EXPRESSION OF EGF RECEPTOR MESSENGER-RNA IN RAT NIGROSTRIATAL SYSTEM

IN SITU hybridization with a cRNA probe was used to determine the cell ular 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 withi n cells of the substantia nigra pars compacta and ventral tegmental ar ea (VTA). Unilateral lesion of the nigrostriatal pathway with the neur otoxin 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, wit h highest levels of expression detected neonatally. These results indi cate that a subpopulation of ventral midbrain dopaminergic neurons, as well as striatal perikarya, express the EGF-R and, thus, may be direc tly responsive to endogenous EGF, transforming growth factor-alpha, or another EGF-R ligand in vivo.