| 摘要: | 壓力是誘導精神障礙的潛在因子，研究證實壓力會影響大腦神經機制與行為表現。觀察恐懼學習是指透過觀察他人的情緒表達而學習恐懼的過程，可以促進個體適應厭惡性刺激，在精神障礙患者中觀察恐懼學習缺失為常見的症狀之一。本實驗室先前的研究指出雙重壓力會降低雄性小鼠觀察恐懼學習並降低杏仁核神經活性，然而壓力與觀察恐懼學習之間的分子機制並不清楚，因此本論文將利用雄性壓力小鼠模型進一步探討壓力與觀察恐懼學習之間的分子機制。首先將各組壓力與對照組小鼠杏仁核組織進行RNA定序，定序結果指出雙重壓力與觀察恐懼學習影響下降低大部分差異表現基因的表達，分析後有81個基因僅顯著差異表達於雙重壓力雄性小鼠，81個基因經過生物過程基因體分析後指出雙重壓力與觀察恐懼學習主要影響髓鞘以及膠細胞相關途徑，例如Cntn2和Sgpp2。接著我們利用聚合酶鏈鎖反應檢測各組壓力與對照組小鼠杏仁核髓鞘和膠細胞相關基因表達量，發現壓力與觀察恐懼學習確實降低Cntn2 以及Mbp在杏仁核的表達。為了驗證雙重壓力與觀察恐懼學習是否共同影響杏仁核中髓鞘和膠細胞相關基因表現，我們同樣利用聚合酶鏈鎖反應檢測 Naïve-Ctrl、Naïve-DS、OFL-Ctrl以及OFL-DS小鼠杏仁核Cntn2和Sgpp2表達，本論文發現Sgpp2的表達會受到雙重壓力和觀察恐懼學習的影響而下降。由於文獻表明血清素、催產素和多巴胺系統與精神
障礙有高度相關，同時我們也在RNA定序中發現這些基因可能參與調控雙重壓力與觀察恐懼學習，因此我們利用相同實驗方式對相關基因進行探討。本論文表明雙重壓力與觀察恐懼學習會降低杏仁核CD38以及增加Oxt與SLC6A4表達，另外也證明這些基因表達變化確實是受到雙重壓力與觀察恐懼學習共同的影響。綜合上述結果表明杏仁核髓鞘形成、血清素和催產素系統參與調控雄性小鼠雙重壓力與觀察恐懼學習的行為，也為精神障礙中觀察恐懼學習缺失的機制提供進一步見解。;Stress is known to increase the risk of mental illness. Previous studies have shown that stress affects both neuronal mechanisms in the brain and behavior. Observational fear, the process of learning fear through others, helps individuals adapt to negative stimuli, and its impairment is a common symptom in patients with mental illness. In our preliminary data, we found that male DS-Ob mice exhibited reduced freezing time during observational fear learning
test and decreased neural activity in the amygdala. However, the underlying mechanisms linking stress and observational fear learning remain unclear. In this study, we used a male
stressed-mice model to investigate this mechanism. We first performed RNA sequencing on the amygdala of each stressed mouse and found that 81 differentially expression genes were
downregulated in male DS-Ob mice. Gene Ontology (GO) analysis indicated that these genes are involved in myelin sheath formation and glial cell function, including genes such as Cntn2 and Sgpp2. Furthermore, we examined the mRNA expression of myelin-related genes in the amygdala of stressed male mice using qPCR, which revealed decreased expression of these genes in male DS-Ob mice. Given that serotonin, oxytocin and dopamine systems are frequently
implicated in mental illness, we also identified these systems in our RNA sequencing data as being related to doubled-stress and observational fear learning.Specifically, we found that the expression of CD38 decreased, while Oxt and SLC6A4 increased in male DS-Ob mice, as confirmed by qPCR. To determine whether these genes are involved in both doubled-stress and observational fear learning, we compared mRNA expression levels between Naïve and OFL groups, with or without doubled-stress. Our results showed that Sgpp2 and CD38 decreased, while Oxt and SLC6A4 increased after doubled-stress and observational fear learning in the amygdala of male mice. In summary, this thesis demonstrates that myelination, serotonin, and oxytocin systems in the amygdala play a role in regulating doubled-stress and observational fear learning in male mice. These findings offer new insights into the mechanisms underlying observational fear learning impairment in stress-induced mental illness disorders. |
