Expression of EGF receptor mRNA in rat nigrostriatal system.

In situ hybridization with a cRNA probe was used to determine the cellular expression of mRNA for the epidermal growth factor receptor (EGF-R) within the rat dopaminergic nigrostriatal system. Hybridization for EGF-R mRNA was distributed throughout the ventral mesencephalon within cells of the substantia nigra pars compacta and ventral tegmental area (VTA). Unilateral lesion of the nigrostriatal pathway with the neurotoxin 6-hydroxydopamine resulted in substantial elimination of EGF-R cRNA hybridization in the ipsilateral substantia nigra and VTA. EGF-R mRNA was also demonstrated within a population of striatal somata, with highest levels of expression detected neonatally. These results indicate that a subpopulation of ventral midbrain dopaminergic neurons, as well as striatal perikarya, express the EGF-R and, thus, may be directly responsive to endogenous EGF, transforming growth factor-alpha, or another EGF-R ligand in vivo.