Effect of electric stimulation of vagus nerves on expression of aquaporin-4 in brain tissues of rats with endotoxemia / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of electric stimulation of vagus nerves on the expression of aquaporin-4 (AQP-4) in brain tissues of rats with endotoxemia.Methods Forty-eight adult male Sprague-Dawley rats,aged 2 months,weighing 200-250 g,were divided into 4 groups (n=12 each) using a random number table:sham operation group (S group),endotoxemia group (E group),vagus nerve transection group (VNT group) and vagus nerve transection plus vagus nerve stimulation group (VNT+VNS group).The model of endoxemia was established by injection of lipopolysaccharide 10 mg/kg via the femoral vein of anesthetized rats.Left cervical vagotomy was performed at 30 min before injection of lipopolysaccharide in VNT and VNT+VNS groups.In VNT+VNS group,electric stimulation of the distal end of the left vagus nerve was performed immediately after the end of surgery.Stimulation parameters were as follows:current intensity 0.5 mA,pulse width 0.5 ms,frequency 20 Hz,once every 5 min,30 s per time,lasting for 1 h.Blood samples were collected from the abdominal aorta at 6 h after establishment of the model,and then the rats were sacrificed and brains were removed.The level of IL-1β in plasma and brain tissues and content of AQP-4 in brain tissues were measured by enzyme-linked immunosorbent assay.The Evans blue (EB) content in brain tissues and brain water content were determined.Results Compared with S group,the levels of IL-1β in plasma were significantly increased,and the contents of IL-1β,AQP-4 and EB in brain tissues and brain water content were increased in E,VNT and VNT+VNS groups (P＜0.01).Compared with E group,the levels of IL-1β in plasma were significantly decreased,and the contents of IL-1β,AQP-4 and EB in brain tissues and brain water content were decreased in VNT+VNS group (P＜0.01),and no significant change was found in the indexes mentioned above in VNT group (P＞ 0.05).Conclusion The mechanism by which electric stimulation of vagus nerves reduces brain injury may be related to decreased content of AQP-4 in brain tissues of rats with endotoxemia.