The effect of growth hormone releasing peptide-2 on upper gastrointestinal contractile activity and food intake in conscious dogs.
BACKGROUND
The aim of this study was to evaluate the effect of growth hormone releasing peptide (GHRP)-2, a synthetic ligand for the growth hormone secretagogue receptor, on upper gastrointestinal motility and food intake.


METHODS
Five neurally intact dogs and five dogs with vagotomy and pyloroplasty were equipped with strain gauge force transducers on the stomach, duodenum and jejunum. GHRP-2 (0.5-10 microg/kg) was administered intravenously in neurally intact dogs in the interdigestive state and after feeding. To study the mechanism of GHRP-2-induced inhibition on postprandial contractions, various antagonists were administered intravenously prior to GHRP-2. The effect of GHRP-2 on postprandial contractions was also studied in dogs with vagotomy. GHRP-2 was also administered immediately before feeding in each group, and its effect on food intake was assessed.


RESULTS
GHRP-2 did not evoke gastrointestinal contractions in the interdigestive state. GHRP-2 induced contractile inhibition continuing for 2-3 min in neurally intact dogs and dogs with vagotomy. This inhibitory effect was reversed by the alpha- and alpha(2)-blockers. GHRP-2 increased food intake in neurally intact dogs, but not in dogs with vagotomy.


CONCLUSIONS
These results indicate that in the upper gut GHRP-2 inhibits postprandial contractions via alpha(2)-receptors on the enteric nervous system, whereas an intact vagal nerve is necessary for a GHRP-2-induced increase in food intake.
Kudoh
Katsuyoshi
K
Division of Biological Regulation and Oncology, Department of Surgery, Tohoku University Graduate School of Medicine, Sendai, Japan.
Shibata
Chikashi
C
Funayama
Yuji
Y
Fukushima
Kouhei
K
Ueno
Tatsuya
T
Hayashi
Keiichi
K
Inui
Akio
A
Bowers
Cyril Y
CY
Sasaki
Iwao
I
D000818:Animals; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D004386:Duodenum / Q000187:drug effects / Q000378:metabolism; D004435:Eating / Q000187:drug effects*; D017615:Enteric Nervous System / Q000187:drug effects / Q000378:metabolism; D005753:Gastric Mucosa / Q000378:metabolism; D005769:Gastrointestinal Motility / Q000187:drug effects*; D007583:Jejunum / Q000187:drug effects / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects; D009842:Oligopeptides / Q000008:administration & dosage / Q000494:pharmacology*; D019518:Postprandial Period; D011708:Pylorus / Q000601:surgery; D018341:Receptors, Adrenergic, alpha-2 / Q000187:drug effects* / Q000378:metabolism; D054440:Receptors, Ghrelin / Q000819:agonists; D013270:Stomach / Q000187:drug effects; D014628:Vagotomy
D009842:Oligopeptides; D018341:Receptors, Adrenergic, alpha-2; D054440:Receptors, Ghrelin; C091874:growth hormone-releasing peptide-2