Opposite changes of gastrointestinal motility in short- and long-term diabetic rats

The aim of the study was to establish whether a motility disturbance could be demonstrated in a rat model of type 1 diabetes and to investigate the correlation of motility dysfunction and diabetes duration and glycemic control.

Materials and methods: Diabetes was induced in male adult rats by streptozotocin. Three groups of rats were investigated: diabetic, insulin treated diabetic and control group. In the treated group rats received 2U mixed insulin daily. Body weights and blood glucose levels were tested weekly. The duration of diabetes was 5 weeks for short-term diabetics (STD) and 10 weeks for long-term diabetics (LTD). Gastric emptying (GE) and small bowel transit (SBT) were tested by the phenol red recovery method. Whole gut transit time (GTT) was estimated by giving carmine red in a test meal through gavage and the period of time until the appearance of the marker in the stool was measured. Distal colonic transit (DCT) was assessed by the beadle expulsion method.

Results: In the STD rats the GE and SBT were slower while the GTT and the DCT were decreased as compared to controls. In contrast, in the LTD rats the GE and SBT were accelerated with an accelerated whole gut transit and an unchanged DCT. Insulin treatment reduced these dysmotilities.

Conclusions: the study suggests that development of motility disturbances needs certain duration of diabetes. The duration of diabetes results in opposite changes in motility in the different regions of the gastrointestinal tract. Both accelerated and delayed transit were observed in rats with hyperglycemia and both were reduced by insulin treatment which suggests that not the actual blood glucose level but sustained hyperglycemia is the primary factor in the development of the diabetic dysmotilities.