Elsevier

Neuroscience Letters

Volume 260, Issue 3, 5 February 1999, Pages 161-164
Neuroscience Letters

Orexin A-like immunoreactivity in the rat brain

https://doi.org/10.1016/S0304-3940(98)00977-XGet rights and content

Abstract

Distribution of orexin-A-like immunoreactivity (ORX-LI) in rat brains was investigated with the use of a rabbit polyclonal antibody against the full length peptide orexin A. Virtually all the ORX-LI cell bodies were observed in the lateral hypothalamus at the level of median eminence. The large majority of ORX-LI neurons appeared spherical or fusiform, 20–30 μm in diameter and issued two to five cell processes with few secondary branchings. Numerous ORX-LI fibers were observed in subregions of the hypothalamus. ORX-LI cell processes were sparsely distributed in the cortex, hippocampus and thalamus. Many varicose ORX-LI cell processes were situated close to the 3rd and lateral ventricles, some of which appeared to be protruding into the lumen. As a corollary, orexin A may be released into the ventricles and interact with neurons in distant targets, in addition to influencing the activity of neurons with which ORX-LI axons make synaptic contacts.

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Acknowledgements

This study was supported by NIH Grants NS18710 and HL51314 from the Department of Health and Human Services.

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