Beagle puppy model of perinatal cerebral infarction. Acute changes in regional cerebral prostaglandins during hemorrhagic hypotension.

Perinatal cerebral infarction is a not uncommon finding in newborn babies surviving intensive care. Asphyxia, with its attendant hypotension, is the most common cause of this problem and may result in neuropathological changes in the periventricular white matter. Previous studies have demonstrated uncoupling of cerebral blood flow and metabolism in the periventricular white matter regions of newborn beagle pups exposed to hemorrhagic hypotension. This work examines the effects of hypotension on serum and regional cerebral prostaglandin levels in the newborn beagle pup. The animals were anesthetized, tracheostomized, and paralyzed. Pups were randomly assigned to two groups: one was subjected to hemorrhagic hypotension and the other received no insult. Hypotension was induced by slow venous hemorrhage calculated to maintain a mean arterial blood pressure at 20 to 30 mm Hg. Serum prostaglandin determinations were made immediately before and 15 minutes after random assignment to hypotension or control groups. In addition, regional cerebral prostaglandin determinations were performed 15 minutes after randomization. Analysis of the serum prostaglandin data revealed that there were no significant differences in the values for thromboxane B2 or 6-keto-prostaglandin (PG) F1 alpha, which are the stable breakdown products of thromboxane A2 and prostacyclin, respectively. Prostaglandin E2 levels increased in response to hemorrhagic hypotension insult. Regional cerebral prostaglandin determinations demonstrated decreases in thromboxane B2 and 6-keto-PGF1 alpha in both gray and white matter. Although gray matter PGE2 was increased in pups exposed to hemorrhagic hypotension, this increase was not found in the periventricular white matter of injured pups. This regional difference in PGE2 synthesis in response to insult may explain the periventricular white matter neuropathological changes attributed to it.