Orexin - History and Nomenclature

History and Nomenclature

In 1996, Gautvik, de Lecea, and colleagues reported the discovery of several genes in the rat brain, including one they dubbed "clone 35." Their work showed that clone 35 expression was limited to the lateral hypothalamus.

Masashi Yanagisawa and colleagues at the University of Texas Southwestern Medical Center at Dallas, coined the term orexin to reflect the orexigenic (appetite-stimulating) activity of these hormones. In their 1998 paper (with authorship attributed to Sakurai and colleagues) describing these neuropeptides, they also reported discovery of two orexin receptors, dubbed OX₁R and OX₂R.

Luis de Lecea, Thomas Kilduff, and colleagues also reported discovery of these same peptides, dubbing them hypocretins to indicate that they are synthesized in the hypothalamus and to reflect their structural similarity to the hormone secretin (i.e., hypothalamic secretin). This is the same group that first identified clone 35 two years earlier.

The name of this family of peptides is currently an unsettled issue. The name "orexin" has been rejected by some due to evidence that the orexigenic effects of these peptides may be incidental or trivial (i.e., orexin induced subjects eat more because they are awake more), though this issue is also unsettled, while other groups maintain that the name "hypocretin" is awkward, pointing out that many neuropeptides have names that are unrelated to their most important functions, and that waking is one of the important factors that supports feeding behavior. Both "orexin" and "hypocretin" will likely continue to appear in published works until a preferred name has been accepted by the scientific community.