The regulation of Pet1 and 5-Ht1a expression by 5-HT in brainstem explants. (A and B) The hindbrain explants of Tph2-/- mice, 5-Ht1a-/- mice and their littermates wild-type mice were treated with 5-HT either alone or in combination with WAY-100635, and the expression level of Pet1 (A) and 5-Ht1a (B) was measured using qRT-PCR. Relative expression was quantified using 18S rRNA as reference gene. Error bars represent SEM. n = 5. *P < 0.05, versus Saline and #P < 0.05, versus 5-HT, one-way ANOVA followed by post hoc analysis. (C) Diagram to show a 5-HT-dependent 5-Ht1a/Pet1 auto regulatory feedback loop.