DISTRIBUTION AND REGULATION OF ESTROGEN-2-HYDROXYLASE IN THE QUAIL BRAIN

The anatomical distribution and endocrine regulation of the estrogen-2 -hydroxylase activity were investigated in the brain of adult male and female Japanese quail. Significant levels of enzymatic activity were detected in all brain regions that were studied, but the highest level s were observed in preoptic and hypothalamic brain nuclei that are kno wn to contain high levels of aromatase activity. These data are consis tent with previous results suggesting that the placental aromatase is also responsible for the estrogen-2-hydroxylase activity. However, the re is a marked sex difference and a control by T of aromatase activity in the quail brain, and no such difference in 2-hydroxylase activity could generally be detected except in the VMN. Further studies will be needed to know whether the previously published conclusions concernin g the human placenta also apply to the brain. The present data are con sistent with the idea that estrogens formed locally in the brain by te stosterone aromatization could affect reproduction by interfering with the catecholaminergic transmission after being metabolized into catec hol-estrogens.