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Opiate binding sites in the cellular immune system: expression and regulation
J J Madden1, W L Whaley, D Ketelsen
1Department of Psychiatry and Behavioral Science, Emory University School of Medicine, Atlanta, GA 30322, USA. jmadden@emory.edu
Abstract:
The direct actions of opiates on the mammalian immune system depend on the existence of ligand binding sites either on the surface of the affected cell or in the interior of the cell. With the cloning of various opiate receptors from neuronal tissue, numerous researchers have screened leukocyte cDNA libraries for the expression of these receptors with some positive results. However, the pattern of expression of neuronal opiate receptors in the cellular immune system does not completely explain the biological action of opiates there. Several possibilities could account for this non-congruence including differential expression of the receptors as determined by such factors as cell population or prior history of the cells; the existence of sequence modified versions of the neuronal receptors such that the amplification methods miss their presence; or the opiates act by a different, non-receptor mechanism in the cellular immune system.
Insights
Opiate effects on the immune system are complex. Researchers are investigating why neuronal opiate receptor expression in leukocytes doesn't fully explain these actions, exploring alternative mechanisms.
Area of Science:
- Immunology
- Neuropharmacology
- Molecular Biology
Background:
- Opiates directly impact the mammalian immune system via ligand binding sites.
- Neuronal opiate receptors have been identified in leukocyte cDNA libraries, suggesting a link.
- However, the expression pattern of these receptors does not fully account for opiate's biological effects on immune cells.
Purpose of the Study:
- To investigate the discrepancy between neuronal opiate receptor expression in leukocytes and the observed biological actions of opiates.
- To explore potential explanations for the non-congruent findings regarding opiate receptor expression and function in the cellular immune system.
Main Methods:
- Screening of leukocyte cDNA libraries for opiate receptor expression.
- Analysis of differential receptor expression based on cell population and history.
- Investigation into sequence-modified receptor variants.
- Exploration of non-receptor mediated mechanisms of opiate action.
Main Results:
- While neuronal opiate receptors are found in leukocytes, their expression pattern does not fully explain opiate's immune effects.
- Potential factors include differential expression, modified receptor versions, or non-receptor mechanisms.
Conclusions:
- The interaction between opiates and the cellular immune system is not solely explained by the presence of known neuronal opiate receptors.
- Further research is needed to elucidate the precise mechanisms, including potential novel receptor variants or non-receptor pathways.