应激对大鼠海马CREB、ERK活性的影响

The effects of different period-stresses on CREB and ERK in hippocampus of rats

目的探讨不同时段的应激对大鼠海马环磷酸腺苷反应元件结合蛋白（CREB）、细胞外信号调节激酶（ERK）活性的影响。方法将成年雄性Sprage Dawley（SD）大鼠随机分为5组：对照组（A）、应激1次组（B）、应激1周组（c）、应激2周组（D）和应激4周组（E），每组动物6只。应激模型为强迫大鼠游泳，每天15min。采用Western blot检测各组大鼠海马CREB、ERK的磷酸化及总蛋白（p-CREB和t-CREB、p-ERK／MAPK和ERK／MAPK）水平。结果B和c组大鼠海马组织的p-CREB水平与对照组比较差异无显著性（P〉0．05）；D和E组大鼠海马组织的p-CREB明显低于对照组（P〈0．05）。各应激组t-CREB水平与对照组比较均差异无显著性（P〉0．05）。C、D和E组大鼠海马p-ERK44和p-ERK42的水平显著低于对照组（P〈0．05或P〈0．01）；B组大鼠海马p-ERK44和p-ERK42的水平与对照组比较差异无显著性（P〉0．05）。各应激组和对照组大鼠海马ERK44和ERK42的总蛋白水平比较均差异无显著性（P〉0．05）。结论慢性应激降低大鼠海马CREB的活性，短时间和慢性应激均能降低大鼠海马ERK的活性。

Objective To explore the effects of different period-stresses on CREB and MAPK in hippo- campus of rats. Methods Adult male Sprague Dawley （SD） rats were used as experimental subjects. They were divided into five groups： control group（A） , group of stress once （B）, group of stress for one week （C）, group of stress for two weeks （ D ） and group of stress for four weeks （ E ）, six rats in each group. Forced-swimming was used as stress model, 15 min per day. Western blot was used to determine the levels p-CREB and t-CREB, p-ERK/ MAPK and ERK/MAPK. Results There were no significant differences of the level of p-CREB between group B and group A, and between group C and group A（ P〉 0.05 ）. The level of p-CREB in group D or group E was sig- nificantly lower than that in group A respectively（ P 〈 0.05 ） , while there were no significant differences of the lev- el of tCREB between each stressed group and control group respectively （ P 〉 0.05 ）. The levels of pERK44 and pERK42 in group C, or group D ,or group E were significantly lower than that in group A respectively（ P〈 0.05 or P〈 0.01 ） ; there were no significant differences of the levels of pERK44 and pERK42 between group B and group A （ P 〉 0.05 ）. There were no significant differences of the levels of ERK44 and ERK42 between each stressed group and control group respectively （ P 〉 0.05 ）. Conclusions Chronic stress could inhibit CREB phos- phorylation,while short-time repeated and chronic stress could inhibit the phosphorylation of ERK44 and ERK42 in hippocampus of rats .