Sex- and age-specific differences in human brain CYP11A1 mRNA expression

While the presence of CYP11A1 (P450SCC, cholesterol side-chain cleavage enz yme) has been well established in the brain of rodents, limited information is available on CYP11A1 expression in human brain. In both species, little is known regarding postnatal changes or sex specific differences in cerebr al CYP11A1 expression. In the present study, we used a sensitive competitiv e reverse transcriptase polymerase chain reaction (RT-PCR) assay to quantif y the amount of CYP11A1 mRNA in a large number of human brain tissue specim ens obtained at neurosurgery. CYP11A1 mRNA is expressed approximate to 200 times lower in the temporal lobe, frontal lobe and hippocampus than in adre nal tissue, known for high CYP11A1 mRNA expression. During childhood CYP11A 1 mRNA concentrations in the temporal lobe increase markedly and reach adul t levels at puberty. CYP11A1 mRNA is significantly higher in the temporal a nd frontal lobe cortex of women than in that of men. Our data demonstrate f or the first time an age and sex dependent expression of CYP11A1 mRNA in th e human brain.