Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
Department of Neuroscience and Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, USA.
Neurobiol Dis. 2023 Sep;185:106248. doi: 10.1016/j.nbd.2023.106248. Epub 2023 Aug 1.
Benzodiazepine (BZ) drugs treat seizures, anxiety, insomnia, and alcohol withdrawal by potentiating γ2 subunit containing GABA type A receptors (GABARs). BZ clinical use is hampered by tolerance and withdrawal symptoms including heightened seizure susceptibility, panic, and sleep disturbances. Here, we investigated inhibitory GABAergic and excitatory glutamatergic plasticity in mice tolerant to benzodiazepine sedation. Repeated diazepam (DZP) treatment diminished sedative effects and decreased DZP potentiation of GABAR synaptic currents without impacting overall synaptic inhibition. While DZP did not alter γ2-GABAR subunit composition, there was a redistribution of extrasynaptic GABARs to synapses, resulting in higher levels of synaptic BZ-insensitive α4-containing GABARs and a concomitant reduction in tonic inhibition. Conversely, excitatory glutamatergic synaptic transmission was increased, and NMDAR subunits were upregulated at synaptic and total protein levels. Quantitative proteomics further revealed cortex neuroadaptations of key pro-excitatory mediators and synaptic plasticity pathways highlighted by Ca/calmodulin-dependent protein kinase II (CAMKII), MAPK, and PKC signaling. Thus, reduced inhibitory GABAergic tone and elevated glutamatergic neurotransmission contribute to disrupted excitation/inhibition balance and reduced BZ therapeutic power with benzodiazepine tolerance.
苯二氮䓬类药物（BZ）通过增强包含 γ2 亚基的 GABA A 型受体（GABARs）来治疗癫痫、焦虑、失眠和酒精戒断。BZ 的临床应用受到耐受性和戒断症状的阻碍，包括癫痫易感性增加、恐慌和睡眠障碍。在这里，我们研究了对苯二氮䓬镇静耐受的小鼠的抑制性 GABA 能和兴奋性谷氨酸能可塑性。重复给予地西泮（DZP）治疗可降低镇静作用，并降低 DZP 对 GABAR 突触电流的增强作用，而不影响整体突触抑制。虽然 DZP 不改变 γ2-GABAR 亚基组成，但存在额外的 GABAR 向突触的重新分布，导致更高水平的突触 BZ 不敏感的 α4 包含的 GABARs，以及随之而来的紧张性抑制减少。相反，兴奋性谷氨酸能突触传递增加，NMDAR 亚基在突触和总蛋白水平上调。定量蛋白质组学进一步揭示了皮质中关键的促兴奋介质和突触可塑性途径的神经适应，突出了 Ca/钙调蛋白依赖性蛋白激酶 II（CAMKII）、MAPK 和 PKC 信号。因此，抑制性 GABA 能张力降低和兴奋性谷氨酸能神经传递增加导致兴奋/抑制平衡紊乱和苯二氮䓬类药物耐受性时 BZ 治疗效力降低。
