Estrogen receptor GPR30 exerts anxiolytic effects by maintaining the balance between GABAergic and glutamatergic transmission in the basolateral amygdala of ovariectomized mice after stress

G-protein-coupled receptor 30 (GPR30)/G-protein-coupled estrogen receptor is a novel estrogen membrane receptor that localizes to the cell membrane and endoplasmic reticulum. GPR30 is widely distributed and has numerous physiological functions in the central nervous system. We found that GPR30 is highly expressed in the basolateral amygdala (BLA). Additionally, GPR30 expression in the amygdala of ovariectomized (OVX) mice significantly increased after acute stress and was accompanied by anxiety-like behaviors. These effects, however, were reversed by local infusion of the GPR30 agonist (G1) in the BLA. Protein assessments revealed that G1 attenuated the up-regulation of the GluR1 subunit of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor and NR2A-containing N-methyl-d-aspartate receptors (NMDARs) in the BLA of OVX mice using an acute stress paradigm. In the same model, we found that the agonist also blocked the down-regulation of γ-aminobutyric acid A (GABAA) receptors and NR2B-containing NMDARs. Electrophysiological recording showed that the activation of GPR30 increased the inhibitory synaptic transmission in the BLA. Overall, our results indicate that estradiol reduces anxiety-like behaviors induced by acute stress at least partially through GPR30 signaling, maintaining the balance between GABAergic and glutamatergic transmission in the BLA of OVX-stressed mice.