title: Melatonin prolongs survival of immunodepressed mice infected with the Venezuelan equine encephalomyelitis virus.
abstract: Male albino mice immunodepressed after the injection of dexamethasone (DEX) were inoculated intraperitoneally with the Guajira strain of Venezuelan equine encephalomyelitis (VEE) virus. Melatonin (MLT) was administered daily, at a dose of 500 micrograms/kg bodyweight, for 3 days before virus inoculation and 10 days after. Serum levels of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-2 (IL-2) were determined in all the experimental groups (control, DEX, DEX + MLT, DEX + VEE, DEX + VEE + MLT, VEE and MLT). At day 6 after the virus inoculation, the survival rate was significantly increased from 0% in group DEX + VEE to 32.5% in the group of immunodepressed infected mice treated with MLT (DEX + VEE + MLT). By day 10 a survival rate of 10% was found in group DEX + VEE + MLT and 0% in group VEE. No alterations in IL-2 serum levels were observed. MLT increased GM-CSF in control and in DEX-treated mice. In the VEE virus-infected mice treated with DEX, serum levels of GM-CSF increased progressively from day 1 to 5 postinoculation. In contrast, the levels of GM-CSF in infected immunodepressed mice treated with MLT decreased significantly from day 1 to 5 postinoculation. At day 5 after viral inoculation, no differences were detected in the cerebral viral titres in groups VEE, DEX + VEE and DEX + MLT + VEE. These results show that MLT does not inhibit VEE viral replication in the brain of immunodepressed mice.
authors.affiliation: Instituto de Investigaciones Clínicas, Universidad de Zulia, Maracaibo, Venezuela. ebonilla@iamnet.com
authors.forename: E
authors.initials: E
authors.lastname: Bonilla
authors.forename: C
authors.initials: C
authors.lastname: Rodón
authors.forename: N
authors.initials: N
authors.lastname: Valero
authors.forename: H
authors.initials: H
authors.lastname: Pons
authors.forename: L
authors.initials: L
authors.lastname: Chacín-Bonilla
authors.forename: J
authors.initials: J
authors.lastname: Garcia Tamayo
authors.forename: Z
authors.initials: Z
authors.lastname: Rodríguez
authors.forename: S
authors.initials: S
authors.lastname: Medina-Leendertz
authors.forename: F
authors.initials: F
authors.lastname: Añez
mesh_terms: D000276:Adjuvants, Immunologic / Q000627:therapeutic use*; D000818:Animals; D003907:Dexamethasone / Q000276:immunology; D004685:Encephalomyelitis, Venezuelan Equine / Q000188:drug therapy* / Q000276:immunology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism; D007165:Immunosuppression Therapy / Q000009:adverse effects*; D007376:Interleukin-2 / Q000097:blood; D008297:Male; D008550:Melatonin / Q000276:immunology / Q000627:therapeutic use*; D051379:Mice; D016019:Survival Analysis
chemical_list: D000276:Adjuvants, Immunologic; D007376:Interleukin-2; D003907:Dexamethasone; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D008550:Melatonin