Acupuncture improves leptomeningeal collateral compensatory efficiency in the affected hemisphere and reduces neuronal damage in cortical M5 region in rats with middle cerebral artery occlusion

ObjectiveTo observe the dynamic compensatory characteristics of the leptomeningeal collateral （LMC） circulation in the affected hemisphere of rats with right middle cerebral artery occlusion （MCAO）， and to investigate the effects of acupuncture on LMC compensatory efficiency and neuronal function in the cortical M5 region. Additionally， to elucidate the neuroprotective mechanism of acupuncture by exploring the temporal pattern of LMC compensation.MethodsThis study was divided into 2 parts. Part 1： 4 male SD rats were randomly selected for monitoring blood perfusion in the affected LMC and cortical M5 region before ischemia， immediately after ischemia， 3 h and 12 h post-ischemia using laser speckle contrast imaging. Part 2： 90 male SD rats were randomly divided into sham operation， model， sham acupuncture， acupuncture， and butylphthalide groups， with 18 rats in each group. Three hours after modeling， acupuncture was applied to bilateral “Neiguan” （PC6） and “Shuigou” （GV26） or non-acupoints （3 mm below the starting point of bilateral axillary midline and 3 mm beside the apex of coccyx） for 30 min. In the butylphthalide group， butylphthalide injection （2.25 mg/kg） was injected into the tail vein once 3 h after successful modeling. Laser speckle blood flow imaging was used to monitor the changes of blood flow perfusion and LMC vascular diameter in LMC and cortical M5 region at different time points before ischemia， immediately after ischemia and 12 h after ischemia. The percentage of cerebral infarction volume was detected by TTC staining. Modified neuropathy symptom score （mNSS） was used to evaluate neurological function. The grip strength of the contralateral upper limb of the rat was detected by the rat grip tester. The ultrastructure of neurons and mitochondria in the M5 region of the affected cortex was observed by transmission electron microscopy. The positive expression of neuronal nuclear protein （NeuN） in the M5 region of the affected cortex was detected by immunofluorescence staining. The content of adenosine triphosphate （ATP） in the cortex of the affected side was detected by colorimetry.ResultsCompared with the pre-ischemia state， the blood perfusion in the affected LMC and cortical M5 region were decreased immediately after ischemia （PPPPPPPPPPConclusionThe compensatory efficacy of the affected LMC in MCAO rats increases through blood flow redistribution at 3 h after ischemia， but declines at 12 h. Acupuncture can enhance the LMC compensatory efficiency， improve cortical M5 blood perfusion， and optimize mitochondrial structure and functional homeostasis， thereby exerting neuroprotective effects.