Purpose: Diabetes mellitus (DM)-induced brain damage is characterized by cellular, molecular and functional changes. The mechanisms include oxidative stress, neuroinflammation, reduction of neurotrophic factors, insulin resistance, excessive amyloid beta (Aβ) deposition and Tau phosphorylation. Both antidiabetic and neuroprotective effects of the phytoestrogen genistein have been reported. However, the beneficial effect of genistein in brain of the ob/ob mouse model of severe obesity and diabetes remains to be determined. Methods: In this study, female ob/ob mice and lean control mice were fed with either a standard diet or a diet containing genistein (600mg/kg) for a period of 4 weeks. Body weight was monitored weekly. Blood was collected for the measurement of glucose, insulin and common cytokines. Mice brains were isolated for Western immunoblotting analyses. Results: Treatment with genistein reduced weight gain of ob/ob mice and decreased hyperglycemia compared to ob/ob mice fed the standard diet. The main findings show that genistein treatment increased insulin sensitivity and the expression levels of the neurotrophic factors nerve growth factor (NGF) and brain-derived neurotrophic factors (BDNF). In these mice, genistein also reduced Aβ deposition and the level of hyper-phosphorylated Tau protein. Conclusion: The results of our study indicate the beneficial effects of genistein in the obese diabetic mouse brain, including improving brain insulin signaling, increasing neurotrophic support, and alleviating Alzheimer's disease-related pathology.
Isoflavones are a class of organic compounds related to flavonoids.Many of them exert estrogen-like effects in mammals, and hence, are classified as phytoestrogens. Daidzein and genistein are two dominant isoflavones that are thought to be responsible for the potential health benefits associated with soy consumption (Gardner et al., 2009).
| Source and metabolism of genisteinLeguminous plant foods contain genistein. Soy-based foods, such as soy milk, soy flour, soy protein isolate, and tempeh, are the best-known sources of genistein. The raw mature seeds of soybeans contain an average of 80.99 mg/100 g of genistein (Bhagwat & Holden, 2008). The second most important source of genistein is legumes including lupin, broad beans, and garbanzo beans
In recent decades, a shift in the nutritional landscape to the Western-style diet has led to an unprecedented rise in the prevalence of obesity and neurodegenerative diseases. Consumption of a healthy diet and engaging in regular physical activity represents safe and affordable approaches known to mitigate the adverse consequences of the Western diet. We examined whether genistein treatment, exercise training, and a combination treatment (genistein and exercise training) mitigated the effects of a Western diet-induced by high-fat, high-sugar (HFHS) in brain of female mice. HFHS increased the amyloid-beta (Aβ) load and phosphorylation of tau, apoptosis, and decreased brain-derived neurotrophic factor (BDNF) levels. Exercise training and genistein each afforded modest protection on Aβ accumulation and apoptosis, and both increased BDNF. The greatest neuroprotective effect occurred with combination treatment. BDNF and all markers of Aβ accumulation, phosphorylation of tau, and apoptosis were improved with combined treatment. In a separate series of experiments, PC12 cells were exposed to high glucose (HG) and palmitate (PA) to determine cell viability with genistein as well as in the presence of tamoxifen, an estrogen receptor antagonist, to assess a mechanism of action of genistein on cell apoptosis. Genistein prevented the neurotoxic effects of HG and PA in PC12 cells and tamoxifen blocked the beneficial effects of genistein on apoptosis. Our results indicate the beneficial effects of genistein and exercise training on HFHS-induced brain damage. The benefits of genistein may occur via estrogen receptor-mediated pathways.
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