Effects of intermittent fasting on brain tissue in male Fisher-344 rats

Abstract

Introduction: Intermittent fasting (IF), time-restricted food intake without any caloric restrictions, has been shown to improve cognition in animal models. Several pathways have been identified in IF-induced neuroprotection; here, we observed the effect of IF on neuroprotection targeting molecular markers of protein synthesis (mTOR), autophagy (ATG5/ LC3A), and antioxidant expression (SOD2). We hypothesized that IF would improve autophagy and antioxidant expression and reduce protein synthesis in male fisher-344 rats. Methods: Twenty-four, 10-week-old male Fisher-344 rats were randomly assigned into two groups (ad-libitum, or IF) and housed 4 per cage, on a 12:12 light: dark cycle. Ad-libitum group had 24/7 access to food and water while the IF group had 24/7 access to water and full access to food on an every-other-day basis (i.e. alternate day fasting) for ten weeks. At 20 weeks of age, animals were euthanized and brain tissues (hippocampus and cortex) were sectioned and snap-frozen in liquid nitrogen. Following homogenization, western blots were completed via Jess Protein Simple automated western blotting (Bio-Techne, Minneapolis, MN). Specific proteins of interested included, LC3 (Novas, NB100-2331), ATG5 (Novas, NB110-538185S), mTOR (Santa Cruz, sc-517464) and SOD2 (Abcam, ab68155). Compass software generated area under the curve values were used to determine protein expression. Group differences were analyzed with a two-tailed T-test per Prism Graph Pad software. Results: In cortex tissue, a significantly lower mTOR expression was observed in the IF group compared to the AL group (p<.001), however, mTOR expression was not significantly different in the hippocampus. Antioxidant enzyme, SOD2, was significantly higher in IF cortex tissues (p<.05) compared to AL controls. In contrast, SOD2 was significantly lower in IF hippocampal tissues (p<.01) compared to controls. No significant effect was documented in the LC3 and ATG5 autophagy markers. Conclusion: In the present study, IF significantly impaired protein synthesis (via mTOR expression) in the cortex only. Previous work has also concluded the downregulation of mTOR with both calorie restriction and fasting. However, the fact that no decline was present in the hippocampus is intriguing and will be the focus of follow-up investigations. As expected, IF increased antioxidant enzyme (SOD2) expression in the cortex and interestedly, IF decreased antioxidant expression in the hippocampus. While the hippocampus is noted for its high antioxidant content, this decreased expression induced with IF warrants more research. P20GM113109 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.