SEX DIFFERENCE IN THE INHIBITORY EFFECT OF ASPIRIN UPON THE DEVELOPMENT OF OCCLUSIVE ARTERIAL THROMBOSIS IN RATS

Abstract

The aim of the study was to investigate the effect of aspirin upon the development of occlusive arterial thrombosis in rats of either sex. For this purpose 3 months old male and female Wistar rats were pretreated with three different doses of aspirin: 10, 30 and 60 mg/kg b.w., orally by stomach tube, 3 hours before the thrombosis procedure. Occlusive arterial thrombosis was induced by the method of Hornstra and Vendel-mans-Starrenburg (1973). The dry thrombus weight (TW) and the obstruction time (OT) of the bypass-cannula served as criteria for the degree of the development of thrombosis.The results showed a dose-dependent statistically significant inhibition of arterial thrombosis in male rats by all doses of aspirin studied. TW was decreased 2, 2.5 and 9 times by 10, 30 and 60 mg/kg aspirin respectively. OT was significantly prolonged in male rats by all doses of aspirin studied. Inhibition of arterial thrombosis in female rats was achieved only by the largest dose of aspirin tested - 60 mg/kg: TW was decreased and OT was prolonged. Paradoxically, female rats treated with 10 mg/kg aspirin showed a tendency for augmentation of arterial thrombosis which contrasted to the significantly decreased TW and prolonged OT of male rats given 10 mg/kg aspirin. Female rats treated with 30 mg/kg aspirin showed only a tendency for inhibition of arterial thrombosis without any significant difference for both, TW and OT. The results were interpreted as suggestive the existance of sex differences in cyclooxygenase inhibition by aspirin and/or the prostaglandin system in rats. The data obtained were in agreement with epidemiological observation of uneffectiveness of aspirin treatment of female patients with stroke. They also showed the need for the most appropriate dose of aspirin for clinical purposes which might be effective in females too.