ABSTRACT
The effect of male hormones on hemostasis were studied. Mesterolone was injected daily [2 mg/kg] for 4 weeks. In another group castration was done and blood was taken 6 weeks after the operation. The results were compared with normal adult male rats. The parameters used were% platelet aggregability induced by collagen, prothrombin time [PT], activated partial thromboplastin time [APTT] in seconds, fibrinogen level [FIB] in mg/100 ml and antithrombin III% [ATIII%]. The results obtained showed that mesterolone stimulated platelet aggregability while castration inhibited it. Male hormones stimulate platelet aggregability most probably through increased generation of thromboxane A2. PT, APTT and FIB showed no significant change, while ATIII% increased significantly under the influence of mesterolone. These negative results may be due to the absence of a stimulatory effect of male hormones on coagulation factors or an increase in the synthesis of some coagulation proteins occurred but was masked by the increase in ATIII%. Prolonged PT, APTT and decreased FIB level in castrated rats could be due to decrease in protein synthesis due to lack of male hormones in castrated rats