2.4 Corticosterone radioimmunoassay

Total serum corticosterone levels were measured using the ImmuChem Double Antibody Corticosterone ¹²⁵I radioimmunoassay kit (MP Biomedicals, LLC, Orangeburg, NY, USA, according the manufacturer's instructions with one modification – the lowest standard was further diluted to detect lower corticosterone concentrations (Taves et al., 2015). The minimum detectable corticosterone concentration was approximately 7.7 ng/mL, and the intra- and inter-assay coefficients of variation were <10 % and <7 %, respectively. All samples were measured in duplicate.