Metabolism of prostaglandin F2alpha during fasting in prepubertal gilts

The study was conducted to investigate a possible mechanism behind earlier observations of fasting-induced increases of blood concentrations of prostaglandin (PG) F2alpha metabolite (P-PG) in gilts. Six animals were fasted for 28 h, then administered i.v. PGF2alpha (500 ng/kg body weight). Blood samples were withdrawn at 1, 3, 5, 7, 10, 15, 20, 30, 40, 60 min, 2 and 3 h after the injection. A control group followed an identical protocol, except that they were fed during the corresponding 28 h-period. P-PG increased as previously observed during the 28 h of fasting. The P-PG increase in terms of area under the concentration time curve (AUC) following injection was significantly larger in the fasted than in the non-fasted gilts. In the fasted animals, the mean P-PG maximum concentration (Cmax) was 7145 pmol/L, the corresponding value for the non-fasted animals was 4566 pmol/L. PGs are metabolised through beta-oxidation in the liver. The results of this study imply that reduced 15-ketodihydro-PGF2alpha breakdown in the liver might contribute to the fasting-induced increases in P-PG.