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Published on: June 25, 2019
Functions of orexins in peripheral tissues
M V Heinonen1, A K Purhonen, K A Mäkelä
1Department of Biotechnology and Molecular Medicine, A. I. Virtanen Institute for Molecular Sciences, University of Kuopio, Kuopio, Finland.
Acta Physiologica (Oxford, England)
|February 26, 2008
Summary
Orexin A (OXA) and orexin B peptides, known for regulating sleep and feeding, also play significant roles in peripheral tissues, particularly the intestine. This review explores their lesser-known functions in metabolic regulation and gut activity.
Area of Science:
- Neuroendocrinology
- Gastroenterology
- Metabolic Research
Background:
- Orexin A (OXA) and orexin B are hypothalamic peptides primarily known for regulating sleep, wakefulness, and feeding behaviors.
- Emerging evidence indicates significant roles for orexins in peripheral tissues, including the gastrointestinal tract.
- Central orexigenic pathways influence the hypothalamus-pituitary axis and sympathetic nervous system activity.
Purpose of the Study:
- To review the current understanding of the peripheral functions of orexins.
- To discuss the potential endocrine, paracrine, and neurocrine roles of orexins in peripheral tissues.
- To highlight the regulation of orexin receptors in the intestine by nutritional status.
Main Methods:
- Literature review of existing studies on orexin A and B.
- Analysis of research on orexin distribution and function in peripheral tissues, especially the intestine.
- Examination of the relationship between orexin levels, metabolic state, and physiological responses.
Main Results:
- Orexin receptors are widely distributed in the intestine and their expression is modulated by nutritional status.
- Orexins influence key intestinal functions, including insulin secretion and intestinal motility.
- Orexin A (OXA) is detectable in plasma, with levels varying according to metabolic state, though its primary source remains unclear.
Conclusions:
- Orexins exert significant physiological effects beyond the central nervous system, impacting metabolic and gastrointestinal functions.
- Further research is warranted to elucidate the precise endocrine, paracrine, and neurocrine mechanisms of peripheral orexin actions.
- Understanding peripheral orexin roles may offer new therapeutic targets for metabolic and digestive disorders.
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