Does Vitamin D Administration Increase the Neuroprotective Effect of Estrogen in Male Rats with Traumatic Brain Injury?

In our previous studies, the effect of sex hormones on brain edema reduction after traumatic brain injury (TBI) was demonstrated. In the current study, alone and combined effects of 17-β estradiol (E2) and vitamin D (Vit D) on TBI in male rats were investigated. Male rats were divided into six groups, including sham, TBI, vehicle, E2, Vit D, and E2+Vit D. In all groups except sham, moderate-intensity diffuse TBI was induced by the Marmarou’s method. Vehicle, E2, Vit D and their combination were intramusculary injected one and 12 hours after the TBI. The brain water content, permeability of blood brain barrier (BBB) and histopathological outcome were assessed 24h after TBI. The neurological outcome score was determined using the veterinary coma scale (VCS). Significant reductions in brain water content (P<0.001, P<0.05 and P<0.01, respectively) and BBB permeability (P<0.001) appeared in the treated groups with E2, Vit D, and E2+Vit D compared to the vehicle group. Twenty-four hours after the injury, the neurological scores in the E2, Vit D, and E2+Vit D groups increased significantly compared to the vehicle group (P<0.05). Dramatic improvement in histopathological outcome was also observed in the treated groups compared to the vehicle group. Alone and combined consumption of estrogen and vitamin D may similarly decrease the development of brain edema and improve the neurological and histopathological consequences of TBI. Therefore, consumption of vitamin D did not enhance the neuroprotective effect of estrogen in TBI.