Leukemia inhibitory factor determines the growth status of injured adult sensory neurons

Conditioning injury to adult mammalian sensory neurons enhances their regen eration potential. Here we show that leukemia inhibitory factor (LIF) is a fundamental component of the conditioning response. Conditioning injury in vivo significantly increases the intrinsic growth capacity of sensory neuro ns in vitro from LIF+/+ mice. This conditioning effect is significantly blu nted in sensory neurons from LIF-/- mice. Enhanced growth is rescued in vit ro in LIF-/- mice by the addition of exogenous LIF, and the effect blocked by human LIF-05, an LIF receptor antagonist. Furthermore, we demonstrate th at LIF promotes elongating but not arborizing neurite outgrowth in vitro an d is required for normal regeneration of injured adult sensory neurons in v ivo. LIF is also functionally protective to peptidergic sensory neurons aft er nerve damage in vivo. Our results indicate that the alteration in intrin sic growth status of injured sensory neurons depends, at least in part, on LIF.