Plasma steroids and immune measures vary with restraint duration in a toad (Rhinella icterica)

Restraint-induced endocrine and immune variation (post-restraint minus baseline) in male R. icterica toads. A: Plasma corticosterone (CORT) concentrations (ng/mL), B: Plasma testosterone (T) concentrations (ng/mL), C: Neutrophil to lymphocyte ratio (NLR), and D: Phagocytosis percentage (PP). Asteris...

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Published inGeneral and comparative endocrinology Vol. 318; p. 113987
Main Authors Christie Monteiro Titon, Stefanny, Titon Junior, Braz, Cobo de Figueiredo, Aymam, Rangel Floreste, Felipe, Siqueira Lima, Alan, Cunha Cyrino, João, Ribeiro Gomes, Fernando
Format Journal Article
LanguageEnglish
Published United States Elsevier Inc 01.03.2022
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Summary:Restraint-induced endocrine and immune variation (post-restraint minus baseline) in male R. icterica toads. A: Plasma corticosterone (CORT) concentrations (ng/mL), B: Plasma testosterone (T) concentrations (ng/mL), C: Neutrophil to lymphocyte ratio (NLR), and D: Phagocytosis percentage (PP). Asterisk (*) denotes differences between baseline and post-restraint values. Dashed lines indicate magnitude variation as a function of restraint duration. [Display omitted] •Restraint increased corticosterone plasma levels from 0.5 up to 48 h of restraint.•Testosterone plasma levels decreased after 12 h under restraint.•Neutrophil to lymphocyte ratio and phagocytosis increased with restraint duration.•Bacterial killing ability was not affected by restraint. Immunoenhancing effects have been widely described following acute stressors in several vertebrates, and valuable contributions have been made from studies on acute stress to understand hormonal-immune interactions. However, most studies focus on hormonal and immune responses after standardized time lapses, neglecting potential influence of duration of exposition to stressor. Herein, we investigate fluctuations of plasma hormone concentrations (corticosterone and testosterone) and immunity (neutrophil to lymphocyte ratio, phagocytosis of blood cells, and plasma bacterial killing ability) in a toad species (Rhinella icterica) in response to six different periods of exposure to restraint stress. We observed increased plasma corticosterone concentrations following restraint in all sampled times (0.5 to 48 h), with the highest values being observed during the first hour (0.5 to 1 h). Restraint-induced increases in the neutrophil to lymphocyte ratio and phagocytosis percentage were observed from the first 0.5 h, gradually increasing after that with the time of restraint. We also observed decreased testosterone plasma concentrations in response to a more prolonged restraint (24 and 48 h). No changes were observed in plasma bacterial killing ability following restraint. Together, our results demonstrate dynamic time-related hormonal and immune changes. These results point to the fact that for some species measuring hormonal and immune variables at single time points following a stressor might work better when preceded by a study of the temporal changes of the response variables to the stimuli applied. Also, time of response needs to be considered when different variables are used as proxies of stress.
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ISSN:0016-6480
1095-6840
DOI:10.1016/j.ygcen.2022.113987