Fig. 2

Fingolimod (FTY720) significantly elevates cAMP levels in the regenerating nerve. a Fourteen-day post-crush, colocalization of cAMP and neurofilament light-chain immunohistochemistry indicates an accumulation of axonal cAMP around and proximal from the injury site. b Representative images of cAMP immunofluorescence. Scale bar indicates 100 μm. c Quantification of cAMP immunofluorescence revealed significantly increased axonal cAMP levels in crushed nerves under fingolimod treatment in wildtype mice and both immunodeficient mouse strains. Note that although fingolimod induced a significant cAMP increase in Rag1 ^−/− mice compared to Rag1 ^−/− controls, overall cAMP levels were reduced in Rag1 ^−/− mice, which correlates with the impairment of regenerative capacity in these mice. N = 4/4/6/4/4/6 animals (from left to right; quantification of one representative slide per animal). Statistical analysis was done by one-way ANOVA and Newman-Keuls post hoc test. Data represent mean ± s.e.m. Statistical significance is indicated by asterisks with P ≤ 0.05*, P ≤ 0.01**, and P ≤ 0.001***