Repetitive Transcranial Magnetic Stimulation Improves Depression-like Behavior in Rats by Promoting Neural Stem Cell Proliferation and Differentiation.

Repetitive transcranial magnetic stimulation (rTMS) is a novel non-invasive neuromodulation technique with neuroprotective properties and is used to treat depression. However, the underlying mechanism of action remains unclear. In this study, we examined the possible mechanism mediating the antidepressant effect of rTMS using animal experiments. Specific pathogen-free rats were treated with rTMS after exposure to social isolation combined with chronic unpredictable mild stress (CUMS). After four weeks of CUMS, the rats exhibited a significant decrease in spatial working memory assessed using open-field testing, a general loss of interest assessed with the sucrose preference test, and a significant reduction in spatial recognition memory ability assessed using the Y-maze. These behavioral deficits were accompanied by decreased numbers of astrocytes in the hippocampus, decreased expression of glial fibrillary acidic protein (GFAP), increased numbers of neural stem cells (NSCs), and increased expression of nestin protein. These results indicated that neuron damage occurred in the depression-like rats. After rTMS intervention, the depression-like behavior was alleviated significantly, and the numbers of NSCs and astrocytes, as well as the expression of GFAP and nestin proteins, returned to normal levels. Overall, it is likely that attenuation of NSC proliferation and differentiation into astrocytes produced a neuroprotective effect on hippocampal neurons, which might partly explain the mechanism by which rTMS alleviates depression.

Executive Functioning in Chinese Patients With Obsessive Compulsive Disorder.

Introduction: Studies have shown that patients with obsessive compulsive disorder (OCD) often perform more poorly than healthy control (HC) participants on cognitive tasks involving executive functions. Most studies, however, have been performed in Western countries and societies, making it uncertain whether impaired executive functions can also be observed among non-Western patients with OCD. To address this gap in the literature, we evaluated several executive functions in Chinese patients with OCD and HCs. Methods: Participants included consisted of 46 Chinese patients with OCD (25 men, 21 women), ranging in age from 19 to 56 years, and 45 matched HCs without any self-reported lifetime psychiatric disorder. They all lived in Shanghai or the surrounding area. Five tests of the Cambridge Neuropsychological Test Automated Battery (CANTAB) were used to evaluate several executive functions (response inhibition, spatial working memory, planning, and cognitive flexibility) along with testing basic learning and visual recognition memory. Statistical tests using a Bonferroni-corrected significance level of p = 0.003 were performed to assess overall patient-control group differences in cognitive performance. Additionally, we explored performance differences between patients classified as having either relatively mild symptoms or severe symptoms based on the individual total scores on the Yale-Brown Obsessive-Compulsive Scale. Results: There were no significant performance differences between patients with OCD and HC in any of the cognitive tests. Similarly, cognitive performance of patients with relatively mild OCD symptoms did not differ significantly from that of patients with severe symptoms. Conclusions: These results do not seem to support the view that impaired executive functioning represents a basic cognitive and pathophysiological feature of Chinese patients with OCD. However, due to study limitations, additional research is required before this conclusion can be well accepted.

rTMS ameliorated depressive-like behaviors by restoring HPA axis balance and prohibiting hippocampal neuron apoptosis in a rat model of depression.

Repetitive transcranial magnetic stimulation (rTMS) has been widely used to treat depression. The mechanistic basis for the effects of rTMS is not well understood, although previous studies have suggested that it involves the regulation of hypothalamic-pituitary-adrenocortical (HPA) axis and protection of hippocampal neurons. We investigated this in the present study using a chronic unpredictable mild stress (CUMS) paradigm in Sprague-Dawley rats. The rats were subjected to rTMS for 15 consecutive days, and body weight, sucrose consumption, and locomotor activity were evaluated. B cell lymphoma-2-associated X protein (Bax) expression was assessed by immunohistochemistry; cell morphology was examined by Nissl staining; and adrenocorticotropic hormone (ACTH) and cortisol (CORT) levels in the hippocampus were measured by enzyme-linked immunosorbent assay. CUMS decreased body weight and sucrose consumption in rats along with horizontal/vertical distance traveled in the open field test. Rats subjected to CUMS also showed increased levels of Bax as well as ACTH and CORT; the hippocampal neurons in these animals had abnormal morphology and were reduced in number. rTMS reversed these changes and improved depression-like behaviors. Thus, rTMS abrogates the loss of hippocampal neurons and restores the balance of the HPA axis in the treatment of depression.