N-acetylcysteine Protects Dopamine-Producing Neurons from Stress Damage and Eases Parkinson's Symptoms

A preliminary clinical study demonstrated the effectiveness of n-acetylcysteine (NAC) in promoting survival of neurons and alleviating symptoms in patients with Parkinson's disease (PD).

Previous studies have shown that oxidative stress in the brain may play an important role in the Parkinson's disease process, and that this stress reduces levels of the antioxidant glutathione. NAC acts to reduce oxidative damage to neurons by restoring glutathione levels.

The purpose of the clinical study carried out by investigators from Thomas Jefferson University (Philadelphia, PA, USA) was to explore the effects of NAC using both an in vitro and in vivo approach. To find supportive data for the pilot clinical study, the investigators performed a cell line tissue culture study in which they used a model of PD that employed midbrain dopamine (mDA) neurons generated from human embryonic stem cells (hESCs) to determine whether NAC could protect these mDA neurons from damage resulting from exposure to increasing doses of the PD-like neurotoxin, rotenone.

In the clinical study, patients continued their standard of care and were randomized to receive either daily NAC, alternating between oral and IV administration, or no NAC. Patients were evaluated before and after three months of receiving NAC with DaTscan to measure dopamine transporter (DAT) binding and the Unified Parkinson’s Disease Rating Scale (UPDRS) to measure clinical symptoms.

Results published in the June 16, 2016, online edition of the journal PLOS One revealed that in the cell line study NAC exposure resulted in significantly more mDA neurons surviving after exposure to rotenone compared to no NAC, consistent with the protective effects of NAC previously observed. In the clinical trial the patients receiving NAC had improvements of 4-9% in dopamine transporter binding and about a 13% improvement in their UPDRS score as compared to untreated control patients.

"This study reveals a potentially new avenue for managing Parkinson's patients and shows that n-acetylcysteine may have a unique physiological effect that alters the disease process and enables dopamine neurons to recover some function," said senior author Dr. Daniel Monti, professor of integrative medicine at Thomas Jefferson University.

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