title: Oral administration of melatonin to old ring doves (Streptopelia risoria) increases plasma levels of melatonin and heterophil phagocytic activity.
abstract: We analyzed the effect of oral melatonin (23 microg/0.1 ml/animal/d; 1 h before dark on 12 consecutive days) in old birds, in natural photoperiods, on the hormone's plasma levels, and phagocytosis. Blood collections were performed daily at 2:00 am and 4:00 pm until 5 days after the treatment. From day 1, the melatonin levels were significantly higher than basal levels at both times. Values at 2:00 am were significantly higher than the 4:00 pm values. After treatment, the melatonin levels declined, returning from day 14 to basal values at both hours. At 2:00 am, phagocytosis was significantly greater than that obtained at 4:00 pm and greater than basal values. The 4:00 pm values were only significantly greater than basal on days 6 and 8, parallel to a decline in superoxide anion levels, which were lowest at 2:00 am. Melatonin administered to old ring doves increases the differences between nocturnal and diurnal plasma levels, and, in parallel, increases phagocytosis and reduces superoxide radical levels in heterophils.
authors.affiliation: M del Pilar Terrón Sánchez, Department of Physiology, Faculty of Science, University of Extremadura, Avda Elvas s/n. 06071- Badajoz, Spain. pilarts@unex.es
authors.forename: Ma Del Pilar
authors.initials: Mdel P
authors.lastname: Terrón
authors.forename: Sergio D
authors.initials: SD
authors.lastname: Paredes
authors.forename: Carmen
authors.initials: C
authors.lastname: Barriga
authors.forename: Eduardo
authors.initials: E
authors.lastname: Ortega
authors.forename: Russel J
authors.initials: RJ
authors.lastname: Reiter
authors.forename: Ana B
authors.initials: AB
authors.lastname: Rodríguez
mesh_terms: D000284:Administration, Oral; D000367:Age Factors; D000818:Animals; D010856:Columbidae; D005260:Female; D007962:Leukocytes / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008550:Melatonin / Q000008:administration & dosage* / Q000097:blood*; D010587:Phagocytosis / Q000187:drug effects*; D013997:Time Factors
chemical_list: D008550:Melatonin