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Postmortem stability of dopamine D1 receptor mRNA and D1 receptors
J H Gilmore1, C P Lawler, A M Eaton
1Department of Psychiatry, University of North Carolina School of Medicine, Chapel Hill 27599-7160.
Abstract:
The effects of postmortem interval on dopamine D1 mRNA and D1 receptors were assessed in rat striatum under conditions simulating the handling of human brain tissue at 0, 6, 12, and 24 h postmortem. The amount of D1 mRNA was measured by both in situ hybridization film and emulsion autoradiography with [35S]dATP-labeled oligonucleotide probes. D1 receptor density was determined by autoradiography with [125I]SCH 23982. Neither the total amount of D1 mRNA in the striatum nor the frequency distribution of striatal cells expressing D1 mRNA varied with the postmortem interval. There was a modest but significant decrease (ca. 10%) in D1 receptors over the 24 h postmortem interval; this decrease occurred within the first 6 h postmortem, with no further decreases up to 24 h postmortem. These findings suggest that the effects of postmortem interval on D1 mRNA and receptors are minimal and should not limit an examination of possible alterations in dopamine D1 receptor mRNA and D1 receptors in the postmortem brains of humans with neuropsychiatric disease.
Insights
Postmortem interval has minimal impact on dopamine D1 mRNA levels in rat brains. However, dopamine D1 receptors show a slight decrease within the first 6 hours postmortem.
Area of Science:
- Neuroscience
- Molecular Biology
- Pharmacology
Background:
- The postmortem interval (PMI) can affect the stability of RNA and proteins in brain tissue.
- Understanding PMI effects is crucial for interpreting molecular findings in postmortem human brains, especially in neuropsychiatric research.
Purpose of the Study:
- To investigate the impact of simulated postmortem handling on dopamine D1 mRNA and D1 receptor levels in rat striatum.
- To determine if PMI affects the reliability of measuring dopamine D1 system components in postmortem brain samples.
Main Methods:
- Assessed dopamine D1 mRNA using in situ hybridization with radiolabeled oligonucleotide probes.
- Quantified D1 receptor density via autoradiography with a specific radioligand ([125I]SCH 23982).
- Examined tissue at postmortem intervals of 0, 6, 12, and 24 hours.
Main Results:
- Dopamine D1 mRNA levels and the distribution of cells expressing D1 mRNA remained stable across all postmortem intervals.
- A significant, modest decrease (approximately 10%) in D1 receptor density was observed within the first 6 hours postmortem.
- No further significant changes in D1 receptor density occurred between 6 and 24 hours postmortem.
Conclusions:
- The postmortem interval has a limited effect on dopamine D1 mRNA integrity in rat striatum.
- Dopamine D1 receptor levels are relatively stable beyond 6 hours postmortem, suggesting minimal impact on studies using tissue within this timeframe.
- These findings support the utility of postmortem brain tissue for investigating alterations in the dopamine D1 system in neuropsychiatric disorders.