Rho-kinase inhibitor prevents acute injury against transient focal cerebral ischemia by enhancing the expression and function of GABA receptors in rats

Abstract Studies have shown hydroxyfasudil-mediated inhibition of Rho-kinase (ROCK) has efficacy in rodent models of focal ischemia and in in vitro systems that recapitulate stroke conditions. However, the mechanisms underlying the neuroprotective effects of the ROCK inhibitor on stroke are not well understood. In this study, we examined the role of γ-aminobutyric acid (GABA) interneurons in the effects of hydroxyfasudil on transient middle cerebral artery occlusion (tMCAO) induced acute ischemia-reperfusion injury to explore the mechanisms. tMCAO rats developed marked neurological deficits and impaired long-term potentiation; these effects were attenuated by hydroxyfasudil. Expression of GABA A and GABA B receptors after ischemia was decreased to various extents in three brain regions: the cortex, hippocampus, and striatum. Hydroxyfasudil up-regulated expression in the cortex and hippocampus but not in the striatum. Moreover, hydroxyfasudil could suppress the activation of nuclear factor-κB (NF-κB) in these regions during the acute ischemia. We further found that in tMCAO rats, hydroxyfasudil was able to abolish the decrease in GABA A and GABA B receptor phosphorylation triggered by high-frequency stimulation as well as the activation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). In summary, our results suggest ROCK inhibition improved neurological function and mitigated synaptic plasticity deficits caused by transient focal cerebral ischemia through the inactivation of two distinct pathways: (1) a ROCK-NF-κB pathway that leads to the suppression of GABA A and GABA B expression, and (2) a ROCK-PTEN pathway that decreases the phosphorylation of GABA A and GABA B , thereby affecting receptor function by triggering receptor endocytosis and the degradation of internalized receptors.