Long-term administration with levonorgestrel decreases allopregnanolone levels and alters GABAA receptor subunit expression and anxiety-like behavior

► Ethinyl estradiol (EE) or levonorgestrel (LNG) decreases allopregnanolone levels. ► LNG, but not EE, alters GABAA receptor expression and anxiety-like behavior. ► Changes in allopregnanolone levels are not related to GABAA receptor plasticity.