); and enriched environment -antioxidant fortified food (EA). We analyzed the levels of the oxidative stress biomarkers, i.e., protein carbonyls, 3-nitrotyroine (3NT), and the lipid peroxidation product, 4- Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptNeurobiol Aging. Author manuscript; available in PMC 2009 January 1. Published in final edited form as:Neurobiol Aging. 2008 January ; 29(1): 51-70. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript hydroxynonenal (HNE), and observed a decrease in their levels on all treatments when compared to control, with the most significant effects found in the combined treatment, EA. Since EA treatment was most effective, we also carried out a comparative proteomics study to identify specific brain proteins that were differentially expressed and used a parallel redox proteomics approach to identify specific brain proteins that were less oxidized following EA. The specific protein carbonyl levels of glutamate dehydrogenase [NAD (P)], glyceraldehyde-3-phosphate dehydrogenase (GAPDH), α-enolase, neurofilament triplet L protein, glutathione S-transferase (GST) and fascin actin bundling protein were significantly reduced in brain of EA-treated dogs compared to control. We also observed significant increases in expression of Cu/Zn superoxide dismutase, fructose-bisphosphate aldolase C, creatine kinase, glutamate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase. The increased expression of these proteins and in particular Cu/Zn SOD correlated with improved cognitive function. In addition, there was a significant increas...

Redox proteomics: understanding oxidative stress in the progression of age-related neurodegenerative disorders

“…For example, many of the proteins that were identified as oxidatively modified in brain from subjects with AD or mild cognitive impairment belong to the glycolytic or TCA pathways, or are mitochondrial proteins. Since oxidatively modified proteins are generally dysfunctional [3,5,[8][9][10], these findings are consistent with PET studies that demonstrate decreased energy metabolism in AD and mild cognitive impairment compared with that of the control [16,17].…”

“…Computer-assisted detection of these derivatized proteins on 2D western blots is coupled to mass spectrometric analysis to identify oxidatively modified proteins in the sample of interest [6][7][8][9][10][11]. In this method, a parallel analysis is employed: first the 2D western blots and 2D gel images are matched by computer-assisted image analysis, and the anti-DNP immunoreactivity of individual proteins is normalized to protein content that is obtained by measuring the intensity of colloidal Coomassie blue staining or SYPRO ® Ruby-stained spots [6,7,9,10].…”

Strategies for improving cognition with aging: insights from a longitudinal study of antioxidant and behavioral enrichment in canines

“…The combined treatment group showed additional changes in the brain distinct from either treatment alone, as was shown in a comprehensive proteomics study of the parietal cortex of treated animals (Opii et al 2008). For example, there was a significant decrease in the levels of several toxic oxidative stress biomarkers (protein carbonyls and 3-nitrotyrosine) in animals receiving both the antioxidant diet and behavioural enrichment compared with groups receiving the single treatments.…”

“…For example, there was a significant decrease in the levels of several toxic oxidative stress biomarkers (protein carbonyls and 3-nitrotyrosine) in animals receiving both the antioxidant diet and behavioural enrichment compared with groups receiving the single treatments. A global proteomic analysis of the parietal cortex of dogs receiving the combination treatment showed a significant increase in the expression and enzymatic activities of proteins involved in energy metabolism, antioxidant systems, and in the maintenance and stabilization of cell structure, all of which play a significant role in memory and cognitive function (Opii et al 2008). For example, the expression levels of energy metabolism related proteins, i.e., Cu/ Zn superoxide dismutase, fructose-bisphosphate aldolase C, creatine kinase, glutamate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase, were significantly increased in the group of animals receiving the combination treatment when compared with controls.…”

“…More importantly, the reduction in oxidative damage coupled with increased expression and activity of protective proteins and enzymes was found to correlate with improvements in cognitive function (Opii et al 2008). Briefly, the Cu/Zn superoxide dismutase (SOD) protein level was negatively correlated with error scores on a black/white reversal task and on a spatial memory task, i.e., higher antioxidant protein level was associated with improved cognition.…”