The toxic effects of cadmium on the neonatal mouse CNS.

Mice (QS outbred strain) received a single subcutaneous injection of cadmium chloride in saline on postnatal day 1, 8, 15, or 22. Histological examination, 24 hours after cadmium exposure on day 1, revealed petechial hemorrhages, edema, and cellular pycnosis throughout much of the immature brain. Treatment on days 8 or 15 produced similar damage, particularly edema and pycnosis, but affected progressively less of the brain until, by day 22, the brain was apparently unaffected by cadmium. Some animals, allowed to survive six to eight weeks after cadmium injection, showed behavioral anomalies and persistent brain deficits. Electron microscopic examination of parietal cortex from animals exposed to cadmium on day 1 revealed that petechial hemorrhages first occurred tow hours after treatment. The hemorrhages increased during the next six hours, and were accompanied by thinning and vacuolization of the capillary walls and widening of interendothelial gaps. In general, such changes were restricted to the partially differentiated capillaries. Degenerative changes in the brain cells were first seen about six hours after cadmium exposure.