Restoration of gap junctions in the regenerative process of ethanol-induced gastric mucosal injury

Gap junctions mediate intercellular communication and play an important role in cell proliferation and differentiation. The present study examined the expression of the gap junction protein connexin 32 in rat gastric mucosa during the regenerative process of ethanol-induced gastric mucosal injury. Absolute ethanol (0.5 mL/100 g bodyweight) was administered to rats via gastric intubation. Following the treatment, rats were killed periodically, and gastric tissues were processed for indirect immunofluorescence microscopy using an anti-connexin 32 antibody. Haematoxylin and eosin (H&E), periodic acid Schiff (PAS) and Bromodeoxyuridine (BrdU) staining were also performed in serial sections. Gastric injuries were limited in the mucosal layer. The injury was most severe 1 h after treatment, and was completely resolved by the 4th day after treatment. The number of immunoreactive spots for gap junctions was markedly decreased 1 h after the ethanol treatment. Reappearance of these immunostaining gap junctions occurred with repair of the injury. The reappearance of connexin 32 after injury was delayed in comparison with both the histologic resolution of the injury and the normalization of PAS-stained mucus. In contrast, the time course of reappearance of gap junctions closely paralleled the appearance of BrdU-labelled cells. These results indicate that morphologic repair is different to the recovery of cell maturity and cell proliferation in the regenerative gastric mucosa.