Transforming growth factor-alpha delays gastric emptying and small intestinal transit in suckling rats

Transforming growth factor-alpha (TGF-α) is a biologically potent polypeptide detected in the gastrointestinal tract in suckling rats. The major goal of the present study was to test the hypothesis that the administration of TGF-α affects gastric emptying and small intestinal transit in suckling rats. Suckling (12-day-old) rats fasted 16 h received rat TGF-α subcutaneously (s.c.) or orogastrically in varying doses (0, 0.5, 1.0 μg/rat in 0.1% BSA). Control animals received 0.1% BSA only. Poly R-478 dye was used as a motility marker. Rats were decapitated 45 min after marker administration and the amount of dye in the stomach and the small intestine was measured by spectrophotometry. Subcutaneous administration of TGF-α significantly delayed stomach evacuation. In controls, the stomach contained 21.4 ± 1.4% (mean ± s_x) of the Poly R-478 marker, whereas in TGF-α treated rats the stomach contained 37.2 ± 2.8% of the total Poly R-478 dye given to animals. The delaying effect of TGF-α was time and dose-dependent. Small intestinal transit was also significantly delayed. The proximal jejunum of TGF-α treated rats contained a 1.4-fold higher amount of marker in comparison with control rats. Orogastrically administered rTGF-α did not affect gastric emptying or intestinal transit. In conclusion, s.c. administration of rat TGF-α significantly delayed the gastrointestinal motility in vivo in suckling rats.