DEVELOPMENT OF GABA AND CALCIUM-BINDING PROTEINS IMMUNOREACTIVITY IN THE RAT HIPPOCAMPUS FOLLOWING NEONATAL ANOXIA

The consequences of neonatal anoxia (N-2 100% for 25 min at 30 h after birth) on the rat hippocampus were studied 7-60 days postnatally with immunocytochemistry for gamma-aminobutyric acid (GABA), parvalbumin ( PV) and calbindin-D28k (CB). In both sham-treated and anoxic rats, GAB A immunoreactivity presented a mature expression since early stages, w hile PV and CB immunoreactivity showed a major postnatal development. In anoxic animals, a significant reduction in the number of hippocampa l GABA-immunoreactive neurons was observed at all time-points analysed , a transitory effect on PV immunoreactivity was seen at P7 and P21, w hile no modifications in the number of CB-immunoreactive neurons could be found. Thus, selective vulnerability of GABA-containing neurons an d relative resistance of neurons in which PV or CB immunoreactivity is present or is expressed later, occur in the hippocampus after neonata l anoxia. The role of calcium binding proteins (CBP) in nerve cell pro tection is discussed.