Effects of short-term food deprivation on orexin-A-induced intestinal bicarbonate secretion in comparison with related secretagogues
2010 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 198, no 3, 373-380 p.Article, review/survey (Refereed) Published
Studies of gastrointestinal physiology in humans and intact animals are usually conducted after overnight fast. We have compared effects of orexin-A, vasoactive intestinal polypeptide (VIP), melatonin, serotonin, uroguanylin, ghrelin and prostaglandin E2 (PGE2) on duodenal bicarbonate secretion in fed and overnight fasted animals. This review is a summary of our findings. Secretagogues were administered by intra-arterial infusion or luminally (PGE2) Enterocyte intracellular calcium ([Ca2+]i) signaling was studied by fluorescence imaging. Total RNA was extracted, reverse transcripted to cDNA and expression of orexin receptors measured by quantitative real-time PCR.
Orexin-A stimulates the duodenal secretion in continuously fed animals but not in food deprived animals. Similarly, short fasting causes a 100-fold decrease of the amount of the muscarinic agonist bethanechol required for stimulation of secretion. In contrast, fasting does not affect secretory responses to intra-arterial VIP, melatonin, serotonin, uroguanylin and ghrelin, or that to luminal PGE2. Orexin-A induces [Ca2+]i signaling in enterocytes from fed rats but no significant [Ca2+]i responses occurs in enterocytes from fasted animals. In addition, overnight fasting decreases the expression of mucosal and enterocyte orexin receptors.
Short food deprivation thus decreases duodenal expression of orexin receptors and abolishes the secretory response to orexin-A as well as orexin-A induced [Ca2+]i signaling. Fasting, furthermore, decreases mucosal sensitivity to bethanechol. The absence of declines in secretory responses to other secretagogues tested is strong evidence that short fasting does affect not the secretory capacity of the duodenal mucosa in general. Studies of intestinal secretion require particular evaluation with respect to feeding status.
Place, publisher, year, edition, pages
Oxford: Wiley-Blackwell , 2010. Vol. 198, no 3, 373-380 p.
Bicarbonate secretion, duodenum, fasting, ghrelin, melatonin, serotonin
Gastroenterology and Hepatology
Research subject Neuroscience
IdentifiersURN: urn:nbn:se:uu:diva-130658DOI: 10.1111/j.1748-1716.2009.02067.xISI: 000274147900019PubMedID: 20003099OAI: oai:DiVA.org:uu-130658DiVA: diva2:350210
ProjectsFeeding dependency of small intestinal sensitivity to appetite-related hormones