World of Reproduct ive Biology

An area of the brain that regulates mating behavior is masculinized through the removal of methyl groups from DNA, according to a new study in rats and mice [1]. The preoptic area of the hypothalamus, which regulates mating behavior such as mounting, is highly distinct between males and females. For instance, males have more neurons and excitatory synapses in this region than females. Previous studies have shown that the female phenotype is the ‘default’ state, and that testicular androgens promote conversion to the male phenotype. In rats and mice, conversion occurs during a critical developmental window, during the first few days after birth. Androgens drive this masculinization via the metabolite estradiol, produced locally in the preoptic area (local levels of estradiol can have development effects independent of circulating levels of the hormone)