Morphological and histological plasticity in digestive tracts of cold-acclimated Kunming laboratory mice

The present study investigated adaptive changes in the intestinal tissue structure of mice subject to long-term cold exposure. The body weight (P<0.05), total digestive-tract length (P<0.05) and small intestine length (P<0.01) of the mice were increased by cold exposure, whereas the lumen area of the duodenum remained unchanged, indicating that the digestive volume and food capacity of mice are increased in cold environment. In addition, the section and wall areas of the duodenum were significantly reduced by cold exposure (P<0.01), whereas the villus height was increased, indicating the increased thickness of mucosal layer but the decreased thickness of submucous layer in mice under long-term cold exposure. These results demonstrate that gastrointestinal tracts of small mammals are capable of adaptive changes to cope with cold environments by increasing digestive tract length and absorption area for higher absorption rate and efficiency. In contrast, the stomach size, cecum length, caecum weight, and rectum histology were not attested significantly, indicating that the morphology of these structures is relatively stable. Collectively, these results demonstrate that mice are able to adapt to changes in environment temperature and energy demand via phenotypic plasticity in digestive morphology and histology.