Table 2.
Comparison of gastrointestinal motility-stimulating actions of ghrelin in several vertebrates.
| Species | In vitro study | In vivo study | Action site | Reference | |
|---|---|---|---|---|---|
| Unstimulated | Stimulated | ||||
| Fish | |||||
| Rainbow trout | No effect | (112) | |||
| Gold fish | No effect | No effect (EFS) | (112) | ||
| Zebrafish | No effect | (35) | |||
| Amphibians | |||||
| Bullfrog | No effect | (36) | |||
| Japanese fire belly newt | No effect | (36) | |||
| Reptiles | Research not available | ||||
| Birds | |||||
| Chicken | Contraction | Smooth muscle (crop and proventriculus) | (77) | ||
| Potentiation of EFS | Enteric neurons (proventriculus) | (77) | |||
| Quail | No effect | (113) | |||
| (41) | |||||
| Mammals | |||||
| Human | No effect | (99) | |||
| Contraction (Premature phase-III) | (114) | ||||
| Increase in gastric emptying | (115) | ||||
| Increase in gastrointestinal transit | (116) | ||||
| Dog | No effect (motility and gastric emptying) | (117) | |||
| Inhibition of phase-III | Decrease in motilin release | (49) | |||
| Rat | No effect | Potentiation of EFS | Enteric neurons | (99, 118) | |
| Contraction | Enteric neurons and vago-vagal reflex | (118, 119) | |||
| Increase in phase-III | (26) | ||||
| Contraction (colon) | Defecation center | (120, 121) | |||
| Mouse | No effect | Potentiation of EFS | Enteric neurons | (24, 122) | |
| Increase in gastric emptying | Enteric neurons | (122) | |||
| Increase in phase-III | (27) | ||||
| Guinea-pig | No effect | (123–125) | |||
| No effect (ganglion stimulant) | (124) | ||||
| Contraction (stomach) | Vago-vagal reflex | (123) | |||
| Rabbit | No effect | (126) | |||
| Asian house musk shrew | Contraction | Enteric neurons (presence of motilin required) | (19, 68) | ||
| Contraction (phase-II), potentiation of phase-III | Enteric neurons and vago-vagal reflex | (20) | |||
EFS, Electrical field stimulation for excitation of enteric neurons.