The study investigates the role of the insulin-like growth factor type 1 receptor (IGF-1R) in regulating lifespan and resistance to oxidative stress in mice. The researchers inactivated the IGF-1R gene in mice, creating a heterozygous knockout (IGF-1R+/−) model. These mice had half the normal number of IGF-1R receptors but were healthy. The IGF-1R+/− mice lived 26% longer than their wild-type littermates, with female mutants living 33% longer and male mutants living 16% longer. The long-lived IGF-1R+/− mice did not exhibit dwarfism, and their energy metabolism, nutrient uptake, physical activity, fertility, and reproduction were unaffected. These mice showed greater resistance to oxidative stress, a major determinant of aging. The study suggests that the IGF-1 receptor may play a key role in regulating mammalian lifespan and resistance to oxidative stress.The study investigates the role of the insulin-like growth factor type 1 receptor (IGF-1R) in regulating lifespan and resistance to oxidative stress in mice. The researchers inactivated the IGF-1R gene in mice, creating a heterozygous knockout (IGF-1R+/−) model. These mice had half the normal number of IGF-1R receptors but were healthy. The IGF-1R+/− mice lived 26% longer than their wild-type littermates, with female mutants living 33% longer and male mutants living 16% longer. The long-lived IGF-1R+/− mice did not exhibit dwarfism, and their energy metabolism, nutrient uptake, physical activity, fertility, and reproduction were unaffected. These mice showed greater resistance to oxidative stress, a major determinant of aging. The study suggests that the IGF-1 receptor may play a key role in regulating mammalian lifespan and resistance to oxidative stress.