Glycine antagonist and NO synthase inhibitor protect the developing mouse brain against neonatal excitotoxic lesions

The prevention of cerebral palsy and neuroprotection of the immature brain continue to be health care priorities. The pathophysiology of perinatal brain lesions associated with cerebral palsy seems to be multifactorial and includes pre- and perinatal factors such as preconceptional events, hormone and growth factors deficiencies, maternal infections with production of cytokines, and hypoxic/ischemic perfusion failures. Excitotoxic cascade could represent a common pathway that leads to neural cell death and subsequent brain damage. Brain injuries induced by ibotenate, a glutamatergic analog, which are essentially mediated through the N-methyl-D-aspartate receptor, mimic some aspects of the white matter cysts and transcortical necrosis observed in human perinatal brain damage. The purpose of the present study was to assess the protective role of several pharmacological agents, administered in conjunction with ibotenate, against induced excitotoxic lesions. We injected ibotenate in the developing mouse brain 5 d postnatally, after the full settlement of neuronal layers. Co-treatment with kynurenic acid, an antagonist of the facilitating glycine site of the N-methyl-D-aspartate receptor, or with N(G)-nitro-L-arginine, an inhibitor of nitric oxide synthesis, induced a dose-dependent neuroprotective effect. Conversely, zinc gluconate, a blocking agent of the channel linked to the N-methyl-D-aspartate receptor, and a free radical scavenger (U74389F), were unable to protect the developing brain against excitotoxic attack. These data help to clarify some molecular mechanisms involved in excitotoxic lesions of the developing mouse brain and permit us to envision new strategies in the prevention of cerebral palsy.