The Protective Effect Of Vitamin A And Vitamin Eagainst Free Radical Damage By Radiation In Rat And The Relationship Between Dosages-effect

Free radical biology and radiation medical science are the extremely active studies and research areas. The preventive and treatment of radiation injury are difficult areas which are not still solved. People are seeking for ways to solve them. Recently, more and more attention has been payed to the relations between radiation and free radical. To prevent the radiation damage, people have found a new way to scavenge free radical. Some laboratories focus on effective antioxidants and use them to inhibit peroxidation induced by radiation reasonably.In 1990, the hypothesis of "Multi-antioxidants chain" was raised and then was proved by some laboratories. The basis of theory is: distinct form of antioxidant that to acqure high efficient electric charge, should be one with different warter-solvable or fat-solvable, different molecular weight different staying and action site, different electric change, and that could play an important role on inhibiting reactive oxygen species injury, Accoring the above hypothesis, the aims of this thesis were to demostrate the relationship between vitamin A and vitamin E against oxidative stress and the relation between dosages of VA, VE in order to provide experimental basis for combine ation of antioxidants using .71Those data suggested that reciprocal protective effects between vitamin A and vitamin E might strongly contribute to the defence of membranes against oxidative stress. Radical scavenger or oxidation is a chain-breaking antioxidant that prevents the propagation of free radical damage. A few radical scavengers can not block this chain reaction. Some external antioxidant as SOD, GSH etc. cannot enter the cells, so it is very difficult for them to take an effect.Lately, professor L.Packer, the president of international free radical association, has raised a new concept of "antioxidants network", trying to explain why singal antioxidant can not have a good effect on getting rid of Ros in systematic level of body. It is possible to use antioxidants compound to refrain radiation damage. Therefore, it is very important to study the interaction between vitamin A and vitamin E in anti-radiation and the interrelation between their dosages and effects.In our study, we payed our attention to the following points: 1. Radiation injury style determined through lipid peroxidation in vivo of rat. 2. Vitamin A and vitamin E may strongly contribute to the defence of membranes against oxidative stress. Vitamin A and E represent an important defensive system against free radicals. Particularly, vitamin E acts as an anti-oxidant by scavenging free radicals. 3. Vitamin A consumes Vitmamin E during antilipid peroxidation. 4.Pathological changes obscued during the later phase of protection factor stress.As results we found that MDA significantly rised in rat. Vitamin A and E were reduced after the radiation, whichsuggested those Vitamin A and E both have the function of antioxidation. As a free radical scavenger, the content of SOD rised, which suggested that it could induce increase of some enzyme content when radiated. We also found that the contents of some enzymes and vitamins changed after giving Vitamin A and E. Vitamin A could consume Vitamin E when both of them were used. Thus we concluded that radiation could irratate lipid peroxidation. Vitamin A and E represent an important defensive system against free radicals reactions. Vitamin A consumes Vitmamin E during they are used at the same time. So we must pay attention to using combining medicine.