Central and Peripheral Actions of Adenosine and Its Analogues on Intestinal Myoelectric Activity and Propulsion in Rats

Abstract

The effects of centrally and peripherally administered adenosine and its analogues on intestinal myoelectric activity were examined in conscious fasted and fed rats fitted with electrodes implanted in the duodenojejunal wall and a cannula in a lateral ventricle of the brain. The effects on small intestinal transit were evaluated in rats equipped with a duodenal catheter and killed 30 minutes after duodenal administration of a marker (Na51CrO4). In fasted rats intraperitoneal administration of adenosine and its analogues induced either a disrupted migrating myoelectric complex (MMC) pattern, which was replaced by irregular spike activity, or an inhibition of the MMC pattern, depending on the compound and dose. The change from a cyclic MMC pattern to continuous spike activity was correlated with an increase of intestinal propulsion, while inhibition of myoelectrical activity was characterized by a marked decrease in propulsion. Peripheral administration of adenosine and its analogues after a meal induced a short inhibition of intestinal myoelectric activity. In contrast, central administration, induced the reappearance of the MMC pattern, with an associated decrease in intestinal propulsion. It is concluded that adenosine and its analogues are able to modulate fed and fasted intestinal motor profiles at both peripheral and central levels and, as a result, the propulsion of intestinal contents.