Acute Cold Exposure On The Permeability Of The Blood-brain Barrier In Rats And The Protective Effects Of Luteolin

Cold environment may have a major impact on the body. After the body is in a cold environment for a period of time, a series of changes will happen from the stability, physiology, behaviors of the local environment in the body, and so on. The history of research on the cold has been long. the current study for cold injury is focused on the damage by the cold in metabolism , circulatory system and skin, and so on, however no more attention is paid for the research on the central nervous system injury by the cold and nerve injury-induced changes in behavior, as well as protective measures. Luteolin widely distributed in nature, which can be isolated from a variety of natural medicines, vegetables and fruit.It is able to protect the body in the cold environment. We can create models of rats exposed to the cold, study the changes the permeability of the blood-brain barrier in rats caused by acute exposure to cold, as well as changes in the behaviors,and preliminary observe probable protection effect from luteolin flavonoids to clarify the cold the damage mechanism of the nervous system and provide the theoretical basis and experimental data to find effective protective measures. ObjectiveRats were exposed to the cold acutely and the models of cold injury animal were established to discuss the permeability of the blood-brain barrier on the cold-exposed rats and the central nervous system injury of the blood-brain barrier in the opening up cold, and explore the possibility of brain protection of luteolin. Dietary nutrients in the process of the possible protective effect for the protection of cold injury was basically studied to provide a new theoretical basis, as well as possible ways.MethodsSD rats, sub-rearing caged with normal diets. SD rats, sub-rearing caged with normal diets. Experiments were randomly divided with weight: Control group: fed by the basic diet, from the beginning of the experiment put in the same environment as the cold-exposed group, but with no cold exposure; Cold-exposured group: fed by the basic diets, from the beginning of the experiment exposed to cold; Low protection groups: fed by the basic diets, from the beginning of the experiment oral administrated with 10mg/kg concentration of luteolin per day for 14 days; Medium protected group: oral administrated with 20mg/kg concentration of luteolin per day; Highly protected group: oral administrated with 40mg/kg concentration of luteolin per day. At the beginning, these groups were fed without water, except the comparison group, the other four groups were in -15℃ice frozen bank for 3hrs to the establish acute exposure to the cold animal models. With Evans blue dye and water content of brain tissue, the degree of openness of blood-brain barrier was detected, and on this basis the possible protective effect of luteolin was explored. At the same time, Morris water maze was applied to test the spatial memory on rats. Comparison with rats in the cold before and after stimulation was made to discuss whether the brain and memory space had been changed, and whether damage from the cold stimulation of the brain took place was discussed.Results1.In exposed-to-cold group and all protected groups, the EB content were significantly higher than the normal group at the same time, so there was a significant difference (p <0.05).2. After exposed to cold, brain water content of the comparison group and protected group were higher than that of the normal group, so there was a significant difference (p <0.05).But low protection and high-protection groups did not show the difference.3. EB content of protection group was significantly lower than that of the group exposed to the cold, so there was a significant difference (p <0.05).The water content of each group was lower than that of exposed-to-cold group respectively ,so the difference was significant (p <0.05).4. After exposed to the cold, spatial memory of control group and the protected groups of rats changed. It decreased, and the difference was significant(p<0.05)Conclusions1. EB content increased, which proved in the cold stimulation, rat blood-brain barrier permeability was open.2. Wet and dry ratio in the brain increased, which indicated that in the frozen period blood-brain barrier was significantly higher.3. Luteolin has a protective effect on the permeability of the blood-brain barrier in rats.4. Acutely exposed to the cold, the memory of rats have an obvious downward trend.