Striatal tyrosine hydroxylase immunoreactive neurons are induced by L-dihydroxyphenylalanine and nerve growth factor treatment in 6-hydroxydopamine lesioned rats.

Only a few studies mention the existence of tyrosine hydroxylase immunoreactive neurons in the striatum. These neurons are known to be increased following lesion of the dopaminergic nigrostriatal pathway. Recently it has been shown that glial cell line-derived neurotrophic factor treatment was able to increase the number of these neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intoxicated primate. Here we report that, in the rat, these neurons are responsive to intrastriatal injection of 6-hydroxydopamine and that following the lesion their number tends to increase with time. Moreover, we have shown that L-DOPA treatment for 2 weeks or nerve growth factor treatment for 8 weeks are able to dramatically augment their number.