235 INFLUENCE OF EPIDERMAL GROWTH FACTOR AND DEXAMETHASONE ON THE MATURATION OF BRUSH BORDER ENZYMIC ACTIVITIES OF THE FETAL MOUSE SMALL INTESTINE IN ORGAN CULTURE

Abstract

We have shown that Epidermal Growth Factor (EGF) as well as dexamethasone (Dx) exert a direct positive influence on the maturation of some brush border enzymic activities in the fetal mouse small intestine in organ culture. We report herein the effect of a combination of these two hormones. Mouse duodenal explants resected at 17 days of gestation were cultured during 48 h at 37°C in Leibovitz L-15 serum-free medium alone or supplemented with EGF (100 ng/ml) and/or Dx (300 ng/ml). Maturation of absorptive cells was evaluated by measuring alkaline phosphatase (ALP), maltase (M), lactase (L), trehalase (T) and sucrase (S) activities. In control explants, protein and DNA contents and the level of the ALP, M, T and S specific activities remain comparable to the values measured in 17-day explants at the beginning of the culture period except for L activity that falls drastically. In explants cultured in presence of EGF and Dx, protein contents and the level of ALP, M, T and S activities increase significantly but only at levels comparable to those obtained with EGF or Dx separately while DNA contents remain unchanged and L activity remains under the level observed at the beginning of the culture period. These results suggest that EGF and glucocorticoids can influence the maturation of some brush border enzyme at a similar level in the small intestine during the fetal period.