Fig. 2

The elevation of peripheral blood 5-HT levels induced by the tryptophan-rich diet promoted the proliferation and activation of Htr7⁺ Tregs. A-C Representative dot plots, histogram (A) and percentages of Tregs (B) and Htr7⁺ Tregs (C) detected via flow cytometry in the cervical lymph nodes (n = 7/group). D-F Representative dot plots (D) and percentages of Tregs (E) and Htr7⁺ Tregs (F) detected via flow cytometry in the hippocampus (n = 7/group). G Representative images of CD8 immunostaining in the hippocampal DG. Scale bar = 200 μm. H Quantification of CD8⁺ cells (n = 7/group). I, J Representative dot plots (I) and the percentages of CD44^highCD62L^low cells on CD8⁺ T lymphocytes determined via flow cytometry (J) in the hippocampal DG 24 h after LPS treatment (n = 7/group). ^*P < 0.05, ^**P < 0.01, ^***P < 0.001, ns indicates nonsignificant