1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine: A dopaminergic neurotoxic compound which produces irreversible clinical, chemical, and pathological alterations that mimic those found in Parkinson disease.MPTP Poisoning: A condition caused by the neurotoxin MPTP which causes selective destruction of nigrostriatal dopaminergic neurons. Clinical features include irreversible parkinsonian signs including rigidity and bradykinesia (PARKINSON DISEASE, SECONDARY). MPTP toxicity is also used as an animal model for the study of PARKINSON DISEASE. (Adams et al., Principles of Neurology, 6th ed, p1072; Neurology 1986 Feb;36(2):250-8)Parkinsonian Disorders: A group of disorders which feature impaired motor control characterized by bradykinesia, MUSCLE RIGIDITY; TREMOR; and postural instability. Parkinsonian diseases are generally divided into primary parkinsonism (see PARKINSON DISEASE), secondary parkinsonism (see PARKINSON DISEASE, SECONDARY) and inherited forms. These conditions are associated with dysfunction of dopaminergic or closely related motor integration neuronal pathways in the BASAL GANGLIA.1-Methyl-4-phenylpyridinium: An active neurotoxic metabolite of 1-METHYL-4-PHENYL-1,2,3,6-TETRAHYDROPYRIDINE. The compound reduces dopamine levels, inhibits the biosynthesis of catecholamines, depletes cardiac norepinephrine and inactivates tyrosine hydroxylase. These and other toxic effects lead to cessation of oxidative phosphorylation, ATP depletion, and cell death. The compound, which is related to PARAQUAT, has also been used as an herbicide.Parkinson Disease, Secondary: Conditions which feature clinical manifestations resembling primary Parkinson disease that are caused by a known or suspected condition. Examples include parkinsonism caused by vascular injury, drugs, trauma, toxin exposure, neoplasms, infections and degenerative or hereditary conditions. Clinical features may include bradykinesia, rigidity, parkinsonian gait, and masked facies. In general, tremor is less prominent in secondary parkinsonism than in the primary form. (From Joynt, Clinical Neurology, 1998, Ch38, pp39-42)Substantia Nigra: The black substance in the ventral midbrain or the nucleus of cells containing the black substance. These cells produce DOPAMINE, an important neurotransmitter in regulation of the sensorimotor system and mood. The dark colored MELANIN is a by-product of dopamine synthesis.Dopamine Agents: Any drugs that are used for their effects on dopamine receptors, on the life cycle of dopamine, or on the survival of dopaminergic neurons.Neurotoxins: Toxic substances from microorganisms, plants or animals that interfere with the functions of the nervous system. Most venoms contain neurotoxic substances. Myotoxins are included in this concept.Dopamine: One of the catecholamine NEUROTRANSMITTERS in the brain. It is derived from TYROSINE and is the precursor to NOREPINEPHRINE and EPINEPHRINE. Dopamine is a major transmitter in the extrapyramidal system of the brain, and important in regulating movement. A family of receptors (RECEPTORS, DOPAMINE) mediate its action.Corpus Striatum: Striped GRAY MATTER and WHITE MATTER consisting of the NEOSTRIATUM and paleostriatum (GLOBUS PALLIDUS). It is located in front of and lateral to the THALAMUS in each cerebral hemisphere. The gray substance is made up of the CAUDATE NUCLEUS and the lentiform nucleus (the latter consisting of the GLOBUS PALLIDUS and PUTAMEN). The WHITE MATTER is the INTERNAL CAPSULE.Dopaminergic Neurons: Neurons whose primary neurotransmitter is DOPAMINE.Tyrosine 3-Monooxygenase: An enzyme that catalyzes the conversion of L-tyrosine, tetrahydrobiopterin, and oxygen to 3,4-dihydroxy-L-phenylalanine, dihydrobiopterin, and water. EC 1.14.16.2.Parkinson Disease: A progressive, degenerative neurologic disease characterized by a TREMOR that is maximal at rest, retropulsion (i.e. a tendency to fall backwards), rigidity, stooped posture, slowness of voluntary movements, and a masklike facial expression. Pathologic features include loss of melanin containing neurons in the substantia nigra and other pigmented nuclei of the brainstem. LEWY BODIES are present in the substantia nigra and locus coeruleus but may also be found in a related condition (LEWY BODY DISEASE, DIFFUSE) characterized by dementia in combination with varying degrees of parkinsonism. (Adams et al., Principles of Neurology, 6th ed, p1059, pp1067-75)Striatonigral Degeneration: A sporadic neurodegenerative disease with onset in middle-age characterized clinically by Parkinsonian