ONTOGENIC AND GLUCOCORTICOID-ACCELERATED EXPRESSION OF RAT 14 KDA BILE ACID-BINDING PROTEIN

Background: A 14 kDa protein is a major rat ileal cytosolic bile acid- binding protein (14 kDa I-BABP), This report describes the normal and glucocorticoid-accelerated postnatal expression of 14 kDa I-BABP. Meth ods: 14 kDa I-BABP and its mRNA were detected by antiserum and antisen se cRNA probe, respectively, in ileum and ovary from 7-, 14-, 21-, 28- , and 35-day-old rats. Results: A positive histochemical reaction with 14 kDa I-BABP antiserum was found in cytosol of heal enterocytes and ovarian luteal cells at 21 and 35 days of age, respectively. Likewise, Northern blot analysis indicated that the cRNA probe hybridized to a single transcript of 500 bp in total cellular RNA prepared from the il eum of 21-day-old and ovary of 35-day-old rats, Corticosteroid treatme nt resulted in a histochemical reaction in ileum of 14-day-old animals as compared to the appearance of this reaction in 21-day-old control littermates. Similarly, Northern blot analysis detected the earlier ap pearance of mRNA levels in corticosteroid-treated animals (11 days vs. 17 days in control animals). Conclusions: 14 kDa I-BABP and its mRNA are normally expressed in rat ileum at 17 days of postnatal life. 14 k Da I-BABP is expressed considerably later in rat ovary, Corticosteroid treatment results in precocious expression of heal 14 kDa I-BABP. (C) 1996 Wiley-Liss, Inc.