Assessment of proliferative activity in rat brain with AgNOR following exposure to magnetic field

Abstract

Objective: Nucleolar organizer region (NORs) is directly related to cell cycle and is an indicator of cell proliferation. We explored, in the present study, whether there was a difference in proliferation between brain tissues subjected to magnetic field for different durations. Study Design: The study comprised 5 groups with six rats each. Groups A and B were exposed to magnetic fields for 2.5 hours/day and 2.5 minutes/day, respectively, everyday for three months. Sham groups for Group A (SA) and Group B (SB) were constructed and switched-off cellular phones were left in the same environment for the same duration as their corresponding experimental groups. Rat's brains were removed, placed in 10% formalin and 3 micron thick sections were obtained following routine histological methods. Sections were stained with AgNOR stain. The number of AgNORs for each 100 cortical neurons, hippocampal neurons, ependymal and choroid plexus cells were counted on every section with an immersion microscope objective. Results: Statistical analyses revealed that mean number of AgNORs was highest in Group A (3.69±0.54), followed by Group B (3.06±0.48). Even though there was no statistically significant difference between sham groups (SA=1.76±0.56 and SB=1.84±0.65, p=0.990), mean number of AgNORs in sham groups was significantly higher than the control group (1.29±0.42) (p?0.05). Groups A and B differed significantly from the sham and control groups in terms of mean number of AgNORs (p?0.001). Conclusion: Increased proliferative activity and protein synthesis in neuronal and glial cells of the brain tissue in response to exposure to magnetic field is demonstrated by AgNORs.