Multiphoton Confocal Microscopy (in vivo Imaging) in the Study of Early Response of Macrophages/Microglia in Damaged Midbrain of Juvenile Chum Salmon Oncorhynchus keta

Abstract

We used multiphoton confocal microscopy for the in vivo study of early response of macrophages/microglia in the damaged midbrain of juvenile chum salmon Oncorhynchus keta. The results obtained allow the use of injection of DiI in the area of brain injury as a method to identify a population of phagocytic cells in the brain, based on the physiological response of macrophages/microglia. Thus, the injury with injection of small particles of dye DiI causes the phagocytic response from macrophages within a 30 minutes after the application of the damaging effects. This allows the use of DiI as a vital nonspecific marker of macrophages/microglia. It can be regarded as an effective method of identifying populations of phagocytic cells in the brain, as the effective molecular markers that allow selective identification of populations of macrophages and microglia in the brain of the fish have not been developed so far. We supposed that using multiphoton confocal microscopy in vivo experiments allow to have the substantial preference. Damage to living cells decreases photo induced processes, because of the much lower absorption of tissues and cells in the infrared region as compared with the ultraviolet one. For this reason, it provides more depth of penetration in biological objects (animal). The main beneficial consequence of this is the better survival of a biological object with good image quality.