MR Spectroscopic Analysis of Neonatal Rat Striatum: An Early Biomarker for Adult Hyperemotionality Following Perinatal Asphyxia

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In vivo proton (1H) MR spectroscopy (MRS) can be used to identify neurological impairments in human and animal subjects. We hypothesized that neurochemical profiles acquired from one-week-old perinatally asphyxiated (PA) rats could be used to predict adult hyperemotionality. Gestational day 22 pregnant rat dams were administered spinal anesthesia and the uterus externalized into a heated (37.5 C) saline bath. Controlled asphyxia was produced by occluding the blood supply feeding one uterine horn (12 min). The other uterine horn remained undisturbed (non-occluded control). Fetuses were immediately delivered by cesarean section, then fostered to newly parturient dams. On Postnatal day 7, high resolution in vivo proton MR spectra were acquired from the striatum using a 7T small animal MRI scanner using single-voxel (3 x 3 x 3 cu mm) MRS imaging. The point-resolved spectroscopy (PRESS) sequence was applied, and positioning of MRS voxels based on T2-weighted images. Neurometabolites derived from spectral analysis were corrected for creatine + phosphocreatine (Cr + pCr). Significant changes in N-acetyl aspartate (NAA) and glutamate and glutamine (Glx) were observed in PA rats as compared to non-asphyxiated controls. At 8-weeks of age, subjects were singly housed (24 hrs), placed in an open field and exposed to a 52 min test comprised of a concatenation of novel stimuli. Videographic analysis revealed magnified emotional responses to novelty in PA rats as measured by position within the open field, responses to novel stimuli, and social interactions. In vivo MRS is a sensitive imaging tool for detecting neurochemical changes in early life that can be used to predict adult hyperemotionality.


Abstract of poster presented at the 38th Annual Meeting of the Society for Neuroscience, Washington, DC, November 15-19, 2008.