Nerve growth factor (NGF) potentiates the changes in striatal proenkephalin mRNAs subsequent to 6-hydroxydopamine-induced lesions of the substantia nigra.

The topographical changes in proenkephalin (PEK) mRNAs which occur in the caudate-putamen (CPu) after 6-hydroxydopamine (6-OHDA)-induced unilateral lesion of the mesostriatal dopamine (DA) pathway were evaluated by quantitative in situ hybridization. These lesions caused significant increases in PEK mRNA in all regions of the caudate-putamen (CPu). The chronic intraventricular administration of NGF potentiated the increases in PEK mRNA, with the magnitude of changes being greater in the dorsomedial and dorsolateral regions of the striatum. NGF did not affect the loss of tyrosine hydroxylase mRNA observed in the substantia nigra ipsilateral to the 6-OHDA-induced lesion. These results demonstrate that alterations which occur in a neuropeptide system as a consequence to 6-OHDA-induced denervation of the striatum can respond to NGF administration in a topographical fashion.