Postmortem changes of amino compounds in human and rat brain

Area of Science:

• Neurochemistry
• Post-mortem Biochemistry
• Forensic Science

Background:

• Understanding post-mortem changes in brain chemistry is crucial for interpreting findings in neurological and psychiatric disorders.
• Previous studies have not comprehensively detailed the stability of various amino acids and related compounds in the human brain after death under simulated mortuary conditions.

Purpose of the Study:

• To quantify the changes in 35 amino acids and related compounds in rat and human brain tissue over time after death.
• To establish the stability profiles of key neurochemicals to aid in the interpretation of post-mortem brain samples.

Main Methods:

• Measurement of 35 amino acids and related compounds in whole rat brain and superficial human brain biopsies/autopsies.
• Incubation of samples at temperatures simulating post-mortem conditions for various intervals.
• Utilized techniques to analyze amino acid content and stability over time.

Main Results:

• In human brain, glutamic acid, glutamine, taurine, phosphoethanolamine, cystathionine, and homocarnosine remained stable long-term.
• Aspartic acid was stable for 4 hours, then increased; glycine and most protein amino acids increased rapidly post-mortem.
• Glutathione decreased rapidly, while GABA showed initial stability (30 min) followed by a rise and plateau within 2-3 hours.

Conclusions:

• Specific amino acids exhibit distinct stability patterns in the post-mortem human brain, informing diagnostic interpretations.
• Differences in GABA and aspartate kinetics were observed between rat and human brains, highlighting species-specific post-mortem changes.