Cold Exposure during the Active Phase Affects the Short-Chain Fatty Acid Production of Mice in a Time-Specific Manner

Natsumi Ichikawa,Hiroyuki Sasaki,Katsuki Hayashi,Shigenobu Shibata,Aato Watabe,Yijin Lyu,Momoko Imamura,Shota Furuhashi

doi:10.3390/metabo12010020

Abstract

Chronic or acute ambient temperature change alter the gut microbiota and the metabolites, regulating metabolic functions. Short-chain fatty acids (SCFAs) produced by gut bacteria reduce the risk of disease. Feeding patterns and gut microbiota that are involved in SCFAs production are controlled by the circadian clock. Hence, the effect of environmental temperature change on SCFAs production is expected depending on the exposure timing. In addition, there is limited research on effects of habitual cold exposure on the gut microbiota and SCFAs production compared to chronic or acute exposure. Therefore, the aim was to examine the effect of cold or heat exposure timing on SCFAs production. After exposing mice to 7 or 37 °C for 3 h a day at each point for 10 days, samples were collected, and cecal pH, SCFA concentration, and BAT weight was measured. As a result, cold exposure at ZT18 increased cecal pH and decreased SCFAs. Intestinal peristalsis was suppressed due to the cold exposure at ZT18. The results reveal differing effects of intermittent cold exposure on the gut environment depending on exposure timing. In particular, ZT18 (active phase) is the timing to be the most detrimental to the gut environment of mice.

Highlights

Ambient temperature is closely related to human health and depends on the strength and period of temperature
Weights corrected by body weight were increased during cold exposure at zeitgeber time (ZT)0, ZT6, and zeitgeber time 12 (ZT12) (Figure 1D)
Changes in the gut environment were evaluated by cecal pH change and the concentration of short-chain fatty acids (SCFAs)

Summary

Introduction

Ambient temperature is closely related to human health and depends on the strength and period of temperature. Cold exposure increases the risk of various diseases by affecting trauma such as chilblains, and metabolic and immune functions. Described detriments include increased risk of death in patients with ischemic heart disease [1], declined cognitive function [2], an induction of anti-inflammatory reaction [3], and increased susceptibility to infection [4]. A benefit to cold exposure is an anti-obesity effect, with enhanced function of brown fat reported in mice by exposed to a cold environment [5]. Exposure to heat temperature causes heat stroke by increasing permeability due to destruction of the intestinal mucosa [7,8,9]. Thermal acclimation due to continuous high-temperature environments improves thermoregulation and reduces the risk of serious heat illness [10]

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