Evidence that central pathways that mediate defecation utilize ghrelin receptors but do not require endogenous ghrelin

Ruslan V Pustovit, Brid Callaghan, Mitchell T. Ringuet, Nicole F. Kerr, Billie Hunne, Ian M Smyth, Claudio Pietra, John B. Furness

Research output: Contribution to journalArticleResearchpeer-review

Abstract

In laboratory animals and in human, centrally penetrant ghrelin receptor agonists, given systemically or orally, cause defecation. Animal studies show that the effect is due to activation of ghrelin receptors in the spinal lumbosacral defecation centers. However, it is not known whether there is a physiological role of ghrelin or the ghrelin receptor in the control of defecation. Using immunohistochemistry and immunoassay, we detected and measured ghrelin in the stomach, but were unable to detect ghrelin by either method in the lumbosacral spinal cord, or other regions of the CNS. In rats in which the thoracic spinal cord was transected 5 weeks before, the effects of a ghrelin agonist on colorectal propulsion were significantly enhanced, but defecation caused by water avoidance stress (WAS) was reduced. In knockout rats that expressed no ghrelin and in wild-type rats, WAS-induced defecation was reduced by a ghrelin receptor antagonist, to similar extents. We conclude that the ghrelin receptors of the lumbosacral defecation centers have a physiological role in the control of defecation, but that their role is not dependent on ghrelin. This implies that a transmitter other than ghrelin engages the ghrelin receptor or a ghrelin receptor complex.

Original languageEnglish
Article numbere13385
Number of pages11
JournalPhysiological Reports
Volume5
Issue number15
DOIs
Publication statusPublished - 1 Aug 2017

Keywords

  • Defecation reflex
  • ghrelin
  • intestinal innervation

Cite this

Pustovit, Ruslan V ; Callaghan, Brid ; Ringuet, Mitchell T. ; Kerr, Nicole F. ; Hunne, Billie ; Smyth, Ian M ; Pietra, Claudio ; Furness, John B. / Evidence that central pathways that mediate defecation utilize ghrelin receptors but do not require endogenous ghrelin. In: Physiological Reports. 2017 ; Vol. 5, No. 15.
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abstract = "In laboratory animals and in human, centrally penetrant ghrelin receptor agonists, given systemically or orally, cause defecation. Animal studies show that the effect is due to activation of ghrelin receptors in the spinal lumbosacral defecation centers. However, it is not known whether there is a physiological role of ghrelin or the ghrelin receptor in the control of defecation. Using immunohistochemistry and immunoassay, we detected and measured ghrelin in the stomach, but were unable to detect ghrelin by either method in the lumbosacral spinal cord, or other regions of the CNS. In rats in which the thoracic spinal cord was transected 5 weeks before, the effects of a ghrelin agonist on colorectal propulsion were significantly enhanced, but defecation caused by water avoidance stress (WAS) was reduced. In knockout rats that expressed no ghrelin and in wild-type rats, WAS-induced defecation was reduced by a ghrelin receptor antagonist, to similar extents. We conclude that the ghrelin receptors of the lumbosacral defecation centers have a physiological role in the control of defecation, but that their role is not dependent on ghrelin. This implies that a transmitter other than ghrelin engages the ghrelin receptor or a ghrelin receptor complex.",
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Evidence that central pathways that mediate defecation utilize ghrelin receptors but do not require endogenous ghrelin. / Pustovit, Ruslan V; Callaghan, Brid; Ringuet, Mitchell T.; Kerr, Nicole F.; Hunne, Billie; Smyth, Ian M; Pietra, Claudio; Furness, John B.

In: Physiological Reports, Vol. 5, No. 15, e13385, 01.08.2017.

Research output: Contribution to journalArticleResearchpeer-review

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