Intravenous N-acetylcysteine for the Treatment of Gaucher's Disease and Parkinson's Disease

• Brain GSH [ Time Frame: Baseline and up to 110 minutes post-NAC administration ]
  change in brain GSH levels from baseline to post-NAC administration (90 - 110 minutes) in all subjects
  
  

Oxidative stress is implicated in the pathogenesis of a number of neurodegenerative diseases such as Parkinson's disease (PD). Further, levels of glutathione (GSH), a prevalent endogenous antioxidant, are decreased in the postmortem substantia nigra (SN) of individuals with PD, indicating increased oxidative stress, although this has yet not been confirmed in vivo. Increases in intracellular oxidative stress have also been observed in primary fibroblast cultures obtained from patients with GD, where enzyme replacement therapy resulted in increases in total GSH. The hypothesis that oxidative stress plays a key role in the neurodegeneration associated with PD suggests that antioxidants may be useful in altering disease progression.

N-acetylcysteine (NAC) is a well-known antioxidant that is thought to act both as a free radical scavenger and as a cysteine donor for the synthesis of GSH. NAC may be beneficial in the treatment of PD and GD. Magnetic resonance spectroscopy (MRS) methods may be able to determine if there are effects from NAC on central nervous system GSH levels. In addition, use of red blood cell (RBC) measurements of GSH, if correlated with brain concentrations, could serve as an easily measured biomarker to help characterize and monitor response to therapy. The investigators therefore propose to conduct a study of the effect of a single, intravenous dose of NAC on central (brain) measures of GSH and peripheral (RBC) measures of GSH in people with PD and healthy controls, through the use of simultaneous MRS techniques and pharmacokinetic studies. The investigators hypothesis and specific aims are as follows:

Hypothesis: RBC and brain GSH concentrations will increase following oral NAC administration in individuals with Parkinson's disease (PD), Gaucher's disease (GD), and control participants.

Specific Aims:

1. Quantitate baseline plasma and red blood cell GSH concentrations in those with PD and GD and controls; and characterize NAC and GSH pharmacokinetics after a single intravenous NAC administration.
2. Quantitate brain GSH levels (as ascertained through MRS) in those with PD and GD and controls at baseline and after a single intravenous NAC administration simultaneously with Aim 1.
3. Construct a pharmacokinetic model to evaluate the relationship between peripheral (plasma and RBC) and central (brain) GSH measurements.