Title: 612 DIFFERENCES IN PROCESSING OF ORALLY ADMINISTERED PROSTAGLANDIN F2α IN THE GASTROINTESTINAL TRACT AND LIVER OF SUCKLING AND WEANLING RATS
Abstract: The presence of prostaglandin F2α (PGF) in milk led us to explore developmental differences in its metabolism between suckling and weanling rats. Disposition of orally administered 3H-PGF (20 μCi/kg/b.w.) to 12-day-old suckling (Su) and 30-day-old weanling (We) rats was evaluated quantitatively by determination of total radioactivity (TRA) recovery; and qualitatively by column and thin layer chromatography of extracts of liver (L), gastric wall and lumen (G), and small intestinal wall and lumen (I) two hours after administration. Recovery of TRA in these organs was 32.6% ± 2.1,8 (mean ± SE, N) of counts administered in Su, and 22.7% ± 4.8,5 in We (p < 0.03). In Su, G values tended to be higher than in We (11.1% ± 1.3,8 vs 8.5% ± 3.2,5); I values were 15.9% ± 0.7 vs 10.3% ± 1.8 (p < 0.01). Despite the presence of higher nonabsorbed TRA in G and I of Su, increased TRA was present in L [9.1% ± 1.7 vs 3.4% ± 0.6 (p < 0.05)]. Qualitatively, there was no substantial difference in distribution of TRA (un-metabolized parent PGF vs metabolites) in G and I. However, L of Su when compared to L of We, exhibited more unmetabolized PGF (12% ± 0.9 vs 7% ± 1.1 of TRA in L (p < 0.01) and less of the polar metabolites (21% ± 3.7 vs 35% ± 3.1 (p < 0.02). Conclusions. Qualitative and quantitative differences in metabolism of orally administered PGF were found between suckling and weanling rats. Despite slower absorption of PGF from the gastrointestinal tract of suckling rats, a larger proportion of prostaglandin was found in the liver in an unmetabolized form.