Fig. 2.

The free fatty acid receptor 3 agonist propionate exerts neuroprotective effects on Schwann cells and dorsal root ganglia by increased catalase expression. Treatment of Schwann cells with both free fatty acid receptor 3 ligands, propionate or β-hydroxybutyrate, reduced H₂O₂ induced cell death significantly compared to control in flow cytometry (A). In line, pretreatment with propionate increased axonal outgrowth after SNAP application in comparison to control (B). Vice versa, addition of the G protein receptor inhibitor pertussis toxin abolished the neuroprotective effect of propionate in SNAP treated dorsal root ganglia (B). Similar, DRGs of control rats, but not propionate treated rats, showed a significantly reduction of axonal outgrowth after SNAP application (C). Propionate treatment of Schwann cells for 72 h significantly increased the relative expression of catalase compared to control (D), whereas the expression was also increased after 24-h treatment but did not reach the level of significance. In dorsal root ganglia, the catalase expression was increased 24 h after propionate treatment (E). No significant changes in the relative mRNA expression of HO-1 and NQO1 were shown after 24 h PA treatment in DRG (F, G). Data are provided as mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.