Ribonuclease protection assays (RPA) were performed to quantify μ- opioid receptor mRNA expression in specific brain regions of day 70 Rhesus Macaque fetuses that were exposed to cocaine (3 mg/kg) or saline from days 22-70 of gestation. The content of μ-receptor mRNA was high in the diencephalon and moderate in the mesencephalon. In contrast, μ-receptor mRNA was lightly expressed in areas such as the frontal codex, striatum and the temporal lobe. The content of μ-opioid receptor mRNA was significantly higher in the diencephalon than in other brain regions (P < 0.001; n = 4). Cocaine exposure significantly decreased the expression of μ-receptor mRNA in the fetal diencephalon (P < 0.05; n = 4 in each group). Our data would indicate that prolonged gestational cocaine exposure causes μ-opioid receptor mRNA down-regulation in specific brain regions of the fetus.
- Monkey fetus
- Ribonuclease protection assay
- μ-Opioid receptors
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