BACKGROUND The importance of the brain renin-angiotensin system in cardiovascular function is well accepted. However, not knowing the precise source of renin in the brain has been a limitation toward a complete understanding of how the brain renin-angiotensin system operates. METHODS Highly sensitive in situ hybridization techniques and conditional knockout mice were used to address the location and function of renin in the brainstem. RESULTS We identified novel renin-expressing cholinergic neurons in the nucleus ambiguus (NuAm), a major vagal cardioinhibitory center in the brainstem. The expression of renin-angiotensin system genes was relatively abundant in the NuAm, implying that angiotensin II might mediate an important regulatory role in this nucleus and other regions with neural connectivity to the NuAm. Then, we generated conditional knockout mice lacking the classical renin isoform (Ren-aChAT-KO), specifically in cholinergic neurons. Ablation of Ren-a in cholinergic neurons abrogated renin expression in the NuAm. Moreover, studies using radiotelemetry, heart rate variability analyses, and pharmacological approaches revealed that the parasympathetic nervous system is depressed in Ren-aChAT-KO males while augmented in the Ren-aChAT-KO females. Subsequently, transcriptomic approaches were used to infer putative genes and signaling pathways regulated by renin within the NuAm. CONCLUSIONS This study revealed that renin in cholinergic neurons plays a fundamental role in preserving autonomic balance and cardiovascular homeostasis in a sex-dependent manner. These findings define the NuAm as an endogenous, local source of renin with biological function and serve as conclusive evidence for the presence and functionality of the brain renin-angiotensin system.

中文翻译：

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在模糊核中表达肾素的胆碱能神经元的鉴定和功能的明确证据。


背景 脑肾素-血管紧张素系统在心血管功能中的重要性已被广泛接受。然而，不知道大脑中肾素的确切来源一直是完全了解大脑肾素-血管紧张素系统如何运作的限制。方法 采用高灵敏度原位杂交技术和条件性敲除小鼠来研究肾素在脑干中的位置和功能。结果我们在脑干中的主要迷走神经心脏抑制中心模糊核 （NuAm） 中鉴定了新的表达肾素的胆碱能神经元。肾素-血管紧张素系统基因在 NuAm 中的表达相对丰富，这意味着血管紧张素 II 可能介导该细胞核和其他与 NuAm 有神经连接的区域的重要调节作用。然后，我们生成了缺乏经典肾素亚型 （任-aChAT-KO） 的条件性敲除小鼠，特别是在胆碱能神经元中。胆碱能神经元中 任-a 的消融消除了 NuAm 中肾素的表达。此外，使用放射遥测、心率变异分析和药理学方法的研究显示，任-aChAT-KO 男性的副交感神经系统受到抑制，而 任-aChAT-KO 女性的副交感神经系统得到增强。随后，使用转录组学方法推断 NuAm 内肾素调节的推定基因和信号通路。结论 本研究揭示了胆碱能神经元中的肾素以性别依赖性方式在维持自主神经平衡和心血管稳态方面起着重要作用。这些发现将 NuAm 定义为具有生物学功能的内源性局部肾素来源，并作为脑肾素-血管紧张素系统存在和功能的决定性证据。