DEVELOPMENTAL-CHANGES IN THE NGF CONTENT IN THE BRAIN OF YOUNG, GROWING, LOW-BIRTH-WEIGHT RATS

The NGF content in each region of the brain of four-week-old rats was ranked in the decreasing order of cerebral cortex, hippocampus, cerebe llum, midbrain/diencephalon, and pons/medulla oblongata, and the NGF c oncentration, in the decreasing order of hippocampus, cerebral cortex, cerebellum, midbrain/diencephalon, and pons/medulla oblongata in both AFD and SFD groups. The NGF content and concentration in the cerebral cortex were about the same value at each age between those in the AFD and SFD groups. Those in the hippocampus were a little higher in the SFD group than in the AFD group at the ages of three and four weeks, u nlike those in the other regions, where the values for the cerebellum, midbrain/diencephalon and pons/medulla oblongata tended to be somewha t higher in the AFD group than in the SFD group. The NGF concentration s in the hippocampus and cerebral cortex increased with growth: the co ncentration in the hippocampus at four weeks of age was about 4-fold o f that at one week in the AFD group and about 5.7-fold of that at one week in the SFD group; and likewise the concentration in the cerebral cortex at four weeks of age was about 5.3-fold in the AFD group and ab out 7-fold in the SFD group. The NGF concentrations in the cerebellum decreased, and those in midbrain/diencephalon and pons/medulla oblonga ta hardly changed with growth in either AFD or SFD group. From these r esults NGF may have stronger implications for the neuronal growth in t he hippocampus compared with those in the lower brain regions of the S FD rats.