Brain tissue haemoglobin expression in saline-perfused vs non-perfused rodents

Area of Science:

• Neuroscience
• Molecular Biology
• Hematology

Background:

• Haemoglobin beta (Hbb) and delta-aminolevulinate synthase 2 (Alas2) mRNA are primarily found in immature red blood cells.
• These mRNAs are also expressed in brain cells, particularly neurons, complicating quantification in neural tissue homogenates.
• Residual blood in brain vasculature can lead to falsely elevated Hbb/Alas2 expression values.

Purpose of the Study:

• To investigate and compare the contribution of local Hbb/Alas2 mRNA expression in brain tissue.
• To assess the impact of saline-perfusion on Hbb/Alas2 transcript levels in rodent brains.
• To determine the extent to which Hbb/Alas2 expression in perfused brains can be attributed to residual blood.

Main Methods:

• Investigated mRNA expression of Hbb and Alas2 in the hippocampus and prefrontal cortex of mice and rats.
• Compared mRNA levels in post-sacrifice saline-perfused and non-perfused animals.
• Quantified Hbb/Alas2 transcripts to assess local expression versus blood contamination.

Main Results:

• Non-perfused animals exhibited higher levels of Hbb/Alas2 transcripts compared to perfused animals.
• Significant Hbb/Alas2 mRNA expression was detected in saline-perfused brains.
• The expression in perfused brains could only be partially explained by residual blood, indicating local neural expression.

Conclusions:

• Hbb and Alas2 mRNA are expressed locally in brain tissue, beyond what can be attributed to blood contamination.
• Saline-perfusion is a crucial step for accurate quantification of neural Hbb/Alas2 transcripts.
• The study recommends saline-perfusion for reliable measurement of brain Hbb/Alas2 expression in homogenates.