Distribution of the orexin-1 receptor (OX1R) in the mouse forebrain and rostral brainstem: A characterisation of OX1R-eGFP mice

• We examined eGFP immunoreactivity throughout the mouse brain using OX1R-eGFP mice.
• Our findings agree with previous studies documenting OX1R mRNA expression, OX1R immunoreactivity and orexin innervation patterns.
• Supports the use of the OX1R-eGFP mice for future anatomical and functional studies.

We have utilised a transgenic reporter mouse in which green fluorescent protein (GFP) expression is driven by the orexin-1 receptor (OX1R) promoter to systematically map the distribution of OX1R-expressing neurons throughout the mouse forebrain and rostral brainstem. GFP labelling was observed in perikarya and fibres in an extensive range of brain loci encompassing the olfactory and cerebral cortices, dorsal and ventral pallidum, hippocampus, amygdaloid regions, septal areas, thalamic nuclei, hypothalamic nuclei and several brainstem regions, consistent with previous studies of OX1R mRNA expression. This is the first study to systematically characterise the neuroanatomical distribution of OX1R in the OX1R-eGFP mouse, confirming its veracity as a faithful reporter of OX1R expression and utility for future studies assessing the role of OX1R in more complex behaviours.