Department of Physiology, School of Basic Medicine, Qingdao University, Qingdao, China.
Department of Physiology, School of Basic Medicine, Qingdao University, Qingdao, China.
Neuropeptides. 2020 Apr;80:102019. doi: 10.1016/j.npep.2020.102019. Epub 2020 Jan 16.
The amygdala is a complex structure involved in the regulation of emotional behaviors including fear and anxiety. The central amygdala is the main output of the amygdala and plays an important role in emotional processing. Recent studies indicate that orexin, a kind of neuropeptides responsible for maintaining wakefulness, is also associated with emotion-related behaviors, such as depression- and anxiety-like behaviors. Central amygdala receives orexinergic fibers originating from the lateral hypothalamus and expresses OX receptors in rats. To test the electrophysiological and behavioral effects of orexins in the central amygdala, single unit in vivo extracellular recordings, open field and elevated plus maze tests were performed in rats. Micro-pressure administration of orexin-A (0.01 mmol/L) increased the firing rate in 18 out of the 31 central amygdala neurons, while the other 13 neurons were not excited by orexin-A. The excitatory effects of orexin-A on central amygdala neurons were mainly mediated by OX receptors rather than OX receptors. Orexin-B (0.01 mmol/L) did not change the firing activity in all recorded central amygdala neurons. Selectively blocking OX receptors by SB-334867 (0.01 mmol/L) significantly decreased the spontaneous firing rate in 14 out of the 33 central amygdala neurons, leaving the remaining 19 neurons were not affected. However, blocking OX receptors by TCS-OX2-29 (0.01 mmol/L) did not change the firing activity. Finally, both open field test and elevated plus maze test showed that bilateral microinjection of orexin-A into the central amygdala induced significantly anxiolytic-like behaviors. The specific OX receptor antagonist tended to produce opposite effects although there was no statistical difference. The present electrophysiological and behavioral studies suggested that orexin-A participates in anxiety-like behaviors by modulating the spontaneous firing activity of central amygdala neurons.
杏仁核是一个参与调节情绪行为的复杂结构，包括恐惧和焦虑。中央杏仁核是杏仁核的主要输出，在情绪处理中起着重要作用。最近的研究表明，食欲素，一种负责维持觉醒的神经肽，也与情绪相关的行为有关，如抑郁和焦虑样行为。中央杏仁核接收来自外侧下丘脑的食欲素能纤维，并在大鼠中表达 OX 受体。为了测试中央杏仁核中食欲素的电生理和行为效应，在大鼠中进行了单细胞在体细胞外记录、旷场和高架十字迷宫测试。微压给予食欲素-A（0.01mmol/L）增加了 31 个中央杏仁核神经元中的 18 个的放电率，而其他 13 个神经元不受食欲素-A的兴奋。食欲素-A对中央杏仁核神经元的兴奋作用主要是通过 OX 受体而不是 OX 受体介导的。食欲素-B（0.01mmol/L）没有改变所有记录的中央杏仁核神经元的放电活动。选择性地用 SB-334867（0.01mmol/L）阻断 OX 受体显著降低了 33 个中央杏仁核神经元中的 14 个的自发放电率，而其余 19 个神经元不受影响。然而，用 TCS-OX2-29（0.01mmol/L）阻断 OX 受体没有改变放电活动。最后，旷场试验和高架十字迷宫试验均显示，双侧微注射食欲素-A 到中央杏仁核诱导了明显的抗焦虑样行为。虽然没有统计学差异，但特定的 OX 受体拮抗剂倾向于产生相反的效果。本电生理和行为研究表明，食欲素-A 通过调节中央杏仁核神经元的自发放电活动参与焦虑样行为。
