Dexmedetomidine alleviates cerebral ischemia-reperfusion injury in rats via inhibition of hypoxia-inducible factor-1α

Dexmedetomidine (Dex) was reported to reduce ischemia-reperfusion (I/R) injury in kidney and brain tissues. Thus, we aimed to study the role and mechanism of Dex in cerebral I/R injury by inhibiting hypoxia-inducible factor-1 alpha (HIF-1 alpha) and apoptosis. First, I/R injury models were established. Six groups were assigned after different treatments: sham, I/R, I/R+Dex, I/R+2-methoxyestradiol (2ME2) (HIF-1 alpha inhibitor), I/R+CoCl2 (HIF-1 alpha activator), and I/R+Dex+CoCl2 groups. Neurological function, cerebral infarction volume, survival, and apoptosis of brain cells were then analyzed. Besides, immunohistochemistry and Western blot analysis were used to detect the expression of HIF-1 alpha, BCL-2[B-cell leukemia/lymphoma 2] adenovirus E1B interacting protein 3 (BNIP3), B-cell leukemia/lymphoma 2 (BCL2), BCL2[B-cell leukemia/lymphoma 2] associated X (Bax), and cleaved-caspase3 proteins in brain tissues. I/R rats showed cerebral infarction, increased neurological function score, number of terminal-deoxynucleoitidyl transferase mediated nick end labeling (TUNEL)-positive cells and HIF-1 alpha-positive cells as well as decreased neurons. Inhibition of HIF-1 alpha can reduce the apoptosis induced by I/R, and overexpression of HIF-1 alpha can aggravate apoptosis in brain tissue of I/R rats. Furthermore, activation of HIF-1 alpha expression blocks the inhibitory effect of Dex on neuronal apoptosis in I/R rats. Dex may inhibit the neuronal apoptosis of I/R rats by inhibiting the HIF-1 alpha pathway and then improve the cerebral I/R injury in rats.