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

摘要: Abstract Fluctuations in the concentrations of neuroactive steroid allopregnanolone are thought to influence γ-amino-butyric acid type A (GABA ) receptor gene expression and function. Long-term treatment with ethinyl estradiol (EE) plus levonorgestrel (LNG), two most widely used steroids hormonal contraceptive pill, decreases levels rat cerebral cortex plasma, alters GABA induces anxiety-like behavior. We evaluated which component pill is responsible for aforementioned changes. Female rats were injected subcutaneously (s.c.) EE (0.030 mg) or LNG (0.125 mg) once a day 4 weeks. Compared respective vehicle-treated control groups, decreased cortical allopregnanolone, progesterone pregnenolone by 76, 72 33%, respectively hippocampal 52, 56 50%, respectively. Likewise, 75, 68 respectively, 55, 65 60%, Administration LNG, but not EE, increased abundance γ2 subunit peptide hippocampus 38 59%, Further, time spent number entries into open arms elevated maze 43%, an index These results suggest that alterations behavior induced long-term combined EE/LNG appear be caused LNG. Given both decrease similar manner, these further changes associated expression.