HTR1A and Anxiety: Thus, upon hyper-activation of the 5-HT system (High 5-HT, Figure 1), interneurons are predicted to be suppressed by interneuronal 5-HT1A activation while 5-HT2A receptors are predicted to respond to high 5-HT to activate pyramidal neurons and desensitize pyramidal 5-HT1A and GABA signaling via protein kinase C activation (Lembo and Albert, 1995; Wu et al., 2002), leading to a hyper-activated pyramidal activity and an anxiety phenotype.