Brain metabolic derangements examined using 1H MRS and their (in)consistency among different rodent models of depression

Major depressive disorder (MDD) is underlined by neurochemical changes in the brain. Proton magnetic reso-nance spectroscopy (1H MRS) is a useful tool for their examination as it provides information about the levels of metabolites. This review summarises the current knowledge of 1H MRS findings from rodent models of MDD, assesses the results from both a biological and a technical perspective, and identifies the main sources of bias. From a technical point of view, bias-introducing factors are the diversity of the measured volumes and their positioning in the brain, the data processing, and the metabolite concentration expression. The biological var-iables are strain, sex, and species, as well as the model itself, and in vivo vs. ex vivo exploration. This review identified some consistency in the 1H MRS findings in the models of MDD: lower levels of glutamine, glutamate + glutamine, and higher levels of myo-inositol and taurine in most of the brain regions of MDD models. This may suggest changes in regional metabolism, neuronal dysregulation, inflammation, and a compensatory effect re-action in the MDD rodent models.

Automated summary

This review summarises the current knowledge of 1H MRS findings from rodent models of MDD, which suggest lower levels of glutamine, glutamate + glutamine, and higher levels of myo-inositol and taurine in most of the brain regions of MDD models. Bias-introducing factors in these studies include the diversity of measured volumes, data processing, and metabolite concentration expression. Biological variables such as strain, sex, species, model, and exploration method also contribute to the variability of the results.