Actions Of N-acetylcysteine Research Articles

N-acetylcysteine improves autism-like behavior by recovering autophagic deficiency and decreasing Notch-1/Hes-1 pathway activity.

N-acetylcysteine (NAC) has been reported to improve social interaction behavior, irritability, self-injury, and anxiety-like behavior in autism. However, the molecular mechanism underlying the therapeutic roles of NAC in autism remains unknown. This study mainly aimed to investigate the therapeutic effect of NAC on valproic acid (VPA)-induced autism model and the underlying mechanisms. Our results showed that NAC ameliorated the deficits in sociability and the anxiety- and repetitive-like behaviors displayed by VPA-exposed rats. In addition, VPA exposure induced autophagic deficiency and enhanced Notch-1/Hes-1 pathway activity based on lowered Beclin-1 and LC3B levels, while increased expression of p62, Notch-1, and Hes-1 expression at the protein level. However, NAC recovered VPA-induced autophagic deficiency and reduced Notch-1/Hes-1 pathway activity in a VPA-exposed autism rat model and SH-SY5Y neural cells. The present results demonstrated that NAC improves autism-like behavioral abnormalities by inactivating Notch-1/Hes-1 signaling pathway and recovering autophagic deficiency. Taken together, this study helps to elucidate a novel molecular mechanism that underlies the therapeutic actions of NAC in autism and suggests its potential to ameliorate behavioral abnormalities in neurodevelopmental disorders.

N-Acetyl-cysteine and Mechanisms Involved in Resolution of Chronic Wound Biofilm

Chronic wounds are a major global health problem with the presence of biofilm significantly contributing to wound chronicity. Current treatments are ineffective in resolving biofilm and simultaneously killing the bacteria; therefore, effective biofilm-resolving drugs are needed. We have previously shown that, together with α-tocopherol, N-acetyl-cysteine (NAC) significantly improves the healing of biofilm-containing chronic wounds, in a diabetic mouse model we developed, by causing disappearance of the bacteria and breakdown of the extracellular polymeric substance (EPS). We hypothesize that NAC creates a microenvironment that affects bacterial survival and EPS integrity. To test this hypothesis, we developed an in vitro biofilm system using microbiome taken directly from diabetic mouse chronic wounds. For these studies, we chose mice in which chronic wound microbiome was rich in Pseudomonas aeruginosa (97%). We show that NAC at concentrations with pH < pKa causes bacterial cell death and breakdown of EPS. When used before biofilm is formed, NAC leads to bacterial cell death whereas treatment after the biofilm is established NAC causes biofilm dismantling accompanied by bacterial cell death. Mechanistically, we show that NAC can penetrate the bacterial membrane, increase oxidative stress, and halt protein synthesis. We also show that low pH is important for the actions of NAC and that bacterial death occurs independently of the presence of biofilm. In addition, we show that both the acetyl and carboxylic groups play key roles in NAC functions. The results presented here provide insight into the mechanisms by which NAC dismantles biofilm and how it could be used to treat chronic wounds after debridement (NAC applied at the start of culture) or without debridement (NAC applied when biofilm is already formed). This approach can be taken to develop biofilm from microbiome taken directly from human chronic wounds to test molecules that could be effective for the treatment of specific biofilm compositions.

N-acetylcysteine ameliorates repetitive/stereotypic behavior due to its antioxidant properties without activation of the canonical Wnt pathway in a valproic acid-induced rat model of autism.

N-acetylcysteine (NAC) is widely used as an antioxidant, and previous studies have suggested that it may have potential as an alternative therapeutic strategy for the treatment of patients with autism. However, the exact effects of NAC administration on the development of autism, as well as the molecular mechanisms underlying its actions, have yet to be fully elucidated. The present study aimed to investigate the effects of NAC on the oxidative status of rats in a valproic acid (VPA)‑induced model of autism, and to examine the involvement of the canonical Wnt signaling pathway in the actions of NAC. Rats exposed to VPA were monitored for behavioral changes, and oxidative stress indicators and key molecules of the canonical Wnt pathway were investigated using colorimetric and western blot analysis, respectively. The present results demonstrated that NAC ameliorated repetitive and stereotypic activity in autism model rats. Furthermore, NAC was revealed to relieve oxidative stress, as demonstrated by the increased glutathione and reduced malondialdehyde levels compared with VPA‑treated rats. However, NAC did not appear to affect the activity of the canonical Wnt signaling pathway. The present findings suggested that the beneficial effects of NAC in autism may be associated with its antioxidative properties, and may not be mediated by the canonical Wnt pathway. However, it may be hypothesized that the canonical Wnt pathway can be indirectly regulated by NAC through the activation of other signaling pathways or upstream factors. Taken together, the present study has contributed to the elucidation of the molecular mechanisms that underlie the actions of NAC in autism, suggesting its potential for the development of novel therapeutic strategies for the treatment of patients with autism.

