Alterations of neuroimmune cell density and pro-inflammatory cytokines in response to thimerosal in prefrontal lobe of male rats

Abstract

Evidence suggests that the effect of heavy metals on neuroimmune cells lead to neurogenic inflammatory responses. In this study, immune cells [mast cells (MCs) and microglia] and pro-neuroinflammation cytokines (interleukin-1b and tumor necrosis factor-α) were assessed in the prefrontal lobe of rat brains exposed to thimerosal in different timeframes. A total of 108 neonatal Wistar rats were divided into three groups having three subgroups. The experimental groups received a single dose of thimerosal (300 μg/kg) postnatally at 7, 9, 11, and 15 days. The vehicle groups received similar injections of phosphate-buffered saline in a similar manner. The control groups received nothing. Samples of the prefrontal cortex were collected and prepared for stereological, immunohistochemical, and molecular studies at timeframes of 12 or 48 h (acute phase) and 8 days (subchronic phase) after the last injection. The average density of the microglia and MCs increased significantly in the experimental groups. This increase was more evident in the 48 h group. At 8 days after the last injection, there was a significant decrease in the density of the MCs compared to the 12 and 48 h groups. Alterations in pro-inflammatory cytokines were significant for all timeframes. This increase was more evident in the 48 h group after the last injection. There was a significant decrease in both neuroinflammatory cytokines at 8 days after the last injection. It was found that ethylmercury caused abnormal neurogenic inflammatory reactions and alterations in the neuroimmune cells that remained for a longer period in the brain than in the blood.

Keywords:

• Thimerosal
• neuroimmune cells
• pro-inflammatory cytokines
• neonatal rats

Acknowledgements

This article has been extracted from a PhD thesis written by Ms. Kobra Afsordeh in the School of Medicine of Shahid Beheshti University of Medical Sciences (Registration No. 112).

Disclosure statement

The authors declare that they have no conflict of interest.