| Objective:To observe the expression of beta-Endorphin in hypothalamus and blood plasma,the apoptosis of neuron in hippocampus and changes of paw withdrawal thermal latency after WBH in rats;to investigate the effects and significances of propofol on beta-Endorphin in brain tissue and plasma after thermal stress in rats.Methods:1.72 male Wister rats were divided into 3 groups randomly.Some rats received neither anesthesia nor WBH treatment as control group(group C,n=8),some other rats were anesthetized with intraperitoneal injection of chloral hydrate followed with thermal stress by a heat instrument(450W,50Hz) as model group(group M,n=32) and other rats were anesthetized with intraperitoneal injection of propofol followed with whole body hyperthermia keeping rat core temperature at 42℃for 30 min as hyperthermia group(group HP,n=32).Sodium Chloride was given via intraperitoneal injection by the micro pump with a speed of 16 mL·kg-1·h-1 during WBH for keeping balance of fluid and elctrolyte.2.The paw withdrawal thermal latency were checked at the time of 2h,6h,12h and 24h after hyperthermia intervention in group M and group HP,and group C as well.3.Rat hypothalamus of every group was then removed rapidly according to the anatomic structure after checking the paw withdrawal thermal latency,and then was preserved under -20℃after centrifuged for 15 min.Blood plasma was preserved under -20℃after centrifuged for 15 min as well.4.Beta-Endorphin was detected with radioimmunoassay method(RIA) and neuron apoptosis of hippocampus was detected with TdT mediated dUPT nick and labeling(TUNEL) respectively.5.The design is completely random design,and one-way analysis of variance (ANOVA) was used for the measurement of data by SPSS 15.0 analysis.P-values less than 0.05 were considered to represent statistically significant differences.Result:1.The paw withdrawal thermal latency of group M and group HP were increased compared to that of control group(P＜0.05).The paw withdrawal thermal latency of group HP were increased compared to that of group M on 6 h and 12 h after thermal stress(P＜0.05).2.Beta-Endorphin in hypothalamus of group M and group HP were increased greatly compared to that of control group(P＜0.05).Beta-Endorphin in hypothalamus of group HP were increased compared to that of group M on 6 h and 12 h after thermal stress(P＜0.05).3.Beta-Endorphin in plasma of group M on T1 and group HP on T1,T2 and T3 were increased greatly compared to that of control group(P＜0.05).Beta-Endorphin in plasma of group HP were increased compared to that of group M on 6 h and 12 h after thermal stress(P＜0.05).4.The amount of apoptotic neurons increased orderly as following:group C＜group HP＜group M(P＜0.05).There were more apoptotic cell in hyperthermia group which were stained into dark brown with concentration of nuclear chromatin and lots of apoptotic bodies than that in control group(group C).Conclusion:WBH could increase the expression of stress hormone greatly which include beta-Endorphin as well.Beta-Endorphin could weaken the physiologic reaction during thermal stress as endogenous analgesic matter.The findings of present study demonstrated that hyperthermia was able to increase beta-Endorphin in brain tissue and blood plasma and could improve the paw withdrawal thermal latency in rats,and propofol could decrease the apoptosis of nureons in brain and enhance the heat adaption during thermal stress via alleviating the decreasing degree of beta-Endorphin in hypothalamus and blood plasma in rats in 24 h after thermal stress. |
PDF Full Text Request