Neurochemistry of Parkinson's disease

Publisher Summary This chapter focuses on the neurochemical changes in Parkinson's disease (PD). PD is the second most common neurodegenerative disorder. The neurochemical changes noted in the basal ganglia (BG) is summarized. Some of the changes include (1) the profound loss of dopamine and its consequences observed, not just in the striatum, but also in both segments of GP and the subthalamic nucleus (STN), dominate the neurochemical pathology in the BG. Loss of >50% 5-hydroxytryptophan (5-HT) in the striatum adds to the clinical spectrum of PD in the later stages of the disease; (2) the melanized dopaminergic neurons of substantia nigra pars compacta (SNpc) and ventral tegmental area (VTA) are selectively more vulnerable to neurodegeneration than the dopaminergic neurons of other areas of the brain, and (3) dopamine denervation and chronic levodopa administration affect the indirect and the direct path ways differently. The neurochemical changes in PD are mostly, but not exclusively, in the BG. Even though dopamine denervation in the BG is the predominant feature of PD, it is emphasized that the decreased levels of monoamines in the cerebral cortex, hypothalamus, brainstem and spinal cord could play an equally formidable role in PD.