Does N-Acetylcysteine Decrease Spontaneous Oxidation of Central Neural Dopamine in Parkinson's Disease?

Parkinson Disease, Cerebrospinal Fluid

5-S-Cysteinyldopamine, Cerebrospinal Fluid, PARKINSONS DISEASE, MONOAMINE OXIDASE INHIBITOR

Background: Parkinsons disease (PD) causes slow movement, stiffness, and poor balance. Many symptoms are due to the loss of brain cells that make the brain chemical dopamine. The cells may be damaged by the breakdown of dopamine by a process called oxidation. The drug N-acetylcysteine (NAC) can act as an antioxidant. Researchers want to test if NAC can decrease the oxidation of brain dopamine in people with PD. Objective: To look at the effect of NAC on brain chemistry in people with PD. Eligibility: People ages 18 and older with PD that were diagnosed within the past 5 years. They must be taking a monoamine oxidase inhibitor. Healthy volunteer participants ages 18 and older. Design: Participants will be screened with: Medical history Physical exam Blood and urine tests Participants will be hospitalized for 4 to 8 days. On day 1, participants will have blood and urine tests. For several hours, they cannot eat or drink anything but water and their medications. Late in the morning they will have a meal. About 2 hours later they will have a spinal tap (lumbar puncture). For this, a numbing medicine is injected into the back. A needle is inserted between the bones in the back to remove a small amount of fluid. The spinal tap may use x-rays to see inside the body. After the spinal tap, they will start taking NAC by mouth. They will take NAC twice a day for 2 more days. On the next day, they will not eat until a meal in the late morning. They will take a final NAC dose. About 2 hours later they will have a second spinal tap. Healthy Volunteer (HV) participants will receive a spinal tap on day one, followed by a second spinal tap 48 hours after the first spinal tap. HV participants will not receive NAC.

Objective: This study is to test whether N-acetylcysteine (NAC) inhibits the spontaneous oxidation of central neural dopamine as indicated by the cerebrospinal fluid (CSF) concentration of 5-S-cysteinyl-dopamine (Cys-DA) in patients with Parkinsons disease (PD). Study population: The study population comprises up to 35 participants with early (less than or equal to 5 years from diagnosis), mild, levodopa-untreated PD and up to 6 healthy volunteer participants. The PD participants will be on an inhibitor of monoamine oxidase (MAO) that is prescribed for their disease. Design: The study has a two groups employing a pretest-posttest design. Each participant undergoes a lumbar puncture (LP) as an inpatient at the NIH Clinical Center to obtain cerebrospinal fluid (CSF) for assays of Cys-DA, 3,4-dihydroxyphenylacetic acid (DOPAC), and related biochemicals. For PD participants, the second LP is done after the participant has taken at least 5 doses of NAC (2 grams orally twice per day). The LP takes place about 2 hours after the last NAC dose. For HV participants the second LP takes place approximately 48 hours after the first LP. Outcome measures: The main outcome measure is the CSF concentration of Cys-DA. Other outcome measures are levels of other catecholamine-related neurochemicals or of indices of oxidative stress. Depending on the results, an exploratory study may be done involving NAC at 1 gram orally twice per day.

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