Propofol Pretreatment Attenuates Aquaporin-4 Over-Expression and Alleviates Cerebral Edema After Transient Focal Brain Ischemia Reperfusion in Rats

BACKGROUND: Cerebral edema is a major threat for stroke victims. Most studies have focused on the neuroprotective activities of propofol, addressing infarct volume rather than cerebral edema. Aquaporin-4 (AQP4) plays an important role in maintaining brain water homeostasis under various neurological insults. We explored the effect of propofol pretreatment on cerebral edema in a rat model of brain ischemia reperfusion and assessed the involvement of AQP4. METHODS: To induce brain ischemia reperfusion, we introduced a silicone-coated monofilament nylon suture into the origin of the middle cerebral artery, withdrawing it after 90 min. Treatment groups (n = 32), received propofol (0.1 mL . kg(-1) . min(-1)) infusion for 30 min before occlusion; the vehicle group (n = 32) and the sham-operated group (n = 28), which received the intralipid vehicle at the same time and rate. To assess cerebral infarct volume, we used 2, 3, 5-triphenyltetrazolium chloride staining; wet-dry weight ratio was the basis for cerebral edema estimation, and we used immunohistochemistry and Western blot to detect AQP4 expression. RESULTS: The wet-dry weight ratio decreased from 86.89% +/- 0.71%, in the vehicle group (n = 6) to 72.42% +/- 0.74% in the propofol group (n = 6), corresponding to an average decrease of 16%. In parallel and based on immunohistochemical semi-quantification, the propofol group exhibited remarkable attenuation of AQP4 over-expression in the ischemic border zone compared with the vehicle group: 1.28 +/- 0.03 vs 1.40 +/- 0.05, n = 7, respectively; P < 0.05. Values derived from Western blot quantification were similarly decreased ill the propofol group compared to the vehicle group: 20.85% +/- 4.18% vs 31.67% +/- 3.23%, 11 = 4, respectively; P < 0.05. However, infarct volume and neurologic deficit in postischemic rats in the propofol group were not statistically different from values in the vehicle group. CONCLUSIONS: We conclude that prestroke treatment with propofol reduces postischemic cerebral edema in rats, possibly through inhibiting AQP4 over-expression in the boundary zone of ischemia.