Bladder, Bowel, and Sexual Dysfunction in Parkinson's Disease
Figure 2
Possible relationship between basal ganglia circuit (left side) and micturition circuit (right side; modified from Sakakibara et al. [39]). DA, dopamine; GABA, gamma-aminobutyric acid; SNc, substantia nigra pars compacta; GPi, globus pallidus internus; SNr, substantia nigra pars reticulate; STN, subthalamic nucleus; GPe, globus pallidus externus; VTA, ventral tegmental area; PMC, pontine micturition centre; Glu, glutamate; black line, inhibitory neurons; white line, excitatory neurons; hatched line, neurons of undetermined property. The micturition reflex (right-side pathway) is under the influences of dopamine (DA; both inhibitory in and facilitatory in ) and gamma-aminobutyric acid (GABA; inhibitory). The substantia nigra pars compacta (SNc) neuronal firing and the released striatal dopamine seem to activate the dopamine -GABAergic direct pathway, which not only inhibits the basal ganglia output nuclei (e.g., the globus pallidus internus (GPi), substantia nigra pars reticulata (SNr)), but also may inhibit the micturition reflex via GABAergic collateral to the micturition circuit. High-frequency stimulation (leading to inhibition) in the subthalamic nucleus (STN) also results in bladder inhibition. See text.
