Biosynthesis and catabolism of prostaglandins during animal development

Catabolism of [9beta-3H1]prostaglandin F2alpha (PGF2alpha) was investigated in several organs (lung, kidney, brain, and liver) of the rat and lamb with respect to the product-type formed as well as the capacity of the observed enzymes. Biosynthesis of PGE2alpha and PGF2alpha in the same tissues was measured by dual ion mass fragmentography after incubation of the tissue homogenate with excess exogenous arachidonic acid (100 mug/g tissue). Further confirmation of the products was obtained through computer-operated multiple ion mass plots for each compound investigated. The results demonstrate that 1. Total PG-catabolizing activity in most organs is not constant but varies with animal age; highest activity (10-60-fold greater than the adult) being observed at certain stages of organ development. 2. The diverse catabolizing enzymes are dissociated in their activity, some enzymes being most active in immature animals (15-PGDH, 13PGR) and others being most active in the adult (9 PGDH, beta-oxide). 3. The activity profile for PG catabolism is both organ and species-specific. 4. PB biosynthesis in developing animals does not change significantly. The observed higher activity of PG catabolism with little change in PG biosynthesis strongly suggests an important need for the rapid inactivation of prostaglandins at certain critical stages of development serving as a protective mechanism likely in the control of cell differentiation and against the potentially harmful vasocative properties of prostaglandins during organogenesis.