Oestrogen produced locally by aromatase is thought to participate in numerous biological functions in the adult central nervous system (CNS). However, little is known about aromatase expression in the human CNS.

We examined aromatase expression in human brain regions, (4 men, 2 women) obtained from autopsy, by reverse transcriptase (RT)‐polymerase chain reaction (PCR) and also studied alternative use of multiple exons 1 of its gene, which is involved in tissue specific expression of aromatase in human.

The amount of aromatase mRNA determine by RT‐PCR assay in 6 cases tended to be highest in pons, thalamus, hypothalamus and hippocampus. Analysis of multiple exons 1 revealed that 1f, considered specific for brain, as well as 1b (fibrolast type) and 1d (gonadal type), were expressed. 1d and 1f tended to be utilized in hypothalamus, thalamus and amygdala. The amount of overall mRNA expression was also higher in hypothalamus, thalamus and amygdala than in other regions of the brain. There were no differences of utilization of exons 1 and mRNA expression of aromatase between female and male brain.

These results demonstrate that aromatase is expressed widely in various regions of human brain tissues in both men and women.