Progesterone selectively increases amygdala reactivity in women

Area of Science:

• Neuroendocrinology
• Neuroimaging
• Psychiatry

Background:

• Progesterone's neuroactive metabolites, allopregnanolone and pregnanolone, modulate gamma-aminobutyric acid (GABA) activity.
• While progesterone has anxiolytic effects, altered allopregnanolone levels may paradoxically increase anxiety and negative mood.

Purpose of the Study:

• To investigate the neural effects of progesterone on amygdala reactivity in healthy women using functional magnetic resonance imaging (fMRI).
• To explore how progesterone administration influences amygdala functional connectivity with other brain regions.

Main Methods:

• Healthy young women in the follicular phase received a single progesterone dose.
• Functional MRI (fMRI) was used to assess amygdala response to salient stimuli.
• Plasma concentrations of progesterone and allopregnanolone were measured.

Main Results:

• Progesterone administration significantly increased plasma levels of progesterone and allopregnanolone.
• Progesterone selectively enhanced amygdala reactivity to stimuli.
• Functional connectivity analyses revealed progesterone modulated amygdala coupling with distant brain areas.

Conclusions:

• Progesterone administration alters amygdala reactivity and its functional connectivity.
• These neurobiological changes provide a potential mechanism for progesterone's influence on anxiety and mood regulation.