Repeated stressor exposure enhances contextual fear memory in a beta-adrenergic receptor-dependent process and increases impulsivity in a non-beta receptor-dependent fashion.
Repeated stressor exposure enhances contextual fear memory in a beta-adrenergic receptor-dependent process and increases impulsivity in a non-beta receptor-dependent fashion.
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DOI：
10.1016/j.physbeh.2015.03.008
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发表时间：
2015-10-15
影响因子：
2.9
通讯作者：
Johnson JD
中科院分区：
文献类型：
--
作者：
Camp RM;Johnson JD
压力通过释放去甲肾上腺素和刺激-肾上腺素能受体（β-ARs）促进记忆的形成。先前的数据表明，反复的压力源暴露会增加杏仁核内的去甲肾上腺素的转换和β-AR信号，这导致了一些压力引起的行为改变可能是由于促进了联想学习的假设。为了验证这一点，费舍尔大鼠暴露在慢性轻度压力下四天。第5天，受试者（包括非应激对照组）在进入操作箱（动物接受两次轻度足部电击）或被动回避装置（动物在进入暗室时接受一次足部电击）之前注射β受体阻滞剂普萘洛尔或vehicle。24小时后，受试者返回操作箱进行冻结测量或返回被动回避仪进行进入暗室潜伏期测量。研究对象还在一个开放的领域进行了测试，以评估情境无关的焦虑样行为。暴露于慢性压力下的动物在操作箱中表现出比对照组明显更多的冻结行为，而在条件反射试验中，这种夸张的冻结被普萘洛尔阻止了。在开阔的场地上，压力对行为没有影响。出乎意料的是，暴露于慢性压力下的受试者的滞留潜伏期显著降低。这些结果表明，长期暴露在压力下会导致复杂的行为变化。虽然反复的压力似乎会增强恐惧记忆的形成，但它也会导致类似于冲动行为的行为反应，从而导致糟糕的决策。
Memory formation is promoted by stress via the release of norepinephrine and stimulation of beta-adrenergic receptors (β-ARs). Previous data demonstrate that repeated stressor exposure increases norepinephrine turnover and β-AR signaling within the amygdala, which led to the hypothesis that some stress-induced behavioral changes are likely due to facilitated associative learning. To test this, Fischer rats were exposed to chronic mild stress for four days. On day 5, subjects (including non-stressed controls) were injected with the beta-blocker propranolol or vehicle prior to conditioning in an operant box (animals receive two mild foot shocks) or passive avoidance apparatus (animals received a foot shock upon entry into the dark chamber). Twenty-four hours later, subjects were returned to the operant box for measurement of freezing or returned to the passive avoidance apparatus for measurement of latency to enter the dark chamber. Subjects were also tested in an open field to assess context-independent anxiety-like behavior. Animals exposed to chronic stress showed significantly more freezing behavior in the operant box than did controls, and this exaggerated freezing was blocked by propranolol during the conditioning trial. There was no effect of stress on behavior in the open field. Unexpectedly, retention latency was significantly reduced in subjects exposed to chronic stress. These results indicate that chronic exposure to stress results in complex behavioral changes. While repeated stress appears to enhance the formation of fearful memories, it also results in behavioral responses that resemble impulsive behaviors that result in poor decision-making.