In vitro macrophage activity: biphasic effect of prolactin and indirect evidence of dopaminergic modulation.
OBJECTIVE
Prolactin (PRL), a peptide hormone produced by the pituitary gland, is involved in the interaction between the neuroendocrine and immune system. Since dopamine receptor antagonists increase serum levels of PRL, both PRL and dopamine receptors might be involved in the modulation of macrophage activity, providing means of communication between the nervous and immune systems. This study evaluated the effects of PRL and the dopamine antagonist domperidone (DOMP) on macrophage activity of female rats.


METHODS
Oxidative burst and phagocytosis of peritoneal macrophages were evaluated by flow cytometry. Samples of peritoneal liquid from female rats were first incubated with PRL (10 and 100 nM) for different periods. The same procedure was repeated to evaluate the effects of DOMP (10 and 100 nM).


RESULTS
In vitro incubation of macrophages with 10 nM DOMP decreased oxidative burst, after 30 min, whereas the PMA-induced burst was decreased by DOMP 10 nM after 2 and 4 h. Treatment with PRL (10 and 100 nM) for 30 min decreased oxidative burst and rate of phagocytosis (10 nM). After 2 h of incubation, 10 nM PRL decreased oxidative burst and phagocytosis intensity, but increased the rate of phagocytosis. On the other hand, after 4 h, PRL 10 and 100 nM increased oxidative burst and the rate of phagocytosis, but decreased intensity of phagocytosis.


CONCLUSIONS
These observations suggest that macrophage functions are regulated by an endogenous dopaminergic tone. Our data also suggest that both PRL and dopamine exert their action by acting directly on the peritoneal macrophage.
Carvalho-Freitas
Maria I R
MI
Department of Pathology, School of Veterinary Medicine, University of São Paulo, São Paulo, Brazil. rothvet@yahoo.com.br
Rodrigues-Costa
Elaine C
EC
Nasello
Antonia G
AG
Palermo-Neto
João
J
Felicio
Luciano F
LF
D000818:Animals; D002478:Cells, Cultured; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000276:immunology; D004294:Domperidone / Q000494:pharmacology; D004298:Dopamine / Q000494:pharmacology / Q000502:physiology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D005260:Female; D007155:Immunologic Factors / Q000494:pharmacology / Q000502:physiology*; D017737:Macrophages, Peritoneal / Q000187:drug effects / Q000276:immunology*; D015213:Neuroimmunomodulation / Q000276:immunology*; D010587:Phagocytosis / Q000187:drug effects / Q000276:immunology; D011388:Prolactin / Q000494:pharmacology / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D016897:Respiratory Burst / Q000187:drug effects / Q000276:immunology; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
D018492:Dopamine Antagonists; D007155:Immunologic Factors; D004294:Domperidone; D011388:Prolactin; D004298:Dopamine