Specific neuronal protein: a new tool for histological evaluation of excitotoxic lesions.

An important issue in the interpretation of behavioral data obtained from animals with excitotoxic lesions is evaluation of the extent of the lesions. Animals often have to be excluded from the behavioral analysis because the lesions are either not at the intended location or extend beyond it. Therefore, a clear cut histological evaluation is imperative for a meaningful interpretation of the behavioral results. Although Nissl staining is the most commonly used histological method for the evaluation of lesions, it is very difficult, if not impossible, to obtain a clear delineation of the lesioned area in Nissl-stained sections in some regions of the brain, such as the nucleus accumbens. This is especially the case when long survival times are used. In the present study, we introduce a simple and reliable immunohistochemical marker for the evaluation of excitotoxic lesions in the brain, the neuronal nuclei (NeuN) protein. With this staining, we have been able to delineate the lesions in problematic areas, such as the shell territory of the nucleus accumbens, with far greater accuracy than conventional Nissl staining.