Related Experiment Videos
Characterization of a triple opioid system in the human neuroblastoma NMB cell line
Y Baumhaker1, T Ben-Dor, R Bar-Hamburger
1Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel-Aviv University, Israel.
Abstract:
The human neuroblastoma NMB cell line was found to contain the three types of opioid receptors (60% delta 25% kappa and 15% mu). The opioid receptors were negatively coupled to adenylyl-cyclase. Maximal reduction in cAMP content was achieved by selectively activating single receptor types, indicating the co-presence of the various opioid receptors in the same cells. The opioid receptors in NMB cells were up-regulated following prolonged exposure to the opioid antagonist naloxone and down-regulated following chronic treatment with the opioid agonist etorphine. Down-regulation was time-, dose- and temperature-dependent and was inhibited by colchicine and sodium azide. The NMB culture is presented as an excellent experimental model for studying the selective activation and regulation of the different opioid receptor types when they are co-expressed in the same neuron, as well as for studying interactions between the various opioid receptors.
Insights
The NMB cell line expresses all three opioid receptor types, which are linked to adenylyl cyclase. This model allows study of opioid receptor activation and regulation in co-expressed neurons.
Area of Science:
- Neuroscience
- Pharmacology
- Cell Biology
Background:
- Opioid receptors are crucial in pain modulation and addiction.
- Understanding co-expression and regulation of opioid receptors is vital for therapeutic development.
- The NMB cell line's opioid receptor profile was previously uncharacterized.
Purpose of the Study:
- To characterize the opioid receptor subtypes present in the human neuroblastoma NMB cell line.
- To investigate the functional coupling of these receptors to adenylyl cyclase.
- To examine the regulation of opioid receptors following exposure to agonists and antagonists.
Main Methods:
- Ligand binding assays to quantify receptor subtypes.
- Measurement of cyclic AMP (cAMP) levels to assess receptor coupling.
- Chronic exposure experiments with opioid agonists (etorphine) and antagonists (naloxone).
- Investigation of factors affecting receptor down-regulation (time, dose, temperature, colchicine, sodium azide).
Main Results:
- NMB cells express delta (60%), kappa (25%), and mu (15%) opioid receptors.
- Opioid receptors are negatively coupled to adenylyl cyclase, reducing cAMP levels upon activation.
- Selective activation of single receptor types maximally reduced cAMP, confirming co-expression.
- Receptors upregulated with naloxone and downregulated with etorphine.
- Etorphine-induced downregulation was time-, dose-, and temperature-dependent and inhibited by colchicine and sodium azide.
Conclusions:
- The NMB cell line serves as a valuable model for studying co-expressed opioid receptors.
- This model facilitates research into selective receptor activation and intercellular opioid receptor interactions.
- Findings contribute to understanding opioid receptor dynamics in neuronal systems.