TY - JOUR T1 - Distinct Opsin 3 (<em>Opn3</em>) expression in the developing nervous system during mammalian embryogenesis JF - eneuro JO - eNeuro DO - 10.1523/ENEURO.0141-21.2021 SP - ENEURO.0141-21.2021 AU - Wayne I. L. Davies AU - Soufien Sghari AU - Brian A. Upton AU - Christoffer Nord AU - Max Hahn AU - Ulf Ahlgren AU - Richard A. Lang AU - Lena Gunhaga Y1 - 2021/08/20 UR - http://www.eneuro.org/content/early/2021/08/20/ENEURO.0141-21.2021.abstract N2 - Opsin 3 (Opn3) is highly expressed in the adult brain, however, information for spatial and temporal expression patterns during embryogenesis is significantly lacking. Here an Opn3-eGFP reporter mouse line was utilized to monitor cell body expression and axonal projections during embryonic and early postnatal to adult stages. By applying 2D and 3D fluorescence imaging techniques, we have identified the onset of Opn3 expression, which predominantly occurred during embryonic stages, in various structures during brain/head development. In addition, this study defines over twenty Opn3-eGFP positive neural structures never reported before. Opn3-eGFP was first observed at E9.5 in neural regions, including the ganglia that will ultimately form the trigeminal, facial and vestibulocochlear cranial nerves. As development proceeds, expanded Opn3-eGFP expression coincided with the formation and maturation of critical components of the central and peripheral nervous systems, including various motor-sensory tracts, such as the dorsal column-medial lemniscus sensory tract, and olfactory, acoustic and optic tracts. The widespread, yet distinct, detection of Opn3-eGFP already at early embryonic stages suggests that Opn3 might play important functional roles in the developing brain and spinal cord to regulate multiple motor and sensory circuitry systems, including proprioception, nociception, ocular movement and olfaction, as well as memory, mood and emotion. This study presents a crucial blueprint from which to investigate autonomic and cognitive opsin-dependent neural development and resultant behaviors under physiological and pathophysiological conditions.Significance StatementThe expression of the mammalian Opsin 3 (Opn3) has only recently been characterized in adults, with no significant study during embryonic development. This study utilized an Opn3-eGFP mouse line to identify Opn3-related development of the CNS and PNS. 2D and 3D fluorescence imaging revealed cell body and axonal Opn3-eGFP expression, which indicated an early onset of Opn3-eGFP in cranial and spinal nerve ganglia, and sensory organs. Embryonic expression of Opn3-eGFP was also identified in the brainstem, cerebellum, hypothalamus and thalamus, whereas Opn3-eGFP expression in the cerebral cortex and associated limbic system regions were observed postnatally. The presence of Opn3, a short-wavelength-sensitive photopigment, in many brain regions during embryogenesis is of great interest when investigating autonomic and cognitive photo-dependent neural development. ER -