Effect of Estradiol on Heme Biosynthetic Pathway in Lead-Poisoned Rabbits

Objectives：To clarify the effect of the female hormone estradiol (Est) on heme biosynthesis in lead-poisoned rabbits, parameters indicating lead exposure, such as free erythrocyte protoporphyrin (FEP) level and δ-aminolevulinic acid dehydratase (ALA-D) activity, were determined. Methods：Twenty-six male Japanese white rabbits (body weight (BW), 3 kg) were divided into four groups：I (control), II (Est), III (Pb), IV (Est+Pb). About 3 weeks after castration, Est (3 mg/kg of BW) was injected intramuscularly, and 2 weeks thereafter, lead (1.2 mg/kg of BW) was injected intravenously. After the initial injection of each of these substances, the same dose of each of these substances was injected once a week until the 9th week. Results： In groups III and IV, FEP level increased and ALA-D activity in the erythrocytes, bone marrow and liver decreased with an increase in lead concentration in blood. FEP level decreased significantly (p