Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China; Laboratory of Neuropsychiatric Diseases, Institute of Brain Research, Huazhong University of Science and Technology, Wuhan, China; Key Laboratory for Drug Target Researches and Pharmacodynamic Evaluation of Hubei Province, Wuhan, China; Key Laboratory of Neurological Diseases, Ministry of Education of China, Wuhan, China.
Biol Psychiatry. 2019 Feb 1;85(3):202-213. doi: 10.1016/j.biopsych.2018.09.024. Epub 2018 Oct 4.
Benzodiazepines (BZDs) have been used to treat anxiety disorders for more than five decades as the allosteric modulator of the gamma-aminobutyric acid A receptor (GABAR). Little is known about other mechanisms of BZDs. Here, we describe how the rapid stabilization of postsynaptic GABAR is essential and sufficient for the anxiolytic effect of BZDs via a palmitoylation-dependent mechanism.
Palmitoylated proteins in the basolateral amygdala (BLA) of rats with different anxious states were assessed by a biotin exchange protocol. Both pharmacological and genetic approaches were used to investigate the role of palmitoylation in anxiety behavior. Electrophysiological recording, reverse transcription polymerase chain reaction, Western blotting, and coimmunoprecipitation were used to investigate the mechanisms.
Highly anxious rats were accompanied by the deficiency of gephyrin palmitoylation and decreased the synaptic function of GABAR in the BLA. We then identified that the dysfunction of DHHC12, a palmitoyl acyltransferase that specifically palmitoylates gephyrin, contributed to the high-anxious state. Furthermore, diazepam, as an anxiolytic drug targeting GABARs, was found to increase gephyrin palmitoylation in the BLA via a GABAR-dependent manner to activate DHHC12. The anxiolytic effect of diazepam was nearly abolished by the DHHC12 knockdown. Specifically, similar to the effect of BZD, the overexpression of DHHC12 in the BLA exerted a significant anxiolytic action, which was prevented by flumazenil.
Our results support the view that the strength of inhibitory synapse was controlled by gephyrin palmitoylation in vivo and proposes a previously unknown palmitoylation-centered mode of BZD's action.
苯二氮䓬类药物（BZDs）作为γ-氨基丁酸 A 受体（GABAR）的别构调节剂，已被用于治疗焦虑症超过五十年。关于 BZDs 的其他机制知之甚少。在这里，我们描述了快速稳定突触后 GABAR 对于 BZD 的抗焦虑作用是如何通过棕榈酰化依赖机制成为必要和充分的。
通过生物素交换协议评估不同焦虑状态大鼠基底外侧杏仁核（BLA）中的棕榈酰化蛋白。使用药理学和遗传学方法来研究棕榈酰化在焦虑行为中的作用。电生理记录、逆转录聚合酶链反应、Western 印迹和共免疫沉淀用于研究机制。
高度焦虑的大鼠伴随着神经胶质蛋白棕榈酰化不足和 BLA 中 GABAR 突触功能下降。然后，我们确定了特异性棕榈酰化神经胶质蛋白的棕榈酰基转移酶 DHHC12 的功能障碍导致了高度焦虑状态。此外，作为一种针对 GABAR 的抗焦虑药物，地西泮被发现通过 GABAR 依赖性方式增加 BLA 中的神经胶质蛋白棕榈酰化，从而激活 DHHC12。DHHC12 的敲低几乎消除了地西泮的抗焦虑作用。具体而言，与 BZD 的作用相似，DHHC12 在 BLA 中的过表达对焦虑产生了显著的缓解作用，而氟马西尼则阻止了这一作用。
我们的结果支持了在体内抑制性突触强度受神经胶质蛋白棕榈酰化控制的观点，并提出了一种以前未知的 BZD 作用的棕榈酰化中心模式。
