053 Psychological Stress Impairs Healing and Oxygenation in Cutaneous Wounds

Human and animal studies have shown that psychological stress impairs wound healing. Catecholamines released in response to stress could cause vascular changes that would restrict oxygen delivery to the healing wound. Hence, we hypothesized that stress impairs healing by disrupting oxygen balance in the wounds. 6–8 week, female SKH‐1 mice were subjected to stress by confinement in well‐ventilated 50‐ml conical tubes. Stressing was done three days prior to wounding and five days post wounding, during the active cycle of the mice. Wounds were placed using a standard, 3.5 mm‐diameter biopsy punch. Each mouse received two wounds on their dorsum, behind their shoulder blades. Wound oxygenation was measured by EPR oximetry. Gene expression was measured by real time PCR. Phentolamine, an alpha‐adrenergic antagonist was used in conjunction with EPR oximetry to determine catecholamine‐mediated modulation of wound oxygenation during healing. Our results on the effects of stress on wound healing were consistent with previous results in the model, and showed 19%– 30% larger wounds in the stressed animals when compared to controls. Oxygen levels in the wounds showed a 17.49 to 34.38%(p < 0.001) decrease in the stressed animals on days 1 through 5 post wounding. Furthermore, gene expression studies of a hypoxia driven gene, iNOS, showed an increase in expression on days 1 (205%; p < 0.0003), 3(96%; p < 0.04) and 5 (249%; p < 0.0003). eNOS expression increased by 66%(p < 0.02) on day 1 post‐wounding, with no significant difference in nNOS expression. Phentolamine ameliorated the effect of stress on wound oxygenation on day 1 post wounding. These findings show that stress‐impaired healing is associated with reduced tissue oxygen and altered expression of a hypoxia‐induced gene. Furthermoe, the data suggests a role for catecholamines in stress‐induced impairment of wound oxygenation during early healing.