Age-related changes in haemostatic responses to oxidative stress

ABSTRACT

Altered haemostatic mechanisms are known to occur in stressful situations, yet the pathophysiology of stress related dyshaemostasis is still poorly understood. In the present work, age-related changes in haemostatic responses to oxidative stress in rats with different ages were investigated. Also, the effects of vitamin E supplementation, prior to stress induction, on the haemostatic responses of those stressed rats were evaluated. Three different age groups were studied, young mature rats [4 months], middle age [14 months] and old rats [24 months]. The animals were subjected to oxidative stress by adding H[2]O[2] solution to their drinking water, in a final concentration of 3%, daily, for 21 days. The age-matched control rats drink normal tap water. A group of old rats was injected intramuscularly by vitamin E in a dose of 150 mg/kg body weight, prior to the stress induction, daily, for 21 days.Results obtained in this study demonstrated an elevation in mean arterial blood pressure, plasma malondialdehyde, and plasma fibrinogen concentrations, and fibrin degradation products, in addition to shortened prothrombin and partial thromboplastin times and inhibited antithrombin III activity, in the young and old rats subjected to H[2]O[2]-induced oxidative stress, being statistically significant compared to their age matched controls. Moreover, there were an increase in platelet aggregation and a decrease in platelet count in the stressed young and old groups, but they were statistically significant only in old rats, compared to their age matched controls. However, stressed middle-age rats showed non-significant changes in the studied parameters, except for the mean arterial blood pressure that was significantly elevated, compared to their age matched controls. From these results, it is clear that the changes in the haemostatic responses to stress were more manifest in the young and old rats, with more marked responses in the older ones. On the other hand, vitamin E supplementation in old rats, prior to the stress induction, produced a decrease in mean arterial blood pressure, platelet aggregation, plasma fibrinogen concentration and fibrin degradation products, as well as increase in platelet count and antithrombin III activity. All these changes were statistically significant compared to the vitamin E-unsupplemented stressed old rats, but they were non significantly changed from the normal controls. It is concluded that vitamin E injection, prior to stress induction, produces marvelous effects on the stress-induced derangement of the haemostatic system