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Assessment of oxidative stress in leukocytes and granulocyte function following oral administration of a silibinin-phosphatidylcholine complex in cats

Craig B. Webb PhD, DVM1, Kelly W. McCord DVM2, and David C. Twedt DVM3
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  • 1 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.
  • | 2 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.
  • | 3 Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523.

Abstract

Objective—To determine the effect of oral administration of a silibinin-phosphatidylcholine complex (SPC) on oxidative stress in leukocytes and granulocyte function in healthy cats.

Animals—10 purpose-bred adult cats.

Procedures—Cats were administered SPC (10 mg/kg/d) orally for 5 days; blood samples were collected prior to and immediately after the 5-day treatment period. Leukocytes were incubated with monochlorobimane for detection of reduced glutathione (GSH) via flow cytometry. Leukocytes were also incubated with dihydrorhodamine 123 and mixed with Escherichia coli conjugated to a fluorescent marker to measure E coli phagocytosis and the subsequent oxidative burst via flow cytometry. Activities of the antioxidant enzymes superoxide dismutase and glutathione peroxidase, along with the reduced glutathione-to-oxidized glutathione (GSH:GSSG) ratio and a measure of lipid peroxidation (malondialdehyde concentration [Mmol/L of blood]), were measured spectrophotometrically.

Results—The mean fluorescence intensity (MFI), representing GSH content, increased significantly in feline lymphocytes and granulocytes following 5 days of oral administration of SPC. Mean ± SD lymphocyte MFI significantly increased from 27.8 ± 9.0 to 39.6 ± 6.7, and the granulocyte MFI increased from 508.6 ± 135.6 to 612.1 ± 122.9. Following 5 days of SPC administration, the percentage of phagocytic cells that were responding optimally significantly increased (from 37 ± 11.8% to 45 ± 17.5%). Other measures of oxidative stress did not change significantly.

Conclusions and Clinical Relevance—In cats, oral administration of supplemental SPC appears to increase granulocyte GSH content and phagocytic function, both of which would be potentially beneficial in cats with diseases associated with oxidative stress.

Contributor Notes

Supported in part by Nutramax Laboratories (provision of the silibinin-phosphatidylcholine complex).

Submitted in abstract form for the 32nd Annual American College of Veterinary Internal Medicine Forum, San Antonio, Tex, June 2008.

Address correspondence to Dr. Webb.