Low-frequency repetitive transcranial magnetic stimulation (1-Hz rTMS) is a promising noninvasive tool for the treatment of depression. Hippocampal neuronal plasticity is thought to play a pivotal role in the pathophysiology of depressive disorders and the mechanism of action of antidepressant treatments. We investigated the effect of 1-Hz rTMS treatment on hippocampal dentate gyrus structural plasticity and related emotional behaviors modifications. Experimentally, adult male mice received either five days of 1-Hz rTMS or Sham stimulation. After stimulation, the mice underwent a battery of tests for anxiety-like and depression-like behaviors. We also tested the effect of treatment on mature and newly generated granule cell dendritic complexity. Our data showed that 1-Hz rTMS induced structural plasticity in mature granule cells, as evidenced by increased dendritic length and number of intersections. However, the stimulation did not increase the proliferation of the dentate gyrus progenitor cells. On the contrary, the stimulated mice showed increased dendritic complexity of newly generated neurons. Moreover, 1-Hz rTMS resulted in antidepressant-like effects in the tail suspension test, but it did not affect anxiety-like behaviors. Therefore, our results indicate that 1-Hz rTMS modulates dentate gyrus morphological plasticity in mature and newly generated neurons. Furthermore, our data provide some evidence of an association between the antidepressant-like activity of 1-Hz rTMS and structural plasticity in the hippocampus.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an emerging human coronavirus responsible for coronavirus disease 2019 (COVID-19), a predominantly respiratory disease that has become a global pandemic. Millions of people worldwide are suffering from COVID-19, and hundreds of thousands of those infected have died. Nevertheless, many more people who have been infected with SARS-CoV-2 are asymptomatic or suffer a mild disease characterized by dry cough and mild fever. This new pandemic poses a threat to public health on a global scale, and an intervention to prevent continued spread of SARS-CoV-2 virus is of the utmost importance. To assess preventive and therapeutic strategies, it is imperative to understand the pathogenesis and immune response against SARS-CoV-2. In this review, we concentrate on the protective adaptive immune response elicited by this novel coronavirus as well as requirements for a successful vaccine inducing optimal protection.