Short- and long-term exposure to alternating magnetic field (50 Hz, 0.5 mT) affects rat pituitary ACTH cells: Stereological study

Abstract

The aim of the present study was to determine does extremely low frequency magnetic field (ELF-MF, 50 Hz, 0.5 mT) affect pituitary adrenocorticotroph (ACTH) cells in adult animals. We performed two series of experiments: (1) short-term exposure of 3-month-old rats to ELF-MF for 1 and 7 days, and (2) long-term exposure of rats to ELF-MF from their conception to 3 months of age. Stereological study was performed on immunolabeled pituitary ACTH cells. The total number and volume of ACTH cells, the volume of their nuclei and pituitary volume were measured. ELF-MF exposure for 1 day significantly decreased total number and volume of ACTH cells, the volume of their nuclei, as well as pituitary volume. ELF-MF exposure for 7 days significantly reduced only the volume of ACTH cells. Life-long exposure to ELF-MF induced decrease in the volume of ACTH cells and pituitary volume. We can conclude that the applied ELF-MF has a strong influence on morphometrical parameters of the pituitary ACTH cells and could be considered as a stressogenic factor.

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

“…These results may be explained by the greater release of ACTH into the circulation 7 days after the onset of the experiment. This is supported by our earlier findings that rat ACTH cells recognize and respond to short‐term (1 and 7 days) and long‐term exposure (from conception to 3 months of age) to an ELF magnetic field with the same characteristics as in the current study [Rauš Balind et al, ]. The immediate effects of a 1‐day exposure to the ELF magnetic field were the most prominent, concerning decreases in the number and size of ACTH cells and their nuclei [Rauš Balind et al, ].…”

“…This is supported by our earlier findings that rat ACTH cells recognize and respond to short‐term (1 and 7 days) and long‐term exposure (from conception to 3 months of age) to an ELF magnetic field with the same characteristics as in the current study [Rauš Balind et al, ]. The immediate effects of a 1‐day exposure to the ELF magnetic field were the most prominent, concerning decreases in the number and size of ACTH cells and their nuclei [Rauš Balind et al, ]. Published data related to such effects on circulating ACTH and cortisol/corticosterone levels are not consistent, and different modes of ELF magnetic field treatments increased or failed to evoke changes in hormone concentrations [Selmaoui et al, ; Sert et al, ; Szemerszky et al, ; Touitou and Selmaoui, ; Kitaoka et al, ; Mahdavi et al, ].…”

“…Immediate effects of the combined stressors were a significant decrease of the volume density of ACTH cells, increased intracellular ACTH content, and raised plasma ACTH concentration. The obtained results indicated that both ACTH synthesis and hormone secretion were intensified, as described earlier [Rauš et al, ; Rauš Balind et al, ]. The influence of both stressors on ACTH cells 7 days after onset of the experiment had subsided to the control level by day 14.…”

“…This represents a source of environmental pollution that may induce a variety of effects in organisms. Among them are changes in excitability and synaptic plasticity [Balassa et al, ], cell morphology [Rauš Balind et al, ], the expression, affinity and density of receptors [Janać et al, ; Li et al, ], and oxidative stress [Jelenković et al, ; Selaković et al, ] in the brain, as well as animal behavior [Szemerszky et al, ; Janać et al, ; Madjid Ansari et al, ]. Cerebral ischemia is a pathophysiological condition induced by restricted blood flow through the brain and is a leading cause of death worldwide.…”

“…Altogether these changes lead to cell death, mainly in the hippocampus or the striatum, which are the most vulnerable brain structures [Block, ]. As potential stressors, both an ELF magnetic field and cerebral ischemia can also affect the neuroendocrine system by acting on the hypothalamus‐pituitary‐adrenal (HPA) and hypothalamus‐pituitary‐thyroid (HPT) axes [Rajkovic et al, ; Kitaoka et al, ; de la Tremblaye et al, ; Mahdavi et al, ; Radak et al, ; O'Keefe et al, ; Rauš Balind et al, ; Suda et al, ].…”