Scalp mechanical stimulation alleviates cerebral hypoperfusion in rats with 2-VO by controlling cerebral edema

Abstract

Objective: To illustrate the cerebral protective effect of scalp mechanical stimulation (SMS), similar to scalp acupuncture in basic mechanism, on cerebral edema in rats with cerebral hypoperfusion. Methods: First, we screened the strength of SMS by measuring skin temperature and blood perfusion using laser speckle contrast imaging. Next, we observed the cerebral protective effects on cerebral blood perfusion, cerebral edema, and pathological changes in rats with modified two-vessel carotid artery occlusion (2-VO). Furthermore, the apoptosis-related proteins (caspase-3, cleaved-caspase-3) and cerebral edema related proteins [antiglial fibrillary acidic protein (GFAP) and antiaquaporin-4 (AQP4)] were measured via immunohistochemistry and Western blot analysis. Additionally, the correlation between neural apoptosis and AQP4 protein levels was analyzed. Results: We found that 0.5 N was the best SMS intensity suitable for our study. Compared with the control group, 0.5, 1, and 2 N maintained the scalp temperature and improved scalp blood flow (all P < .05). SMS intervention significantly increased cerebral blood flow and reduced the brain water content in rats with 2-VO (P < .001 and P = .0449, respectively). Compared to the rats with 2-VO, SMS treatment significantly reduced the number of caspase-3-positive cells (P = .0086) and cleaved caspase-3-positive cells (P = .036) in the hippocampal CA1, which was similar to the protein level of caspase-3 (P = .019). Compared to the sham group, the expression of GFAP and AQP4 was higher in the 2-VO group (P = .0369 and P = .0142), which was significantly decreased by SMS (P = .0484 and P = .0229). The expression of AQP4 was positively correlated with the expression of caspase-3 or cleaved caspase-3 (R2 = 0.6071/R2 = 0.8500). Conclusion: This study demonstrated the optimum SMS intensity for ameliorating cerebral hypoperfusion and its possible mechanism of action. Therefore, SMS is a promising and straightforward method for preventing ischemic stroke and cognitive impairment.

Keywords

• Scalp mechanical stimulation
• Cerebral hypoperfusion
• Astrocytes
• Aquaporin 4
• Apoptosis