The influence of road transport on the activities of glutathione reductase, glutathione peroxidase, and glutathione-S-transferase in equine erythrocytes.

Abstract

BACKGROUND: Transport of horses may have significant impact on serum biochemical and hematologic analytes and resistance to infection. OBJECTIVE: The aim of our study was to assess the influence of transport stress on selected enzymatic antioxidants in equine blood. METHODS: The study was conducted on a group of 60 horses of different breeds and ranging in age from 4 to 10 years. Venous blood was collected immediately before loading horses onto trailers for 8 hours of transport (I), immediately after unloading them from the trailer (II), and after subsequent stall rest for 24 hours (III). Hemolysates of blood were prepared, and hemoglobin (Hb) concentration and activities of the enzymatic antioxidants glutathione reductase (GR), glutathione-S-transferase (GST), and glutathione peroxidase (GPx) were measured. Enzyme activities were expressed as units of activity per gram of hemoglobin. RESULTS: There were significant decreases in activities (mean ± SD U/g Hb [minimum-maximum]) of GPx between collection times I (36 ± 14 U/g Hb [9-67 U/g Hb]) and III (30 ± 11 U/g Hb [12-51 U/g Hb]) and of GR between collection times I (54 ± 28 U/g Hb [7-117 U/g Hb]) and II (40 ± 23 U/g Hb [12-145 U/g Hb]). There was no significant difference in activities of GR between collection times I and III (50 ± 27 U/g Hb [9-116 U/g Hb]). There were no differences detected in GST activity among the 3 collection times. CONCLUSION: Road transport has an impact on activities of the antioxidant enzymes GPx and GR, with recovery of GR activity evident by 24 hours post-transport. Decreased activity of these enzymes may be one mechanism for increased susceptibility to infections that are manifest after shipping; alternatively, decreases may indicate utilization as these enzymes work to neutralize increases in reactive oxygen species.