Meeting Abstract
Inflammatory response is a complex process that relies on interactions between multiple endocrine and immune modulators and temporal course of inflammatory responses remains unexplored in amphibians. This study investigated changes in plasma corticosterone (CORT), testosterone (T) and melatonin (MEL) levels, bacterial killing ability (BKA), peritoneal leukocyte phagocytic activity (PP) and neutrophil:lymphocyte ratio (NLR) over time (1, 3, 6 and 18h post injection) following lipopolysaccharide (LPS) immune challenge in toads (Rhinella diptycha). Our prediction was that LPS should increase CORT, NLR, BKA and PP, with concomitant decrease in T and MEL. Regarding time related changes, CORT and PP should increase earlier, while BKA and NLR should present a delayed increase, whereas, MEL and T should present more pronounced decrease when those values are maximum in saline-treated toads. LPS induced inflammatory response. Increased CORT were more pronounced 6h and 18h post LPS injection, while MEL decreased independently of time. Although T was not affected by LPS injection, a decreasing trend was observed. Additionally, BKA and NLR also increased following LPS treatment but this effect was related with animal body condition. Individuals with a better body condition also displaying higher BKA and NLR values. Meanwhile, we observed increased PP 1h after LPS injection followed by a decrease thereafter. These results showed that toads respond to an immune challenge by modulating hormonal and immune parameters in a complex way, with effects observed from the first hour and extending for up to 18h following the stimulus.
