Objective: Tacrolimus is a calcineurin inhibitor that is commonly used following transplantation. Neurological complications can be seen during tacrolimus use. In this study it was aimed to investigate effects of vitamin D on changes in brain tissue induced by tacrolimus in rats.

Material and Method: The study was conducted on 21 male Wistar Albino rats. Animals were assigned into 3 groups. Control rats received no intervention. Tacrolimus (0.8 mg/kg/day) via oral route was given to rats in tacrolimus group while tacrolimus (0.8 mg/kg/day) plus vitamin D (50 IU/day) via oral route was given to rats in tacrolimus plus vitamin D group for 21 days. At the end of the experiment period, the rats were decapitated and brain tissues were removed. After routine process, tissues were embedded to paraffin blocks. Bax immunoreactivity was assessed with avidin-biotin-peroxidase method while malondialdehyde (MDA) level was assessed by using spectrophotometer in tissue samples. TUNEL method was used to assess apoptosis.

Results: When compared to controls, MDA levels, Bax immunoreactivity and TUNEL positivity were significantly increased in tacrolimus group. In addition, there were significant decreases observed in MDA levels, Bax immunoreactivity and TUNEL positivity in tacrolimus plus vitamin D group compared to the tacrolimus group.

Conclusion: This study showed that tacrolimus induce apoptosis in brain tissue and vitamin D may have protective effects against the effects of tacrolimus.