Effects of electroacupuncture on the microvascular structure and related protein expression in the hippocampus of vascular dementia rats

OBJECTIVES

To explore the effect of electroacupuncture (EA) at "Baihui" (GV20) and "Shenting" (GV24) on the microvascular structure and related protein expression in the hippocampus of vascular dementia (VD) rat model, and to investigate the mechanism of EA in the treatment of VD.

METHODS

A total of 24 SD rats were randomly divided into sham operation, model, EA, and oxiracetam groups, with 6 rats in each group. Multiple cerebral infarction method was used to establish VD model. In the EA group, EA was applied to GV20 and GV24 for 30 min, once daily for 14 days. Rats in the oxiracetam group were treated with oxiracetam (50 mg/kg) by intraperitoneal injection, and the course of treatment was the same as that in the EA group. Learning and memory ability were evaluated by using Morris water maze test and new object recognition experiment. The cerebral blood flow was detected by laser doppler. The microvascular structure in the hippocampus was observed by transmission electron microscopy. The expression of vascular structure related proteins of platelet-derived growth factor receptor (PDGFR)-β, platelet endothelial cell adhesion molecule-1(CD31), neural cadherin N-Cadherin, Zonula occludens protein-1(ZO-1) in the hippocampus were measured by Western blot.

RESULTS

Compared with the sham operation group, the rats in the model group had a significant increase in time of first crossing the platform, a significant decrease in the number of crossing platform and the new object preference index (P<0.05), a significant decrease in cerebral blood flow (P<0.05), and a significant increase in the brain weight (P<0.05). The structure boundary of pericyte and endothelial cells in the microvessels of the hippocampal CA1 area of model group was blurred, accompanied by obvious edema around the vessels and the reduction of tight junctions. The protein expression levels of PDGFR-β, CD31, N-Cadherin, ZO-1 were significantly decreased in the model group compared with those in the sham operation group (P<0.05). Compared with the model group, the time of first crossing the platform of rats in the EA and oxiracetam group was shortened, the number of crossing platform were increased (P<0.05), the cerebral blood flow was increased (P<0.05), the brain weight was decreased (P<0.05), the morphology and structure of pericyte and endothelial cells in the microvessels of hippocampal CA1 area were intact, accompanied by the increase of tight junctions. Additionally, Compared with the model group, the EA group had a significant increase in the new object preference index (P<0.05), the protein expression levels of PDGFR-β, CD31, ZO-1 in the EA group were increased (P<0.05), and the expression of PDGFR-β, N-Cadherin, ZO-1 in the oxiracetam group were increased (P<0.05).

CONCLUSIONS

EA at GV20 and GV24 can improve the learning and memory ability of VD rats, and the mechanism may be related to the repair of microvascular structures and improvement of cerebral blood flow.

Analysis of Syk/PECAM-1 signaling pathway in low shear stress induced atherosclerosis based on ultrasound imaging

BACKGROUND AND OBJECTIVE

Low shear stress (LSS) has been demonstrated to be involved in function of vascular endothelial cells. Here we tested the hypothesis that activation of Syk played an important in LSS-induced atherosclerosis via PECAM-1 signaling pathway.

METHODS

In vitro, primary human umbilical vein endothelial cells (HUVECs) were stimulated with parallel plate flow chamber system for 12h under normal shear stress (NSS, 15dyne/cm²), LSS (5dyne/cm²) and high shear stress (HSS, 25dyne/cm²), respectively, followed by inflammatory response analysis. In vivo, animal models of rat fed atherogenic diet were treated with LSS stimulation by constricting abdominal aorta with a blunted needle (0.6mm in diameter). The spatial distribution of WSS of blood vessels was generated by WSS quantitative analysis software through color Doppler flow imaging with a high-frequency small animal ultrasound system. Small molecule R406, a well-demonstrated Syk inhibitor, was applied to animals as well as HUVEC cells.

RESULTS

In vivo, comparison with the control group was performed, the mean value of WSS distribution of blood vessels was lower in LSS model rat. LSS promoted expression of phosphorylated PECAM-1 (p-PECAM-1) and Syk in LSS model rats. Compared with control group, endothelial cells of the abdominal aorta become less elongated and more polygonal in LSS group, and had a slender shape in LSS with R406 group. In vitro, LSS increased the expression of p-PECAM-1, Syk and NF-κB in HUVECs. Inhibition of Syk attenuated LSS-induced inflammatory response.

CONCLUSIONS

Activation of Syk resulted in LSS-induced inflammatory response via PECAM-1 signaling pathway both in vitro and in vivo. Syk might be involved in morphological changes of ECs under the influence of LSS.