Premium
Orexin Expression is Regulated by α‐Melanocyte‐Stimulating Hormone
Author(s) -
López M.,
Lage R.,
Tung Y. C. L.,
Challis B. G.,
Varela L.,
Virtue S.,
O'Rahilly S.,
VidalPuig A.,
Diéguez C.,
Coll A. P.
Publication year - 2007
Publication title -
journal of neuroendocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.062
H-Index - 116
eISSN - 1365-2826
pISSN - 0953-8194
DOI - 10.1111/j.1365-2826.2007.01577.x
Subject(s) - orexin , medicine , endocrinology , melanocortin , energy homeostasis , orexin a , melanocyte stimulating hormone , hypothalamus , biology , neuropeptide , hormone , corticosterone , melanocortin receptor , receptor , obesity
The hypothalamic melanocortin system plays a fundamental role in the regulation of energy homeostasis. Orexins (hypocretins) are also involved in a diverse range of physiological processes, including food intake. Previous evidence has suggested that hypothalamic orexin expression may be influenced by the central melanocortin system. Here, we studied orexin mRNA levels in pro‐opiomelanocortin‐deficient ( Pomc –/– ) mice, a mouse model lacking all endogenously produced melanocortin peptides. Orexin expression in the lateral hypothalamus was significantly increased in corticosterone deficient Pomc –/– mice. Furthermore, when circulating glucocorticoids were restored to levels within the physiological range, orexin expression remained elevated. However, i.c.v. administration of the melanocortin α‐melanocyte‐stimulating hormone (MSH) to Pomc –/– mice reduced orexin expression back down to wild‐type levels. This was independent of the effects of α‐MSH on food intake because elevated orexin expression persisted in Pomc –/– mice pairfed to α‐MSH‐treated animals. These data indicate that α‐MSH may play a role in the regulation of orexin expression in Pomc –/– , with an elevation in orexin levels contributing to the hyperphagia seen in these animals.