background Gonadal steroid hormones influence mood and cognition. The negative mood symptoms in premenstrual dysphoric disorder (pmdd) are likely to be mediated by the progesterone metabolite allopregnanolone, which potentiates the inhibitory actions of gamma-aminobutyric acid (gaba).
method We investigated whether the amygdala could mediate these negative mood effects of allopregnanolone with fmri. Furthermore, we investigated the consequence of the amygdala modulation on emotional memory. Progesterone or placebo was administered orally to healthy young women, after which they first performed a matching task with angry and fearful face stimuli.
results The progesterone administration selectively increased the amygdala response during moderate progesterone and allopregnanolone concentrations. Second, higher concentrations decreased memory performance for faces. The imaging results show that the amygdala and fusiform gyrus supported the successful encoding of faces. Importantly, the progesterone administration decreased the amygdala and fusiform gyrus response to faces during memory encoding, which can explain the memory impairment.
conclusion Together, these results suggest that allopregnanolone could induce adverse effects on mood and anxiety as observed in pmdd by increasing amygdala activity. Furthermore, they show that allopregnanolone influences emotional memory by changing the probability of recruiting the amygdala and fusiform gyrus during memory encoding, which may contribute to the memory bias observed in mood disorders.