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 tablesham 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 followscurrent 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.