Quantifying mRNA in postmortem human brain: influence of gender, age at death, postmortem interval, brain pH, agonal state and inter-lobe mRNA variance.

Author(s): Preece P, Cairns NJ

Publication: Brain Res Mol Brain Res, 2003, Vol. 118, Page 60

PubMed ID: 14559355 PubMed Review Paper? No

Purpose of Paper

The purpose of this paper was to determine the influence of patient gender, age at death, postmortem interval (PMI), brain pH, and agonal state on RNA quantity, quality, and real time quantitative RT-PCR (qRT-PCR) gene expression results. Relationships among factors were also explored.

Conclusion of Paper

Gender, age at death, and brain pH significantly influenced the levels of targeted mRNA species, although the effects were often diagnosis-specific (Alzheimer's disease versus control). mRNA levels were (1) consistently lower in female compared to male brain specimens, (2) negatively correlated to age at death, and (3) positively correlated to brain pH. No clear relationships were observed among mRNA levels and PMI or agonal state.

Studies

Study Purpose

The purpose of this study was to examine the influence and interaction of patient age, gender, diagnosis, and agonal state, brain pH, interlobe variance, and postmortem interval (PMI) on mRNA levels in control and Alzheimer's disease postmortem brain tissue. The genes examined include beta-actin, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), cyclophilin, microtubule-associated protein (MAP) 2, neuron-specific enolase (NSE), glial fibrillary acidic protein (GFAP), and amyloid precursor protein (APP) isoform 770.

Summary of Findings:

While the quantity of total RNA extracted per sample was independent of all analyzed variables, the abundance of mRNA as determined by real time qRT-PCR of five genes was consistently and significantly lower in females compared to males. The abundance of the beta-actin transcript was negatively correlated to age at death in control (normal) specimens, and similar patterns were observed with other genes analyzed. Although significant gender-dependent effects were observed in Alzheimer's disease specimens, control specimens showed no clear correlation between PMI and targeted mRNA levels. Brain pH was (1) positively correlated to PMI in Alzheimer's disease specimens but not controls, (2) inconsistently influenced by diagnosis and agonal state, with a lower brain pH observed after a prolonged death, and (3) positively correlated to expression of 4 of the 5 genes for all specimens examined.

Biospecimens

Tissue - Brain

Preservative Types

Frozen

Diagnoses:

Alzheimer's Disease
Autopsy
Not specified

Platform:

Analyte	Technology Platform
RNA	Electrophoresis
RNA	Real-time qRT-PCR

Pre-analytical Factors:

Classification	Pre-analytical Factor	Value(s)
Preaquisition	Patient age	41 - 91 years
Preaquisition	Patient gender	Female Male
Preaquisition	Diagnosis/ patient condition	Alzheimer's disease No diagnosis of Alzhemier's disease
Biospecimen Aliquots and Components	pH	Brain pH 5.8 - 7.2
Preaquisition	Postmortem interval	4 - 117 h
Preaquisition	Cause of death	Cardiovascular disease Bronchopneumonia Other
Biospecimen Acquisition	Biospecimen location	Frontal lobe Temporal lobe Parietal lobe Occipital lobe
Real-time qRT-PCR Specific	Targeted nucleic acid	beta-actin GAPDH Cyclophilin MAP 2 NSE GFAP APP 770

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