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Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model
Published on: September 7, 2013
Orexin expression is regulated by alpha-melanocyte-stimulating hormone.
1Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, Cambridge, UK.
Journal of Neuroendocrinology
|August 8, 2007
Summary
Alpha-melanocyte-stimulating hormone (MSH) regulates orexin expression in pro-opiomelanocortin-deficient mice. This finding suggests MSH influences orexin levels, potentially contributing to hyperphagia in these models.
Area of Science:
- Neuroendocrinology
- Energy Homeostasis Regulation
Background:
- The hypothalamic melanocortin system is crucial for energy balance.
- Orexins (hypocretins) influence physiological processes, including feeding behavior.
- Central melanocortin signaling may impact hypothalamic orexin expression.
Purpose of the Study:
- To investigate the effect of the central melanocortin system on orexin mRNA levels.
- To examine orexin expression in pro-opiomelanocortin-deficient (Pomc(-/-)) mice lacking endogenous melanocortins.
Main Methods:
- Analysis of orexin mRNA levels in Pomc(-/-) mice.
- Assessment of orexin expression following restoration of circulating glucocorticoids.
- Intracerebroventricular administration of alpha-melanocyte-stimulating hormone (MSH) to Pomc(-/-) mice.
- Pair-feeding studies to differentiate MSH effects from food intake.
Main Results:
- Orexin expression was significantly increased in Pomc(-/-) mice.
- Elevated orexin expression persisted even after normalizing glucocorticoid levels.
- Central MSH administration reduced orexin expression to wild-type levels in Pomc(-/-) mice.
- This reduction was independent of MSH's effects on food intake.
Conclusions:
- Alpha-MSH plays a role in regulating orexin expression in Pomc(-/-) mice.
- Elevated orexin levels in Pomc(-/-) mice may contribute to hyperphagia.
- Melanocortin signaling directly influences orexin expression, independent of feeding behavior changes.
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