Fig. 5

Serum short-chain fatty acid (SCFA) levels in mice treated with vehicle (VH) or Pan-Probiotic (PP) at 3 and 35 days post-TBI. Bar plots illustrate the relative abundance of individual SCFAs (as a percentage of total SCFAs) in male (M) and female (F) mice across treatment groups (VH: vehicle, blue; PP: probiotic, red). SCFAs analyzed include acetate, propionate, butyrate, isobutyrate, 2-methylbutyrate, isovalerate, valerate, and caproate. (a–h) At 3 days post-injury (dpi), no significant differences were observed among the groups. (i–p) At 35 dpi, a significant interaction effect was observed for propionate (j), with males showing a decrease and females showing an increase in propionate levels from VH to PP treatment. In males, PP treatment increased isobutyrate (l), 2-methylbutyrate (m), valerate (o), and caproate (p) levels in male mice, with significant differences indicated (*p < 0.05, **p < 0.01, ^p < 0.05 for sex comparison). Comparisons between males and females within the PP-treated group revealed that males had higher levels of 2-methylbutyrate (m) and caproate (p). Statistical significance between groups was evaluated using two-way ANOVA followed by Tukey’s post-hoc test for multiple comparisons (*p < 0.05, **p < 0.01). Sex differences were indicated by (^^p < 0.05). n = 3–4 mice/ 3 dpi group, n = 9–10 mice/ 35 dpi group. Error bars represent the standard error of the mean (SEM)