Age-related central regulation of orexin and NPY in the short lived African killifish Nothobranchius furzeri.

Orexin A (OXA) and neuropeptide Y (NPY) are two hypothalamic neuropeptides involved in the regulation of feeding behaviour and food intake in all vertebrates. Accumulating evidences document that they undergo age-related modifications, with consequences on metabolism, sleep/wake disorders and progression of neurodegenerations. The present study addressed the age related changes in expression and distribution of orexin A (its precursor is also known as hypocretin - HCRT) and NPY, and their regulation by food intake in the short lived vertebrate model Nothobranchius furzeri. Our experiments, conducted on male specimens, show that: 1) HCRT and OXA and NPY mRNA and protein are localised in neurons of diencephalon and optic tectum, as well as in numerous fibres projecting through the entire neuroaxis, and are co-localised in specific nuclei; 2) in course of aging, HCRT and NPY expressing neurons are localised also in telencephalon and rhombencephalon; 3) HCRT expressing neurons increased slightly in the diencephalic area of old animals, and in fasted animals, whereas NPY increased sharply; 4) central HCRT levels are not regulated neither in course of aging nor by food intake; 5) central NPY levels are augmented in course of aging, and regulated by food intake only in young. These findings represent a great novelty in the study of central orexin and NPY-ergic systems in vertebrates', demonstrating an uncommon and unprecedented described regulation of these two orexigenic neuropeptides. This article is protected by copyright. All rights reserved.