Short-term treadmill exercise does not overcome the effects of cafeteria diet on fecal microbiome while altering adipose and hypothalamic gene expression in rats. Exercise and microbiome

Background: Exercise has been extensively utilised as an effective therapy for overweight- and obesity-associated changes that are linked to health complications. Several preclinical rodent studies have shown that long-term treadmill exercise improves metabolic health and microbiome composition and normalises hypothalamic and adipose tissue gene expression in diet-induced obesity. However, limited work has investigated whether short-term treadmill exercise can provide any health benefits. Methods: To address this gap in the literature, we fed rats a high-fat, high-sugar western-style cafeteria diet and assessed the effects of short-term treadmill exercise on adiposity, diet-induced gut dysbiosis, as well as hypothalamic and retroperitoneal white adipose tissue gene expression. Forty-eight male Sprague-Dawley rats were allocated to either a regular chow or cafeteria diet and after three weeks half the rats on each diet were allocated to moderate treadmill exercise for four weeks while the remainder were exposed to a stationary treadmill. Results: Microbial species diversity was uniquely reduced in exercising chow-fed rats, while microbiome composition was only changed by cafeteria diet. Despite limited effects of exercise on overall microbiome composition, exercise increased inferred microbial functions involved in metabolism, reduced fat mass, and altered adipose and hypothalamic gene expression. After controlling for diet and exercise, adipose Il6 expression and plasma triglyceride concentrations were significantly associated with global microbiome composition.Conclusions: Short-term treadmill exercise induced microbial species diversity changes in chow-fed rats but did not overcome the compositional changes induced by cafeteria diet. In contrast, inferred microbial metabolism was increased by exercise. Moderate treadmill exercise induced subtle microbiome composition changes in chow-fed rats but did not overcome the microbiome changes induced by cafeteria diet. Future work investigating whether exercise in combination with microbiome-modifying interventions can synergistically reduce diet- and obesity-associated comorbidities is warranted.