Estrogen and Parkinson's disease.

Female sex hormones, and more specifically estrogen, can have biochemical and behavioral effects on the dopaminergic system. The effects of estrogen on the dopaminergic system can be classified as either neuroprotective or symptomatic. The neuroprotective effects refer to the ability of estrogen to prevent or modulate insults to the dopaminergic system and therefore to alter the natural history of disease processes affecting the dopaminergic circuitry in the brain. With regards to the symptomatic effects, support for both suppressive and enhancing effects has been documented in humans and laboratory animals. The pre-clinical literature for neuroprotective and symptomatic effects of estrogen on the mesostriatal dopaminergic system forms the basis for studies on the influence of estrogen on the prevalence, disease progression, clinical signs, and medication effects of Parkinson's disease and other movement disorders. Understanding the role of estrogen in modulating the dopaminergic system will allow clinicians to tailor therapies for women with Parkinson's disease and optimize therapies for menstrually related symptom fluctuations. Such clarifications may also guide recommendations on the use of postmenopausal hormonal replacement therapy in women with Parkinson's disease or those genetically at risk.