ABSTRACT
Parkinson’s disease (PD) is a slow, progressive neurological disorder of the central nervous system.1 In 1917, Dr. James Parkinson, a British physician, published an article on The Shaky Palsy describing the major symptoms of the disease that would later bear his name. Since then, pathologists and neurologists have repeatedly reported that loss of dopamine (DA)-producing nerve cells (DA neurons) from the substantia nigra region of the brain is primarily responsible for most of the motor control abnormalities observed in PD patients, although other cells are also affected in this disease. It is estimated that in normal individuals about 3-5% of DA neurons are lost every decade; however, in PD patients, the rate of loss is greater than that found in normal individuals.2 The analysis of autopsied samples of PD brains revealed that about 70-75% of DA neurons are lost by the time the disease becomes detectable.2 This suggests that DA neurons possess a high degree of functional plasticity.