features (e.g., MUSCLE RIGIDITY; HYPOKINESIA; stooped posture) and HYPOTENSION. This condition is considered a clinical variant of MULTIPLE SYSTEM ATROPHY. Pathologic features include a prominent loss of neurons in the zona compacta of the SUBSTANTIA NIGRA and PUTAMEN. (From Adams et al., Principles of Neurology, 6th ed, p1075-6)Monoamine Oxidase: An enzyme that catalyzes the oxidative deamination of naturally occurring monoamines. It is a flavin-containing enzyme that is localized in mitochondrial membranes, whether in nerve terminals, the liver, or other organs. Monoamine oxidase is important in regulating the metabolic degradation of catecholamines and serotonin in neural or target tissues. Hepatic monoamine oxidase has a crucial defensive role in inactivating circulating monoamines or those, such as tyramine, that originate in the gut and are absorbed into the portal circulation. (From Goodman and Gilman's, The Pharmacological Basis of Therapeutics, 8th ed, p415) EC 1.4.3.4.3,4-Dihydroxyphenylacetic Acid: A deaminated metabolite of LEVODOPA.Levodopa: The naturally occurring form of DIHYDROXYPHENYLALANINE and the immediate precursor of DOPAMINE. Unlike dopamine itself, it can be taken orally and crosses the blood-brain barrier. It is rapidly taken up by dopaminergic neurons and converted to DOPAMINE. It is used for the treatment of PARKINSONIAN DISORDERS and is usually given with agents that inhibit its conversion to dopamine outside of the central nervous system.Selegiline: A selective, irreversible inhibitor of Type B monoamine oxidase. It is used in newly diagnosed patients with Parkinson's disease. It may slow progression of the clinical disease and delay the requirement for levodopa therapy. It also may be given with levodopa upon onset of disability. (From AMA Drug Evaluations Annual, 1994, p385) The compound without isomeric designation is Deprenyl.Antiparkinson Agents: Agents used in the treatment of Parkinson's disease. The most commonly used drugs act on the dopaminergic system in the striatum and basal ganglia or are centrally acting muscarinic antagonists.Pyridinium CompoundsNeuroprotective Agents: Drugs intended to prevent damage to the brain or spinal cord from ischemia, stroke, convulsions, or trauma. Some must be administered before the event, but others may be effective for some time after. They act by a variety of mechanisms, but often directly or indirectly minimize the damage produced by endogenous excitatory amino acids.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Saimiri: A genus of the family CEBIDAE consisting of four species: S. boliviensis, S. orstedii (red-backed squirrel monkey), S. sciureus (common squirrel monkey), and S. ustus. They inhabit tropical rain forests in Central and South America. S. sciureus is used extensively in research studies.Homovanillic AcidGlobus Pallidus: The representation of the phylogenetically oldest part of the corpus striatum called the paleostriatum. It forms the smaller, more medial part of the lentiform nucleus.Neostriatum: The phylogenetically newer part of the CORPUS STRIATUM consisting of the CAUDATE NUCLEUS and PUTAMEN. It is often called simply the striatum.Mice, Inbred C57BLPyridines: Compounds with a six membered aromatic ring containing NITROGEN. The saturated version is PIPERIDINES.Sulfonium Compounds: Sulfur compounds in which the sulfur atom is attached to three organic radicals and an electronegative element or radical.Monoamine Oxidase Inhibitors: A chemically heterogeneous group of drugs that have in common the ability to block oxidative deamination of naturally occurring monoamines. (From Gilman, et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p414)Dyskinesias: Abnormal involuntary movements which primarily affect the extremities, trunk, or jaw that occur as a manifestation of an underlying disease process. Conditions which feature recurrent or persistent episodes of dyskinesia as a primary manifestation of disease may be referred to as dyskinesia syndromes (see MOVEMENT DISORDERS). Dyskinesias are also a relatively common manifestation of BASAL GANGLIA DISEASES.Neurons: The basic cellular units of nervous tissue. Each neuron consists of a body, an axon, and dendrites. Their purpose is to receive, conduct, and transmit impulses in the NERVOUS SYSTEM.Mazindol: Tricyclic anorexigenic agent unrelated to and less toxic than AMPHETAMINE, but with some similar side effects. It inhibits uptake of catecholamines and blocks the binding of cocaine to the dopamine uptake transporter.Nerve Degeneration: