Metabolic changes in visual cortex of neonatal monocular enucleated rat: a proton magnetic resonance spectroscopy study.

Neonatal monocular enucleation (ME) is often employed to study the developmental mechanisms underlying visual perception and the cross-modal changes in the central nervous system caused by early loss of the visual input. However, underlying biochemical or metabolic mechanisms that accompany the morphological, physiological and behavioral changes after ME are not fully understood. Male Sprague-Dawley rats (N=14) were prepared and divided into 2 groups. The enucleated group (N=8) underwent right ME (right eye removal) at postnatal day 10, while the normal group (N=6) was intact and served as a control. Three weeks after ME, single voxel proton magnetic resonance spectroscopy ((1)H MRS) was performed over the visual cortex of each hemisphere in all animals with a point-resolved spectroscopy (PRESS) sequence at 7 T. The taurine (Tau) and N-acetylaspartate (NAA) levels were found to be significantly lower in the left visual cortex (contralateral to enucleated eye) for enucleated animals. Such metabolic changes measured in vivo likely reflected the cortical degeneration associated with the reduction of neurons, axon terminals and overall neuronal activity. This study also demonstrated that (1)H MRS approach has the potential to characterize neonatal ME and other developmental neuroplasticity models noninvasively for the biochemical and metabolic processes involved.