Potential use of GAPDH m-RNA in estimating PMI in brain tissue of albino rats at different environmental conditions

Background: Estimation of the postmortem interval (PMI) is a critical issue in forensic science. Various approaches have been used to determine the PMI including physical, biochemical and entomological methods. Most of these methods have practical limitations or provide insufficient results in certain conditions. Postmortem degradation of RNA may be a useful tool for PMI estimation if there is a correlation between the quantity of residual RNA and the elapsed time. This study aimed to evaluate the use of GAPDH mRNA quantity in the brain as a possible indicator for PMI in different environmental conditions. Methods: Seventy-eight adult female albino rats were sacrificed by cervical dislocation. Rats were divided into five groups, the control group and 4 studied groups left after sacrificing in different conditions (ambient air at 30 degrees C and at 6 degrees C, buried in sand and submerged under water). Brain samples were obtained at different intervals (0, 24, 48 and 96 h postmortem). The mRNA of GAPDH gene of rats' brain was quantitatively detected by qRT-PCR. Results: The decrease of GAPDH mRNA levels with increasing PMI were observed in all study groups. There were significant negative correlations between brain GAPDH mRNA and Time intervals in rats left in air at 30 degrees C, buried in sand and recovered from the water. Conclusion: GAPDH mRNA in rat's brain could be a useful marker for PMI estimation in several environmental conditions.