title: Seasonal variation in urinary and salivary reproductive hormone levels in Amazonian manatees (Trichechus inunguis).
abstract: The Amazonian manatee (Trichechus inunguis) is a threatened aquatic mammal endemic to the Amazon basin. The aim of this study was to evaluate the urinary and salivary reproductive hormone levels of captive Amazonian manatees collected during two seasons of the year. Salivary samples from four males and urinary and salivary samples from three females were collected during two seasons (March-June and September-November) over two consecutive years. Salivary testosterone in males was measured by radioimmunoassay and reproductive hormones in females (salivary progesterone and oestradiol and urinary progestogens, oestrogens and luteinising hormone) were measured by enzyme immunoassay. The data were analysed in a 2×2 factorial design, where the factors were year and season. There was no effect of year or season for salivary testosterone. All female hormones showed a seasonal effect (higher hormone levels during March-June than September-November) or an interaction between year and season (P<0.05). These results strongly indicate the existence of reproductive seasonality in Amazonian manatees; however, apparently only females exhibit reproductive quiescence during the non-breeding season. Further long-term studies are necessary to elucidate which environmental parameters are related to reproductive seasonality in T. inunguis and how this species responds physiologically to those stimuli.
authors.affiliation: Faculty of Veterinary Medicine and Animal Science, University of São Paulo - USP, São Paulo, SP 05580-270, Brazil.
authors.forename: Rodrigo S
authors.initials: RS
authors.lastname: Amaral
authors.affiliation: Laboratory of Aquatic Mammals, National Institute of Amazonian Research - INPA, Manaus, AM 69060-001, Brazil.
authors.forename: Fernando C W
authors.initials: FC
authors.lastname: Rosas
authors.affiliation: Laboratory of Aquatic Mammals, National Institute of Amazonian Research - INPA, Manaus, AM 69060-001, Brazil.
authors.forename: Vera M F
authors.initials: VM
authors.lastname: da Silva
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Guelph, ON N1G 2W1, Canada.
authors.forename: Laura H
authors.initials: LH
authors.lastname: Graham
authors.affiliation: Faculty of Veterinary Medicine and Animal Science, University of São Paulo - USP, São Paulo, SP 05580-270, Brazil.
authors.forename: Priscila
authors.initials: P
authors.lastname: Viau
authors.affiliation: Faculty of Veterinary Medicine and Animal Science, University of São Paulo - USP, São Paulo, SP 05580-270, Brazil.
authors.forename: Marcilio
authors.initials: M
authors.lastname: Nichi
authors.affiliation: Faculty of Veterinary Medicine and Animal Science, University of São Paulo - USP, São Paulo, SP 05580-270, Brazil.
authors.forename: Claudio A
authors.initials: CA
authors.lastname: Oliveira
mesh_terms: D000818:Animals; D004958:Estradiol / Q000032:analysis* / Q000652:urine; D005260:Female; D007986:Luteinizing Hormone / Q000652:urine*; D008297:Male; D011374:Progesterone / Q000032:analysis* / Q000652:urine; D012098:Reproduction / Q000502:physiology; D012463:Saliva / Q000737:chemistry; D012621:Seasons; D013739:Testosterone / Q000032:analysis* / Q000652:urine; D020456:Trichechus inunguis / Q000378:metabolism*
chemical_list: D013739:Testosterone; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone