1H MR Spectroscopic Measurement of Neurochemical Alterations in the Hippocampus of a Rat Model of Depression

The forced swimming test (FST) is considered one of the most widely used and reliable animal models of depression for the assessment of antidepressant activity and for examining the pathophysiology of depression pre-clinically [1]. The impaired synaptic efficacy due to the FST procedure involving severe physical and emotional stress has been reported in the rat hippocampus, and the synaptic efficacy shows significant improvement after being treated with repetitive transcranial magnetic stimulation (rTMS) [2]. We recently reported a significantly increased Cho/Cr ratio in the dorsolateral pre-frontal cortex (DLPFC) of rats exposed to the FST compared with control animals [3], which is similar to results obtained from investigations of patients with depression [4]. To extend our previous findings and characterize the variation of the hippocampal Cho/Cr ratio in an animal model of depression, we systematically examined the Cho/Cr ratio in the hippocampus of rats exposed to the FST and controls by using relatively small volume-of-interest (VOI) compared with our previous study that specifically focused on the homogeneous hippocampus tissue