RESUMO
Insulin-like growth factors (IGFs) are involved in cell growth and differentiation. In muscle tissue they regulate axonal in growth and maintain the connection. They also play a role in regeneration of the peripheral nerve system. We hypothesized that IGFs might also be important factors in the recovery of central nervous tissue after traumatic damage such as perinatal asphyxia. Our group developed a rat model to mimic the resulting damage and test the changes of expression of IGF-1, -2 and several of their binding proteins. We also examined the influence of exogenous IGF-1 and -2 after asphyxia in the same model. Rats underwent a unilateral ligation of the A. carotis followed by a 15 or 90 min inhalational hypoxia (8% O2). The treatment resulted in a mild or severe damage in the ligated hemisphere with either selective neuronal loss or complete infarction of the volume, respectively. The treatment induced expression of both IGFs and binding protein 2, 3 and 5. Binding protein 1 is not expressed and binding protein 4 is suppressed soon after hypoxia-ischemia. We conclude that both IGFs and several of their binding proteins are involved in response and wound healing after hypoxic brain damage. This was further tested in a second experiment. Rats were injected with IGF-1 or IGF-2 intra-ventricular soon after the hypoxic damage. IGF-1 treatment significantly reduced neuronal loss, IGF-2 had no effect. Behaviour tests, however, showed no difference between IGF-1 treated rats and controls. Our studies show interesting aspects for further investigation and a possible treatment of perinatal asphyxia and traumatic damage of nerve tissue.