Loss of functional activity and trophic degeneration of nerve axons and their terminal arborizations following the destruction of their cells of origin or interruption of their continuity with these cells. The pathology is characteristic of neurodegenerative diseases. Often the process of nerve degeneration is studied in research on neuroanatomical localization and correlation of the neurophysiology of neural pathways.Dopamine Plasma Membrane Transport Proteins: Sodium chloride-dependent neurotransmitter symporters located primarily on the PLASMA MEMBRANE of dopaminergic neurons. They remove DOPAMINE from the EXTRACELLULAR SPACE by high affinity reuptake into PRESYNAPTIC TERMINALS and are the target of DOPAMINE UPTAKE INHIBITORS.NortropanesDyskinesia, Drug-Induced: Abnormal movements, including HYPERKINESIS; HYPOKINESIA; TREMOR; and DYSTONIA, associated with the use of certain medications or drugs. Muscles of the face, trunk, neck, and extremities are most commonly affected. Tardive dyskinesia refers to abnormal hyperkinetic movements of the muscles of the face, tongue, and neck associated with the use of neuroleptic agents (see ANTIPSYCHOTIC AGENTS). (Adams et al., Principles of Neurology, 6th ed, p1199)Motor Activity: The physical activity of a human or an animal as a behavioral phenomenon.Cistanche: A plant genus of the family OROBANCHACEAE. Members contain phenylethanoid glycosides.Putamen: The largest and most lateral of the BASAL GANGLIA lying between the lateral medullary lamina of the GLOBUS PALLIDUS and the EXTERNAL CAPSULE. It is part of the neostriatum and forms part of the LENTIFORM NUCLEUS along with the GLOBUS PALLIDUS.Macaca fascicularis: A species of the genus MACACA which typically lives near the coast in tidal creeks and mangrove swamps primarily on the islands of the Malay peninsula.Mesencephalon: The middle of the three primitive cerebral vesicles of the embryonic brain. Without further subdivision, midbrain develops into a short, constricted portion connecting the PONS and the DIENCEPHALON. Midbrain contains two major parts, the dorsal TECTUM MESENCEPHALI and the ventral TEGMENTUM MESENCEPHALI, housing components of auditory, visual, and other sensorimoter systems.Clorgyline: An antidepressive agent and monoamine oxidase inhibitor related to PARGYLINE.Dopamine Agonists: Drugs that bind to and activate dopamine receptors.Herbicides: Pesticides used to destroy unwanted vegetation, especially various types of weeds, grasses (POACEAE), and woody plants. Some plants develop HERBICIDE RESISTANCE.Behavior, Animal: The observable response an animal makes to any situation.Macaca mulatta: A species of the genus MACACA inhabiting India, China, and other parts of Asia. The species is used extensively in biomedical research and adapts very well to living with humans.Callithrix: A genus of the subfamily CALLITRICHINAE occurring in forests of Brazil and Bolivia and containing seventeen species.Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.Vesicular Monoamine Transport Proteins: A family of vesicular amine transporter proteins that catalyze the transport and storage of CATECHOLAMINES and indolamines into SECRETORY VESICLES.Vesicular Biogenic Amine Transport Proteins: Integral membrane proteins of the LIPID BILAYER of SECRETORY VESICLES that catalyze transport and storage of biogenic amine NEUROTRANSMITTERS such as ACETYLCHOLINE; SEROTONIN; MELATONIN; HISTAMINE; and CATECHOLAMINES. The transporters exchange vesicular protons for cytoplasmic neurotransmitters.Caudate Nucleus: Elongated gray mass of the neostriatum located adjacent to the lateral ventricle of the brain.Microglia: The third type of glial cell, along with astrocytes and oligodendrocytes (which together form the macroglia). Microglia vary in appearance depending on developmental stage, functional state, and anatomical location; subtype terms include ramified, perivascular, ameboid, resting, and activated. Microglia clearly are capable of phagocytosis and play an important role in a wide spectrum of neuropathologies. They have also been suggested to act in several other roles including in secretion (e.g., of cytokines and neural growth factors), in immunological processing (e.g., antigen presentation), and in central nervous system development and remodeling.Basal Ganglia: Large subcortical nuclear masses derived from the telencephalon and located in the basal regions of the cerebral hemispheres.Receptors, Dopamine D3: A subtype of dopamine D2 receptors that are highly expressed in the LIMBIC SYSTEM of the