title: Immune responsiveness of splenocytes after chronic daily melatonin administration in male Syrian hamsters.
abstract: The interrelationships between the immune system and the pineal hormone, melatonin, have been explored recently. The present studies investigated the effects of daily melatonin injections on reproductive and spleen function in male Syrian hamsters. Testes weights and serum testosterone levels were depressed after 8-10 weeks of daily melatonin injections. Melatonin-treated hamsters exhibited increased splenic lymphoproliferative responses to a polyclonal T-cell mitogen (concanavalin A (Con-A)), but decreased proliferation following stimulation with a polyclonal B-cell mitogen (lipopolysaccharide). It appears that daily melatonin injections in male hamsters increase the T-cell-mediated immune capacity while reducing the antibody-mediated immune potential. These data suggest that chronic, daily melatonin alters immune system responsiveness in hamsters by shifting the balance of cellular and humoral reactivity.
authors.affiliation: Department of Human Anatomy and Medical Neurobiology, College of Medicine, Texas A&M University Health Science Centre, College Station 77843-1114, USA. thchamp@tamu.edu
authors.forename: T H
authors.initials: TH
authors.lastname: Champney
authors.forename: J
authors.initials: J
authors.lastname: Prado
authors.forename: T
authors.initials: T
authors.lastname: Youngblood
authors.forename: K
authors.initials: K
authors.lastname: Appel
authors.forename: D N
authors.initials: DN
authors.lastname: McMurray
mesh_terms: D000818:Animals; D000917:Antibody Formation / Q000187:drug effects*; D001402:B-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D002452:Cell Count / Q000187:drug effects; D003208:Concanavalin A / Q000494:pharmacology; D006224:Cricetinae; D007111:Immunity, Cellular / Q000187:drug effects*; D008213:Lymphocyte Activation / Q000187:drug effects; D008297:Male; D008550:Melatonin / Q000008:administration & dosage / Q000494:pharmacology*; D008647:Mesocricetus; D009929:Organ Size / Q000187:drug effects; D017440:Photoperiod; D013154:Spleen / Q000166:cytology / Q000187:drug effects* / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D013737:Testis / Q000187:drug effects / Q000378:metabolism; D013739:Testosterone / Q000097:blood
chemical_list: D003208:Concanavalin A; D013739:Testosterone; D008550:Melatonin