Key result
Cigarette smoke exposure in rats significantly reduced lung glutathione, elevated protein oxidation markers, increased serum 5-HT, and elevated lung MAO-A activity (p < 0.05 for all).
Why the study?
Does cigarette smoke exposure induce oxidative stress via serotonin metabolism in a rat model?
Does cigarette smoke exposure induce oxidative stress via serotonin metabolism in a rat model?
Cigarette smoke exposure induces oxidative stress in the lung via MAO-A-mediated serotonin metabolism, suggesting a potential mechanism for COPD pathogenesis.
Answers are grounded in this paper and cite their sources.
May disrupt 5-HT homeostasis and amplify MAO oxidative stress in COPD; leaves open targeted interventions for future study.
Recently, we have reported the dysregulation of circulating serotonin (5-hydroxytryptamine, 5-HT) homeostasis in patients with chronic obstructive pulmonary disease (COPD). An increase in metabolism of 5-HT has been reported to induce oxidative stress via monoamine oxidase (MAO)-dependent pathway. The present study aimed at investigating the effect of cigarette smoke exposure on the systemic circulation and local airway 5-HT levels as well as MAO-mediated oxidative pathway using a cigarette smoke-exposed rat model. Male Sprague-Dawley rats (150-200 g) were exposed to either sham air or 4% (v/v, smoke/air) cigarette smoke for 1 hour daily for 56 consecutive days. Sera, bronchoalveolar larvage (BAL) and lung tissues were collected 24 hours after the last exposure. We found a significant reduction in the reduced glutathione (rGSH) and an elevation in advanced oxidation protein products (AOPP), a protein oxidation marker, in the lung of cigarette smoke-exposed group (p < 0.05). A significant increase in 5-HT was found in serum (p < 0.05), but not in the BAL or lung, after cigarette smoke exposure. MAO-A activity was significantly elevated in the lung of cigarette smoke-exposed group (p < 0.05). Furthermore, increased superoxide anion levels were found in lung homogenates of cigarette smoke-exposed rats after incubation with 5-HT (p < 0.05), which was positively associated with the increase in MAO-A activity (r = 0.639, p < 0.05). Our findings supported the presence of GSH disruption and protein oxidation in the lung after cigarette smoke exposure. The metabolism of 5-HT by MAO-A in the lung enhanced cigarette smoke-induced superoxides, which might contribute to the pathogenesis of COPD.
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Lau et al. (2012) studied Cigarette smoke-induced oxidative stress. Cigarette smoke exposure vs. Sham air was evaluated on Reduced glutathione (rGSH), advanced oxidation protein products (AOPP), 5-HT levels, and MAO-A activity (p=< 0.05). Cigarette smoke exposure in rats significantly reduced lung glutathione, elevated protein oxidation markers, increased serum 5-HT, and elevated lung MAO-A activity (p < 0.05 for all).
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