We recently showed that young (1 month old) ovariectomized spontaneously hypertensive rats (OVX-SHR) fed a low dose (0.5%) of grape seed extract (GSE) in the diet exhibited enhanced cognitive abilities, suggestive of beneficial actions of the GSE in mammalian brain. Previous studies had shown that dietary administration of the GSE at a high (5%) but nontoxic concentration altered brain proteins in normal young adult female rats;these proteins included many previously shown to be affected in the brains of Alzheimer's disease patients and in transgenic models of dementia. The majority of the directions of change for the affected brain proteins were in those considered beneficial. More recently, we showed that GSE intake resulted in a reduction in brain protein oxidations in a transgenic mouse model of dementia, suggestive of anti-oxidant actions of GSE in rodent brain, and consistent with our and others'data showing health benefits of GSE in other models of chronic disease. While much experimentation has been carried out with GSE and similar preparations, systematic analysis of the effective dose range of GSE, and the optimal timing of GSE intake, have not been done. Such experimental parameters, as well as an understanding of compositional variability or stability of the preparations during the course of the experiment, are required for rigorous understanding of the actions and mechanisms of action of dietarily administered bioactive compounds. The proposed studies will utilize OVX- SHR, a model of accelerated postmenopausal hypertension, and test the hypothesis that low doses of grape seed extract protect against ovariectomy-induced late-life cognitive impairment. A systematic dose response analysis of OVX-SHR to GSE administered from the time of OVX will determine the lowest effective dose of GSE. Follow up experiments at this dose will then examine whether shorter times of administration of GSE can have behavioral benefit. Once a beneficial dose of GSE is identified, we will identify by 2D gel proteomics approaches protein differences induced by estrogen-deprivation in the SHR brain, and which of these are attenuated by GSE at the protective dose. These will be initial steps in understanding the consequences of the loss of estrogen in cognitive function, and how polyphenolic substances such as GSE counteract estrogen- deprivation. GSE preparations and diet-supplemented with GSE will be monitored by HPLC-mass spectrometry-based methods for composition and stability during the course of the study. Our objective is to define experimental parameters for the study of GSE and related supplements in models of human chronic disease that will lay a foundation for rigorous studies on the mechanisms by which this and other botanically- based dietary supplements protect from aging- and menopause-related cognitive decline.
We will determine in rats the lowest effective dose of grape seed extract (GSE) that protects against late life cognitive decline induced by estrogen deprivation, caused by removal of the ovaries (ovariectomy or OVX). Biochemical experiments will identify the brain protein changes induced by the OVX, and determine which of these are prevented by the GSE at the lowest dose of GSE that still protects against the OVX-induced cognitive impairment, to begin to identify protein changes that are the mechanism of OVX-induced cognitive decline. Because protein oxidations are thought to be involved in age-related brain dysfunction, we will also study what protein oxidations occur following OVX, and which are prevented by protective doses of GSE. The studies will define experimental parameters for future studies with GSE and related dietary supplements to assess mechanisms of action in models of human chronic disease.
| Barnes, Stephen; Kim, Helen (2010) Cautions and research needs identified at the equol, soy, and menopause research leadership conference. J Nutr 140:1390S-4S |
