Effects of Acute Restraint Stress, Prolonged Captivity Stress and Transdermal Corticosterone Application on Immunocompetence and Plasma Levels of Corticosterone on the Cururu Toad (Rhinella icterica)

Autor(es)

de Assis, Vania Regina ^[1] ; Monteiro Titon, Stefanny Christie ^[1] ; Giorgi Barsotti, Adriana Maria ^[1] ; Titon, Jr., Braz ^[1] ; Gomes, Fernando Ribeiro ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Fisiol, Inst Biociencias, BR-05508900 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: PLoS One; v. 10, n. 4 APR 1 2015.
• Citações Web of Science: 17

Resumo

Glucocorticoid steroids modulate immunocompetence in complex ways with both immunoenhancing and immunosuppressive effects in vertebrates exposed to different stressors. Such bimodal effects have been associated with variation in duration and intensity of the stress response. Given that natural populations have been exposed to a multitude of stressors, a better understanding of the functional association between duration and intensity of the stress response, the resulting changes in glucocorticoid plasma levels and their impact on different aspects of immunocompetence emerges as a cornerstone for vertebrate conservation strategies. We investigated the effects of a restraint challenge (with and without movement restriction), long-term captivity, and transdermal corticosterone application on plasma levels of corticosterone (hereinafter referred to as CORT) and different parameters of innate immunocompetence in the male cururu toads (Rhinella icterica). We show that for Rhinella icterica restraint for 24h proved to be a stressful condition, increasing CORT by 3-fold without consistent immunological changes. However, the application of a more intense stressor (restraint with movement restriction), for the same period, potentiated this response resulting in a 9-fold increase in CORT, associated with increase Neutrophil/Lymphocyte ratio (N:L) and a lower bacterial killing ability (BKA). Transdermal application of corticosterone efficiently mimics repeated acute stress response events, without changing the immune parameters even after 13 days of treatment. Interestingly, long-term captivity did not mitigate the stress response, since the toads maintained 3-fold increased CORT even after 3 months under these conditions. Moreover, long-term captivity in the same condition increased total leukocyte count (TLC) and generated an even greater decrease in BKA, suggesting that consequences of the stress response can be aggravated by time in captivity. (AU)

• Processo FAPESP: 11/10560-8 - Níveis plasmáticos de corticosterona, testosterona e imunocompetência em Bufonídeos.
• Beneficiário: Vania Regina de Assis
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 06/54699-1 - Fragmentação das florestas, distribuição geográfica e evolução fisiológica em anuros neotropicais
• Beneficiário: Fernando Ribeiro Gomes
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 13/00900-1 - Estudo comparativo das relações entre imunocompetência e níveis plasmáticos de esteróides inter-renais e gonadais em sapos
• Beneficiário: Fernando Ribeiro Gomes
• Modalidade de apoio: Auxílio à Pesquisa - Regular