Inducible nitric oxide synthase (iNOS) expression in human monocytes triggered by beta-endorphin through an increase in cAMP

Biochem Biophys Res Commun. 1998 Apr 28;245(3):717-21. doi: 10.1006/bbrc.1998.8127.


Evidence suggesting a relationship between neuroendocrine and immune systems is steadily growing. We demonstrate now that inducible nitric oxide synthase (iNOS) is expressed in human peripheral blood monocytes after incubation of lymphomononuclear cells in the presence of beta-endorphin, a neuropeptide released by the pituitary in response to mental or physical stress or by activated lymphocytes. beta-endorphin raised cAMP level in monocytes. The possible relationship between cAMP and iNOS expression on monocytes was investigated. Immunostaining for iNOS decreased, when besides beta-endorphin an inhibitor of protein kinase A (H-89) was added to the medium at the beginning of the incubation. The cAMP level raised by beta-endorphin was lowered by naloxone, which also reduced slightly iNOS expression. These results clearly point to the monocyte as a link between neuroendocrine and immune systems, an observation of potential relevance in our understanding of how stress and autoimmunity could be interconnected.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cells, Cultured
  • Cyclic AMP / metabolism*
  • Cyclic AMP-Dependent Protein Kinase Type II
  • Cyclic AMP-Dependent Protein Kinases / antagonists & inhibitors
  • Enzyme Induction
  • Humans
  • In Vitro Techniques
  • Molecular Sequence Data
  • Monocytes / drug effects
  • Monocytes / enzymology*
  • Naloxone / pharmacology
  • Narcotic Antagonists / pharmacology
  • Nitric Oxide Synthase / biosynthesis*
  • Nitric Oxide Synthase Type II
  • beta-Endorphin / pharmacology*


  • Narcotic Antagonists
  • Naloxone
  • beta-Endorphin
  • Cyclic AMP
  • NOS2 protein, human
  • Nitric Oxide Synthase
  • Nitric Oxide Synthase Type II
  • Cyclic AMP-Dependent Protein Kinase Type II
  • Cyclic AMP-Dependent Protein Kinases