Biomechanical and histomorphometric esophageal remodeling in type 2 diabetic GK rats

Diabetes mellitus induces remodeling of the morphology and mechanical properties in the gastrointestinal tract. This study aimed to investigate the histomorphometric and biomechanical remodeling of esophagus in the diabetic type 2 model Goto-Kakizaki (GK) rats. Five male diabetic GK rats and five male nondiabetic Wistar rats were used in this study. The mechanical test was performed in vitro where the whole esophagus was stretched to its in situ length and distended with pressures up to 10 cm H2O using a ramp distension protocol. The pressure and outer diameter were recorded. Circumferential stress (force per area) and strain (deformation) were computed from the diameter and pressure data using the zero-stress state as reference. The zero-stress state was obtained by cutting esophageal rings radially. This caused the rings to open up into a sector. The thickness, area, and the opening angle were measured from the digitized images. The layer circumference, thickness, and area were measured from histological slides. The collagen fraction was determined from histological slides with Van Gieson stain. Diabetes induced pronounced morphometric changes, e.g., the wall thickness and wall cross-sectional area significantly increased in the GK rats (P<.01). Histologically, the circumference, thickness, and area of the muscle layer and the collagen fraction of mucosa-submucosa layer were significantly increased in the GK rats (P<.01). The opening angle, outer residual strain, and residual strain difference to wall thickness ratio decreased significantly in the GK rats (P<.05 and P<.01). Furthermore, the circumferential stiffness of the esophagus is significantly higher in the GK rats than in the normal rats (P<.01). In conclusion, histomorphometric and biomechanical remodeling is a feature of the esophageal wall in GK rats.