Mammary Transfer of 203Hg from Mothers to Brains of Nursing Rats

Abstract

SummaryAt the 16th day of lactation, rats were force-fed a tracer dose of 203Hg as CH3203HgCl and allowed to continue to nurse their pups. After 1, 2, 3, and 5 days of nursing, representative pups were killed and brains obtained. The mother was also killed at the end of the study and its brain and those from the pups were separated into brain parts and radioactivities determined. In the mother, the concentrations of 203Hg ranged from 0.117 in the medulla to 0.167 in the hypothalamus and 0.205% of dose/g tissue in the pituitary. In the pups, the quantity of labeled mercury deposited in the brain or brain parts increased from 1 day to 5 days of suckling. The concentration (% of dose/g of brain or brain part) also increased with succeeding day of nursing so that at the end of 5 days the pup brain contained a higher concentration than their mothers' brain (0.307 vs 0.131). Correspondingly, pup brain parts contained greater concentrations of labeled mercury than their mothers' brain parts: Cerebrum, 0.287 vs 0.122; cerebellum, 0.353 vs 0.164; pons plus midbrain, 0.319 vs 0.146; medulla, 0.330 vs 0.117; and hypothalamus, 0.392 vs 0.167.