Further investigation of the transcriptional expression profiles of this putative 5-HT4R between active and aestivated A. japonicus and phosphofructokinase (AjPFK) in 5-HT administrated A. japonicus in three peripheral tissues (intestine, muscle and respiratory tree) indicates that Aj5-HT4R is potentially associated with respiratory depression in aestivated A. japonicus. This evidence concerns the gene HTR4 and respiratory depression.