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.
Prolonged administration of norethynodrel with mestranol had a pronounced and selective influence on hormonal target tissues in middleaged male hamsters. Results were compatible with work in other species, which shows the primary site of action to be the pituitary-gonad axis. Markedly reduced gonadotrophin and androgen levels were indicated by atrophy of testes and accessory reproductive glands. The high dosage used also resulted in significant renal hypertrophy, but structural integrity was not conspicuously different from that of controls.
The test agents had no influence on the incidence or metastatic propensity of a wide variety of spontaneous tumours, including adenomatous polyps and adenocarcinoma of the intestine, adrenal cortical nodular hyperplasia or adenoma, islet cell adenoma, melanoma, or adenocareinoma of Cowper's gland. This result is in accord with our previous observations that spontaneous tumorigenesis in the hamster is largely independent of hormonal physiology but is influenced by hormones to the extent that tumorigenesis may require some degree of normal tissue or cell integrity.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.