METABOLIC RESPONSES TO SIV INFECTION REVEALED BY IN VIVO ^1H MR SPECTROSCOPY

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. In vivo ^1H magnetic resonance spectroscopy (MRS) studies of HIV-infected humans have demonstrated significant metabolic abnormalities that vary by brain region and are poorly understood. Metabolic changes in the frontal cortex, basal ganglia and white matter in 15 SIV-infected macaques were investigated using in vivo 1H MRS during the first month of infection. The most significant abnormalities were observed at the time of peak viremia, at 2 weeks post infection (p.i.). Changes in the N-acetylaspartate (NAA), ¿choline¿ (Cho) and myo-inositol (MI) resonances were found relative to the creatine (Cr) resonance and in absolute terms. Changes in Cho and Cho/Cr were most similar across the brain regions, increasing at 2 weeks p.i., and falling below baseline levels at 4 weeks. Complex regional variations in MI/Cr ratios were observed over time. Most interesting were the regional differences in NAA. Significant decreases in NAA and NAA/Cr, reflecting neuronal injury, were observed only in the frontal cortex at the time of peak viremia. While there are several potential mechanisms to explain these results, the data best support the hypothesis that different brain regions have variable intrinsic vulnerabilities to neuronal injury caused by the AIDS virus.