Influence of sex hormones on thrombosis of left atrium in Syrian (golden) hamsters

Abstract

Spontaneous thrombosis of the left atrium is common in aged male and female Syrian (golden) hamsters in our laboratory and occurs at a younger age in females. At necropsy, the thrombus almost completely occludes the swollen atrium and is widely attached to the endocardium Endocrine manipulations unexpectedly influenced the occurrence of these thrombi. Following gonadectomy, development of such thrombi was hastened in male hamsters but was uninfluenced in female hamsters. Testosterone propionate given subcutaneously inhibited left atrial thrombosis in male and female gonadectomized hamsters. Norethynodrel with mestranol given subcutaneously to adult male hamsters was followed by an increased incidence of left atrial thrombosis. This increase may have been due to suppression of endogenous androgen production or action, or both. Microbiological studies of left atrial thrombi were negative. There was no correlation between the occurrence of left atrial thrombi and platelet numbers, prothrombin time, glass-tube clotting time, plastic-tube clotting time, or Russell viper-venom time. Partial thromboplastin time was lengthened in female but not in male hamsters with a left atrial thrombus.