Striatal glutamatergic mechanisms and extrapyramidal movement disorders.
The nonphysiologic stimulation of striatal dopaminergic receptors, as a result of disease- or drug-related denervation or intermittent excitation, triggers adaptive responses in the basal ganglia which contribute to the appearance of parkinsonian symptoms and later to the dyskinesias and other alterations in motor response associated with dopaminergic therapy. Current evidence suggests that these altered responses involve activation of signal transduction cascades in striatal medium spiny neurons linking dopaminergic to coexpressed ionotropic glutamatergic receptors of the N-methyl-D-aspartate (NMDA) and Alpha-amino-3-hydroxy-5-methyl-4-isoxazole proprionic acid (AMPA) classes. These intraneuronal signaling pathways appear capable of modifying the phosphorylation state of NMDA and AMPA receptor subunits; resultant sensitization enhances cortical glutamatergic input which in turn modifies striatal output in ways that compromise motor behavior. The regulation of these spiny neuron glutamate receptors can also be affected by the activation state of coexpressed nondopaminergic receptors as well as by changes associated with Huntington's disease. These observations lend new insight into molecular mechanisms contributing to the integration of synaptic inputs to spiny neurons. They also suggest novel approaches to the pharmacotherapy of extrapyramidal motor dysfunction.
Chase
Thomas N
TN
National Institutes of Health, Experimental Therapeutics Branch, NINDS, NIH, Building 10, Room 5C103, Bethesda, MD, USA. Chase@ninds.nih.gov
Bibbiani
Francesco
F
Oh
Justin D
JD
D000818:Animals; D017690:Cell Transplantation; D004298:Dopamine / Q000502:physiology; D006801:Humans; D009069:Movement Disorders / Q000188:drug therapy*; D009414:Nerve Growth Factors / Q000378:metabolism / Q000627:therapeutic use*; D009474:Neurons / Q000187:drug effects / Q000502:physiology / Q000637:transplantation; D010300:Parkinson Disease / Q000628:therapy; D017475:Receptors, Nerve Growth Factor / Q000378:metabolism
D009414:Nerve Growth Factors; D017475:Receptors, Nerve Growth Factor; D004298:Dopamine