In rodents, several 5-HTRs including 5-HT1AR, 5-HT1BR, 5-HT2AR, 5-HT2BR, 5-HT2CR, 5-HT3R, 5-HT4R, and 5-HT7Rs participate in anxiety-like responses and both agonists and antagonists can be used depending on the subtype to regulate anxiety-like behaviors [172]. This evidence concerns the gene HTR4 and Anxiety.