brain.Conotoxins: Peptide neurotoxins from the marine fish-hunting snails of the genus CONUS. They contain 13 to 29 amino acids which are strongly basic and are highly cross-linked by disulfide bonds. There are three types of conotoxins, omega-, alpha-, and mu-. OMEGA-CONOTOXINS inhibit voltage-activated entry of calcium into the presynaptic membrane and therefore the release of ACETYLCHOLINE. Alpha-conotoxins inhibit the postsynaptic acetylcholine receptor. Mu-conotoxins prevent the generation of muscle action potentials. (From Concise Encyclopedia Biochemistry and Molecular Biology, 3rd ed)Mice, Knockout: Strains of mice in which certain GENES of their GENOMES have been disrupted, or "knocked-out". To produce knockouts, using RECOMBINANT DNA technology, the normal DNA sequence of the gene being studied is altered to prevent synthesis of a normal gene product. Cloned cells in which this DNA alteration is successful are then injected into mouse EMBRYOS to produce chimeric mice. The chimeric mice are then bred to yield a strain in which all the cells of the mouse contain the disrupted gene. Knockout mice are used as EXPERIMENTAL ANIMAL MODELS for diseases (DISEASE MODELS, ANIMAL) and to clarify the functions of the genes.Rotenone: A botanical insecticide that is an inhibitor of mitochondrial electron transport.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Receptors, Dopamine D2: A subfamily of G-PROTEIN-COUPLED RECEPTORS that bind the neurotransmitter DOPAMINE and modulate its effects. D2-class receptor genes contain INTRONS, and the receptors inhibit ADENYLYL CYCLASES.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Glial Cell Line-Derived Neurotrophic Factor: The founding member of the glial cell line-derived neurotrophic factor family. It was originally characterized as a NERVE GROWTH FACTOR promoting the survival of MIDBRAIN dopaminergic NEURONS, and it has been studied as a potential treatment for PARKINSON DISEASE.Cell Death: The termination of the cell's ability to carry out vital functions such as metabolism, growth, reproduction, responsiveness, and adaptability.Oxidopamine: A neurotransmitter analogue that depletes noradrenergic stores in nerve endings and induces a reduction of dopamine levels in the brain. Its mechanism of action is related to the production of cytolytic free-radicals.Subthalamic Nucleus: Lens-shaped structure on the inner aspect of the INTERNAL CAPSULE. The SUBTHALAMIC NUCLEUS and pathways traversing this region are concerned with the integration of somatic motor function.Autoradiography: The making of a radiograph of an object or tissue by recording on a photographic plate the radiation emitted by radioactive material within the object. (Dorland, 27th ed)PC12 Cells: A CELL LINE derived from a PHEOCHROMOCYTOMA of the rat ADRENAL MEDULLA. PC12 cells stop dividing and undergo terminal differentiation when treated with NERVE GROWTH FACTOR, making the line a useful model system for NERVE CELL differentiation.alpha-Synuclein: A synuclein that is a major component of LEWY BODIES that plays a role in neurodegeneration and neuroprotection.Deep Brain Stimulation: Therapy for MOVEMENT DISORDERS, especially PARKINSON DISEASE, that applies electricity via stereotactic implantation of ELECTRODES in specific areas of the BRAIN such as the THALAMUS. The electrodes are attached to a neurostimulator placed subcutaneously.Nerve Tissue ProteinsOxidative Stress: A disturbance in the prooxidant-antioxidant balance in favor of the former, leading to potential damage. Indicators of oxidative stress include damaged DNA bases, protein oxidation products, and lipid peroxidation products (Sies, Oxidative Stress, 1991, pxv-xvi).Serotonin: A biochemical messenger and regulator, synthesized from the essential amino acid L-TRYPTOPHAN. In humans it is found primarily in the central nervous system, gastrointestinal tract, and blood platelets. Serotonin mediates several important physiological functions including neurotransmission, gastrointestinal motility, hemostasis, and cardiovascular integrity. Multiple receptor families (RECEPTORS, SEROTONIN) explain the broad physiological actions and distribution of this biochemical mediator.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Brain Chemistry: Changes in the amounts of various chemicals (neurotransmitters, receptors, enzymes, and other metabolites) specific to the area of the central nervous system contained within the head. These are monitored over time, during sensory stimulation, or under different disease states.