Joint Effects of Low Ambient Temperature and Nocturnal Eating Behavior Contributing to Glycolipid Metabolism Disorder by Changing Gut Microbiota Structure

Objective: Diabetes has emerged as a prominent public health issue significantly impacting human health, evidenced by a consistent annual increase in patient cases. Winter plays a pivotal role in either initiating or exacerbating diabetes, although the precise mechanisms underlying this phenomenon remain unclear. Our previous work was consistent with the findings, indicating an intriguing potential link between glycolipid metabolism and the circadian clock, such as ambient temperature and dietary rhythms. So in this research, we endeavor to delve into the intricate relationship among ambient temperature, diurnal dietary rhythms, and glycolipid metabolism via animal experiments, ultimately aiming to shed light on the potential mechanisms through which the circadian clock may initiate or exacerbate diabetes. Methods: Thirty-six healthy rats were randomly assigned to four groups(N=9), with each group exposed to a unique combination of temperature (25°C or 16°C) and time-restricted feeding schedules (8:00 ~ 20:00 or 20:00 ~ 8:00). After a 10-day experimental period, we assayed the levels of fasting insulin (FINS), adiponectin, cortisol, leptin, and other homeostatic energy substances in serum. Furthermore, we investigated the neurotransmitter content in serum, blood metabolic profiles, and alterations in gut microbiota. Results: Notably, exposure to low temperatures elevated the food consumption and body mass of the rats, whereas nocturnal eating syndromes contributed to hyperinsulinemia and insulin resistance, subsequently improving microbial imbalances. In the experiment, the low-temperature nocturnal eating group rats showed a notable decrease in the relative abundances of Bacteroidetes and Actinobacteria (P < 0.05). Serum metabolite analysis revealed that both ambient temperature and dietary rhythm affect glucose, lipids, and amino acid metabolism. Neurotransmitters and blood lipid profile changes can cause an intestinal flora imbalance. Conclusion: Our study indicates that glycolipid metabolism disorders are caused by low temperatures and nocturnal eating, possibly due to changes in gut microbiota and neurotransmitter levels. Increasing ambient temperature and managing gut microbiota in winter may help prevent and treat diabetes.