We have previously observed using Western blot analysis that the administration of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle causes an increase in the active forms of the MAP kinases (MAPK), ERK1/2 (pERK) and JNK1/2 (pJNK) (Smith et al., SFN, 2004). In this report we describe the effects of 6-OHDA on MAP kinases in the target region of the dopamine (DA) neurons, the dorsal striatum. Adult, male Sprague-Dawley rats received 6-OHDA (6 µg in 1 µl) into the striatum. After 15 min, 30 min, 1 hr, or 3 hr, animals were perfused with 4% paraformaldehyde containing phosphatase inhibitors. Striatal and substantia nigral blocks were then sectioned and stained for pERK and pJNK. By 15 min we observed an increase in pERK that persisted for at least 3 hr. A similar temporal profile was observed for pJNK, although the peak increase was lower than for pERK. The morphology of the cells containing the increased activated MAP kinases suggests that they were medium spiny neurons, although this has not yet be...