The expression of Pet1 but not Gata3 was decreased in 5Ht1a-/-mice. (A) In situ hybridization images to show the expression of Pet1, Gata3, Tph2, AADC and VMAT2 and immunostaining of LMX1B in the dorsal raphe nuclei of 5-Ht1a+/+ mice (upper row) and 5-Ht1a-/- mice (lower row). (B) Quantification of positive cells for Pet1 and Gata3 in B7-8 raphe nuclei. Error bars represent SEM. n = 6. *P < 0.05, versus 5-Ht1a+/+, unpaired t test. Scale bar, 100 μm.