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

Transforming growth factor-alpha (TGF-alpha) is a biologically patent polyp eptide detected in the gastrointestinal tract in suckling rats. The major g oal of the present study was to test the hypothesis that the administration of TGF-alpha affects gastric emptying and small intestinal transit in suck ling rats. Suckling (12-day-old) rats fasted 16 h received rat TGF-alpha su bcutaneously (s.c.) or orogastrically in varying doses (0, 0.5, 1.0 mug/rat in 0.1% BSA). Control animals received 0.1% BSA only. Poly R-478 dye was u sed as a motility marker. Rats were decapitated 45 min after marker adminis tration and the amount of dye in the stomach and the small intestine was me asured by spectrophotometry. Subcutaneous administration of TGF-alpha signi ficantly delayed stomach evacuation. In controls, the stomach contained 21. 4 +/- 1.4% (mean +/- s(x)) of the Poly R-478 marker, whereas in TGF-alpha t reated rats the stomach contained 37.2 +/- 2.8% of the total Poly R-478 dye given to animals. The delaying effect of TGF-alpha was time- and dose-depe ndent. Small intestinal transit was also significantly delayed. The proxima l jejunum of TGF-alpha treated rats contained a 1.4-fold higher amount of m arker in comparison with control rats. Orogastrically administered rTGF-alp ha did not affect gastric emptying or intestinal transit. In conclusion, s. c. administration of rat TGF-alpha significantly delayed the gastrointestin al motility in vivo in suckling rats.