The Rac1-Cofilin signalling pathway and subsequent analysis of involved molecules. The Rac1-Cofilin signalling pathway is shown (A). Signalling from AMPA, NMDA and GPC receptors leads to activation (phosphorylation) of Rac1 via LTP / LTD. This leads to downstream activation (phosphorylation) of PAK1/3, LIMK1 and final inactivation of cofilin via phosphorylation. Cdc42 is also able to phosphorylate PAK1/3. Associated microRNAs are miR-132 regulating Rac1 activity via modulation of a GTP hydrolysis protein (p250GAP) and miR-134 directly suppressing LIMK1 levels. Rac1 activity is regulated via phosphorylation of RhoGDI releasing Rac1 from RhoGDI inhibitory complex. Data from immunoblots (B - E) and quantification of miRNAs associated with the Rac1-Cofilin pathway (F) are shown in hippocampus and cortex from control, and exposed mice (0.5 and 1.0 Gy). The columns represent the fold-changes with standard errors of the mean (SEM) from three biological replicates. The visualisation of protein bands shows the representative change from three biological replicates. *p < 0.05; **p < 0.01; ***p < 0.001 (unpaired Student’s t-test). Normalisation was performed against endogenous GAPDH and endogenous snoRNA135 for immunoblotting and miRNA quantification, respectively. Gene expression analysis of Limk1 in cortex [C] and hippocampus [H] exposed to sham-irradiation, 0.5 Gy and 1.0 Gy is shown in panel G. Columns represent fold-changes with the standard error of the mean (SEM) from 3 biological replicates. Statistical analysis was performed with unpaired Student’s t-test; H: Hippocampus, C: Cortex.