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Published on: May 2, 2018
Unresponsiveness of mu-opioid receptor knockout mice to lipopolysaccharide-induced fever
Khalid Benamar1, Malgorzata McMenamin, Ellen B Geller
1Center for Substance Abuse Research, Temple University School of Medicine, 3400 N. Broad Street, Philadelphia, PA 19140, USA. kbenamar@temple.edu
Abstract:
Recently, we demonstrated that lipopolysaccharide (LPS)-induced fever could be suppressed by a selective mu-opioid receptor antagonist, indicating that the mu-opioid system is involved in the LPS fever. In the present study, to confirm the role of the mu-opioid system in the pathogenesis of LPS fever, we used mice lacking the mu-opioid receptor. In the wild type (WT), following intraperitoneal (i.p.) injection of 100 microg kg(-1) of LPS, body temperature (T(b)) increased approximately 1 degrees C and remained elevated during the 360-min recording period. In the mu-opioid receptor knockout (MOR-KO) mice, the administration of 100 microg kg(-1) i.p. of LPS did not induce fever during the recording period. Saline by itself, given i.p., did not alter the T(b), either in WT or MOR-KO. These results confirm that the mu-opioid system is involved in LPS-induced fever.
Insights
The mu-opioid system plays a key role in lipopolysaccharide (LPS)-induced fever. Mice lacking the mu-opioid receptor did not develop fever after LPS injection, confirming this involvement.
Area of Science:
- Neuroscience
- Immunology
- Physiology
Background:
- Lipopolysaccharide (LPS) triggers fever, a complex immune response.
- Previous studies suggested the involvement of the mu-opioid system in LPS-induced fever.
Purpose of the Study:
- To confirm the role of the mu-opioid system in the pathogenesis of LPS fever.
- To investigate the effect of LPS on body temperature in mice lacking mu-opioid receptors.
Main Methods:
- Utilized wild-type (WT) and mu-opioid receptor knockout (MOR-KO) mice.
- Administered intraperitoneal injections of LPS (100 microg kg(-1)) or saline.
- Monitored body temperature (T(b)) for 360 minutes post-injection.
Main Results:
- WT mice exhibited a significant increase in T(b) after LPS injection.
- MOR-KO mice showed no fever response following LPS administration.
- Saline injections did not affect T(b) in either WT or MOR-KO mice.
Conclusions:
- The mu-opioid system is essential for the development of LPS-induced fever.
- These findings solidify the link between opioid signaling and inflammatory responses causing fever.
