Failure of estrogen to protect the substantia nigra pars compacta of female rats from lesion induced by 6-hydroxydopamine

The immunostaining for tyrosine hydroxylase (TH) in the substantia nigra pars compacta (SNpc) and in the ventral tegmental area (VTA) after intranigral. infusion of 6-hydroxydopamine (6-OHDA, 6 mug/side) was analyzed in ovariectomized adult female Wistar rats. Estrogen replacement for 52 days (400-mug 17-beta-estradiol capsules) did not prevent the loss of TH-immunoreactive cells induced by 6-OHDA in the SNpc. This result indicates that the neuroprotective effect of dopaminergic mesencephalic cells is not observed with long-term estrogen replacement. (C) 2003 Elsevier B.V. All rights reserved.