a statistical trendp = 0.054
post stimulation 18.54 ± 5.25 ng/mL, p = 0.002), with a statistical trend during stimulation (baseline vs. stimulation 23.64 ± 7.84 ng/mL, p = 0.054) ( Figure 4 ). 2.2.4. 5-HIAA Levels Were Selectively Reduced in DYT1 KI Mice During and After Optogenetic Inhibition of PV+ FSI Serotonin (5-HT) was below the limit of detection (< LOD), but its metabolite 5-hydroxyindolacetic acid (5-HIAA) was reliably quantified.