To further explore this hypothesis, we used mice lacking the 5-HT<sub>3</sub> receptor (Htr3a KO) and their wild-type (WT) controls to assess their response in behavioural paradigms relevant to anxiety and depression.
Interestingly, a functional polymorphism in HTR3A, encoding the 5-HT3 receptor A subunit, has been reported to be associated with depression and anxiety related traits.
Regardless of diagnosis, the C/C genotype of the c.-42C>T polymorphism in HTR3A, compared with T carrier status, is associated with increased anxiety and amygdala responsiveness during emotional and nonemotional tasks.