Influence of chronic lead exposure on hormone levels and organ weights in developing rats.

The effect of 5 months' exposure to 0.5% lead acetate in drinking water on the hypothalamo-pituitary-thyroid-adrenal system was evaluated by measuring hypothalamic and striatic noradrenaline (NA), serum thyroxine (T4), 3,5,3'-triiodothyronine (T3) and corticosterone (CS) and blood and adrenal catecholamines (CA) levels in developing rats of both sexes. Blood CA were increased and hypothalamic and striatic NA was decreased by exposure in male rats. In female rats, blood and adrenal CA and serum CS were increased and hypothalamic and striatic NA was decreased by exposure. No changes in the two sexes were observed in serum T3 and T4. Exposure induced an increase in spleen and kidney weights in both sexes; the weight of liver was increased only in female rats. Weights of hypothalamus, striatum, adrenals and thyroid glands were not changed. Female but not male rats exposed to lead gained less weight than controls. The results suggest a non-specific stress response in female rats. In male rats only the sympatho-adrenal system seems to be affected by this lead exposure.