 |
 |
Estrogen: a multifunctional messenger to nigrostriatal dopaminergic neurons. Gonadal steroids affect a wide variety of functions in the mammalian brain ranging from the regulation of neuro-endocrine systems and the modulation of behavior, to the stimulation of differentiation and plasticity of distinct neuronal populations and circuits. The last decades have also demonstrated that estrogen serves as a neuroprotective factor for distinct neurodegenerative disorders. Such neuroprotective effects of estrogen are most obvious for Parkinson's and Alzheimer's disease. Despite this knowledge, little is known about the mechanisms and cellular targets by that estrogen might elicit its protective influence. In the past, we have intensively studied the effects of estrogen on midbrain dopaminergic neurons which represent the most affected cell population during Parkinson's disease. These studies were mainly performed on developing dopaminergic cells and revealed that estrogen is an important regulator of plasticity and function of this neuronal phenotype. Precisely, we found that dopaminergic neurons are direct targets for estrogen and that estrogen stimulates neurite extension/branching and the expression of tyrosine hydroxylase, the key enzyme in dopamine synthesis. Together with other in vivo studies, we might draw the conclusion that estrogen is required for the plasticity and activity of the developing and adult nigrostriatal system. The presence of the estrogen-synthesizing enzyme aromatase within the nigrostriatal system further supports this idea. Surprisingly, estrogen effects on nigrostriatal cell function are not only transmitted by classical nuclear estrogen receptors but also depend on nonclassical estrogen actions mediated through putative membrane receptors coupled to diverse intracellular signaling cascades. In the future, it has to be elucidated whether nonclassical mechanisms besides genomic actions also contribute to estrogen-mediated neuroprotection in the adult CNS. Kuppers E, Ivanova T, Karolczak M, Beyer C. Abteilung Anatomie und Zellbiologie, Universitat Ulm, Germany. 1: J Neurocytol 2000 May-Jun;29(5-6):375-85 PMID: 11424954 janet paterson: an akinetic rigid subtype, albeit perky, parky . pd: 54/41/37 cd: 54/44/43 tel: 613 256 8340 email: [log in to unmask] . snail mail: 375 Country Street, Apt 301, Almonte, Ontario, Canada, K0A 1A0 . a new voice: the nnnewsletter: http://groups.yahoo.com/group/janet313/ . a new voice: the wwweb site: http://www.geocities.com/janet313/ . ---------------------------------------------------------------------- To sign-off Parkinsn send a message to: mailto:[log in to unmask] In the body of the message put: signoff parkinsn