Measuring diurnal and lifespan variations of Brain-derived neurotrophic factor in titi monkeys (Plecturocebus cupreus)

Pair bonding requires substantial neural flexibility to form and maintain complex social relationships in dynamic environments over time. Due to its involvement in synaptic plasticity, Brain-derived neurotrophic factor (BDNF) is a promising candidate for modulating this flexibility, although it has never been studied within the context of pair bonding. The present study sought analytically and biologically validate an enzyme-linked immunosorbent assay (ELISA) to measure BDNF in coppery titi monkeys (Plecturocebus cupreus), a pair bonding non-human primate model. We first validated a commercially available ELISA to detect and measure BDNF in titi monkey serum, and then subsequently characterized the natural decline of BDNF in titi monkeys throughout the day (morning to evening) and across the lifespan (into old age). Titi monkeys showed significantly lower serum levels of BDNF at the end of the day, suggesting a consistent diurnal cycle, and in older age, suggesting age-related decline. This work establishes the foundation for examining BDNF’s role within the behavioral endocrinology of pair bonding.