Orexins and their receptors in the human retina.
OBJECTIVE
Orexins A and B are neuropeptides involved in the regulation of feeding behavior, energy homeostasis and arousal. In the human retina, however, immunohistochemical localization of orexins and their receptors, OX-R1 and OX-R2, has not been ascertained.


METHODS
We localized orexins A and B, OX-R1 and OX-R2 in the human retina using immunohistochemistry. Retinae from 2 Alzheimer's disease (AD) patients provided preliminary evidence for possible orexin alterations.


RESULTS
Orexin A, orexin B and OX-R1 were localized in ganglion and amacrine cells, cellular processes in the inner and outer plexiform layer and in the inner segments of photoreceptor cells. There was no OX-R2 immunoreactivity in the retina. The staining intensity for both orexins was decreased in the AD patients.


CONCLUSIONS
This immunohistochemical study provides the first evidence for the distribution of orexin A, orexin B and OX-R1 in the human retina. The localization pattern suggests a modulatory role for orexins in the interactions of those retinal cells which transmit light information to the suprachiasmatic nuclei, and thus may be involved in circadian rhythm entrainment.
Savaskan
Egemen
E
Psychiatric University Clinic, Basel, Switzerland. esavaskan@datacomm.ch
Müller-Spahn
Franz
F
Meier
Fides
F
Wirz-Justice
Anna
A
Meyer
Peter
P
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000378:metabolism* / Q000473:pathology; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D008297:Male; D009479:Neuropeptides / Q000378:metabolism*; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide / Q000378:metabolism*; D012160:Retina / Q000378:metabolism* / Q000473:pathology
C000596229:HCRT protein, human; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide