Nociceptin, Endomorphins, and Urocortins

There are several newly discovered peptides that are related to those already discussed above and that appear to have, in varying degrees, a role in neuroimmune function. Nociceptin, or Oiphanin FQ, is a 17 amino acid peptide that plays a role in pain sensation as well as other complex CNS functions. The 

Several studies have showm that ORL-1 are expressed in immune cells, including peripheral blood lymphocytes, T and B cells and polymorphonuclear leukocytes (Halford et al., 1995 Peluso et al., 1998 Horn et al., 1999 Serhan et al., 2001), and these receptors are functionally active (Waits et al., 2004 Halford et al., 1995 Horn et al., 1999 Serhan et al., 2001). Following these findings, nociceptin transcripts were found to be present in peripheral blood lymphocytes (Aijomand et al., 2002). It has been suggested, based on differences in transcripts betw een immune cells and neurons, that processing of the message and the final form of nociceptin may be cell type specific, similar to other peptides. 

The function of nociceptin in the immune system and/or in the interaction betw een the nervous and immune systems is not clear at present. Studies suggest that it increases T cell activation, suppresses antibody production and is a potent chemoattractant. However, given the presence of both the neuropeptide and its receptor in immune cells, analogous to beta-endoiphin and the enkephalins, nociceptin is well positioned to play a role similar to that of the better-known and studied opioid-like peptides. 

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