DELAYS IN THE POSTNATAL INCREASE OF CEREBRAL CYTOCHROME CONCENTRATIONS IN LEAD-EXPOSED RATS

Increases in the cytochrome content of the developing rat cerebral cortex were observed spectrally, directly in the tissue using dual-wavelength spectroscopy. It was found that the contribution of hemoglobin entrapped in the tissue contributed significantly to the spectra. However, this interference was equivalent with varying age and could be treated as a constant. Between 10 and 24 days of age, a 4-5-fold increase in absorbance could be attributed to peaks of the cytochrome intermediates. Administration of lead (Pb) (5-200 mg Pb 1) to female rats, from 14 days prior to breeding through weaning of pups, resulted in a delay in the normal increase in the cytochrome of the cerebral cortex of male offspring. Calculated on the basis of rates of cytochrome accumulation, the effect of Pb was most marked between 10 and 15 days after birth. At 30 days of age, Pb-treated animals recovered the cytochrome content displayed by control animals. These data indicate a delay in the biochemical development of rat brain at very modest elevations of blood Pb concentrations relative to that encountered in human populations. © 1979.