Comparative aspects regarding MNU-induced mammary carcinogenesis in immature Sprague-Dowley and Whistar rats
Abstract
The research carried out on an experimental mammary cancer model by using two breeds of rat, such as Sprague-Dawley (n=10) and Wistar (n=9) female rats. There have been used immature rats that received intraperitonealy a single dose of methyl-nitroso-urea (55 mg/kg MNU). The rats were kept in optimal conditions of temperature, food and hygiene for 8 months. The Wistar rats were sacrificed by deep narcosis with Halothane, and were harvested samples for histopathology exam. The Sprague-Dawley rats were not slaughtered being utilized still to test the efficacy of some antioxidative agents in mammary cancer prevention. In Wistar rats, mammary tumor incidence was reduced representing 33,3% of all cases. In 22,2% of all cases precancerous mammary lesions occurred. On the other hand, MNU generated a great variability of tumor types in various tissues and organs, such as: liposarcoma, nephroblastoma, bronchial gland carcinoma, hemangiosarcoma, squamous carcinoma, sebaceous gland carcinoma, small cell lung carcinoma and lipoma. Comparing to this, in Sprague-Dawley rats mammary tumor incidence following to MNU-intake was 80% of all cases. Concluding, the most appropriate breed of rat that could be utilized as experimental model to study canine and human mammary cancer is Sprague-Dawley.
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