Abstract: OBJECTIVE: To investigate the changes in the neuronal microenvironment of the middle cerebral artery(MCA) territory induced by Jing-well points bloodletting acupuncture(WPBA) and to explore the neuroprotective mechanism of WPBA in stroke.METHODS: Adult male Sprague Dawley(n = 32)rats were randomly divided into four groups of eight animals each: WPBA-thalamus group(WT),WPBA-caudate nucleus group(WC), sham-control thalamus group(ST) and sham-control caudate nucleus group(SC). Animals in the WT and WC groups received 2 μL of the extracellular tracer gadolinium-diethylene triamine pentaacetic acid(Gd-DTPA)injected into the thalamus or caudate nucleus, respectively, and 12 Jing-well points in the distal ends of the rats' digits were used for WPBA. Although 2 μL of Gd-DTPA was injected into the thalamus or caudate nucleus, respectively, for animals in the two sham groups(ST and SC), no acupuncture or bloodletting was performed. Brain extracellular space and interstitial fluid flow parameters were measured using Gd-DTPA-enhanced magnetic resonance imaging.RESULTS: The brain interstitial fluid flow speed was decreased in the thalamus after WPBA, with a significantly lower Gd-DTPA clearance rate and longer half-life of Gd-DTPA in the thalamus of treated rats than those in sham-control rats [WPBA-treated rats' clearance rate,(7.47 ± 3.15) × 10~(-5)/s(P = 0.009);half-life,(1.52 ± 0.13) h, P = 0.000]. By contrast, no significant changes in brain extracellular space and interstitial fluid flow parameters were detected in the caudate nucleus after WPBA(P = 0.649). In addition, no differences in the morphology of the brain extracellular space or the final distribution of the traced brain interstitial fluid were demonstrated between the WT and WC groups(P = 0.631, P = 0.970,respectively).CONCLUSION: The WPBA decreased the speed of the local thalamic ISF flow in rats, which is assumed to be a beneficial protection by down-modulated the metabolic rate of the attacked neurons under stroke.

Key words: Bloodletting, Extracellular space, Gadolinium ethoxybenzyl DTPA, Interstitial fluid, Magnetic resonance imaging