Day vs. night variation in the LPS effects on toad's immunity and endocrine mediators

Author(s)

Titon, Stefanny C. M. ; Titon Jr, Braz ; Muxel, Sandra M. ; de Figueiredo, Aymam C. ; Floreste, Felipe R. ; Lima, Alan S. ; Gomes, Fernando R. ; Assis, Vania R.

• Document type: Journal article
• Source: COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY A-MOLECULAR & INTEGRATIVE PHYSIOLOGY; v. 267, p. 9-pg., 2022-05-01.

Abstract

The immune-endocrine interactions following an immune challenge have been demonstrated in amphibians. When considering immune challenges, the immune-endocrine implications can vary with the injection time (day or night), a pattern not explored in amphibians. We investigated the immune response following a lipopolysaccharide -LPS injection, measured as plasma bacterial killing ability -BKA, phagocytosis of blood cells -PP, and neutrophil to lymphocyte ratio -NLR, splenic proinflammatory cytokines mRNA (IL-1 beta and IL-6), and also endocrine mediators (corticosterone -CORT and melatonin -MEL plasma levels) in Rhinella icterica adult male toads injected at day (10 am) or night (10 pm). LPS induced increases in CORT, NLR, PP, and IL-1 beta mRNA compared with amphibian phosphate-buffer saline-injected individuals. For plasma CORT, the response was more pronounced during the night. While for the PP and IL-1 beta mRNA, the effect was more evident during the day. For NLR, the increase happened at both times, day and night, in the LPS-injected toads. Meanwhile, no changes were observed in BKA, IL-6 mRNA, and MEL levels. Overall, our results demonstrated an LPS-induced inflammatory response in R. icterica toads, characterized by higher PP, NLR, and IL-1 beta mRNA, followed by activation of the hypothalamic-pituitary-interrenal axis (higher CORT levels). The time in which the toads received the LPS injection affected the endocrine and immune mediators. The higher CORT and lower inflammatory response at night suggested a potential functional interaction between CORT and immune reactivity associated with the differences in night vs. day in R. icterica toads. These results highlight the relevance of investigating different injection times and mechanistic pathways to understand LPS-induced immunomodulation in anurans. (AU)

• 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
• 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: 19/24950-4 - Temporal dynamics of the inflammatory response in amphibians
• Grantee: Fernando Ribeiro Gomes
• Support Opportunities: Regular Research Grants
• 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