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Food-induced expres...
Food-induced expression of orexin receptors in rat duodenal mucosa regulates the bicarbonate secretory response to orexin-A
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- Bengtsson, Magnus W. (author)
- Uppsala universitet,Fysiologi
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Mäkelä, Kari (author)
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- Sjöblom, Markus (author)
- Uppsala universitet,Fysiologi
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Uotila, Sanna (author)
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- Åkerman, Karl E. O. (author)
- Uppsala universitet,Fysiologi
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Herzig, Karl-Heinz (author)
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- Flemström, Gunnar (author)
- Uppsala universitet,Fysiologi
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(creator_code:org_t)
- American Physiological Society, 2007
- 2007
- English.
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In: American Journal of Physiology - Gastrointestinal and Liver Physiology. - : American Physiological Society. - 0193-1857 .- 1522-1547. ; 293:2, s. G501-G509
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
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- Presence of appetite-regulating peptides orexin-A and orexin-B in mucosal endocrine cells suggests a role in physiological control of the intestine. Our aim was to characterize orexin-induced stimulation of duodenal bicarbonate secretion and modulation of secretory responses and mucosal orexin receptors by overnight food deprivation. Lewis x Dark Agouti rats were anesthetized and proximal duodenum cannulated in situ. Mucosal bicarbonate secretion (pH stat) and mean arterial blood pressure were continuously recorded. Orexin-A was administered intra-arterially close to the duodenum, intraluminally, or into the brain ventricles. Total RNA was extracted from mucosal specimens, reverse transcribed to cDNA and expression of orexin receptors 1 and 2 (OX1 and OX2) measured by quantitative real-time PCR. OX1 protein was measured by Western blot. Intra-arterial orexin-A (60–600 nmol·h–1·kg–1) increased (P < 0.01) the duodenal secretion in fed but not in fasted animals. The OX1 receptor antagonist SB-334867, which was also found to have a partial agonist action, abolished the orexin-induced secretory response but did not affect secretion induced by the muscarinic agonist bethanechol. Atropine, in contrast, inhibited bethanechol but not orexin-induced secretion. Orexin-A infused into the brain ventricles (2–20 nmol·kg–1·h–1) or added to luminal perfusate (1.0–100 nM) did not affect secretion, indicating that orexin-A acts peripherally and at basolateral receptors. Overnight fasting decreased mucosal OX1 and OX2 mRNA expression (P < 0.01) as well as OX1 protein expression (P < 0.05). We conclude that stimulation of secretion by orexin-A may involve both receptor types and is independent of cholinergic pathways. Intestinal OX receptors and secretory responses are markedly related to food intake.
Keyword
- bicarbonate secretion
- enteroendocrine cells
- fed and fasting state
- perfused duodenum in situ
- TRH
- MEDICINE
- MEDICIN
Publication and Content Type
- ref (subject category)
- art (subject category)
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