Quantitative 3D imaging of orexin and orexin receptor distribution in the intact mouse brain

Background & Aim:

Orexins (Ox, also termed hypocretins) and their cognate receptors, Ox1R (Hcrtr1) and Ox2R (Hcrtr2), play an important role in controlling several fundamental physiological functions such as sleep/wakefulness, appetite regulation, energy homeostasis, reward and reproduction. Hence, disturbances in the orexin system are implicated in several diseases, notably narcolepsy, for which there is a considerable interest in developing more effective treatments. To improve circuit-level understanding of the orexin receptor system, the present study aimed to generate a complete 3D map of the orexin system in the intact mouse brain at single-cell resolution using whole-brain immunohistochemistry (IHC) and in situ hybridization (ISH).