Soya bean rich diet is associated with adult male rat aggressive behavior: relation to RF amide-related peptide 3-aromatase-neuroestrogen pathway in the brain.

Relation between soya bean (SB) consumption and aggressive behavior has not been elucidated yet. Thus, this study was conducted to investigate the effect of large amount of SB consumption on adult male rats' aggressive behavior through investigating changes in the expression of gonadotropin-inhibitory hormone/ RF amide-related peptide 3 (GnIH/RFRP3), neuropeptide FF receptor, cytochrome P450, family 19, subfamily A, polypeptide 1 (Cyp19A1), estrogen receptors α and β and the levels of neuroestrogen, dopamine, glutamate and testosterone as well as aromatase activity in the brain. Adult male rats were divided into three equal groups: group I, control group, received standard diet; group II and group III received 25% and 50% SB of their standard diet contents, respectively, for 12 weeks. The obtained results showed that feeding male rats with large amount of SB could induce aggressive behavior in a dose dependant manner possibly through inhibition of brain GnIH/RFRP-aromatase-neuroestrogen pathway. These effects may be through decreasing aromatase activity, neuroestrogen concentration, Cyp19A1 and ER β mRNA levels and increasing ER α mRNA levels and immunostaining as well as testosterone, dopamine and glutamate levels in the brain. These findings also provide further support for the inhibitory role of RFRP3 on aggressive behavior of male rats. These data may open new avenues for the potential harmful effects of consumption large amounts of SB rich food on humans.