Leite-Panissi Christie Ramos Andrade, Ferrarese Aline Aparecida, Terzian Ana Luisa Bernardes, Menescal-de-Oliveira Leda
Department of Morphology, Stomatology and Physiology, Dental School of Ribeirão Preto, University of São Paulo, 14040-904 Ribeirão Preto, SP, Brazil.
Brain Res Bull. 2006 Apr 28;69(4):356-64. doi: 10.1016/j.brainresbull.2006.02.007. Epub 2006 Mar 7.
Tonic immobility (TI), also known as death feigning or animal hypnosis, is a reversible state of motor inhibition that is not only triggered by postural inversion and/or movement restraining maneuvers but also by repetitive stimulation and pressure on body parts. Evidence has demonstrated that the basolateral nucleus of the amygdala (BLA) is particularly associated with defensive behavior that involves the emotional states of fear and anxiety. In addition, some reports have demonstrated that serotonin (5-HT) released in the amygdala is increased during states of stress and anxiety, principally in the BLA. In the present study, we investigated the effects of serotonergic activation of the BLA on the duration of TI. The results showed that the microinjection of 5-HT (3.0 microg) into the BLA decreased the duration of TI. Similarly, the administration of a 5-HT1A agonist (0.1 microg of 8-hydroxy-dipropylaminotretalin) or 5-HT2 agonist (0.1 microg of alpha-methyl-5-HT) into the BLA reduced the TI duration. The effect of 5-HT2 agonist was reversed by pretreatment with a dose that had no effect per se (0.01 microg) of ketanserin (5-HT2 receptor antagonists) into the BLA. Moreover, the activation of 5-HT1A and 5-HT2 receptors in the BLA did not alter the spontaneous motor activity in the open field test. The results of the present study indicate that the serotonergic system of the BLA possibly produces a reduction in fear and/or anxiety that reduces the TI duration in guinea pigs, but this is not due to increased spontaneous motor activity induced by serotonergic activation, which might affect TI duration non-specifically.
紧张性不动（TI），也被称为装死或动物催眠，是一种可逆的运动抑制状态，它不仅可由体位倒置和/或运动限制动作引发，还可由对身体部位的重复刺激和压力引发。有证据表明，杏仁核基底外侧核（BLA）与涉及恐惧和焦虑情绪状态的防御行为特别相关。此外，一些报告表明，在应激和焦虑状态下，杏仁核中释放的血清素（5-HT）会增加，主要是在BLA中。在本研究中，我们研究了BLA的血清素能激活对TI持续时间的影响。结果表明，向BLA微量注射5-HT（3.0微克）可缩短TI的持续时间。同样，向BLA注射5-HT1A激动剂（0.1微克的8-羟基-二丙基氨基四氢萘）或5-HT2激动剂（0.1微克的α-甲基-5-HT）也可缩短TI持续时间。5-HT2激动剂的作用可被预先向BLA注射本身无作用剂量（0.01微克）的酮色林（5-HT2受体拮抗剂）所逆转。此外，BLA中5-HT1A和5-HT2受体的激活在旷场试验中并未改变自发运动活动。本研究结果表明，BLA的血清素能系统可能会减少恐惧和/或焦虑，从而缩短豚鼠的TI持续时间，但这并非由于血清素能激活诱导的自发运动活动增加，而自发运动活动增加可能会非特异性地影响TI持续时间。
