α-melanocyte stimulating hormone modulates the central acyl ghrelin-induced stimulation of feeding, gastrointestinal motility, and colonic secretion
Authors Huang HH, Chen LY, Doong ML, Chang SC, Chen CY
Received 11 June 2017
Accepted for publication 19 July 2017
Published 16 August 2017 Volume 2017:11 Pages 2377—2386
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Rajendra Narayan Mitra
Peer reviewer comments 2
Editor who approved publication: Dr Sukesh Voruganti
Hsien-Hao Huang,1,2 Liang-Yu Chen,3,4 Ming-Luen Doong,5 Shi-Chuan Chang,6,7 Chih-Yen Chen8–10
1Institute of Clinical Medicine, National Yang-Ming University of Medicine, 2Department of Emergency Medicine, Taipei Veterans General Hospital, 3Aging and Health Research Center, National Yang-Ming University, 4Center for Geriatrics and Gerontology, Taipei Veterans General Hospital, 5Institute of Physiology, National Yang-Ming University School of Medicine, 6Institute of Emergency and Critical Medicine, National Yang-Ming University School of Medicine, 7Department of Chest Medicine, Taipei Veterans General Hospital, 8Division of Gastroenterology and Hepatology, Department of Medicine, Taipei Veterans General Hospital, 9Faculty of Medicine, National Yang-Ming University School of Medicine, Taipei, 10Taiwan Association for the Study of Small Intestinal Diseases, Guishan, Taiwan
Background: Acyl ghrelin-induced intake depends on hypothalamic neuropeptide Y and agouti-related protein (AgRP) neurotransmitters. Intracerebroventricular (ICV) injection of AgRP increases feeding through competitive antagonism at melanocortin receptors. ICV administration of α-melanocyte stimulating hormone (α-MSH), a natural antagonist of AgRP, may modulate the acyl ghrelin-induced orexigenic effect.
Objective: This study aimed to investigate the modulating effect of α-MSH on the central acyl ghrelin-induced food intake, gastrointestinal motility, and colonic secretion in rats.
Methods and procedures: We examined the effects of α-MSH and acyl ghrelin on food intake, gastric emptying, small intestinal transit, colonic motility, and secretion in conscious rats with a chronic implant of ICV catheters.
Results: ICV injection of O-n-octanoylated ghrelin (0.1 nmol/rat) significantly increased the cumulative food intake up to 8 h (P<0.01), enhanced non-nutrient semi-liquid gastric emptying (P<0.001), increased the geometric center and running percentage of small intestinal transit (P<0.001), accelerated colonic transit time (P<0.05), and increased fecal pellet output (P<0.01) and total fecal weight (P<0.01). Pretreatment with ICV injection of α-MSH (1.0 and 2.0 nmol/rat) attenuated the acyl ghrelin-induced hyperphagic effect, fecal pellet output, and total fecal weight, while higher dose of α-MSH (2.0 nmol/rat) attenuated the increase in the geometric center of small intestinal transit (P<0.01). However, neither dose of α-MSH altered acyl ghrelin-stimulated gastroprokinetic effect, increase in the running percentage of small intestinal transit, nor accelerated colonic transit time.
Conclusion: α-MSH is involved in central acyl ghrelin-elicited feeding, small intestinal transit, fecal pellet output, and fecal weight. α-MSH does not affect central acyl ghrelin-induced acceleration of gastric emptying and colonic transit time in rats.
Keywords: acyl ghrelin, colon transit time, fecal pellet output, food intake, gastric emptying, intracerebroventricular, small intestinal transit, α-melanocyte stimulating hormone
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