Fluoxetine improves behavioural deficits induced by chronic alcohol addiction by alleviating RNA editing of 5-HT_2C receptors in astrocytes

Abstract

The alcoholism and major depressive disorder are common comorbidity, with alcohol-induced depressive symptoms being eased by selective serotonin re-uptake inhibitors (SSRIs), although the mechanisms underlying pathology and therapy are poorly understood. Chronic alcohol consumption affects the activity of serotonin 2C receptors (5-HT2CR) by regulating adenosine deaminases acting on RNA (ADARs) in neurones. Astrogliopathic changes contribute to alcohol addiction, while decreased release of ATP from astrocytes can trigger depressive-like behaviours in mice. In this study, we discovered that chronic alcohol addiction increased editing of RNA of 5-HT2CR via up-regulating the expression of ADAR2, consequnetly reducing the release of ATP from astrocytes induced by 5-HT2CR agonist, MK212. At the same time SSRI antidepressant fluoxetine decreased the expression of ADAR2 through the transactivation of EGFR/PI3K/AKT/cFos signalling pathway. Reduction in ADAR2 activity eliminated the RNA editing of 5-HT2CR in vivo and increased release of astroglial ATP which was suppressed by chronic alcohol consumption. Meanwhile, fluoxetine improved the behavioural and motor symptoms induced by alcohol addiction and decreased the alcohol intake. Our study suggests that the astrocytic 5-HT2CR contribute to alcohol addiction; fluoxetine thus can be used to alleviate depression, treat alcohol addiction and improve motor coordination.