title: Adrenocortical function in cane toads from different environments.
abstract: The adrenocortical function of cane toads (Rhinella marina) exposed to different experimental procedures, as well as captured from different environments, was assessed by challenging the hypothalamic-pituitary-adrenal (HPA) axis. It was found that restriction stress as well as cannulation increased plasma corticosterone (B) levels for up to 12h. A single dose of dexamethasone (DEX 2mg/kg) significantly reduced B levels demonstrating its potential for use in the evaluation of the HPA axis in amphibia. We also demonstrate that 0.05 IU/g BW (im) of synthetic adrenocorticotropic hormone (ACTH) significantly increased plasma B levels in cane toads. Changes in size area of the cortical cells were positively associated with total levels of B after ACTH administration. We also found differences in adrenal activity between populations. This was assessed by a DEX-ACTH test. The animals captured from the field and maintained in captivity for one year at the animal house (AH) present the highest levels of total and free B after ACTH administration. We also found that animals from the front line of dispersion in Western Australia (WA) present the weakest adrenal response to a DEX-ACTH test. The animals categorized as long established in Queensland Australia (QL), and native in Mexico (MX), do not shown a marked difference in the HPA activity. Finally we found that in response to ACTH administration, females reach significantly higher levels of plasma B than males. For the first time the adrenocortical response in cane toads exposed to different experimental procedures, as well as from different populations was assessed systematically.
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Queensland, Australia; Veterinary School, Universidad Nacional Autónoma de México, Mexico City 4510, Mexico. Electronic address: sandrahm@unam.mx.
authors.forename: Sandra E
authors.initials: SE
authors.lastname: Hernández
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Queensland, Australia.
authors.forename: Conrad
authors.initials: C
authors.lastname: Sernia
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Queensland, Australia.
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Bradley
mesh_terms: D000302:Adrenal Cortex / Q000503:physiopathology*; D000324:Adrenocorticotropic Hormone / Q000008:administration & dosage; D000818:Animals; D002025:Bufonidae / Q000502:physiology*; D003345:Corticosterone / Q000008:administration & dosage; D003907:Dexamethasone / Q000008:administration & dosage; D005260:Female; D008297:Male
chemical_list: D003907:Dexamethasone; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone
keywords: ACTH; Amphibia; Dexamethasone; Rhinella marina; Stress response