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Enhancement of interleukin-1 production in mouse peritoneal macrophages by methionine-enkephalin
Abstract:
Methionine-enkephalin, an endogenous opioid, has been reported to have some effects on immune responses. By thymocyte proliferation method, we herein report that methionine-enkephalin over a wide range of concentrations (1 pmol-0.1 mumol/L) significantly increases both extracellular interleukin-1 release and intracellular interleukin-1 production from peritoneal macrophages induced by lipopolysaccharide in mice. Naloxone, having no effect per se on interleukin-1 production, does not block the enhancing effect of the neuropeptide. Interleukin-1 production was also elevated following ip methionine-enkephalin into mice. The results suggest that methionine-enkephalin mediates the enhancement of interleukin-1 synthesis and release as well, and that the effect is not mediated through classical opioid receptors. The results also provide the further links between immune and nervous systems.
Insights
Methionine-enkephalin significantly boosts interleukin-1 release and production in mice. This neuropeptide
Area of Science:
- Neuroimmunology
- Endocrinology
Background:
- Methionine-enkephalin, an endogenous opioid, influences immune responses.
- Interleukin-1 (IL-1) is a key cytokine in immune regulation.
Purpose of the Study:
- To investigate the effect of methionine-enkephalin on IL-1 production and release.
- To determine if classical opioid receptors mediate this effect.
Main Methods:
- Thymocyte proliferation assay to assess IL-1 activity.
- In vivo administration of methionine-enkephalin and naloxone in mice.
- Measurement of extracellular IL-1 release and intracellular IL-1 production from peritoneal macrophages stimulated with lipopolysaccharide (LPS).
Main Results:
- Methionine-enkephalin significantly increased both extracellular IL-1 release and intracellular IL-1 production.
- The enhancing effect of methionine-enkephalin on IL-1 was observed across a wide concentration range.
- Naloxone, an opioid antagonist, did not block the IL-1 enhancing effect of methionine-enkephalin.
- In vivo administration of methionine-enkephalin also elevated IL-1 production.
Conclusions:
- Methionine-enkephalin enhances IL-1 synthesis and release.
- The observed effects are not mediated through classical opioid receptors.
- These findings highlight a connection between the nervous and immune systems via methionine-enkephalin and IL-1.