Figure 1.

Immunofluorescence images of orexin A immunoreactive profiles in the rat brain. All of these micrographs were generated by using the polyclonal antiserum against orexin A. (A) Coronal section through rat lateral hypothalamus showing orexin A immunofluorescence labeling in cell bodies (block arrows) and varicose axonal fibers (small arrows). (Bar = 50 μm.) (B) Coronal section through rat locus coeruleus (LC) showing dense plexus of immunolabeled axon fibers and terminals. CBM, cerebellum; IV, fourth ventricle. (Bar = 200 μm.) (C) An orexin A-responsive cell in a locus coeruleus brain slice, filled with Neurobiotin via the recording electrode. The red signal illustrates orexin A immunoreactivity, and the green signal indicates intracellular Neurobiotin. The large arrow indicates a neuronal soma bearing two main dendrites. The dendrites extend throughout the field of dense orexin A-positive varicosities. The arrowheads indicate varicosities that are closely apposed to a dendritic structure. The image is a brightest point projection of 64 confocal optical sections taken at 2-μm intervals. (Bar = 35 μm.) (Inset) Higher-power micrograph of a similarly treated section showing detail of proximity of orexin A-immunoreactive fiber varicosities to a process of an intrinsic locus coeruleus neurone. (Bar = 10 μm.)