Cerebral hunger maps in rodents and humans by diffusion weighted MRI.

We design, implement and validate a novel image processing strategy to obtain in vivo maps of hunger stimulation in the brain of mice, rats and humans, combining Diffusion Weighted Magnetic Resonance Imaging (DWI) datasets from fed and fasted subjects. Hunger maps were obtained from axial/coronal (rodents/humans) brain sections containing the hypothalamus and coplanar cortico-limbic structures using Fisher's Discriminant Analysis of the combined voxel ensembles from both feeding situations. These maps were validated against those provided by the classical mono-exponential diffusion model as applied over the same subjects and conditions. Mono-exponential fittings revealed significant Apparent Diffusion Coefficient (ADC) decreases through the brain regions stimulated by hunger, but rigorous parameter estimations imposed the rejection of considerable number of pixels. The proposed approach avoided pixel rejections and provided a representation of the combined DWI dataset as a pixel map of the "Hunger Index" (HI), a parameter revealing the hunger score of every pixel. The new methodology proved to be robust both, by yielding consistent results with classical ADC maps and, by reproducing very similar HI maps when applied to newly acquired rodent datasets. ADC and HI maps demonstrated similar patterns of activation by hunger in hypothalamic and cortico-limbic structures of the brain of rodents and humans, albeit with different relative intensities, rodents showing more intense activations by hunger than humans, for similar fasting periods. The proposed methodology may be easily extended to other feeding paradigms or even to alternative imaging methods.

Imaging hypothalamic activity using diffusion weighted magnetic resonance imaging in the mouse and human brain.

Hypothalamic appetite regulation is a vital homeostatic process underlying global energy balance in animals and humans, its disturbances resulting in feeding disorders with high morbidity and mortality. The objective evaluation of appetite remains difficult, very often restricted to indirect measurements of food intake and body weight. We report here, the direct, non-invasive visualization of hypothalamic activation by fasting using diffusion weighted magnetic resonance imaging, in the mouse brain as well as in a preliminary study in the human brain. The brain of fed or fasted mice or humans were imaged at 7 or 1.5 Tesla, respectively, by diffusion weighted magnetic resonance imaging using a complete range of b values (10

[Knowledge and attitude of adolescent girls regarding folic acid use]. / Conocimiento y actitud de las adolescentes en el consumo del ácido fólico.

OBJECTIVE: To determine the adolescent's knowledge and attitude on the use of folic acid to avoid congenital neural tube defects. METHOD: Three hundred and three (303) adolescent students from two different schools, one private and one public, were asked to complete a pre-test survey. After completing the survey, a lecture was given addressing the importance of folic acid and the benefits of taking this vitamin at an early stage to avoid neural tube defect. Two weeks later a post-test was administered to evaluate the knowledge acquired. The variables were grouped based on the knowledge of folic acid used, the attitudes toward folic acid consumption and the economic level of the participants. RESULTS: On the pre-test the adolescents demonstrated 52.5% of knowledge on the use of folic acid. After the educational conference, the tested knowledge increased to 87.5%. Eighteen percent (18%) of the adolescents reported on the pre-test that they consumed folic acid; this result increased to 69.3% on the post-test. On the pre-test, 31.7% of the participants related folic acid as an etiology of neural tube defect. Following the post-test, 96% of the adolescents were able to provide correct answers about the benefits of folic acid. CONCLUSION: Less than 50% of the adolescents recognized that folic acid is a vitamin. More than 80% of the surveyed adolescents do not consume folic acid. In general, the majority of the adolescents did not know the benefits of folic acid during the pre-conception period.

Hypothalamic metabolic compartmentation during appetite regulation as revealed by magnetic resonance imaging and spectroscopy methods.

We review the role of neuroglial compartmentation and transcellular neurotransmitter cycling during hypothalamic appetite regulation as detected by Magnetic Resonance Imaging (MRI) and Spectroscopy (MRS) methods. We address first the neurochemical basis of neuroendocrine regulation in the hypothalamus and the orexigenic and anorexigenic feed-back loops that control appetite. Then we examine the main MRI and MRS strategies that have been used to investigate appetite regulation. Manganese-enhanced magnetic resonance imaging (MEMRI), Blood oxygenation level-dependent contrast (BOLD), and Diffusion-weighted magnetic resonance imaging (DWI) have revealed Mn(2+) accumulations, augmented oxygen consumptions, and astrocytic swelling in the hypothalamus under fasting conditions, respectively. High field (1)H magnetic resonance in vivo, showed increased hypothalamic myo-inositol concentrations as compared to other cerebral structures. (1)H and (13)C high resolution magic angle spinning (HRMAS) revealed increased neuroglial oxidative and glycolytic metabolism, as well as increased hypothalamic glutamatergic and GABAergic neurotransmissions under orexigenic stimulation. We propose here an integrative interpretation of all these findings suggesting that the neuroendocrine regulation of appetite is supported by important ionic and metabolic transcellular fluxes which begin at the tripartite orexigenic clefts and become extended spatially in the hypothalamus through astrocytic networks becoming eventually MRI and MRS detectable.