Specific serotonin reuptake inhibitors (SSRIs) are the most widely prescribed drugs for treatment of depressive disorders. Preliminary data have shown that acute fluoxetine (FLX) administration significantly suppresses mitogen-induced lymphocyte proliferation and NK cell cytolytic activity. The mechanism and implications of SSRI immune suppression are not yet known. The suppressive effects were found to be dose-dependent, reversible, and selective for serotonin reuptake. The lymphocyte effects, but not NK cell affects, appear to be 5HT2A receptor mediated. These data suggest that SSRI therapy may potentiate the immunosuppression observed in depression, therefore, it is important to characterize the mechanism and effects of acute and chronic treatment with FLX. To test the hypothesis that acute and chronic SSRI treatment suppresses Cell-mediated immunity via serotonin receptor activation in normal animals and in animal models of depression, I propose to determine: 1) the serotonin receptor subtype(s) involved in the acute immunomodulatory effects of FLX, 2) the mechanism/site of action by which acute FLX suppresses immune function, 3)the effects of chronic FLX treatment on immune function in normal animals, and 4) the effects of acute and chronic FLX in an animal model for depression. The results of these studies will provide insight into the mechanism of SSRI immunomodulation and the implications they might have on depressed patients receiving SSRI therapy. In addition, these studies will increase understanding of the role of endogenous serotonergic systems in modulating the immune response.

Agency
National Institute of Health (NIH)
Institute
National Institute of Mental Health (NIMH)
Type
Predoctoral Individual National Research Service Award (F31)
Project #
5F31MH011589-02
Application #
2674550
Study Section
Psychobiological, Biological, and Neurosciences Subcommittee (MHAI)
Program Officer
Goldschmidts, Walter L
Project Start
1998-07-16
Project End
Budget Start
1998-07-16
Budget End
1999-07-15
Support Year
2
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Georgetown University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
049515844
City
Washington
State
DC
Country
United States
Zip Code
20057
Pellegrino, Trisha C; Bayer, Barbara M (2002) Role of central 5-HT(2) receptors in fluoxetine-induced decreases in T lymphocyte activity. Brain Behav Immun 16:87-103
Pellegrino, T C; Dunn, K L; Bayer, B M (2001) Mechanisms of cocaine-induced decreases in immune cell function. Int Immunopharmacol 1:665-75
Pellegrino, T C; Bayer, B M (2000) Specific serotonin reuptake inhibitor-induced decreases in lymphocyte activity require endogenous serotonin release. Neuroimmunomodulation 8:179-87
Pellegrino, T C; Bayer, B M (1998) Modulation of immune cell function following fluoxetine administration in rats. Pharmacol Biochem Behav 59:151-7