Neural Mechanism Study For Obese Adolescence:Evaluated With MR-neuroimages And Laboratory Animals

Part I Meta-analysis of fMRI studies associated with food and appetitePurpose:To determine the concurrence in the brain regions activated in response to different food and to assess the modulating effects of hunger state and the food’s energy content. Materials and Method:Signed differential mapping (SDM) voxel-wise meta-analysis was carried out on fMRI data from healthy normal weight subjects in order to compare the different activated brain regions when food and non-food pictures were shown separately, when subjects were in hunger or full, and when the food contains different energy. Results:1. Compared to non-food picture, bilateral posterior fusiform gyrus, the left lateral orbitofrontal cortex (OFC) and the left middle insuia were activated;2. Hunger modulated the response to food pictures in the right amygdala and left lateral OFC;3. Energy content modulated the response in the hypothalamus and ventral striatum. Limitation According to the results, the concurrence between studies was moderate, meaning other factors might have effects to activation. Regions that were not mentioned in the studies might take a part in the moderation. Conclusions:To reduce neurofunctional activation in posterior fusiform gyrus, OFC, amygdale, hypothalamus and ventral striatum might suppress the desire for food. Part II Effects of Acupuncture Therapy on Obese Adolescence’s Central Nervous SystemPurpose:To investigate obese adolescence’s brain with acupuncture therapy via fMRI and voxel-based morphometry using Diffeomorphic Anatomic Registration through Exponentiated Lie algebra algorithm (DARTEL) approach. Materials and Method:10subjects with simple obesity (M:7, F:3, Aged14-18, right handed, BMI29.03±4.81kg/m2) underwent periodical acupuncture therapy and were taken high resolution T1W MR Images of the brain before and after the therapy respectively. Another10gender-and age-matched volunteers with normal BMI (right handed, BMI25.05±5.02kg/m2) were enrolled as control group. fMRI methods:Activation regions were caculated by fMRI when food pictures were shown to subjects. fMRI would be performed once more during stimulation of two acupoints (ST36and ST40). DARTEL-VBM analysis:Compare the regional volumetric difference in grey/white matter between before and after the periodic acupuncture therapy. All the analysis was carried out using SPM8software on MATLAB7.8.0.347platform. Results:1. Brainstem, left thalamus, bilateral OFC, insular cortex, hippocampus and parahippocampal gyrus, posterior cingulate gyrus, precuneus lobe, cerebellum, occipital lobe were more activated when food pictures were shown.2. Acupuncture therapy suppressed activation in brainstem, bilateral OFC, insular cortex, posterior cingulate gyrus, occipital lobe and left cerebellum.3. DARTEL results:Partial grey matter decrease was found in cortices of right gyri frontalis superior and pyramis oi cerebellum posterior lobe and that volume increase in gyri centralis anterior between subjects before and after acupuncture therapy. Left fusiform in parahippocampa gyrus, pontine and precentral gyrus were found decrease in volume of white matter. Volume oi white matter in right precuneus turned out to be increased. Obese subjects compared to control group showed volume increase in GM of cerebellum and lateral globus pallidus and volume decrease in WM of pontine and cerebellum. After the therapy, Obese subjects compared to control group showed even larger GM increase in lateral globus palidus and larger pontine WM increase. Previous differences in cerebellum in both GM and WM were not shown. Conclusion:1. Acupuncture therapy might not only have short-term effects on the neural activation but also might influence the process of brain development, leading to reorganization of cortices.2. Microstructural difference might exit in brain because of obesity. Part III Assessment of Obesity in Modeled Rats with Neuroimages and Immunohistochemical MethodsPurpose:To get further understanding of neural mechanism in obesity and effects of acupuncture therapy by studying obese rats. Materials and Method:Using high fat diets to create obese modeled SD rats.11rats (Female,6) were modeled.15rats with normal weight were set to be control. Rest-fMRI and Diffusion Tensor Imaging were used to image and analyze rats’brain. Meanwhile acupuncture was performed on obese rats to confirm its effect with MR abdominal imaging measuring fat distribution. In the end, rats were sacrificed for its brain and liver needed in immunohistochemical experiments. Results:1. Acupuncture therapy could effectively help obese rats to lose weight as well as reducing proportion of fat within abdomen (P<0.05).2. Neuroimaging in rats suggested functional differences in several regions between rats with normal weight and the obese. Rest-state fMRI showed that bilateral hippocampus and right medial thalamus more active in obese ras than that of control, while occipital cortex was opposite. Acupuncture therapy would enhance the activation of bilateral olfactory bulb, frontal cortex, right insula and hippocampus while deactivating right thalamus.3. DTI showed another perception on the brain function. There seemed different between obese and normal rats in regions of ponstine, olfactory bulb and amygdale (P<0.05). Ponstine might be with sexual difference in structure. Logistic regression about risk factors causing obesity was carried out and found that fraction anisotropy (FA), ADC (apparent diffusion coefficients) of fibers and ages were the risks. They were all positively associated with obesity.4. Pathological exam on rats’ liver suggested that acupuncture therapy might be able to change fat distribution within organs. In immunohistochemical experiments, regions of brain were found dyed in different degrees by antibodies of neural transmitters. The difference might exist between obese rats and normal ones. Compared to the control, amygdale and hippocampus were dyed in larger scales in obese rats with5-HT, while in insular lobe, ponstine and cerebellum were opposite. Leptin was not strongly dyed, yet ponstine and cerebellum were in larger scales in obese rats, while insular lobe was found dyed in the normal rats. NPY showed a greater scale in all regions in obese rats. And acupuncture therapy was considered to enhance NPY in all regions of rats’ brain. Conclusion:Neural abnormalities and structural difference as well as physiological changes in body were associated with obesity. Acupuncture therapy might have effects on molecular level.