HTR5A and Anxiety: While MAO-A inhibition produces anxiolytic effects in rats (Caille et al. 1996; Eroğlu and Güven 1998), both acute activation of the serotonergic dorsal raphé nucleus (Urban et al. 2015) and acutely administered selective 5-HT inhibitors (Birkett et al. 2011; Mombereau et al. 2010) increase anxiety.