Seasonal and Sexual Variations in Corticosterone and Total Triiodothyronine : A Pilot Study in Mediterranean Tortoises (Testudo hermanni)
Olvera-Maneu, Sergi (University of Nicosia)
Navarro Mañero, Xavier (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)
Serres Corral, Paula (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)
Carbajal, Annaïs (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)
Martínez Silvestre, Albert (Centre de Recuperació d'Amfibis i Rèptils de Catalunya (Masquefa, Catalunya))
López Béjar, Manel (Universitat Autònoma de Barcelona. Departament de Sanitat i d'Anatomia Animals)

Data:	2024
Resum:	The Hermann's tortoise (Testudo hermanni), or Mediterranean tortoise, is one of the two native species of terrestrial tortoises that inhabit the Iberian Peninsula. This is a vulnerable species protected by legislation and subjected to conservation and captive breeding programs. The present study is the first to simultaneously evaluate the four-season variations in corticosterone and total triiodothyronine in semi-captive adults and juvenile individuals of Western Hermann's tortoises (T. hermanni hermanni). The current investigation revealed that corticosterone concentrations changed seasonally depending on the sex, whereas total triiodothyronine changed seasonally in both sexes. Juvenile individuals did not show seasonal variations in any of the evaluated hormones. Overall, this study adds evidence and provides novel information about the seasonal variations in corticosterone and total triiodothyronine in adult and juvenile individuals of this protected species. The Mediterranean tortoise Testudo hermanni inhabits different regions bordering the northwestern Mediterranean. This species is vulnerable, protected by legislation, and involved in various breeding and reintroduction programs. Wild populations face numerous environmental and anthropogenic stressors that can potentially interfere with their conservation. While seasonal changes in stress-response biomarkers, such as glucocorticoids and thyroid hormones, have been widely studised in mammals and birds, there is a paucity of research in reptile species. Therefore, the present study aimed to evaluate the seasonal fluctuations in corticosterone and total triiodothyronine levels in adult and juvenile Hermann's tortoises (Testudo hermanni) as a measure of the physiological stress response. Blood samples were collected seasonally (winter, spring, summer, and autumn) and posteriorly analyzed by using a specific and validated enzyme immunoassay for both hormones, respectively. The results showed that corticosterone levels varied seasonally and differed between sexes, whereas total triiodothyronine levels changed seasonally but did not differ between sexes. Notably, juveniles exhibited no seasonal changes in either corticosterone or total triiodothyronine levels. Additionally, no correlation between blood extraction duration and hormonal concentrations was observed. This study is pioneering in its comprehensive evaluation of corticosterone and total triiodothyronine changes across all four seasons, including winter, and its focus on juvenile Hermann's tortoises.
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Adrenal ; Thyroid ; Stress ; Reptile ; Chelonian ; Annual variation ; Conservation ; Homeostasis
Publicat a:	Animals, Vol. 14 (september 2024) , ISSN 2076-2615

DOI: 10.3390/ani14192810
PMID: 39409758

11 p, 553.5 KB

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