Alongside the improvement in depression-related effects, 6 days of treatment with the three TM peptides (5-HT1AR-TM4, 5-HT1AR-TM5, and OX1R-TM5) reduced the amount of 5-HT1AR/OX1R heterodimers in the hippocampus. Here, HCRTR1 is linked to depressive symptom measurement.