N-Acetyl Cysteine Mitigates the Acute Effects of Cocaine-Induced Toxicity in Astroglia-Like Cells

Abstract

Cocaine has a short half-life of only about an hour but its effects, predominantly on the central nervous system (CNS), are fairly long-lasting. Of all cells within the CNS, astrocytes may be the first to display cocaine toxicity owing to their relative abundance in the brain. Cocaine entry could trigger several early response changes that adversely affect their survival, and inhibiting these changes could conversely increase their rate of survival. In order to identify these changes and the minimal concentrations of cocaine that can elicit them in vitro, rat C6 astroglia-like cells were treated with cocaine (2–4 mM for 1h) and assayed for alterations in gross cell morphology, cytoplasmic vacuolation, viability, reactive oxygen species (ROS) generation, glutathione (GSH) levels, cell membrane integrity, F-actin cytoskeleton, and histone methylation. We report here that all of the above identified features are significantly altered by cocaine, and may collectively represent the key pathology underlying acute toxicity-mediated death of astroglia-like cells. Pretreatment of the cells with the clinically available antioxidant N-acetyl cysteine (NAC, 5 mM for 30 min) inhibited these changes during subsequent application of cocaine and mitigated cocaine-induced toxicity. Despite repeated cocaine exposure, NAC pretreated cells remained highly viable and post NAC treatment also increased viability of cocaine treated cells to a smaller yet significant level. We show further that this alleviation by NAC is mediated through an increase in GSH levels in the cells. These findings, coupled with the fact that astrocytes maintain neuronal integrity, suggest that compounds which target and mitigate these early toxic changes in astrocytes could have a potentially broad therapeutic role in cocaine-induced CNS damage.

Drugs of abuse and blood-brain barrier endothelial dysfunction: A focus on the role of oxidative stress

“…97 Furthermore, cocaine at doses that exceed the physiological range was shown to rapidly elevate ROS levels with concomitant reduction in cellular GSH leading to increased oxidative stress in astroglia-like cells. 100 However, the clinical relevance of these latter findings needs further investigation. Notably, in addition to its direct inflammatory responses at BBB endothelium, cocaine administration (5 mg/kg) in rats was also shown to stimulate induction and release of proinflammatory cytokines (such as TNFa and IL-1b) in reward regions of the brain 101 that would further aggravate regional BBB damage.…”

Cocaine effects on generation of reactive oxygen species and DNA damage: formation of 8-hydroxydeoxyguanosine in active abusers

“…In fact, in mitochondrial isolated from rats liver treated with a single dose of cocaine, have been observed to have significantly increased rates of ROS generation and this effect was significantly inhibited by pre-treatment of the rats with the cytochrome inhibitor SKF525A (Devi & Chan 1996). In a recent paper Badisa et al (2015) the acute exposure of astroglia-like cells to cocaine causes an excessive release of ROS with a decrease in glutathione (GSH) level in dose-dependent manner. This depletion of GSH may be prevented with a pretreatment of N-acetylcysteine (NAC), a well-known antioxidant and therapeutic agent for oxidant related diseases and recently this compound has been viewed as a pharmacological drug that could provide protection against drug abuse in addicts (LaRowe et al (2006)).…”

Targeting redox regulation to treat substance use disorder using N‐acetylcysteine

“…Following uptake of cystine into cells via system xc‐, cystine can be converted back into cysteine to allow for the synthesis of further glutathione. This has been shown in an experiment where incubation of cultured astroglial cells with a cocaine/NAC mixture prevented the cocaine‐induced decrease in cell viability by increasing cellular glutathione levels (Badisa et al ., , ). Furthermore, NAC may also increase the expression of antioxidant enzymes, with a cell culture model of cocaine‐induced hepatotoxicity finding increased manganese‐ and copper, zinc‐superoxide dismutase, catalase and glutathione peroxidase levels following NAC supplementation (Zaragoza et al ., ).…”