Evaluation of estrogen neuroprotective effect on nigrostriatal dopaminergic neurons following 6-hydroxydopamine injection into the substantia nigra pars compacta or the medial forebrain bundle.
Studies involving estrogen treatment of ovariectomized rats or mice have attributed to this hormone a neuroprotective effect on the substantia nigra pars compacta (SNpc) neurons. We investigated the effect of estradiol replacement in ovariectomized rats on the survival of dopaminergic mesencephalic cell and the integrity of their projections to the striatum after microinjections of 1 microg of 6-hydroxydopamine (6-OHDA) into the right SNpc or medial forebrain bundle (MFB). Estradiol replacement did not prevent the reduction either in the striatal concentrations of DA and metabolites or in the number of nigrostriatal dopaminergic neurons following lesion with 1 microg of 6-OHDA into the SNpc. Nevertheless, estradiol treatment reduced the decrease in striatal DA following injection of 1 microg of 6-OHDA into the MFB. Results suggest therefore that estrogen protect nigrostriatal dopaminergic neurons against a 6-OHDA injury to the MFB but not the SNpc. This may be due to the distinct degree of lesions promoted in these different rat models of Parkinson's disease.
Ferraz
Anete Curte
AC
Laboratório de Neurofisiologia, Departamento de Fisiologia, Universidade Federal do Paraná, C.P. 19 031, 81 531-990, Curitiba, PR, Brazil. anete@ufpr.br
Matheussi
Francesca
F
Szawka
Raphael Escorsim
RE
Rizelio
Vanessa
V
Delattre
Ana Márcia
AM
Rigon
Paula
P
Hermel
Erica do Espírito Santo
Edo E
Xavier
Léder Leal
LL
Achaval
Matilde
M
Anselmo-Franci
Janete A
JA
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D004298:Dopamine / Q000378:metabolism / Q000502:physiology*; D004343:Drug Implants; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D006719:Homovanillic Acid / Q000378:metabolism; D008474:Medial Forebrain Bundle / Q000378:metabolism / Q000502:physiology*; D008845:Microinjections; D009474:Neurons / Q000187:drug effects*; D018696:Neuroprotective Agents; D010052:Ovariectomy; D016627:Oxidopamine; D011247:Pregnancy; D051381:Rats; D013378:Substantia Nigra / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013566:Sympathomimetics
D004343:Drug Implants; D004967:Estrogens; D018696:Neuroprotective Agents; D013566:Sympathomimetics; D004958:Estradiol; D016627:Oxidopamine; D004298:Dopamine; D006719:Homovanillic Acid