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Delta opioid receptors in human neuroblastoma cell lines
Abstract:
Opioid receptor sites were detectable in 4 out of 9 human neuroblastoma cell lines tested, in the human retinoblastoma line Y79 NHT C10 and in the mouse neuroblastoma line Neuro 2A. All of these cell lines expressed delta sites, while only one coexpressed mu sites (SK-N-SH). Together with delta sites previously found in rodent neuroblastoma lines, these results suggest that the expression of delta sites is under less stringent control than that of mu and chi sites. A large number of delta sites (greater than 10,000 sites per cell) is expressed in IMR-32 and NMB neuroblastoma lines. Agonist binding was sensitive to Na+ and guanine nucleotides. The delta sites in IMR-32 and NMB cells were further characterized with delta selective ligands and [3H]DADL tracer. Their delta binding affinities were identical to those of the mu and delta cell line SK-N-SH; therefore the presence of mu sites does not appear to affect the binding behavior of the delta sites by any potential interaction among the binding proteins. Further, close correlations were found when comparing ligand binding in the human neuroblastoma cell lines with those of mouse neuroblastoma cells and rodent brain, an indication that the delta receptor is highly preserved among different species.
Insights
Opioid delta receptor sites are present in human neuroblastoma and retinoblastoma cell lines. These delta sites show high preservation across species and are expressed independently of mu opioid receptors.
Area of Science:
- Neuroscience
- Molecular Biology
- Pharmacology
Background:
- Opioid receptors are crucial in pain modulation and other physiological processes.
- Understanding opioid receptor expression in neuronal cell lines provides insights into their function.
- Previous studies identified opioid receptors in rodent neuroblastoma lines.
Purpose of the Study:
- To investigate the presence and characteristics of opioid receptor sites in human neuroblastoma and retinoblastoma cell lines.
- To compare the expression patterns of delta, mu, and chi opioid receptor subtypes.
- To assess the conservation of delta opioid receptors across species.
Main Methods:
- Screening of human neuroblastoma and retinoblastoma cell lines for opioid receptor binding sites.
- Characterization of delta opioid receptor sites using selective ligands and radioligands ([3H]DADL).
- Analysis of agonist binding sensitivity to sodium ions (Na+) and guanine nucleotides.
Main Results:
- Opioid receptor sites were detected in 4 out of 9 human neuroblastoma lines and in human retinoblastoma (Y79 NHT C10) and mouse neuroblastoma (Neuro 2A) lines.
- All detected cell lines expressed delta opioid receptor sites; only one line (SK-N-SH) coexpressed mu opioid receptor sites.
- High numbers of delta sites (>10,000/cell) were found in IMR-32 and NMB lines, with binding sensitive to Na+ and guanine nucleotides.
- Delta binding affinities in IMR-32 and NMB cells were similar to those in SK-N-SH, indicating no interference from mu sites.
- Ligand binding data showed strong correlations between human neuroblastoma lines, mouse neuroblastoma cells, and rodent brain, suggesting high delta receptor preservation.
Conclusions:
- Delta opioid receptor expression is common in human neuroblastoma and retinoblastoma cell lines.
- Delta opioid receptor expression appears to be under less stringent control compared to mu and chi sites.
- The delta opioid receptor is highly conserved across species, from human to rodent.
- These findings support the use of these cell lines as models for studying delta opioid receptor pharmacology.