Maternal exposure to daidzein alters behaviour and oestrogen receptor α expression in adult female offspring

Daidzein is an important isoflavone in soy. The potential role of daidzein in the prevention of chronic diseases is attracting growing scientific and public attention. This has led to an increase in the consumption of daidzein by humans, including adolescent and pregnant women. However, it remains unclear whether developmental exposure to daidzein affects behaviour and/or oestrogen receptor a (ERa) expression in adults. After dietary exposure to daidzein in mice during pregnancy and lactation, we observed behaviours in their female offspring during adulthood during open field, novel cage, elevated plus-maze, Morris water maze and social interaction tests. Central ERa expression was also examined using immunocytochemistry. Compared with a control group, female mice exposed to daidzein during early development through their mother showed significantly more affiliation behaviours when they encountered female stimuli. The acquisition and retrieval of spatial memory in the water maze test were also significantly improved by exposure to daidzein. Finally, females exposed to daidzein showed significantly less ERa expression in bed nucleus of the stria terminalis and medial amygdala. In combination, our findings show that maternal exposure to daidzein has a masculinisation effect on memory and social behaviour, suggesting a potential role of ERa distribution in the brains of female mice when regulating these behaviours. Behavioural Pharmacology 21:283–291 c 2010 Wolters Kluwer Health | Lippincott Williams & Wilkins.