Relationship between serotonin and the immune system in a teleost model.
An immunomodulatory role for serotonin (5-HT) has been demonstrated in mammals and evidence for a similar role for 5-HT has recently emerged in fish. However, as limited studies are available, discrepancies often exist regarding the role of 5-HT in the teleost immune response. Therefore, studies were undertaken to help clarify this relationship. Lymphocyte proliferation and extracellular superoxide (O2.-) production were examined in cells from bluegill sunfish injected with either 5-HTP (the immediate precursor to 5-HT) or pCPA (an inhibitor of the rate-limiting enzyme in 5-HT synthesis), or, in vitro following exposure of immune cells to either 5-HT, the 5-HT(1A) receptor agonist, 8-OH-DPAT, or the receptor antagonist, NAN-190. Exposure of fish to 5-HTP increased whole brain 5-HT levels, while pCPA exposure decreased whole brain and splenic 5-HT. In vivo exposure of fish to pCPA depressed T- and B-lymphocyte proliferation; exposure to 5-HTP failed to alter either immune endpoint. In vitro exposure of bluegill splenocytes to 5-HT or 8-OH-DPAT inhibited lymphoproliferation; treatment with NAN-190 had no effect on immune function. Results suggest a link in bluegill between immune function and the serotonergic system. The disparity observed following in vivo- and in vitro-induced serotonergic alterations indicates the complexity of this neuro-immune relationship and emphasizes the need for further studies in this regard.
Duffy-Whritenour
J E
JE
New York University School of Medicine, Department of Environmental Medicine, 57 Old Forge Road, Tuxedo, NY 10987, USA.
Zelikoff
J T
JT
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000276:immunology* / Q000378:metabolism; D010134:Fenclonine / Q000494:pharmacology; D007107:Immune System / Q000502:physiology*; D023421:Models, Animal; D015213:Neuroimmunomodulation / Q000187:drug effects / Q000502:physiology*; D010473:Perciformes; D010879:Piperazines / Q000494:pharmacology; D012701:Serotonin / Q000276:immunology* / Q000378:metabolism; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013154:Spleen / Q000276:immunology / Q000378:metabolism
D010879:Piperazines; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C058895:1-(2-methoxyphenyl)-4-(4-(2-phthalimido)butyl)piperazine; D012701:Serotonin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D006916:5-Hydroxytryptophan; D010134:Fenclonine