急性恐惧应激对大鼠行为、激素水平及脑Erk1/2活化表达的影响

目的:探讨急性恐惧应激对大鼠情感行为、激素水平及不同脑区Erk1/2活化表达的影响。方法:采用足电击 白噪声刺激方式建立急性恐惧应激大鼠模型,观察其情感行为的改变;放射免疫法及荧光分光光度法检测血浆和脑组织激素水平;Westernblot检测Erk1/2的活化表达。结果:应激后大鼠旷场活动性降低、拒俘反应性增加、惊吓反应增强(P<0.01);血浆及脑组织去甲肾上腺素、5-羟色胺、皮质醇水平增高,而肾上腺髓质素水平降低(P<0.01);海马、纹状体、前额皮质、小脑等脑区磷酸化Erk1/2蛋白的表达均显著增高(P<0.01)。结论:急性恐惧应激可以显著影响大鼠的情感行为和激素水平,Erk1/2蛋白磷酸化水平的增高可能参与了急性恐惧应激所致的情感行为异常。

The effects of acute fear stress on emotional behaviors, plasmic hormone levels and the activation of cerebral Erk1/2 of rats

Aim:To study the effect of acute fear stress on emotional behaviors,Hormone levels,and the expression and activation of cerebra Erk1/2 of rats in vivo.Methods:Fourty eight male SD rats were divided randomly into control group and stress group.Rats of stress group received 30 min's acute stress including foot shock and white noise,and then the emotional behaviors were observed.The hormone level in plasm and brain was determined by spectrophotofluorometry and radioimmunoassay kit.In the following experiments,Western blot was performed to determine the expression and phosphorylation of extracellular signal-regulated protein kinase(Erk)of four different regions of the brain.Results:Rats tested after acute fear stress displayed substantial decreases in open-field activity,increases in resistance to capture,and increases in fright reaction(P<0.01).The stress also resulted in significantly higher plasmic and cerebral noradrenaline,corticosteroid,5-hydroxytryptamine levels,and lower adrenomedulin level in comparison with the control(P<0.01)after stress.At the time point of 0 min and 30 min after stress,the phosphorylation of Erk1/2 were increased in all four brain regions examined(hippocampus,striatum,prefrontal cortex and cerebellum).Conclusion:Acute fear stress can induce abnormalities of emotional behaviors,such as behavioral habits,anxiety and defense,startle and delayed adaptation to startle,as well as the alteration of hormone levels.The phosphorylation of Erk1/2 may play a role in the abnormality of emotional behaviors of rats induced by acute fear stress.