Sensory Stimuli Directly Acting at the Central Nervous System Regulate Gastric Ghrelin Secretion. An ex Vivo Organ Culture Study

Abstract

Ghrelin, a novel gastrointestinal hormone involved in GH regulation, has been postulated as a relevant orexigenic peptide released by splanchnic tissues. Descriptive studies have shown that plasma ghrelin levels increase in states of negative energy balance or fasting, while decreasing in obesity and after feeding. In the present study, a novel organ-culture model of gastric tissue explants obtained from rat donors has been validated for ex vivo experiments. Fasting induced gastric ghrelin release as well as ghrelin mRNA expression that were reflected in plasma. Interestingly, those changes were fully reverted by 15 min of refeeding before stomach extraction. Unexpectedly, when animals were allowed 15 min before explant extraction to see or smell, but not eat, the food (tease feeding), ghrelin secretion was suppressed just like in gastric explants from refed animals. This effect was blocked when the animals were subjected to surgical vagotomy or treated with atropine sulphate. In conclusion, gastric explants were a suitable model for testing ghrelin mechanism of secretion in vitro, and they were found to maintain memory of the previously received signals. Similar to feeding, tease feeding resulted in suppression of ghrelin discharge by explants.