Immunochemical analysis of dopamine transporters in Parkinson's disease

The identification of specific and selective markers of the dopamine-producing neurons that are lost in Parkinson's disease has been a major research focus since Hornykiewicz first reported a dopamine deficiency in the disease (1). Antibodies to dopamine or tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, have been used to identify these neurons. Recently, considerable attention has been given to the plasma membrane dopamine tranporter (DAT) and the vesicular monoamine transporter (VMAT2), which are responsible for the transport, packaging, and release of dopamine (2). DAT acts to terminate dopamine transmission by rapid reuptake of dopamine from the synapse, and VMAT2 packages cytoplasmic dopamine into vesicles for storage and subsequent release. We have developed specific antibodies to these transporters and used them to characterize the distribution and expression of DAT and VMAT2 in brain from human idiopathic Parkinson's disease and animal models of the disease. The purpose of this chapter is to describe the immunochemical techniques involved in assessing damage to dopamine neurons in Parkinson's disease and experimental models of the disease.