[The effects of cold exposure on the ileum mechanical barrier in mice and its mechanisms].

Objective: To study the mechanisms of cold exposure mediated ileum mechanical barrier injury in mice. Methods: Twenty mice were randomly divided into the control and cold exposure groups. Both the control and cold exposure groups were placed in the climate room with (24±2)℃ and 40% humidity. The mice in the cold exposure group were moved to the climate room at (4±2)℃ every day for 3 hours for three consecutive weeks. Three weeks later, the ileum tissues of mice were collected. Changes in ileum tissue structure were observed by hematoxylin-eosin staining and Masson staining. The related protein expression levels of the tight junction, inflammatory cytokines, and the NF-κB pathway were detected by Western blot. Results: Compared with the control group, the circular muscle layer of the ileum in cold exposed mice became thin, a large number of inflammatory cells infiltrated, the length of villi became short, the depth of recess was increased, and tissue fibrosis appeared. The expression levels of ideal tight junction-associated proteins in cold exposed mice were decreased significantly (P＜0.05), while the protein expression levels of IL-1ß, IL-6 and phosphorescent p65 were increased significantly (P＜0.05). Conclusion: Cold exposure can damage the tight junction of the mouse ileum, destroy the integrity of the mechanical barrier and activate the NF-κB signaling pathway to promote the occurrence of the inflammatory response.

[Effects of prenatal maternal cold stress on spontaneous, exploratory and anxious behaviors in offspring].

OBJECTIVE: To study the effects of prenatal cold stress on the behavior and mood of offspring in pregnant rats. METHODS: Six SPF-class Wister pregnant rats were randomly divided into normal temperature control group and cold stress group with 3 rats in each group. The pregnant female rats in the normal temperature control group were kept in the environment of (22 ±2)℃, and the pregnant female rats in the cold stress group were placed in the artificial intelligence climate chamber at(4 ±0.1)℃ for 7 days before the birth, and the young rats were divided into normal temperature after the young rats were born. After the young rats were born, they were divided into normal temperature control group of male rats (MR, 22), normal temperature control group of mother rats (FR, 15), cold stress group of male rats (MC, 15), and cold stress group of female rats (FC, 15) .In the fourth generation of the offspring, the open field experiment and the elevated cross maze test were carried out. RESULTS: In the open field experiment, there was no significant difference in spontaneous activity and exploration behavior between the normal temperature control group and the cold stress group (P＞0.05). In the elevated plus maze experiment, the retention time of the open arms, the number of open arms and the distance of the male and female rats in the cold stress group were significantly higher than those in the normal temperature control group (P＜0.05). CONCLUSION: Prenatal maternal cold stress has no significant effect on spontaneous activity, exploration behavior and activity level of offspring, but the offspring have obvious abnormal behaviors with reduced anxiety behavior.