NAC for noise: From the bench top to the clinic

Noise-induced hearing loss (NIHL) is an important etiology of deafness worldwide. Hearing conservation programs are in place and have reduced the prevalence of NIHL, but this disorder is still far too common. Occupational and recreational pursuits expose people to loud noise and ten million persons in the US have some degree of noise-induced hearing impairment. It is estimated that 50 million in the US and 600 million people worldwide are exposed to noise hazards occupationally. Noise deafness is still an important and frequent cause of battlefield injury in the US military. A mainstay of hearing conservation programs is personal mechanical hearing protection devices which are helpful but have inherent limitations. Research has shown that oxidative stress plays an important role in noise-induced cochlear injury resulting in the discovery that a number of antioxidant and cell death inhibiting compounds can ameliorate deafness associated with acoustic trauma. This article reviews one such compound, N-acetylcysteine (NAC), in terms of its efficacy in reducing hearing loss in a variety of animal models of acute acoustic trauma and hypothesizes what its therapeutic mechanisms of action might be based on the known actions of NAC. Early clinical trials with NAC are mentioned.

Transforming growth factor β1 induction of Tissue Inhibitor of MetalloProteinases 3 in articular chondrocytes is mediated by reactive oxygen species

Transforming growth factor β1 (TGF-β1) stimulates cartilage extracellular matrix synthesis but, in excess, evokes synovial inflammation, hyperplasia, and osteophyte formation in arthritic joints. TGF-β1 induces tissue inhibitor of metalloproteinases 3 (TIMP-3), an inhibitor of cartilage-damaging matrix metalloproteianases and aggrecanases. We investigated the role of reactive oxygen species (ROS) in TIMP-3 induction by TGF-β1. In primary human and bovine chondrocytes, ROS scavenger and antioxidant N-acetylcysteine (NAC) inhibited TGF-β1-induced TIMP-3 mRNA and protein increases. Ebselen and ascorbate also reduced this induction. TGF-β1 time-dependently induced ROS production that was suppressed by NAC. Hydrogen peroxide, a ROS, induced TIMP-3 RNA. The TIMP-3 increase induced by TGF-β1 was partly Smad2-dependent. TGF-β1-stimulated Smad2 phosphorylation was inhibited by NAC. Reduced glutathione and L-cysteine also blocked Smad2 and TIMP-3 induction by TGF-β1, whereas a nonthiol, N-acetylalanine, did not. Smad2 was not activated by H 2O 2. Smad2 phosphorylation was independent, and TIMP-3 expression was dependent, on new protein synthesis. TGF-β-stimulated ERK and JNK phosphorylation was also inhibited by NAC. However, inhibitory actions of NAC were not mediated by ERK activation. Thus, ROS mediate TGF-β1-induced TIMP-3 gene expression. Blocking TGF-β1-induced gene expression by modulating cellular redox status with thiols can be potentially beneficial for treating arthritic and other disorders caused by excessive TGF-β1.

Transforming growth factor $beta;1 induction of Tissue Inhibitor of Metallo Proteinases 3 in articular chondrocytes is mediated by reactive oxygen species

Transforming growth factor β1 (TGF-β1) stimulates cartilage extracellular matrix synthesis but, in excess, evokes synovial inflammation, hyperplasia, and osteophyte formation in arthritic joints. TGF-β1 induces tissue inhibitor of metalloproteinases 3 (TIMP-3), an inhibitor of cartilage-damaging matrix metalloproteianases and aggrecanases. We investigated the role of reactive oxygen species (ROS) in TIMP-3 induction by TGF-β1. In primary human and bovine chondrocytes, ROS scavenger and antioxidant N-acetylcysteine (NAC) inhibited TGF-β1-induced TIMP-3 mRNA and protein increases. Ebselen and ascorbate also reduced this induction. TGF-β1 time-dependently induced ROS production that was suppressed by NAC. Hydrogen peroxide, a ROS, induced TIMP-3 RNA. The TIMP-3 increase induced by TGF-β1 was partly Smad2-dependent. TGF-β1-stimulated Smad2 phosphorylation was inhibited by NAC. Reduced glutathione and L-cysteine also blocked Smad2 and TIMP-3 induction by TGF-β1, whereas a nonthiol, N-acetylalanine, did not. Smad2 was not activated by H2O2. Smad2 phosphorylation was independent, and TIMP-3 expression was dependent, on new protein synthesis. TGF-β-stimulated ERK and JNK phosphorylation was also inhibited by NAC. However, inhibitory actions of NAC were not mediated by ERK activation. Thus, ROS mediate TGF-β1-induced TIMP-3 gene expression. Blocking TGF-β1-induced gene expression by modulating cellular redox status with thiols can be potentially beneficial for treating arthritic and other disorders caused by excessive TGF-β1.

Augmentation of human neutrophil and alveolar macrophage LTB4 production by N-acetylcysteine: role of hydrogen peroxide.

