Meeting Abstract
Insulin-like growth factor-1 (IGF-1) is an evolutionary conserved hormonal signal that regulates major life-history processes in all animals. Reduced IGF-1 signaling increases lifespan and the expression of genes involved in stress resistance in model organisms. However, it is unknown whether free-living organisms can adaptively respond to stressful stimuli by changing their IGF-1 levels. Here, we analyzed circulating IGF-1 levels in response to capture- restraint stress in a free-living songbird, the bearded reedling, Panurus biarmicus, a species characterized by an unusually fast life-history strategy. We found that IGF-1 levels significantly decreased compared to baseline levels even after 15 minutes of restraint, and this response showed marked individual and seasonal differences. Interestingly, the changes in IGF-1 levels were independent from the increase in glucocorticoid levels, which play a prominent role in the vertebrate stress response. Our results represent the first investigation of the effects of stress on IGF-1 levels in free-living organisms and suggest that the IGF-1 pathway can have an autonomous but important role in how individuals cope with environmental challenges.
