SOMATOTROPIN TRANSGENIC MICE HAVE REDUCED JEJUNAL ACTIVE GLUCOSE-TRANSPORT RATES

Small intestinal glucose absorption and gastrointestinal morphology we re compared in adult bovine somatotropin transgenic (MT-bGH) and contr ol mice. The MT-bGH mice were 57% heavier than controls, although both groups consumed comparable amounts of food during the 5 d before tran sport measurements were made. Stomach, cecum and colon were 98, 53, an d 81% heavier (P < 0.001), and small intestinal tract 52% heavier and 27% longer in MT-bGH than in control mice (P < 0.001). As a proportion of live weight, MT-bGH mice tended to have a shorter small intestine than controls (P < 0.07), whereas there was no difference for either s mall or large bowel relative weights. Villus dimensions, crypt depth a nd thickness of external muscle layers in the jejunum were not signifi cantly different in control and MT-bGH mice. Active glucose transport rate per milligram of jejunum was 24% less than in control mice (P < 0 .05). Jejunal active glucose transport rate per gram of live weight in MT-bGH mice was approximately half that of control mice. The larger s mall intestinal mass of MT-bCH mice compensated for the reduced rate o f glucose transport per unit weight of intestine such that there was n o significant difference in total small intestinal tract glucose trans port between control and MT-bGH mice. These results suggest that there are substantial differences in nutrient absorptive efficiency between intestinal tract from MT-bGH and control mice.