Short-term stressors and corticosterone treatment effects on toad’s immunity


SOCIETY FOR INTEGRATIVE AND COMPARATIVE BIOLOGY
2021 VIRTUAL ANNUAL MEETING (VAM)
January 3 – Febuary 28, 2021

Meeting Abstract


43-2  Sat Jan 2  Short-term stressors and corticosterone treatment effects on toad’s immunity Titon, SCM*; Titon Jr, B; Gomes, FR; Assis, VR; University of Sao Paulo, Sao Paulo, Brazil; University of Sao Paulo, Sao Paulo, Brazil; University of Sao Paulo, Sao Paulo, Brazil; University of Sao Paulo, Sao Paulo, Brazil stefannychristie@gmail.com

In recent years it is growing the idea that stress-induced immunomodulation is bimodal: with acute stress associated with enhancing effects while chronic stress with suppressive effects. However, the immune-endocrine interactions and its implications are often overlooked in amphibians. We investigated the effects of corticosterone (CORT) treatment and short-term stressors on CORT plasma levels and the immunity of toads (Rhinella icterica), using distinct protocols: restraint, immune challenge (with lipopolysaccharide, LPS), and CORT transdermal application (TA). Our results showed increased CORT and neutrophil: lymphocyte ratio (NLR) regardless of the stress input. While the bacterial killing ability (BKA) was not affected by any treatment, suggesting this immune parameter might be a more constitutive and robust response. The cellular immune response showed distinct patterns. Increased phagocytosis of blood leukocytes and phytohemagglutinin edema following LPS and CORT TA (15ug), respectively. In contrast, the phagocytosis of peritoneal leukocytes decreased after CORT TA (1 and 10ug). Together these results signalize the local immune function, but not the systemic immune function, might be impaired by acute increases in CORT. Although such differences in cellular immunity might be linked to distinct CORT doses or the interaction between CORT and other immune mediators. Overall, our results highlight the relevance of investigating distinct contexts for CORT increase (physiological and pharmacological), arising from different situations (CORT treatment and acute stressors), as well as diverse immune components (local and systemic, cellular and protein) for a better understanding of the stress-induced immunomodulation.

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