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Specific receptors for beta-endorphin on mesangial cells
P C Singhal1, A L Driesbach, M Abramovici
1Department of Medicine, Long Island Jewish Medical Center, Albert Einstein College of Medicine, New York, N.Y.
Nephron
|January 1, 1992
Summary
Beta-endorphin, an endogenous opioid, binds to specific receptors on rat mesangial cells. This binding influences cell proliferation, suggesting a role in immune modulation.
Area of Science:
- Immunology
- Neuroendocrinology
- Cell Biology
Background:
- Beta-endorphin is an endogenous opioid peptide.
- It is known to modulate immune responses and injury.
- Its role in kidney mesangial cells is not well understood.
Purpose of the Study:
- To investigate the presence and characteristics of beta-endorphin binding sites on cultured rat mesangial cells.
- To determine if beta-endorphin binding affects mesangial cell proliferation.
Main Methods:
- Radioligand binding assays using [125I]beta-endorphin on cultured rat mesangial cells.
- Competition binding studies with unlabeled beta-endorphin, opiate agonists, and antagonists.
- Saturation binding studies to determine receptor affinity (Kd) and density.
- Assessment of [3H]thymidine incorporation to measure cell proliferation.
Main Results:
- Rat mesangial cells possess specific, high-affinity binding sites for beta-endorphin (apparent Kd = 15.3 nM).
- Binding was concentration-dependent and time-dependent, with approximately 8.48 x 10(5) sites/cell.
- Opiate agonists and antagonists did not affect beta-endorphin binding.
- Exposure to beta-endorphin (10(-6) M) for 48 hours significantly enhanced [3H]thymidine incorporation, indicating increased proliferation.
Conclusions:
- Cultured rat mesangial cells express specific receptors for beta-endorphin.
- Beta-endorphin binding to these receptors may stimulate mesangial cell proliferation.
- These findings suggest a potential role for beta-endorphin in regulating kidney cell growth and immune responses.