The role of estrogens in Parkinson's disease

Parkinson's disease (PD) is a chronic progressive neurodegenerative disorder of the central nervous system. It has a high prevalence, which significantly increases with age. This disease significantly deteriorates the quality of life and, despite treatment, may lead to disability. For these reasons, PD is not only a medical problem, but also a social one. The neuropathological basis of Parkinson's disease is selective degeneration of dopaminergic neurons in the brain's substantia nigra, which results in an imbalance between neurotransmitters in the central nervous system, mainly between dopamine and acetylcholine. The basic symptoms of PD are tremor at rest, extrapyramidal rigidity, bradykinesia, and disturbances of postural reflexes. PD is described as a hypertonic-hypokinetic syndrome. It is also characterized by coexisting vegetative and psychopathological disturbances. In spite of considerable advances in knowledge about the mechanisms of dopaminergic neuron injury, the etiology and pathogenesis of PD are not yet well established. In this paper the authors briefly review agents which influence neurodegenerative processes of the extrapyramidal system based on available literature concerning clinical trials in Parkinson's disease. Since it is known that female sex hormones also influence dopaminergic transmission, special attention is paid to the potential role of estrogens as agents modulating the risk of PD occurrence and their neuroprotective action.