Oklahoma Center for Neuroscience , Oklahoma City, Oklahoma.
Department of Veterans Affairs Medical Center , Oklahoma City, Oklahoma.
Am J Physiol Gastrointest Liver Physiol. 2018 Mar 1;314(3):G448-G457. doi: 10.1152/ajpgi.00370.2017. Epub 2017 Dec 14.
In vivo optogenetics identifies brain circuits controlling behaviors in conscious animals by using light to alter neuronal function and offers a novel tool to study the brain-gut axis. Using adenoviral-mediated expression, we aimed to investigate whether photoactivation with channelrhodopsin (ChR2) or photoinhibition with halorhodopsin (HR3.0) of fibers originating from the central nucleus of the amygdala (CeA) at the bed nucleus of the stria terminalis (BNST) had any effect on colonic sensitivity. We also investigated whether there was any deleterious effect of the adenovirus on the neuronal population or the neuronal phenotype within the CeA-BNST circuitry activated during the optogenetic stimulation. In male rats, the CeA was infected with vectors expressing ChR2 or HR3.0 and fiber optic cannulae were implanted on the BNST. After 8-10 wk, the response to graded, isobaric colonic distension was measured with and without laser stimulation of CeA fibers at the BNST. Immunohistochemistry and histology were used to evaluate vector expression, neuronal integrity, and neurochemical phenotype. Photoactivation of CeA fibers at the BNST with ChR2 induced colonic hypersensitivity, whereas photoinhibition of CeA fibers at the BNST with HR3.0 had no effect on colonic sensitivity. Control groups treated with virus expressing reporter proteins showed no abnormalities in neuronal morphology, neuronal number, or neurochemical phenotype following laser stimulation. Our experimental findings reveal that optogenetic activation of discrete brain nuclei can be used to advance our understanding of complex visceral nociceptive circuitry in a freely moving rat model. NEW & NOTEWORTHY Our findings reveal that optogenetic technology can be employed as a tool to advance understanding of the brain-gut axis. Using adenoviral-mediated expression of opsins, which were activated by laser light and targeted by fiber optic cannulae, we examined central nociceptive circuits mediating visceral pain in a freely moving rat. Photoactivation of amygdala fibers in the stria terminalis with channelrhodopsin induced colonic hypersensitivity, whereas inhibition of the same fibers with halorhodopsin did not alter colonic sensitivity.
在体光遗传学通过用光改变神经元功能来识别控制意识动物行为的大脑回路，并提供了一种研究脑-肠轴的新工具。我们使用腺病毒介导的表达，旨在研究来自杏仁中央核（CeA）的纤维在终纹床核（BNST）处用光激活通道视紫红质（ChR2）或光抑制卤化视紫红质（HR3.0）对结肠敏感性是否有任何影响。我们还研究了腺病毒对 CeA-BNST 回路中激活的神经元群体或神经元表型是否有任何有害影响，该神经元群体或神经元表型在光遗传学刺激过程中被激活。在雄性大鼠中，CeA 被表达 ChR2 或 HR3.0 的载体感染，并在 BNST 上植入光纤套管。8-10 周后，在 BNST 处用光刺激 CeA 纤维时，测量对分级等压结肠扩张的反应。使用免疫组织化学和组织学评估载体表达、神经元完整性和神经化学表型。用光激活 BNST 处的 CeA 纤维会引起结肠过敏，而用光抑制 BNST 处的 CeA 纤维则对结肠敏感性没有影响。用表达报告蛋白的病毒处理的对照组在激光刺激后，神经元形态、神经元数量或神经化学表型没有异常。我们的实验结果表明，离散脑核的光遗传学激活可用于在自由移动的大鼠模型中推进对复杂内脏伤害性回路的理解。新的和值得注意的是我们的发现表明，光遗传学技术可以用作工具来推进对脑-肠轴的理解。使用通过激光光激活并通过光纤套管靶向的 opsin 的腺病毒介导表达，我们在自由移动的大鼠中检查了介导内脏疼痛的中枢伤害性回路。用光激活终纹床核中的杏仁核纤维会引起结肠过敏，而用光抑制相同的纤维不会改变结肠敏感性。
