Refeeding reverses fasting-induced remodeling of afferent nerve activity in rat small intestine.

Intestinal afferents play an important role in coordinating intestinal motor control. Fasting induces morpho-mechanical intestinal remodeling. This study aimed to characterize the effect of fasting and refeeding on mechanosensitivity in mesenteric afferent nerves in isolated Sprague-Dawley rat jejunum. A control group fed ad libitum, a group fasted for 7 days and a group refed 7 days after 7 days fasting were studied. Jejunal segments were used for electrophysiological, histomorphological and mechanical studies. Mesenteric afferent nerve firing was recorded during a ramp distension up to 40 mmHg luminal pressure. Multiunit afferent recordings were separated into low threshold and wide-dynamic-range single-unit activity. Intestinal deformation (strain), bowel distension load (stress) and firing frequency of mesenteric afferent nerve bundles [spike rate increase ratio (SRIR)] were compared among groups. Fasting induced intestinal histomorphometric remodeling, which was reversed by refeeding. The firing frequency increased with distension in all groups. SRIR was largest in the fasting group (P < 0.05). Compared to the control group, fasting increased afferent activity in whole nerve bundles and wide-dynamic-range units at high degrees of distensions (P < 0.05 at pressure 40 mmHg; P < 0.05 at strain 1.2; P < 0.01 at stress 8 kPa). Refeeding reversed the fasting-induced afferent hypersensitivity and the shift between receptor subtypes. In conclusion, refeeding reversed fasting-induced remodeling.