Izražaj kalpaina u moždanim strukturama osoba preminulih nakon traumatske ozljede mozga

Objectives The purpose of this study was to examine: a) the expressions of calpain, b) the types of the cell populations that express calpain, c) the expression of caspase-3 and the possible colocalization of calpain and caspase-3, and d) to analyze the potential sex-related differences in the calpain expressions in the different regions of the brain (ipsilateral cortex, the thalamus and dentate nucleus) in a people who died following traumatic brain injury (TBI), at different time points following the brain trauma. Patients and Methods The study group included 50 brains of the persons who died the same day or since the first to the tenth day after TBI, in the period since December 2001 to December, 2011, and who underwent forensic medical autopsy at the Institute of Forensic Medicine and Criminology, School of Medicine, University of Rijeka. Exclusion criteria for the study were suffered cerebrovascular accident and diseases of the central nervous system (CNS), including malignant or degenerative disease of the CNS and type 2 diabetes. The control group contained 34 samples of the persons’ brains who have died a natural death due to sudden heart failure, and whose brains were not affected by TBI or the CNS diseases. These people were not suffering from type 2 diabetes. Samples of the brain tissue of the control group were aligned with the brain tissue samples from the study group by age and sex. To analyze pathohistological changes in the brain tissue Hemalaun-eosin staining was used. Expressions of calpain and caspase-3 in the brain parenchyma were analyzed by immunohistochemistry. Statistical analyses were performed by the program Statistica 9.0. Results TBI induced significant damage of the cerebral parenchyma, especially at the site of the contusion in the cortex. The signs of the brain damage occur more frequently in the patients who died after TBI than in the control group. Increased calpain expressions in neurons, glial cells and endothelial cells were detected in all studied brain structures in the study group (all P <0.001). Calpain expression changed over time elapsed since TBI in all brain regions with maximum activity observed at day 3 post injury in the cortex and the nucleus dentatus and day 6 post inury in the thalamus. Correlations between the calpain expressions in all cell populations in the cortex and the time periods between TBI and persons’ death were negative (R Spearman rank coefficient is) and significant (all P<0.05). In the study group, in all investigated brain regions increased, the percentages of the caspase-3 positive cells were detected (all P <0.001). Statistical analysis showed that the percentage of the caspase-3 positive cells was significantly changed dependently on the time periods elapsed since TBI, and the highest values in all investigated brain regions were recorded at day one after TBI. In the cortex, the correlation between the calpain and caspase-3 expressions was positive that means that increased calpain expression was followed by an increased number of the caspase-3 positive cells. Only in the cortex this correlation was significant (P<0.001). In the study group, the analysis of the calpain differences according to sex showed significantly higher expression of calpain in the cortex of women than men (P=0.020). Significant differences in the expressions of calpain regarding sex were not observed in the thalamus and the nucleus dentatus (both P> 0.05). Conclusion Calpain expressions were detected in neurones, glial and endothelial cells of different brain regions in the persons who died following TBI. Gender differences in the calpain expression were recorded. Analysis of the calpain expression could serve as a forensic marker for determining the age of the brain injury in situations in which the time of its occurrence is unknown.