HTR5A and major depressive disorder: Contrary to fluoxetine-treated IMS mice that exhibit significantly reduced depression-like behavior in the forced swim test (FST; Fig. 1d) and reduced anxiety-like behavior in the Elevated Plus Maze (EPM; Fig. 1e), the FST and EPM behaviors of fluoxetine-treated IMS mice that were depleted of 5-HT did not differ from the corresponding behavioral phenotypes of non-treated IMS mice (Fig. 1d–e).