N-Acetyl Cysteine Protects against Methamphetamine-Induced Dopaminergic Neurodegeneration via Modulation of Redox Status and Autophagy in Dopaminergic Cells

Abstract

Methamphetamine- (MA-) induced neurotoxicity is associated with mitochondrial dysfunction and enhanced oxidative stress. Our previous study demonstrated that MA induces autophagy in a dopaminergic neuronal cell model (N27 cells). The cellular mechanisms underlying MA-induced autophagy and apoptosis remain poorly characterized. In the present study we sought to investigate the importance of GSH redox status in MA-induced neurotoxicity using a thiol antioxidant, N-acetylcysteine (NAC). Morphological and biochemical analysis revealed that MA-induced autophagy in N27 dopaminergic cells was associated with pronounced depletion of GSH levels. Moreover, pretreatment with NAC reduced MA-induced GSH depletion and autophagy, while depletion of GSH using L-buthionine sulfoximine (L-BSO) enhanced autophagy. Furthermore, treatment with NAC significantly attenuated MA-induced apoptotic cell death as well as oxidative stress markers, namely, 3-nitrotyrosine (3-NT) and 4-hydroxynonenal (4-HNE). Together, these results suggest that NAC exhibits significant protective effects against MA-induced dopaminergic cell death, presumably via modulation of the GSH level and autophagy. Collectively, our data provide mechanistic insights into the role of cellular GSH redox status in MA-induced autophagy and apoptotic cell death, and additional studies are needed to determine the therapeutic effectiveness of cellular redox modifiers in attenuating dopaminergic neurodegeneration in vivo.

Cellular metabolic and autophagic pathways: Traffic control by redox signaling

“…N-acetyl cysteine has been shown to reverse the activation of autophagy by neuregulin in prostate cancer cells, and also prevents the hypoxia induced autophagic cell death of retinal ganglion cells [202, 203]. In a methamphetamine-induced model of Parkinson’s disease in N27 cells, N-acetyl cysteine can prevent dopaminergic cell death by preventing the depletion of GSH and activating autophagy [204]. …”

Glutathione and redox signaling in substance abuse

“…Given the important role of GSH in redox homeostasis, it is not surprising that changes in GSH and redox-sensitive enzymes have been found in vitro and preclinical and clinical studies of METH addiction. METH-induced autophagy and apoptotic cell death in the N27 dopaminergic neuronal cell model were accompanied by GSH depletion and increases in 3-nitrotyrosine and 4-hydroxynonenal [63]. Mice treated with METH have shown a decrease in GSH in the striatum, amygdala, hippocampus and frontal cortex [64].…”

“…In addition, a decrease in DAT immunoreactivity was observed 7 days post-treatment, which was also attenuated by SMTC pretreatment [68]. NAC has provided protection against METH-induced dopaminergic neurodegeneration in vitro [63] and improved memory consolidation in METH-treated mice [64]. The NAC derivative and novel antioxidant, N -acetylcysteine amide (NACA), has shown to be protective against METH-induced oxidative stress in vitro [69].…”

Oxidative and nitrative stress in neurodegeneration

“…Shivalingappa et al found that MA treatment in N27 cells induces formation of 3-NT and 4-HNE in a DA-dependent mechanism at least partially attributed to MA's concurrent reduction in GSH levels relative to untreated controls. They additionally propose 3-NT may correspond to a prior increase in ONOO - where ONOO - can inhibit the DA transporter (Chandramani Shivalingappa et al, 2012). Supplementation with the antioxidant N-acetylcysteine (NAC) restored LPO product and antioxidant levels compared to untreated controls.…”