PROSTAGLANDIN E(2) IN CEREBROSPINAL-FLUID OF FETAL AND NEWBORN SHEEP - CENTRAL VERSUS PERIPHERAL SOURCE

During the perinatal period, prostaglandin (PG) E(2) levels show paral lel changes in cerebrospinal fluid (CSF) and blood which may be import ant for the adaptation of the fetus to extrauterine life. It is not kn own, however, whether PGE(2) in the CSF originates from a local or a p eripheral source. Experiments were carried out in term fetal and newbo rn sheep chronically instrumented with a cannula inside the third vent ricle and vascular lines. Indomethacin was given intracerebroventricul arly (i.c.v.) (50 or 100 mu g at hourly intervals), alone or in combin ation with intravenous (i.v.) PGE(2) (1 or 1.5 mu g/kg/ min). In the f etus, i.c.v. indomethacin reduced PGE(2) levels in both CSF and plasma . Conversely, no significant change was noted at either site when indo methacin was given i.c.v. to the newborn. At both ages, PGE(2) increas ed in the CSF during i.v. infusion of the compound, but this elevation was proportionately smaller than in plasma. We conclude that, in the perinatal period, brain and peripheral circulation function as separat e compartments with respect to PGE(2), though there is passage of the compound across the blood-brain barrier. Results provide indirect evid ence that perinatal brain produces PGE(2) in measurable amounts.