Department and Institute of Physiology, School of Medicine, National Yang Ming Chiao Tung University, Taipei, 112, Taiwan.
Department of Psychiatry, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, 704, Taiwan.
J Biomed Sci. 2022 Jul 11;29(1):51. doi: 10.1186/s12929-022-00835-w.
Disruption of normal brain development is implicated in numerous psychiatric disorders with neurodevelopmental origins, including autism spectrum disorder (ASD). Widespread abnormalities in brain structure and functions caused by dysregulations of neurodevelopmental processes has been recently shown to exert adverse effects across generations. An imbalance between excitatory/inhibitory (E/I) transmission is the putative hypothesis of ASD pathogenesis, supporting by the specific implications of inhibitory γ-aminobutyric acid (GABA)ergic system in autistic individuals and animal models of ASD. However, the contribution of GABAergic system in the neuropathophysiology across generations of ASD is still unknown. Here, we uncover profound alterations in the expression and function of GABA receptors (GABARs) in the amygdala across generations of the VPA-induced animal model of ASD.
The F2 generation was produced by mating an F1 VPA-induced male offspring with naïve females after a single injection of VPA on embryonic day (E12.5) in F0. Autism-like behaviors were assessed by animal behavior tests. Expression and functional properties of GABARs and related proteins were examined by using western blotting and electrophysiological techniques.
Social deficit, repetitive behavior, and emotional comorbidities were demonstrated across two generations of the VPA-induced offspring. Decreased synaptic GABAR and gephyrin levels, and inhibitory transmission were found in the amygdala from two generations of the VPA-induced offspring with greater reductions in the F2 generation. Weaker association of gephyrin with GABAR was shown in the F2 generation than the F1 generation. Moreover, dysregulated NMDA-induced enhancements of gephyrin and GABAR at the synapse in the VPA-induced offspring was worsened in the F2 generation than the F1 generation. Elevated glutamatergic modifications were additionally shown across generations of the VPA-induced offspring without generation difference.
Taken together, these findings revealed the E/I synaptic abnormalities in the amygdala from two generations of the VPA-induced offspring with GABAergic deteriorations in the F2 generation, suggesting a potential therapeutic role of the GABAergic system to generational pathophysiology of ASD.
正常大脑发育的中断与许多具有神经发育起源的精神疾病有关，包括自闭症谱系障碍 (ASD)。最近的研究表明，神经发育过程失调引起的大脑结构和功能的广泛异常会对后代产生不利影响。兴奋性/抑制性 (E/I) 传递失衡是 ASD 发病机制的假设假说，这一假说得到了自闭症个体和 ASD 动物模型中抑制性 γ-氨基丁酸 (GABA) 能系统的具体影响的支持。然而，GABA 能系统在 ASD 代际神经病理学中的贡献尚不清楚。在这里，我们在 VPA 诱导的 ASD 动物模型的代际杏仁核中发现 GABA 受体 (GABAR) 的表达和功能发生了深刻变化。
通过在 F0 中对胚胎第 12.5 天 (E12.5) 的 F0 进行单次 VPA 注射，将 F1 VPA 诱导的雄性后代与未处理的雌性交配，产生 F2 代。通过动物行为测试评估类似自闭症的行为。使用 Western blot 和电生理技术检测 GABAR 及其相关蛋白的表达和功能特性。
在两代 VPA 诱导的后代中均表现出社交缺陷、重复行为和情绪共病。在两代 VPA 诱导的后代的杏仁核中发现突触 GABAR 和 Gephyrin 水平以及抑制性传递降低，且 F2 代的降低幅度更大。与 F1 代相比，F2 代 Gephyrin 与 GABAR 的结合较弱。此外，与 F1 代相比，VPA 诱导的后代中 NMDA 诱导的 Gephyrin 和 GABAR 在突触处的增强作用在 F2 代中更严重。在两代 VPA 诱导的后代中还显示出谷氨酸能修饰升高，且没有代际差异。
综上所述，这些发现揭示了两代 VPA 诱导的后代杏仁核中的 E/I 突触异常，F2 代的 GABA 能恶化，这表明 GABA 能系统对 ASD 的代际病理生理学具有潜在的治疗作用。
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