IGF-I expression is decreased in LIF-deficient mice after peripheral nerve injury

We investigated the regulation of insulin-like growth factor 1 (IGF-1) expression after sciatic nerve crush using leukemia inhibitory factor (LIF)-deficient mice. One day post-crush, IGF-1 mRNA levels were lower in the LIF-deficient mouse nerve than in the wild type nerve. IGF-1 protein, analyzed by immunohistochemistry, was also decreased 1 day post-crush in LIF-deficient nerves relative to wild type nerves. By 3 days post-crush, IGF-1 immunoreactivity was induced in Schwann cells to equivalent levels in both types of nerve. After crush, IGF-1 expression was also found in mast cells, and these were initially decreased in the LIF-deficient mice. Thus, LIF appears to regulate IGF-1 expression in the peripheral nerve basally and early in the regeneration response in vivo.