Assessment of the Biodistribution and Safety of 123-I MZINT in Healthy Subjects and Parkinson Disease Patients

Inclusion Criteria: Health Control: * The subject is aged 18-70. * Written informed consent is obtained. * The participant has no clinically significant clinical laboratory value and/or clinically significant unstable medical, neurological or psychiatric illness. * For females, non-child bearing potential or negative urine pregnancy test on day of \[123I\] mZINT injection. * Willingness to comply with the study protocol Parkinson disease: * The subject is aged 18-70. * Participants have a clinical diagnosis (at least two of the three cardinal symptoms: resting tremor, rigidity, bradykinesia) of idiopathic Parkinson's disease. * Hoehn and Yahr stages \< 3. * Written informed consent is obtained. * The participant has no clinically significant clinical laboratory value and/or clinically significant unstable medical, neurological or psychiatric illness. * For females, non-child bearing potential or negative urine pregnancy test on day of \[123I\] mZINT injection. Willingness to comply with the study protocol Exclusion Criteria: All Subjects will be excluded from participation for the following reasons: * The subject has a clinically significant clinical laboratory values abnormality, and/or medical or psychiatric illness. * The subject has any disorder that may interfere with drug absorption, distribution, metabolism, or excretion (including gastrointestinal surgery). * The subject has evidence of clinically significant gastrointestinal, cardiovascular, hepatic, renal, hematological, neoplastic, endocrine, neurological, immunodeficiency, pulmonary, or other disorder or disease. * Use of all prescription drugs or non-prescriptions drugs that may effect serotonin such as antidepressants including sertraline, fluoxetine, fluvoxamine, venlafaxine. * The participant has a history of alcohol, narcotic, or any other drug abuse as defined by the Diagnostic and Statistical Manual of the American Psychiatric Association, 4th Edition (DSM IV) {American Psychiatric Association, 1994 #2} within the past 2 years. * Pregnancy