In vivo proton magnetic resonance spectroscopy reveals region specific metabolic responses to SIV infection in the macaque brain.
BACKGROUND
In vivo proton magnetic resonance spectroscopy (1H-MRS) studies of HIV-infected humans have demonstrated significant metabolic abnormalities that vary by brain region, but the causes are poorly understood. Metabolic changes in the frontal cortex, basal ganglia and white matter in 18 SIV-infected macaques were investigated using MRS during the first month of infection.


RESULTS
Changes in the N-acetylaspartate (NAA), choline (Cho), myo-inositol (MI), creatine (Cr) and glutamine/glutamate (Glx) resonances were quantified both in absolute terms and relative to the creatine resonance. Most abnormalities were observed at the time of peak viremia, 2 weeks post infection (wpi). At that time point, significant decreases in NAA and NAA/Cr, reflecting neuronal injury, were observed only in the frontal cortex. Cr was significantly elevated only in the white matter. Changes in Cho and Cho/Cr were similar across the brain regions, increasing at 2 wpi, and falling below baseline levels at 4 wpi. MI and MI/Cr levels were increased across all brain regions.


CONCLUSIONS
These data best support the hypothesis that different brain regions have variable intrinsic vulnerabilities to neuronal injury caused by the AIDS virus.
Ratai
Eva-Maria
EM
Neuroradiology Division, Department of Radiology and A.A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA. ratai@nmr.mgh.harvard.edu
Pilkenton
Sarah J
SJ
Greco
Jane B
JB
Lentz
Margaret R
MR
Bombardier
Jeffrey P
JP
Turk
Katherine W
KW
He
Julian
J
Joo
Chan-Gyu
CG
Lee
Vallent
V
Westmoreland
Susan
S
Halpern
Elkan
E
Lackner
Andrew A
AA
González
R Gilberto
RG
D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism / Q000473:pathology / Q000821:virology; D001931:Brain Mapping; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D007294:Inositol / Q000378:metabolism; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging / Q000379:methods; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D011522:Protons; D016097:Simian Acquired Immunodeficiency Syndrome / Q000473:pathology*; D015302:Simian Immunodeficiency Virus
D011522:Protons; D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline