Distribution of Radio-LabeledN-Acetyl-L-Cysteine in Sprague-Dawley Rats and Its Effect on Glutathione Metabolism Following Single and Repeat Dosing by Oral Gavage

Abstract

The distribution of radio-labeled N-Acetyl-L-Cysteine (NAC) and its impact on glutathione (GSH) metabolism was studied in Sprague-Dawley rats following single and multiple dosing with NAC by oral gavage. Radioactivity associated with administration of (14)C-NAC distributed to most tissues examined within 1 hour of administration with peak radioactivity levels occurring within 1 hour to 4 hours and for a majority of the tissues examined, radioactivity remained elevated for up to 12 hours or more. Administration of a second dose of 1,200 mg/kg NAC + (14)C-NAC 4 hours after the first increased liver, kidney, skin, thymus, spleen, eye, and serum radioactivity significantly beyond levels achieved following 1 dose. Administration of a third dose of 1,200 mg/kg NAC + (14)C-NAC 4 hours after the second dose did not significantly increase tissue radioactivity further except in the skin. GSH concentrations were increased 20% in the skin and 50% in the liver after one dose of 1,200 mg/kg NAC whereas lung and kidney GSH were unaffected. Administration of a second and third dose of 1,200 mg/kg NAC at 4 hours and 8 hours after the first did not increase tissue GSH concentrations above background with the exception that skin GSH levels were elevated to levels similar to those obtained after a single dose of NAC. Glutathione-S-transferase (GST) activity was increased 150% in the kidney and 10% in the liver, decreased 60% in the skin, and had no effect on lung GST activity following a single dose of 1,200 mg/kg NAC. Administration of a second dose of 1,200 mg/kg NAC 4 hours after the first decreased skin GST activity a further 20% whereas kidney GST activity remained elevated at levels similar to those obtained after 1 dose of NAC. Administration of a third dose of NAC 4 hours after the second dose increased liver GST activity significantly as compared to background but did not affect skin, kidney, or lung GST activity. Transient decreases in glutathione reductase (GR) activity were measured in the skin and kidney in association with repeat administration of 1,200 mg/kg NAC. Glutathione peroxidase (GxP) activity was increased in the skin, kidney, and liver suggesting that oxidative stress was occurring in these tissues in response to repeat dosing with NAC. Overall, the results of this study present the possibility that NAC could provide some benefit in preventing or reducing toxicity related to exposure to chemical irritants (particularly sulfur mustard) in some tissues by increasing tissue NAC and/or cysteine levels, GSH concentrations, and GST activity. However, follow-on studies in animals are needed to confirm that oral administration of single and multiple doses of NAC can significantly reduce skin, eye, and lung toxicity associated with sulfur mustard exposure. The finding that GxP activity is elevated, albeit transiently, following repeat administration of NAC suggests that repeat administration of NAC may induce oxidative stress in some tissues and further studies are needed to confirm this finding.

Efficacy of Glutathione in Ameliorating Sulfur Mustard Analog-Induced Toxicity in Cultured Skin Epidermal Cells and in SKH-1 Mouse Skin In Vivo

“…CEES-caused mitochondrial oxidative damage and altered mitochondrial membrane potential are also reported in lung, liver, and other tissues, further indicating a role of oxidative stress in CEES-caused toxicity (Jafari, 2007;Gould et al, 2009;Black et al, 2010). Therefore, supplementing GSH or its precursors, including NAC, could help minimize this oxidative stress and reduce HD/CEES-caused toxicity, although its associated mechanism and defined biological systems are not well known (Amir et al, 1998;Atkins et al, 2000;Han et al, 2004;Arfsten et al, 2007;Paromov et al, 2007Paromov et al, , 2008. The protective role of extracellular GSH is highlighted in a study using the macrophage monocyte cell line J774 as well as in the mitotically active SVK 14 keratinocyte cell line (Smith et al, 1997;Amir et al, 1998).…”

“…HD/CEES-caused oxidative stress results in the 8-oxo-2-deoxyguanosine DNA adduct as well as lipid and protein oxidation, which can cause inflammation and other toxic responses in skin Black et al, 2010). The exogenous addition of antioxidants such as GSH, N-acetyl cysteine (NAC), vitamin E, superoxide dismutase, catalase, sulforaphane, quercetin, and catalytic antioxidants such as manganese (III) meso-tetrakis (di-N-ethylmidazole)porphyrin (AEOL 10150) has been reported to attenuate lung and skin injury by HD/CEES (Gross et al, 1993;Smith et al, 1997;Amir et al, 1998;Han et al, 2004;Arfsten et al, 2007;Paromov et al, 2007Paromov et al, , 2008Gould et al, 2009;Black et al, 2010;O'Neill et al, 2010). Whereas most of these efficacy studies with antioxidants indicate that they have beneficial effects in attenuating HD/ CEES-caused lung injury, there are few, if any, reports of efficacy studies with GSH and its associated mechanism of action in relevant skin epidermal cells and skin toxicity models of HD/CEES (Paromov et al, 2007).…”

N-acetylcysteine ameliorates acute kidney injury but not glomerular hemorrhage in an animal model of warfarin-related nephropathy

“…Ischemia-reperfusion was created after unilateral nephrectomy of the right kidney and clamping of the left renal artery for 30 min as we described earlier (8). Treatment with NAC was started 24 h before the ischemia was initiated to achieve the pharmacologic NAC concentrations in the circulation by the time of ischemia-reperfusion (1).…”

The role of N-acetyl-cysteine in the lung remote injury after hepatic ischemia and reperfusion in rabbits

“…Thus its offer directly into the bloodstream are loosely based on reports suggesting that this dose and time prior to application, are suitable for tissue concentrations sufficient to minimize or eliminate the effects of biochemical and structural repercussions on the parenchyma pulmonar [27][28][29] .…”

“…The use of NAC 15 minutes before starting the ischemia is based on the biodistribution of drug in plasma and tissues 27 .…”