title: beta-Endorphin regulates diverse functions of splenic phagocytes through different opioid receptors in freshwater fish Channa punctatus (Bloch): an in vitro study.
abstract: In this in vitro study, the role of beta-endorphin in the control of phagocytic and cytotoxic activities of fish splenic phagocytes was investigated. Further, the involvement of specific opioid receptor was explored. beta-Endorphin stimulated phagocytosis, whereas inhibited nitric oxide production as assessed by nitrite release. However, it had concentration-related biphasic effects on superoxide production, stimulatory at low and inhibitory at high concentration. Naltrexone, non-selective opioid receptor antagonist, antagonized the effect of beta-endorphin on phagocyte functions. Moreover, CTAP, selective mu-receptor antagonist, completely blocked the effect of beta-endorphin on phagocytosis and nitrite release. With regard to superoxide production, CTAP blocked the stimulatory effect of beta-endorphin at low concentration, while the inhibitory effect at high concentration was completely antagonized by selective delta-receptor antagonist, NTI. In conclusion, beta-endorphin acting via mu-receptor stimulated phagocytosis and inhibited nitric oxide production, while its biphasic effect on superoxide production seems to be mediated by mu- and delta-receptors.
authors.affiliation: Department of Zoology, University of Delhi, Delhi 110 007, India.
authors.forename: Rajeev
authors.initials: R
authors.lastname: Singh
authors.forename: Umesh
authors.initials: U
authors.lastname: Rai
mesh_terms: D000818:Animals; D005399:Fishes; D009271:Naltrexone / Q000031:analogs & derivatives / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D010446:Peptide Fragments; D010455:Peptides / Q000494:pharmacology; D010586:Phagocytes / Q000378:metabolism*; D010587:Phagocytosis / Q000187:drug effects / Q000502:physiology; D011957:Receptors, Opioid / Q000378:metabolism*; D013004:Somatostatin; D013154:Spleen / Q000166:cytology / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D001615:beta-Endorphin / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: C529311:CTAP octapeptide; C114628:NTI compound; D009292:Narcotic Antagonists; D010446:Peptide Fragments; D010455:Peptides; D011957:Receptors, Opioid; D013481:Superoxides; D009569:Nitric Oxide; D013004:Somatostatin; D009271:Naltrexone; D001615:beta-Endorphin