Histopathological efficacy of tacrolimus in an experimental head trauma study

This study aimed to investigate the protective effect of tacrolimus (FK506), an immunosuppressive agent, on secondary brain damage in rats with experimental head trauma.

40 Sprague-Dawley rats, aged 10-12 weeks and weighing 250-350 g, were used without gender selection. The subjects that were divided into five groups of 8 rats per group (sham control, negative control, positive control, vehicle control, and treatment) were sacrificed 1 month after head trauma was induced under appropriate conditions, their brains were then removed en bloc and evaluated histopathologically. Secondary brain injury was evaluated with the immunoreactive score (IRS) after Glial Fibrillary Acid Protein staining of gliosis that would occur in brain tissue.

The evaluation of the histopathological IRS values of all groups showed significant statistical differences between all groups. The pairwise group comparison revealed the highest increase in IRS value in the treatment group (p<0.05), with no statistical significance despite the increase in the negative control, positive control, and vehicle control groups. The sham group had the lowest rate of severe histopathological reaction score.

It was observed that the group treated with FK506 had a statistically significant increase in gliosis in the traumatic area compared to the other control groups. This shows that FK506 cannot prevent and even increase gliosis by a mechanism that has not yet been clarified. In conclusion, it is obvious that the FK506 immunosuppressive agent does not reduce post-traumatic brain injury; on the contrary, it increases gliosis.