Experiment Study Of Impaction Of Change Of Stress Intensity And Duration On The Expression And The Habituational Expression Of HSP70mRNA In Different Month Rats Hippocampus

When creature were faced with different noxiouses, such as hyperthemic, hypoxic and inflammation, heat shock response which is cellular processional responses would take place in order to protect themselves. Heat Shcok Proteins (HSPs) are a sequence of conservative company proteins relating with the protection of cellular stress and enhancing the anti-imflammation, thermotolerance, anti-shock ability of the creature. Stress will induce the expression of multiorganizes' HSPs , HSP70 is the most important one in all HSP families and has wide expression scope and quantity.HSP70 can be found in normal cell cytoplasm and endoplasm, it has many kinds of biologic functions:taking part in immune regulation; restraining the production of the ROS and cellular factor in order to protect the cell and organizes;HSP70 is also one of the molecular chaperones,. which takes part in the transfer, congregate, collapse , and removes the denatured protein .In addition , HSP70 has the function of anti-oxyzation and mudulation of the cell cycle.The expression of HSP70rnRNA increases notablely and has differentexpressional duration because of the diversity of the character and continuance of the stressor during stress. Some reserches indicate that the expression of HSP70 can be observed in 15min in cerebraK cerebellum and brain stem after injury. The expression of HSP70mRNA keeps relative high level in 6 hour after stress. Hyperthemia can induce the experession of HSP70mRNA of the rats hypothalamia and gyrus dentatus cell, but there is hardly HSP70 expression in brain stem nerve cells. At the same time , there were some researches report that the expression of HSP70 is influenced by age. In vitro experiment , the expression of HSP70 reduced in the aging cell . Nitta once improved that terminal T cell would express HSP70 more fewer than early T cell in heat shock response (HSR ), and the inducement of HSP70 tooks place at transcription level. In vitro ,the HSP70-induced would weaken in aged rats' skin, lung and brain. Therefore, the cellular ability of sythesizing the HSP70 depressed during ageing. In our experiment , we build stress animal model by using differntent intensity forced-swimming .Animals divided into two groups, young rats(3 month old) and aged rats(15 month old) , every group is randomly divided into subgroups , every gourp is forced to swming in the 4°C admixture of ice and water and the 25°C warm water . In chronic stress experiment , we random choose one subgroup as the habituation group, and choose the unstimulate animal as the control group. After the stress ,we get the rats hippocampus at Ominu 30min, lhu 3hu 6h, and examine the expression of the HSP70mRNA by RT-PCR, in order to observe the difference of HSP70mRNA expression between the basic level and the stressed level . We take the blood samples after the stress , and determine the cortisol level of serum by radioimmunoassaym metheod , in order to evaluate the infulence of the stress on the body hormone .To observe the inflence of different intensive stress and age on the change of animal' s behavior by using open-field test .The result of the experiment are as follows:1. Influence on the expression of HSP70mRAN under chronic forced-swimming stress of hippocampus at different month rats: After 8 days 25°C warm forced-swimming stress, the expressions of the HSP70mRNA of young rats and old rats are all obvious different with the control groups separately at 2 time points (KO. 01) and 4 points(K0. 01) , the expression of the HSP70mRNA is also distinction with each other at 4 time points (K0. 01) between the two different age groups. The expression of the HSP70mRNA increases after the stress, and then it becomes decreasing.2. Influence on the expression of HSP70mRAN under different intensity and duration stress at different month rats hippocampus: The rats were separately forced-swimming in the 4°C ice water and in the 25 °C warm water. There is significant difference between experiment group and control group at every time point(/<0. 01). Meanwhile , the expressions of HSP70mRNA are very different between intensity group and chronic stress group at 5 time points (KO. 05) , and with the prolong of time , the expressions of HSP70mRNA become decreasing.3. Change of the expression of HSP70mRAN under chronic stress habituation and enforced stress: The chronic stress habituation group was forced swimming in 25°C warm water for 8 days;the enforced stress group was forced-swimming in 25°C warm water for 7 days and then in 4 °C ice water for 1 day . The result shows that the expression of HSP70mRNA between two groups is different at every time pionts (FKO. 05) .4. Influence on the cortisol level of serum under different duration stress at different month age rats :Diffferent intensive stress have no significent influence on the serum level of cortisol at the same aged rat . Otherwise the same stress mode has obviously influence at different month rats (K0. 05) .5. Change of different month rats behavior under chronic stress habituation and enfored stress : Observe the change of rats'behaviors by recording the number of quadrant crossing , time delay in center grid ,the number of face cleaning. The results show that all the behaviours have changed notably (KO. 05) . Conclusion:1. Influence on the expression of HSP70mRAN under chronic foced-swinuning stress of the rats hippocampus: After 8 days forced-swimming stress, the expressions of HSP70mRNA of young and old rats are all higher than that of the control groups , and it rises immediately and then falls down to the basic level after 6 hours of stress . The result shows that when body is exposed to chronic stressor , the HSP70 synthesis will increase immediately , but then it will decrease with the prolong of time. The difference between the young and old groups indicates that ageing is one of the influence factors of responsive ability to stress.2. Influence on the expression of HSP70mRAN under different intensity and duration stress of different month rats hippocampus: All kinds mode stresses can induce the increasing of the HSP70mRNA expression , but with the prolong of the time and the addtion of the stress intensity , the index aslo increase notably.3. Change of the expression of HSP70mRAN under the stress habituation and enforced stress : After repeated forced-swimming , the expression of HSP70mRAN represents habituation , then if the animal were forced to swimm in 4°C cold water , the expression rises up obviously . These results reveal that the adaption takes place when organism were exposed to low repeated stress .At that time , if the stressor was changed , it would reverse the habituation.4. Change of the cortisol level of serum : Both intensive and chronic stress induce the increasing of the cortisol level of serum. The changeof the cortisol level of serum in different old rats who accept the same9stress is very significent (/KO. 05) .5. Change of the animal behavior: Chronic stress and enhanced stress both have notable effect on the animal behaviors. Most behavioral index decreased after the stress . After that , if the stressor enhanced , the habituation can be reversed and behaviors increase.