Journal: bioRxiv
Article Title: Brain serotonin circuit reverses decline in physical activity with age
doi: 10.64898/2025.12.27.695444
Figure Lengend Snippet: A-G. (A) Effect of d-fenfluramine (d-fen, 3 mg/kg, i.p.) versus vehicle (saline) on TSE PhenoMaster home cage physical activity in young adult (2-3 months old) male and female mice on a C57BL/6 background (n = 16) showed: (B) reduced beam breaks as illustrated in representative ambulation home cage heatmaps (W, water; F, food); (C) decreased total beam breaks over time (RM ANOVA Treatment: F (1,14) = 37.13, p = <0.0001); (D) increased percent time spent inactive (t(30)= 2.101, p = 0.0442); (E) reduced cumulative daily distance (RM ANOVA Treatment: F (1,14) = 30.72, p = <0.0001); (F) decreased average speed (t(15) = 3.467, p = 0.0034); (G) no change in cumulative food intake (RM ANOVA Treatment: F (1,14) = 2.542, p = 0.1332). H-J. Dorsal raphe nucleus 5-HT expression. (H) Spatial representation of 5-HT DR neurons using Tph2 immunoreactivity in a young adult mouse. (I) Representative heatmap of Tph2 positive cells expression in DR at bregma -4.60 (scale bar = 400 µm). (J) Tph2-immunofluroescent cell number at bregma level -4.60 (2-4 months old, n = 7; 12-24 months old, n=8; t(13) = 0.04933, p = 0.9614). K-M . (K) 5-HT DR cell activity in younger (2-4 months old, n=4 mice/36 cells) and older (12-24 months old, n=4/20 cells) adult male and female ePet YFP mice in the light and dark cycle (scale bars: main image = 500 µm; magnified = 20 µm). (L) Median spike count demonstrates 5-HT DR neurons from older adult mice exhibit increased firing in the dark cycle and lower firing in the light cycle compared to younger adult mice (ANOVA Interaction F (1,52) = 7.433, p = 0.0087). (M) Example traces during the dark cycle.
Article Snippet: Locomotor activity and food intake measurements were performed using TSE PhenoMaster System cages (TSE, Germany).
Techniques: Saline, Activity Assay, Expressing