Plasma and cerebrospinal fluid hyperinsulinism in asphyxiated piglets.

Insulin (I) plays a crucial role in the maturation of the perinatal brain, and it may also be involved in the pathogenesis of neonatal brain injuries. The aim of the present study was to reveal the effect of neonatal asphyxia on the regulation of I and glucose (G) metabolism in plasma and cerebrospinal fluid (CSF) in newborn piglets. The I concentrations were measured by radioimmunoassay, while the G levels were analyzed by the G oxidase method during three phases (basal, critical, recovery) of bilateral pneumothorax in newborn piglets. We observed a significant hyperinsulinism (p < 0.001) both in plasma and CSF and a mild hypoglycemia (p < 0.05) during the recovery period. Postasphyxial G infusion (1.1 M, 10 ml.kg-1) amplified the hyperinsulinism. The ICSF/plasma ratio (mean +/- SEM; n = 16) was decreasing during cardiovascular failure (0.09 +/- 0.02; NS) as compared with the initial value (0.12 +/- 0.04), then it returned to basal values by 60 min (0.14 +/- 0.04; NS), and increased significantly 180 min (0.40 +/- 0.14; p < 0.05) after resuscitation of the piglets. There was a similar increase in GCSF/plasma ratio in asphyxiated animals at the end of experiments (0.99 +/- 0.15 vs. initial 0.76 +/- 0.05; p < 0.05). In conclusion, neonatal asphyxia resulted in plasma and CSF hyperinsulinism which may alter hypoxic-ischemic cerebral damages.