Protective Effects of Propolis Extract in a Rat Model of Traumatic Brain Injury via Hsp70 Induction

Background: Traumatic brain injury (TBI) is one of the major global health problems. Secondary brain injury is a complex inflammation cascades process that causes brain cell apoptosis. Propolis is a natural product that has neuroprotective property.

Aim: This study aimed to investigate the effect of propolis toward Hsp70 expression with apoptosis marker in brain tissue after TBI.

Methods: Thirty-three Sprague Dawley rats were randomised into three treatments group, i.e. sham-operated controls, closed head injury (CHI), and CHI with propolis extract (treatment group). In the treatment group, propolis was given 200 mg/kg per oral for 7 days then harvested brain tissues after sacrificed by cervical dislocation at day 8. We investigated Hsp70, Caspase 3, apoptosis-inducing factor (AIF), and TUNEL assay expression using immunohistochemistry staining. Statistical test using one-way ANOVA test and Tukey HSD as post hoc test.

Results: Mean of positive Hsp70 stained cells in group 1 was 6.82 ± 2.14, group 2 was 3.91 ± 2.26, and group 3 was 9.64 ± 3.53 with a significant difference of Hsp70 expression distribution within groups (p = 0.0001). Mean of positive caspase 3 stained cells in group 1 was 5.45 ± 2.30, group 2 was 13.82 ± 2.44, and group 3 was 7.03 ± 1.54 with a significant difference of caspase3 expression distribution within groups (p=0.0001). Mean of positive AIF stained cells in group 1 was 5.36 ± 2.11, group 2 was 12.82 ± 1.40, and group 3 was 8.09 ± 1.81 with a significant difference of AIF expression distribution within groups (p = 0.0001). Mean of positive TUNEL assay stained cells in group 1 was 4.82 ± 2.04, group 2 was 11.55 ± 1.51, and group 3 was 7.64 ± 1.96 with a significant difference of TUNEL test expression distribution within groups (p = 0.0001).

Conclusion: Propolis may protect brain cell from apoptosis after injury by maintaining Hsp70 expression in addition to antioxidant and anti-inflammatory.