Validation of non-invasive stress hormone monitoring in Tropidurus spinulosus, an endemic lizard from Argentina and Brazil.

LOPEZ JURI GUADALUPE; MASTROMONACO GABRIELA; EGUIZABAL GABINA; BUSSO JUAN MANUEL

Orlando

Conferencia; 6th Annual ISWE Conference, Non-Invasive Hormone Monitoring Conference.; 2018

Disney's Animals, Science and Environment, Orlando, USA and the International Society of Wildlife Endocrinology (ISWE).

Tropidurus spinulosus is a lizard inhabiting Argentina and Brazil. Despite its wide distribution, its conservation status has recently been upgraded to vulnerable. Measurements of glucocorticoids can be used to assess adrenocortical activity and stress response to environmental challenges, which may are negatively affecting the status of populations. Thus, the purpose of this study was to validate a corticosterone enzyme immunoassay (EIA) for the analysis of lizard feces. Wild lizards were captured in Cordoba (Argentina) and transported to the laboratory. Animals (males=4, and females= 3) were exposed to treatments of ACTH (Day 8; 5IU/kg), dexamethasone (Day 20; 0.1mg/kg) and transport (Day 36; 24h-period in a black out bag). Fresh feces were collected daily and fecal corticosteroid metabolite (FCM;ng/g) were assessed by EIA with corticosterone antiserum (CJM006; C. Munro). Biochemical validation of the corticosterone EIA was performed by demonstrating parallelism with the corticosterone standard. Kruskal Wallis test revealed differences in measurements according to sex (P=0.01) and individuals (P=0.0006). Changes from baseline were analyzed for 5 days during each treatment. Post-ACTH increments were detected (24h: 92.1±16.5 ng/g or 72h: 105.9±25.5 ng/g, individual differences). In contrast, no effect was revealed after dexamethasone administration, although a trend for reduction was observed. Four lizards exhibited decreased FCM after transport, while three lizards showed increased concentrations (change from baseline: 45±7 and 110±64 %, respectively). Based on these results, adrenocortical activity was stimulated by exposure to ACTH, showing a peak between 24-72h. Unexpectedly, dexamethasone did not inhibit adrenocortical activity; the treatment dose and/or number of lizards should be increased and may improve results of the study. Although no overall differences were detected after transport, individual profiles perhaps are indicative of coping styles. Finally, the corticosterone EIA is biochemically and pharmacologically validated, showing biological relevance to support further studies focused on adrenocortical response to environmental factors.