Growing evidence has demonstrated the benefits of regular exercise on cardiovascular, neural, and cognitive function in humans with Alzheimer’s disease (AD). However, the consequences of AD on gastrointestinal morphology and the effects of regular exercise, which plays an important role against the development of certain gastrointestinal-related diseases, are still poorly understood. Therefore, to assess the changes in intestinal structure in a mouse model of AD and the impact of exercise, 2-month-old 3xTg-AD male mice were subjected to treadmill running 5 days per week for a period of 5 months. Jejunum from 3xTg-AD mice analyzed by histochemical methods revealed significant alterations in morphology. Compared to age-matched wild-type (WT) mice, villi length and crypt depth were increased, and collagen content of jejunum was elevated in 3xTg-AD mice. Jejunum wall dimensions, expressed as total wall thickness, outer longitudinal thickness, and inner circular thickness were decreased in 3xTg-AD compared to WT. Smooth muscle actin expression in jejunal wall was decreased in 3xTg-AD. Most of these aberrations were improved with exercise. Western blot expression of cyclin dependent kinase 5 (CDK5, involved in neural cell death and hyperphosphorylation of tau), was elevated in 3xTg-AD jejunum. This was associated with a 4-fold increase in tau5 expression. Exercise prevented the increase in expression of CDK5 and tau5. Expression of caspase 3 (an apoptotic marker) was elevated in 3xTg-AD jejunum and exercise prevented this. The results of our study indicate that the abnormalities in jejunum of the 3xTg mouse model of AD were prevented with exercise training.
Background: Metabolic syndrome includes a plethora of symptoms ultimately leading to obesity and type 2 diabetes. Obesity has been linked to chronic gastrointestinal dysfunction (constipation, or diarrhea) and specifically females with high BMI have been associated with increased prevalence of diarrhea. We aimed to better understand the influence of high fat-high sugar diet (Western diet) on small intestinal function and to assess sex-dependent effects. Methods: We measured transepithelial short circuit current (Isc) a measure of chloride secretory function, across freshly isolated segments of jejunum from male and female C57Bl/6J mice fed a high fat high sugar diet (HFS) for 12 weeks, compared to lean controls. At the completion of the study, segments of jejunum were frozen for western blot determination of key proteins involved in secretory and absorptive functions and senescence. Intestinal morphology was assessed. Serum cytokine assays were performed. Results: Basal Isc was significantly decreased 70% ( P<0.05) in HFS both females and males versus leans. In females, the HFS-induced decrease in Isc was attributed to a significant loss of CLC2, NKCC1 and CFTR expression whereas in males the decrease in Isc was due to a significant loss of Na/K-ATPase, KCa and NKCC1 expression (indicating interesting sex-dependent etiology). A2BR levels were also dysregulated in HFS fed male and female mice. Inflammatory state and shadowed body weight changes with feeding a western diet. Assessment of intestinal morphology and metabolic profile is being further evaluated. Conclusions: Our data suggests that the reduced basal jejunal Isc in HFS mice is attributed to sex-dependent mechanisms. Improved understanding of Western diet-induced intestinal dysfunctions may provide improved drug targets to treat gastrointestinal disturbances in obesity and diabetes. Midwestern Arizona Alzheimer’s Consortium and Diabetes Action Research and Education Foundation This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
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