Land Benjamin B, Brayton Catherine E, Furman Kara E, Lapalombara Zoe, Dileone Ralph J
Department of Psychiatry, Yale University School of Medicine New Haven, CT, USA.
Front Behav Neurosci. 2014 Apr 1;8:108. doi: 10.3389/fnbeh.2014.00108. eCollection 2014.
Optogenetics is an extremely powerful tool for selective neuronal activation/inhibition and dissection of neural circuits. However, a limitation of in vivo optogenetics is that an animal must be tethered to an optical fiber for delivery of light. Here, we describe a new method for in vivo, optogenetic inhibition of neural activity using an internal, animal-generated light source based on firefly luciferase. Two adeno-associated viruses encoding luciferase were tested and both produced concentration-dependent light after administration of the substrate, luciferin. Mice were co-infected with halorhodopsin- and luciferase-expressing viruses in the striatum, and luciferin administration significantly reduced Fos activity compared to control animals infected with halorhodopsin only. Recordings of neuronal activity in behaving animals confirmed that firing was greatly reduced after luciferin administration. Finally, amphetamine-induced locomotor activity was reduced in halorhodopsin/luciferase mice pre-injected with luciferin compared to controls. This demonstrates that virally encoded luciferase is able to generate sufficient light to activate halorhodopsin and suppress neural activity and change behavior. This approach could be used to generate inhibition in response to activation of specific molecular pathways.
光遗传学是用于选择性神经元激活/抑制以及剖析神经回路的一种极其强大的工具。然而，体内光遗传学的一个局限性在于，动物必须与一根光纤相连以进行光传递。在此，我们描述了一种利用基于萤火虫荧光素酶的动物体内产生的内源性光源，在体内对神经活动进行光遗传学抑制的新方法。对两种编码荧光素酶的腺相关病毒进行了测试，在给予底物荧光素后，两者均产生了浓度依赖性的光。将小鼠纹状体共感染表达嗜盐菌视紫红质和荧光素酶的病毒，与仅感染嗜盐菌视紫红质的对照动物相比，给予荧光素后Fos活性显著降低。对行为动物的神经元活动记录证实，给予荧光素后放电大大减少。最后，与对照组相比，预先注射荧光素的嗜盐菌视紫红质/荧光素酶小鼠中，安非他明诱导的运动活动减少。这表明病毒编码的荧光素酶能够产生足够的光来激活嗜盐菌视紫红质并抑制神经活动以及改变行为。这种方法可用于响应特定分子途径的激活而产生抑制作用。
