Response of Hippocampal Neurons and Glial Cells to Alternating Magnetic Field in Gerbils Submitted to Global Cerebral Ischemia

Abstract

The purpose of this study was to determine whether exposure to an extremely low-frequency magnetic field (ELF-MF, 50 Hz) affects the outcome of postischemic damage in the hippocampus of Mongolian gerbils. After 10-min bilateral carotid occlusion, the gerbils were continuously exposed to ELF-MF (average magnetic induction at the center of the cage was 0.5 mT) for 7 days. The impact of ELF-MF was estimated immediately (the 7th day after reperfusion) and 7 days after cessation of exposure (the 14th day after reperfusion) compared with ischemic gerbils without ELF-MF exposure. Applying stereological methods, histological evaluation of changes in the hippocampus was done for determining its volume, volume densities of degenerating neurons and astrocytes, as well as the number of microglial cells per unit area. ELF-MF per se did not induce any morphological changes, while 10-min global cerebral ischemia led to neuronal death, especially in CA1 region of the hippocampus, as expected. Ischemic gerbils exposed to ELF-MF had significantly a lower degree of cell loss in the examined structure and greater responses of astrocytes and microglial cells than postischemic gerbils without exposure on the seventh day after reperfusion (immediate effect of ELF-MF). Similar response was observed on the 14th day after reperfusion (delayed effect of ELF-MF); however, differences in measured parameters were low and insignificant. Applied ELF-MF has possible neuroprotective function in the hippocampus, as the most sensitive brain structure in the model of global cerebral ischemia, through reduction of neuronal death and activation of astrocytes and microglial cells.

An Extremely Low Frequency Magnetic Field and Global Cerebral Ischemia Affect Pituitary ACTH and TSH Cells in Gerbils

“…The animals were exposed to an ELF magnetic field (50 Hz, average magnetic field of 0.5 mT) for 7 days and/or global cerebral ischemia for 10 min. This study is a continuation of previous research [Rauš et al, ; Rauš Balind et al, ] and provides further insight into the effects of an ELF magnetic field immediately and 1 week after cessation of exposure and global cerebral ischemia at different time points after reperfusion. These studies contribute not only to detecting biological effects of the applied ELF magnetic field, as an external stressor but also in assessing the consequences of such exposure on recovery following global cerebral ischemia in gerbils.…”

Extremely Low Frequency Magnetic Field (50 Hz, 0.5 mT) Reduces Oxidative Stress in the Brain of Gerbils Submitted to Global Cerebral Ischemia

“…In this study we applied ELF-MF (50 Hz, 0.5 mT) for 7 days in gerbils submitted to 10-min global cerebral ischemia and measured oxidative stress parameters in distinct brain structures (forebrain cortex, striatum and hippocampus) on the 7 th (immediate effect of ELF-MF) and 14 th day after reperfusion (delayed effect of ELF-MF). These results are part of our comprehensive investigations concerning the effects of ELF-MF in animals with experimentally induced cerebral ischemia [19], [20] and contribute to the explanation of spatial and temporal patterns of oxidative stress in the brain of these animals.…”

Resveratrol downregulates type-1 glutamate transporter expression and microglia activation in the hippocampus following cerebral ischemia reperfusion in rats

“…Tissue GFAP-ir expression in sham-operated animals contrasted by a uniform expression within the CA1 with thin and long processes of the labeled astrocytes. Noteworthy, time-dependent alterations of glial cell and cytokine expression following ischemia has been proposed: an initial glial activation phase rapidly occurring within 48 h of the ischemic insult and a delayed phase coincidental with neuronal death occurring over a period of several days postischemia (Yasuda et al, 2011) and under some circumstances, astrocyte proliferation has been observed concurrent with neuronal protection and improved post-ischemic recovery (Raus et al, 2013).…”