Effect of N-acetylserotonin on brain edema after cerebral ischemia reperfusion with DWI in rats

Objective: To observe the protective effect of N-acetylserotonin (NAS) on brain edema induced by focal cerebral ischemia reperfusion (IR) in rats using DWI. Methods: Sixty-six rats were divided randomly into Sham-operation group (n=10), middle cerebral artery occlusion (MCAO) group (n=28) and NAS group (n=28). The rats of NAS and MCAO groups were performed DWI and pathological examination at 6 h, 24 h, 72 h and 7 days after IR, performed at 72 h for sham-operation group. And the relative apparent diffusion coefficient (rADC), relative exponential apparent diffusion coefficient (reADC) and AQP4 positive cells in cerebral infarction area were measured. 72 h after IR, the changes of brain water content were measured in all the three groups. Results: In Sham-operation group, no abnormal signal was seen on DWI. In the NAS and MCAO groups, abnormal high signals in the cerebral cortex and striatum in the injured side on DWI, low signal on ADC map and high signal on eADC map were shown respectively. 6 h, 24 h and 72 h after IR, the value of rADC in NAS group was significantly higher than that in MCAO group (all P<0.05), while the value of reADC and AQP4 positive cells were significantly lower than those in MCAO group (all P<0.05). 7 days after IR, there were no significant differences of rADC, reADC, and AQP4 positive cells in all groups (all P>0.05). The water content of the NAS group was much lower than that in the MCAO group (P<0.05). Conclusion: NAS can reduce brain edema and down-regulated the AQP4 expression in IR rats. DWI plays an important role in the evaluation of the neuroprotective effect of NAS.