Short-term stressors and corticosterone effects on immunity in male toads (Rhinella icterica): A neuroimmune-endocrine approach

Author(s)

Titon, Stefanny Christie Monteiro ; Titon Junior, Braz ; Gomes, Fernando Ribeiro ; Assis, Vania Regina

• Document type: Journal article
• Source: BRAIN, BEHAVIOR, & IMMUNITY - HEALTH; v. 13, p. 10-pg., 2021-05-01.

Abstract

In the last decades, 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 ectotherms. We investigated the impact of corticosterone (CORT) treatment and short-term stressors on CORT plasma levels and the immunity of male toads (Rhinella icterica), using three 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 (restraint, LPS challenge) or CORT TA. In the meantime, the bacterial killing ability (BKA) was not affected by any treatment, suggesting this immune parameter might be a more constitutive and robust response. Interestingly, the cellular immune response showed distinct patterns. Increased phagocytosis of blood leukocytes and phytohemagglutinin edema followed LPS and CORT TA (15 & mu;g), respectively. In contrast, the phagocytosis of peritoneal leukocytes decreased after CORT TA (1 and 10 & mu;g), indicating that short-term increases in CORT levels might impair local immune function. Such differences in cellular immunity might also be associated with CORT doses or the interaction between CORT and other immune mediators, such as melatonin, testosterone, and cytokines. Overall, our results highlight the immune-enhancing effects of the acute stress response and CORT TA, and the complexity of the immune-endocrine interaction in anurans. It also highlights the relevance of investigating distinct contexts for CORT increase arising from different situations, as well as diverse immune components for a better understanding of the stress-induced immunomodulation. (AU)

• FAPESP's process: 13/00900-1 - Comparative study of the relationships between immunocompetence and plasmatic levels of gonadal and inter-renal steroids in toads
• Grantee: Fernando Ribeiro Gomes
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/23801-4 - Immunomodulatory effects of acute stress in toads from Genus Rhinella
• Grantee: Vania Regina de Assis
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 14/16320-7 - Impacts of climate/environmental change on the fauna: an integrative approach
• Grantee: Carlos Arturo Navas Iannini
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 16/01782-0 - Relations between environmental and physiological conditions of activity and its importance for the distribution alterations of toads with climatic changes
• Grantee: Braz Titon Junior
• Support Opportunities: Scholarships in Brazil - Post-Doctoral