目的　探讨慢性应激对大鼠海马CA3区长时程增强 (LTP)的影响及机制。方法　将 34只Wistar大鼠随机分成应激组 (8只 )、应激 +盐水组 (8只 )、应激 +MK 80 1组 (8只 )及空白对照组 (1 0只 ) ,应激刺激为饮水冲突模型 ,分别于实验初和LTP检测前 1天评定大鼠情绪性行为 ,在应激 1 5天后检测大鼠强直性LTP ,测量强直后 1 ,5 ,1 0 ,30 ,60 ,90 ,1 2 0minLTP群体峰电位幅度及峰潜期。结果(1 )应激前各组情绪性行为评分的差异均无显著性 ;应激后 ,应激 +盐水组 [(4 33± 0 50 )分 ]、应激 +MK 80 1组 [(3 60± 0 55)分 ]及应激组 [(2 90± 0 74)分 ]的评分均高于对照组 [(2 0 2± 1 1 6)分 ] ,差异有显著性 (P =0 0 0 0 ) ;(2 )应激组测试刺激阈值较对照组高 (45V∶30V) ;(3)在强直后第 1 ,90min时的LTP群体峰电位变化率应激组 [分别为 (2 1 1± 58) %和 (2 4 3± 69) % ]、应激 +盐水组 [分别为 (1 69±92 ) %和 (1 82± 1 61 ) % ]低于对照组 [分别为 (30 2± 2 1 0 ) %和 (30 3± 1 4 1 ) % ]和应激 +MK 80 1组 [分别为(375± 99) %和 (489± 2 36) % ] ,差异有显著性 (P <0 0 5) ,应激 +MK 80 1组与对照组的差异无显著性 ;(4)各应激组于各时点LTP峰潜期均较对照组长 ,但差异未呈显著性。结论　慢性 Objective To investigate the effect and mechanism of chronic stress on long-term potentiation (LTP) in hippocampal CA3 region of rats. Methods Thirty - four Wistar rats were randomly divided into stress group (n = 8), stress + saline group (n = 8), stress + MK 80 1 group (n = 8) and blank control group The stimulus was drinking water conflict model. Emotional behavior of rats was assessed one day before LTP test and one day before LTP test. TTP was measured at 15 days after stress, and the rats were sacrificed at 1, 5, 10, 30, 60, 90, 120minLTP population peak potential amplitude and peak potential. Results (1) There was no significant difference in the scores of emotional behavior among groups before stress. After stress, the stress + saline group [(433 ± 0 50) 60 ± 0 55) and stress group [(2 90 ± 0 74) points] were significantly higher than that of the control group [(2 0 2 ± 1 1 6) points], the difference was significant (P = 0 0 (2) The stimulus threshold of the stress group was higher than that of the control group (45V: 30V); (3) The stress of the LTP group at the first and the 90th minutes after tonic stress was [2 1 1 ± 58%, and 24 ± 69%, respectively, and those in stress + saline group were (1 69 ± 92)% and (1 82 ± 1 61)%, respectively 2 ± 2 1 0% and 30 3 ± 1 4 1%, respectively) and stress + MK 80 1 group (375 ± 99% and 489 ± 2 36%, respectively), with significant difference ( P <0.05). There was no significant difference between the stress + MK 80 1 group and the control group. (4) The LTP peak latency of each stress group was longer than that of the control group at each time point, but the difference was not significant . Conclusion Chronic