Development of an imaging system for in vivo real-time monitoring of neuronal activity in deep brain of free-moving rats

Prospects of Therapeutic Target and Directions for Ischemic Stroke

Stroke is a serious, adverse neurological event and the third leading cause of death and disability worldwide. Most strokes are caused by a block in cerebral blood flow, resulting in neurological deficits through the death of brain tissue. Recombinant tissue plasminogen activator (rt-PA) is currently the only immediate treatment medication for stroke. The goal of rt-PA administration is to reduce the thrombus and/or embolism via thrombolysis; however, the administration of rt-PA must occur within a very short therapeutic timeframe (3 h to 6 h) after symptom onset. Components of the pathological mechanisms involved in ischemic stroke can be used as potential biomarkers in current treatment. However, none are currently under investigation in clinical trials; thus, further studies investigating biomarkers are needed. After ischemic stroke, microglial cells can be activated and release inflammatory cytokines. These cytokines lead to severe neurotoxicity via the overactivation of microglia in prolonged and lasting insults such as stroke. Thus, the balanced regulation of microglial activation may be necessary for therapy. Stem cell therapy is a promising clinical treatment strategy for ischemic stroke. Stem cells can increase the functional recovery of damaged tissue after post-ischemic stroke through various mechanisms including the secretion of neurotrophic factors, immunomodulation, the stimulation of endogenous neurogenesis, and neovascularization. To investigate the use of stem cell therapy for neurological diseases in preclinical studies, however, it is important to develop imaging technologies that are able to evaluate disease progression and to “chase” (i.e., track or monitor) transplanted stem cells in recipients. Imaging technology development is rapidly advancing, and more sensitive techniques, such as the invasive and non-invasive multimodal techniques, are under development. Here, we summarize the potential risk factors and biomarker treatment strategies, stem cell-based therapy and emerging multimodal imaging techniques in the context of stroke. This current review provides a conceptual framework for considering the therapeutic targets and directions for the treatment of brain dysfunctions, with a particular focus on ischemic stroke.

Advanced genetic and viral methods for labelling and manipulation of oxytocin and vasopressin neurones in rats

Rats have been widely used as one of the most common laboratory animals for biological research, because their physiology, pathology, and behavioral characteristics are highly similar to humans. Recent developments in rat genetic modification techniques have now led to further their utility for a broad range of research questions, including the ability to specifically label individual neurones, and even manipulate neuronal function in rats. We have succeeded in generating several transgenic rat lines that enable visualization of specific neurones due to their expression of fluorescently-tagged oxytocin, vasopressin, and c-fos protein. Furthermore, we have been able to generate novel transgenic rat lines in which we can activate vasopressin neurones using optogenetic and chemogenetic techniques. In this review, we will summarize the techniques of genetic modification for labeling and manipulating the specific neurones. Successful examples of generating transgenic rat lines in our lab and usefulness of these rats will also be introduced. These transgenic rat lines enable the interrogation of neuronal function and physiology in a way that was not possible in the past, providing novel insights into neuronal mechanisms both in vivo and ex vivo.