Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Poland.
Department of Neurophysiology and Chronobiology, Institute of Zoology and Biomedical Research, Jagiellonian University in Krakow, Poland.
Brain Res. 2021 Oct 1;1768:147603. doi: 10.1016/j.brainres.2021.147603. Epub 2021 Jul 29.
Pronounced environmental changes between the day and night led to evolution of specialised mechanisms organising their daily physiology, named circadian clocks. Currently, it has become clear that the master clock in the suprachiasmatic nuclei of the hypothalamus is not an exclusive brain site to generate daily rhythms. Indeed, several brain areas, including the subcortical visual system have been recently shown to change their neuronal activity across the daily cycle. Here we focus our investigation on the olivary pretectal nucleus (OPN) - a retinorecipient structure primarily involved in the pupillary light reflex. Using the multi-electrode array technology ex vivo we provide evidence for OPN neurons to elevate their firing during the behaviourally quiescent light phase. Additionally, we report the robust responsivity to orexin A via the identified OX receptor in this pretectal centre, with higher responsiveness noted during the night. Interestingly, we likewise report a daily variation in the response to PAC1 receptor activation, with implications for the convergence of orexinergic and visual input on the same OPN neurons. Altogether, our report is first to suggest a daily modulation of the OPN activity via intrinsic and extrinsic mechanisms, organising its temporal physiology.
昼夜环境变化导致了专门的机制进化，以组织它们的日常生理学，这些机制被称为生物钟。目前，很明显，下丘脑视交叉上核中的主钟并不是产生日常节律的唯一大脑部位。事实上，最近已经有几个大脑区域，包括皮质下视觉系统，被证明在日常周期中改变了它们的神经元活动。在这里，我们将研究重点放在橄榄状前髓核（OPN）上，这是一个主要参与瞳孔光反射的视网膜接受结构。使用多电极阵列技术，我们提供了证据证明 OPN 神经元在行为静止的光相期间增加了它们的放电。此外，我们报告了在这个前髓质中心中，通过已识别的 OX 受体对食欲素 A 的强大反应性，在夜间反应性更高。有趣的是，我们同样报告了对 PAC1 受体激活的反应的每日变化，这对同样的 OPN 神经元上的食欲素能和视觉输入的汇聚具有影响。总之，我们的报告首次表明，通过内在和外在机制，对 OPN 活性进行每日调节，组织其时间生理学。
