Effect Of HSF1 Polymerization On The Temperature And CAMP Content Of Hypothalamus In Fever Rabbits

IntroductionHeat shock transcription factor (HSF) are sets of proteins rifeness exist in biology cell. Their structure and function have abroad alike. On all kinds stresses stimulative, HSF1 transforms form inactivated monomer to activated trimerization, especially heat stimulus can activate HSF1 direct.Generally speaking, the body temperature never exceed 41°C when organism communicated by inflammation. These phenomenon called fever limit which points out human body exist the systems of fever control. Our laboratory's study results show that HSF1 can depress exterior EP's production, thus restrict the increase of body temperature. But whether HSF1 takes part in the process of centrum temperature control of fever body or the possible mechanism is not clear.This study is to discuss HSF1 of thermoregulation centrum how to participate in fever limit further. We use LPS (lipopolysaccharide) to make rabbit fever model to observe the expression of HSF1 polymerization and cAMP in hypothalamus and their relationship during different fever stages; at the same time by giving quercetin to restrain HSF1 activating, we hope to study further the expression of HSF1, HSP70 and changes of cAMP content in hypothalamus in LPS-feverish rabbits.Methods1. Animol model preparationMale healthy New Zealand rabbits, 70 rabbits were divided into 4 groups by random: the control group, the quercetin group, LPS-feverish group, the quercetin+LPS -feverish group.2. Body temperature measuringThe digital thermometer probe was inserted 10 centimeters in rabbits' rectum. Value was recorded after stabilization. Mean of three values before administration was taken taken as basis temperature. In experiment process, every 10 min records temperature, until the experiment is over.3. Sample collecting and checkingTake off hypothalamus at the just time of every model. Then put them into liquid nitrogen 20 min. At last, put them into -70°C refrigerator to examine. The expression of cAMP: Radialization immunoassay. The expression of HSF1 and HSP70: Western blot. Use electrophoresis gel imaging analysisinstrument (Chemi Imager 5500) scan NC membrane. Use Flour Chen V2.0 analysis IDV to be the relatively content of HSF1 and HSP70.4. Statistic analysisAll the data use ((x|-)±s) to express. Use Excel to t test. Use Correlation anlysis to anslysis relativity.Results1. The body temperature changeIntravenous injection of LPS (1.0ug/kg) produced double-phase fever in rabbits. The body temperature increased to the first peak value at 60min (△T wasl.32±0.17°C), and to the second peak value at 180 min (△T was 1.84±0.15°C). In Q+L group, the fever period lengthened and the fever extent had a bit rising.2. cAMP expression in the hypothalamusThe expression of cAMP was increase at 60min, 180min reached the peak, then 360 min decreased to basic level. The expression of cAMP and the body temperature was positive correlation (r=0.890, P＜0.01). 3. HSF1 expression in the hypothalamusThe total expression of HSF-1 (including monomer and trimerization) wasn't obviously change. But the trimerization was gradually increased when the body temperature reached the peak (180 min) and kept some time. After the temperature reached the maximal value. The content of HSF1 trimerization and the body temperature was negative correlation (r=-0.897, P＜0.01).4.The correlation between the expression of HSF-1 and the content ofcAMPAfter the fever peak (180min～300min), the trimerization of HSF1 manifested the negative correlation with the content of cAMP (r=-0.807, P＜0.01).5. HSP70 expression in the hypothalamus:The HSP70 expression in the hypothalamus reached the peak at 180min. In Q+L group, the HSP70 expression was lower than the corresponding LPS group obviously.Brief summary1. Intravenous injection of LPS (0.5ug/kg) produced double-phase fever in rabbits and the second peak was higher than the first. Giving quercetin intracerebrovencularly strengthened the effect of LPS and made the fever period lengthened and the fever extent rised.2. The expression of cAMP and the body temperature was positive correlation.3. The total expression of HSF-1 (including monomer and trimerization) wasn't obviously change. But the trimerization was gradually increased and manifested the negative correlation with the body temperature.4. After the fever peak, the trimerization of HSF1 manifested the negative correlation with the content of cAMP.ConclusionsDuring the LPS-induced fever, it was possible that HSF1 polymerization limited the rise of the body temperature through repressing the expression of the centrum fever medium cAMP.