The hypothesis goes beyond the serotonin hypothesis of depression and moves into molecular integration performed in diverse 5-HT1A and other 5-HTR heterocomplexes where, e.g., fibroblast growth factor receptor 1 (FGFR1) [19] and oxytocin receptor [30] protomers participate. This evidence concerns the gene FGFR1 and depressive symptom measurement.