1. The actions of N-acetylcysteine (NAC) on hydrogen peroxide (H2O2) and leukotriene B4 (LTB4) production by human resting and stimulated peripheral blood neutrophils and alveolar macrophages were investigated. 2. At a concentration of 100 microM, NAC significantly (P < 0.01) suppressed the accumulation of H2O2 in the incubation medium of resting and opsonized zymosan (OZ; 0.5 mg ml[-1])- or N-formylmethionyl-leucyl-phenylalanine (fMLP; 1 microM)-stimulated neutrophils and of resting and OZ-stimulated macrophages. At concentrations of 10 microM and above, NAC augmented significantly the level of LTB4 in the supernatants of OZ- and fMLP-stimulated neutrophils (P < 0.01 and P < 0.05, respectively) and OZ-stimulated macrophages (P < 0.05 at 10 microM, P < 0.01 at 100 microM NAC). 3. NAC (100 microM) caused a significant (P < 0.01) reduction in the quantity of measurable H2O2 when incubated with exogenous H2O2 concentrations equivalent to those released from OZ-stimulated neutrophils and macrophages. At no concentration did NAC affect quantitites of measurable LTB4 when incubated with exogenous LTB4. 4. Superoxide dismutase (SOD), which catalyzes the conversion of superoxide anion to H2O2 had no significant effect on LTB4 production by human neutrophils. In contrast, catalase, which catalyzes the conversion of H2O2 to H2O and O2, caused a pronounced, statistically significant (P < 0.01) increase in the levels of LTB4 measured in the supernatants of OZ- and fMLP-stimulated neutrophils. 5. H2O2 (12.5 microM and 25 microM, concentrations equivalent to those measured in the supernatants of activated neutrophils and alveolar macrophages, respectively) caused a small (13%) decrease in the quantity of measurable LTB4 (P = 0.051 and P < 0.05 at 12.5 microM and 25 microM, respectively) that was inhibited by NAC (100 microM) but not by catalase (400 u ml[-1]). 6. In conclusion, the anti-oxidant drug, NAC, increases LTB4 production by human neutrophils and alveolar macrophages, probably through the elimination of cell-derived H2O2. LTB4 undergoes a H2O2-dependent oxidation that is inhibited by NAC but this is unlikely to account fully for the increased levels of LTB4, suggesting that NAC may increase LTB4 production by blocking the H2O2-dependent inhibition of a synthetic enzyme, such as 5-lipoxygenase.

N-Acetylcysteine-promoted Survival of PC12 Cells Is Glutathione-independent but Transcription-dependent

Our prior work established that comparable concentrations of N-acetylcysteine (NAC) both block the proliferation of PC12 cells and prevent death of trophic factor-deprived sympathetic neurons and PC12 cells. The present work addresses several aspects of the mechanisms of these actions. NAC increases intracellular levels of glutathione (GSH) by approximately 10-fold in PC12 cells. However, blockade of this increase by treatment with buthionine sulfoximine did not affect either promotion of survival or inhibition of DNA synthesis. Thus, these actions of NAC are independent of its effects on intracellular GSH. NAC's actions in our system do not appear to be dependent on its anti-oxidant/radical scavenger properties, but may be due to its activity as a reductant. Consistent with this, several other reducing agents, the most effective of which was 2,3-dimercaptopropanol, mimicked NAC in blocking DNA synthesis and suppressing death of PC12 cells and sympathetic neurons. Finally, we observed that in striking contrast to nerve growth factor and a number of other trophic agents, the survival-promoting effects of NAC on PC12 cells are blocked by actinomycin D. This suggests that NAC may act by inducing specific gene expression.

Effects of N-acetylcysteine on in vitro diaphragm function are temperature dependent

Recent evidence has shown that systemic administration of N-acetylcysteine (NAC), a compound structurally similar to the intracellular antioxidant glutathione, inhibits skeletal muscle fatigue. To further elucidate the actions of NAC, we studied its effects on in vitro rat diaphragm contractile function. Rat diaphragm strips were incubated in tissue baths containing physiological salt solution (n = 29) or physiological salt solution containing 4 mg/ml of NAC (n = 29). Strips were stimulated by either indirect or direct means. After determination of baseline contractile characteristics, strips were fatigued for 4 min at 20 Hz (1 train/s, 0.33 ms train duration). Force-frequency relationships were then studied over a 60-min recovery period. We found that 1) NAC had significant effects on the baseline force-frequency relationship; treated strips had increased peak tension but diminished twitch tension and accelerated twitch kinetics; 2) NAC had significant fatigue-sparing effects that were magnified at 37 degrees C; and 3) NAC treatment did not improve postfatigue recovery. The effects of NAC were generally independent of the stimulation method. We conclude that NAC has direct temperature-dependent effects on diaphragm function. These effects are consistent with the properties of NAC as an antioxidant and suggest important but complex effects of oxidant stress on skeletal muscle.