FOS and Anxiety: Whereby in all conditions and cell types the number of c-fos is increased in 5-HT1A(-/-) mice (Wt naïve 22.14±2.06, 1A-ko naïve 43.43±2.47, p≤0.001, Wt anxiety 74.47±5.48, 1A-ko anxiety 141.14±7.8 p≤0.001) (Fig 1C and 1D), probably due to missing feedback inhibition of the 5-HT1A receptor [34].