Effects of Neonatal Asphyxia on the Central Nervous System in Mice

I. Brain Damages Caused by Two Different Types of Total Asphyxia

Abstract

Effects on mortality, morphological changes, proliferation kinetics of cerebellar neurons and ECG were compared between two types of total asphyxia in newborn mice which was produced by either CO₂ or N₂ breathing.
Mortality was significantly higher in the CO₂ group than in the N₂ group. The neuropathological study of N₂-exposed mice showed neuronal degenerations in the cerebral cortex, striatum and colliculus posterior. In contrast to the prolongation of the generation time in CO₂-exposed mice, the cell-cycle study using 3H-thymidine autoradiography revealed no change in cell proliferation kinetics in the cerebellum of N₂-exposed mice. ECG changes were severer in the CO₂ group than in the N₂ group.
These results may suggest that brain damage is more serious in the CO₂ group than in the N₂ group and also that changes in cell proliferation seen in the CO2 group are caused by metabolic changes rather than hypoxemia per se.