Meeting Abstract
Correlational and experimental studies have demonstrated both within and across taxa that investment in growth comes at a cost to longevity. Despite this, little is known about the physiological mechanisms that underlie this tradeoff. One mechanism that may be important in this regard is insulin-like growth factor-1 (IGF-1). IGF-1 is essential for post-natal growth and development and has been linked with longevity across species. One mechanism by which IGF-1 might impact cellular aging is through its effects on telomere dynamics. To test this, we manipulated circulating IGF-1 in house sparrow (Passer domesticus) nestlings during the post-natal growth period in the summer of 2016 and 2017. Nests were assigned to one of three treatment groups: control, experimental, and non-handled control. Experimental nests were injected with a physiologically relevant does of recombinant-human IGF-1 in a carrier matrix from days 3-10 post-hatch. Control nests were injected with only the carrier matrix. We collected blood samples at day 3 and day 10 to quantify telomere length and loss and IGF-1 concentrations. Growth measurements were collected every 3 days until day 10 in control and experimental nestlings. Non-handled controls were only sampled at day 2 and 10 post-hatch. We predicted nestlings injected with IGF-1 would exhibit faster growth, higher IGF-1 concentrations, and greater telomere loss compared to control and non-handled control nestlings. Results will be discussed within the context of life-history theory.
