Brain tryptophan rather than pH-value is altered as consequence of artificial postmortem interval and storage conditions

Brain bank centers around the world attempt to standardize postmortem brain collection and quality control. Antemortem as well postmortem factors may influence tissue quality. Previously, we could demonstrate that increased tryptophan (TRP) levels significantly correlate to prolonged postmortem interval (PMI) and storage duration, whereas pH-value altered merely as consequence of prolonged agonal state and ischemic brain damage additionally to repeated freeze and thaw cycles. Therefore, we aimed to investigate in artificial PMI conditions, with three brain tissue storage temperatures (4 °C, room temperature and 37 °C) as well as oxidizing conditions (open/close tube), whether TRP levels and pH-value alter. We could confirm that prolonged PMI at higher storage temperatures and oxidizing conditions significantly correlate to increased TRP levels, while pH-value did not correlate at all. In conclusion, from these results PMI intervals until autopsy should be kept as short as possible and storage until autopsy should be at 4 °C in order to preserve brain tissue quality as much as possible.

Research highlights▶ Quality of postmortem brain tissue. ▶ Tryptophan levels increase with increased PMI and high storage temperature. ▶ pH-value does not alter as consequence of PMI or temperature, is affected by pre-mortem factors.