Response of gut microbiota to fasting and hibernation in Syrian hamsters

Abstract

Although hibernating mammals wake occasionally to eat during torpor, this period represents a state of fasting. Fasting is known to alter the gut microbiota in nonhibernating mammals; therefore, hibernation may also affect the gut microbiota. However, there are few reports of gut microbiota in hibernating mammals. The present study aimed to compare the gut microbiota in hibernating torpid Syrian hamsters with that in active counterparts by using culture-independent analyses. Hamsters were allocated to either torpid, fed active, or fasted active groups. Hibernation was successfully induced by maintaining darkness at 4 degrees C. Flow cytometry analysis of cecal bacteria showed that 96-h fasting reduced the total gut bacteria. This period of fasting also reduced the concentrations of short chain fatty acids in the cecal contents. In contrast, total bacterial numbers and concentrations of short chain fatty acids were unaffected by hibernation. Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments indicated that fasting and hibernation modulated the cecal microbiota. Analysis of 16S rRNA clone library and species-specific real-time quantitative PCR showed that the class Clostridia predominated in both active and torpid hamsters and that populations of Akkermansia muciniphila, a mucin degrader, were increased by fasting but not by hibernation. From these results, we conclude that the gut microbiota responds differently to fasting and hibernation in Syrian hamsters.

Figures

FIG. 1.

PCR-DGGE analysis of the cecal microbiota based on 16S rRNA gene sequences in hamsters. (Top) DGGE gel image stained with SYBR green. (Bottom) Similarities among DGGE band profiles of cecal bacteria of hamsters were calculated based on the positions and intensities of bands, and the dendrogram of DGGE band profiles was constructed by the unweighted pair-group method with arithmetic mean clustering method. Each lane in the gel and each line in the dendrogram represent individual hamsters. Distances were measured in arbitrary units.

FIG. 2.

Populations of Akkermansia muciniphila in cecal contents of hamsters. RT-qPCR with a species-specific primer pair was performed to estimate the populations of A. muciniphila. Each closed circle represents a value for an individual hamster, and horizontal bars represent mean values. Mean values with different letters were significantly different (P < 0.05) as estimated by Tukey-Kramer's test following a one-way analysis of variance.