| Acupuncture is an important component of Traditional Chinese Medicine. Its validity has been proved by long-term clinical practices, and gained worldwide recognition gradually. Stomach 36 (ST36, Zusnali) is one of the acupoints used most commonly in acupuncture, especially for the treatment of gastrointestinal diseases. However, its therapeutic mechanism, particularly the central nerve mechanism, is not clearly known. In this series of experiments, data on human cerebral glucose metabolism was acquired by positron emission tomography (PET), and regional cerebral blood flow (rCBF) in humans and rats were measured with functional magnetic resonance imaging (fMRI), during acupuncture at the right ST36, in order to explore its central therapeutic mechanism by analyzing changes in metabolic and hemodynamic brain function.Methods:1. The whole brain data on cerebral glucose metabolism were acquired on1 ftsix healthy volunteers with F-FDG-PET, before and after acupuncture at the ST36 acupoint (the right leg). Images of cerebral glucose metabolism were realigned and spatially normalized into Talairach space. Statistical parametric mapping (SPM) was then used to analyze the data with paired one-side t-statistics, and then localize brain areas with both increased and decreased metabolic changes relative to the baseline.2. The human brain fMRI data were obtained with BOLD-fMRI, during acupuncture at the right ST36, and then analyzed by a region of interest (ROI) method to acquire the time signal curve in some select regions.3. The fMRI data were collected on 9 male Sprague-Dawley rats with a 4.7 Tesla MR imager before and after electro-acupuncture. Five rats received electro-acupuncturing at the right ST 36 (Zusanli) while 4 others served as controls and were stimulated at the nonmeridian point (lateral area of the leg 5mm from ST 36). Images from each rat were analyzed individually by statisticalparametric mapping (SPM) to localize regional changes in fMRI signal. Results:1. Stimulation of acupoint ST36 by hand acupuncture, resulted in significantly increased glucose metabolism in the contralateral precentral and postcentral gyri, hypothalamus, hippocampus, superior and middle temporal gyri, cerebellum and ipsilateral paracentral lobule and superior margin in the middle cingulate gyrus, medial and superior frontal gyri. Metabolism decreased in the ipsilateral septal area, middle cingulate gyrus, inferior frontal and middle temporal gyri, and bilaterally in the cerebellum and inferior temporal gyrus.2. In the hypothalamus and temporal lobe, that displayed high glucose metabolism, regional cerebral blood flow given by fMRI signals was also increased. In addition, fMRI signals fluctuated around baseline before needling, and increased temporally with needling. The signals fluctuated at a high level while twisting the needle for 3 minutes, and did not decrease to the baseline even 1 minute after withdrawal.3. All the rats in the ST 36 group showed significant fMRI signal increase in the lateral, anterior and ventromedial hypothalamus (P=0.001). The increased signal was also evident mostly in the sensorimotor gyri I & II, caudate and putamen in both groups but at different levels of statistical significance (puncturing ST 36: p=0.001; nonmeridian point p=0.01or p=0.05).Conclusions:1. Acupuncture at the ST36 can lead to glycometabolic and hemodynamic changes in some regions of human brain. Thus visual experimental evidence of acupuncturing ST36 was obtained in this study by PET/fMRI.2. Acupunctuing ST36 can result in functional changes on different parts of the autonomic nerve system: the activation in hypothalamus, hippocampus, paracentral lobule, superior margin in middle cingulate gyrus, and the deactivation in septal area and middle cingulate gyrus. These regions are correlated with gastric function. Therefore, acupuncture at ST36 may achieve its therapeutical effects on gastrointestinal disorders by modulating the activity of above relevant brain sites.
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