Activity-dependent neurotrophic factor-14 requires protein kinase C and mitogen-associated protein kinase kinase activation to protect the developing mouse brain against excitotoxicity

Activity-dependent neurotrophic factor (ADNF) is a newly identified compound that prevents in vitro neuronal death when present in fentomolar concentrations. ADNF-14, a 14 amino acid peptide derived from ADNF, has the same effects on growth as the parent molecule. However, the transduction pathways and target cells for these highly potent trophic factors are still unknown. We previously described a mouse model of excitotoxic lesions of the developing neocortex mimicking several hypoxic or hypoxic-like brain lesions observed in human fetuses and neonates. In this model, cotreatment with the excitotixin ibotenate and ADNF-14 prevented both neuronal death in pups injected on the day of birth and white matter cystic lesions in pups treated 5 d after birth. In the present study, coadministration of ibotenate, ADNF-14, and selective transduction pathway inhibitors showed that activation of protein kinase C (PKC) and mitogen-associated protein kinase kinase was critical for neuroprotection. Immunocytochemistry revealed that ADNF-14 activated PKC and mitogen-associated protein kinase in cortical neurons on the day of birth and in white matter astrocytes on the fifth postnatal day. Taken in concert, these data identify PKC and mitogen-associated protein kinase pathways as critical to ADNF-14-induced neuroprotection of the developing brain against excitotoxic damage.