Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia.
Novosibirsk State University, Novosibirsk, Russia.
BMC Neurosci. 2020 Mar 26;21(1):12. doi: 10.1186/s12868-020-00560-w.
Medium spiny neurons (MSNs) comprise the main body (95% in mouse) of the dorsal striatum neurons and represent dopaminoceptive GABAergic neurons. The cAMP (cyclic Adenosine MonoPhosphate)-mediated cascade of excitation and inhibition responses observed in MSN intracellular signal transduction is crucial for neuroscience research due to its involvement in the motor and behavioral functions. In particular, all types of addictions are related to MSNs. Shedding the light on the mechanics of the above-mentioned cascade is of primary importance for this research domain.
A mouse model of chronic social conflicts in daily agonistic interactions was used to analyze dorsal striatum neurons genes implicated in cAMP-mediated phosphorylation activation pathways specific for MSNs. Based on expression correlation analysis, we succeeded in dissecting Drd1- and Drd2-dopaminoceptive neurons (D1 and D2, correspondingly) gene pathways. We also found that D1 neurons genes clustering are split into two oppositely correlated states, passive and active ones, the latter apparently corresponding to D1 firing stage upon protein kinase A (PKA) activation. We observed that under defeat stress in chronic social conflicts the loser mice manifest overall depression of dopamine-mediated MSNs activity resulting in previously reported reduced motor activity, while the aggressive mice with positive fighting experience (aggressive mice) feature an increase in both D1-active phase and D2 MSNs genes expression leading to hyperactive behavior pattern corresponded by us before. Based on the alternative transcript isoforms expression analysis, it was assumed that many genes (Drd1, Adora1, Pde10, Ppp1r1b, Gnal), specifically those in D1 neurons, apparently remain transcriptionally repressed via the reversible mechanism of promoter CpG island silencing, resulting in alternative promoter usage following profound reduction in their expression rate.
Based on the animal stress model dorsal striatum pooled tissue RNA-Seq data restricted to cAMP related genes subset we elucidated MSNs steady states exhaustive projection for the first time. We correspond the existence of D1 active state not explicitly outlined before, and connected with dynamic dopamine neurotransmission cycles. Consequently, we were also able to indicate an oscillated postsynaptic dopamine vs glutamate action pattern in the course of the neurotransmission cycles.
中棘神经元（MSNs）构成背侧纹状体神经元的主体（在小鼠中占 95%），代表多巴胺能 GABA 能神经元。在 MSN 细胞内信号转导中观察到的 cAMP（环磷酸腺苷单磷酸）介导的兴奋和抑制反应级联对于神经科学研究至关重要，因为它参与了运动和行为功能。特别是，所有类型的成瘾都与 MSNs 有关。揭示上述级联的机制对于该研究领域至关重要。
我们使用一种在日常争斗互动中的慢性社会冲突的小鼠模型来分析与 MSNs 特异性的 cAMP 介导的磷酸化激活途径相关的背侧纹状体神经元基因。基于表达相关性分析，我们成功地分离了 Drd1 和 Drd2 多巴胺能神经元（分别为 D1 和 D2）基因途径。我们还发现，D1 神经元基因聚类分为两种相反相关的状态，被动和主动，后者显然对应于 PKA 激活时 D1 放电阶段。我们观察到，在慢性社会冲突中的失败应激下，失败者小鼠表现出多巴胺介导的 MSNs 活性总体下降，导致先前报道的运动活动减少，而具有积极战斗经验（攻击性小鼠）的攻击性小鼠则表现出 D1 活性相和 D2 MSNs 基因表达增加，导致我们之前报道的多动行为模式。基于替代转录本异构体表达分析，我们假设许多基因（Drd1、Adora1、Pde10、Ppp1r1b、Gnal），特别是那些在 D1 神经元中的基因，显然通过启动子 CpG 岛沉默的可逆机制保持转录抑制，从而导致其表达率显著降低后，替代启动子的使用。
基于背侧纹状体的动物应激模型的组织 RNA-Seq 数据，我们限制在 cAMP 相关基因子集，首次阐明了 MSNs 的稳态全面投影。我们对应了以前没有明确描述的 D1 活性状态的存在，并与动态多巴胺神经传递循环相关联。因此，我们还能够在神经传递循环过程中指示交替的突触后多巴胺与谷氨酸作用模式。
