To evaluate the age dependent involvement of Rho GTPases (key regulators of synaptic plasticity) in brain metabolism and function, we administered fasudil (for three months in drinking water), an inhibitor of the RhoA downstream effectors Rho kinases (ROCKs) on young adult CD1 mice (5 months), and to an older group (19 months age). Fasudil is proved to attenuate symptoms and progression of neurodegenerative diseases in animal models making ROCK inhibition a promising target for new therapeutic approaches.

A battery of behavioral tests was performed to analyze anxiety, locomotor and cognitive function.

MRI/MRS experiments were performed on a 7T Bruker system. MR spectra were collected from 3 regions selected for evaluating possible cognitive alterations (prefrontal cortex and hippocampus) and deficits in motor coordination (cerebellum). The quantitative protocol adopted included ex vivo brain water content determination. Protein expression analysis in the same regions were performed after sacrifice.  An age-dependent effect on anxiety and fear memory was found in fasudil treated mice.

Two-ways ANOVA (treatment and age factors) was used to determine statistical significance for metabolite levels, MD and FA parameters and frontal cortex and hippocampus thickness. Age dependent metabolic, anatomic and structural brain alterations were detected after fasudil treatment. A decrease in GABAa receptor subunity expression was found as well as decrease on the synaptic plasticity biomarker PSD95 in the selected brain areas. All together these results show age dependent and brain region specific effects of fasudil which appear to modulate anxiety behaviour with possible negative effects on memory and synaptic plasticity.