慢性应激对不同月龄大鼠行为学及雌激素水平的影响

目的：观察慢性应激对不同月龄大鼠行为学及雌激素水平的影响。方法：青年（2月龄）及老年（15月龄）雌性Wistar大鼠共36只，随机分为对照组（16只）和应激组（20只）。应激组接受慢性不可预见性应激刺激21d，随后正常饲养1周。对照组不进行任何处理。各组均于应激前、应激结束后即刻及应激后1周进行旷场实验，观察动物行为学改变。然后经尾静脉取血2ml，以放射免疫法测定血清雌二醇含量。结果：与对照组相比，应激组大鼠行为学得分和血清雌二醇水平均显著下降（P＜0.05）；老年组大鼠较青年组大鼠变化显著（P＜0.01）。且应激结束后1周差异仍具有统计学意义（P＜0.05）。结论：慢性应激对不同月龄大鼠的应激损伤程度存在差异，应激对老年大鼠的外显行为和生殖内分泌功能的损伤程度均较青年大鼠严重，提示衰老是影响机体应激反应性的重要因素之一。

Effect of chronic stress on the behavior and estradiol level in different age rats

Objective: To study the effect of chronic stress on the behavior and the estradiol level in different age rats.Methods: Thirty-six two-month-old and fifteen-month-old female Wistar rats were used in the experiments.They were randomly divided into four groups: young normal control(n=8),young stress(n=10),aged normal control(n=8) and aged stress(n=10),respectively. The stress groups were exposed to a chronic unpredictable stress for 21 days,and then they were raised normally for one week.Their behavior was determined with the method of Open field before and right after stress and one week after stress respectively.A blood sample was obtained from the vena caudalis and the serum level of estradiol was detected by radio-immunoassay.Results: Compared with the control groups,the behavioral score and the serum level of estradiol were significantly lower in the stress groups after stress(P<0.05),and they decreased more remarkably in the aged group than in the young group(P<0.01),which remained at one week after stress(P<0.05).Conclusion: Damage induced by chronic stress is different in young and aged rats,and the damages to the behavior and reproductive endocrine system are more serious in the aged rats than in the young,indicating that aging is one important influencial factor in physical stress reactivity.