effect of methotrexate on agnor count in liver of wistar rats

a study was undertaken to evaluate the nucleolar organizing regions (nor) count and histopathological changes in rat’s liver treated with methotrexate (mtx). male wistar rats aged 4 months, maintained in our institution were used in the present study. animals were injected intraperitonealy with 3 different doses of methotrexate on alternative days for one week and the animals were sacrificed on the seventh day by using ether. paraffin slides were prepared and histopathology as well as agnor studies were done. in the histopathological study, liver showed disruption of normal hepatic plates, vaculation of the hepatocytes, nuclear variability and enlarged blood vessels. in agnor study, data showed an overall decrease in the total count (numerical) from normal to 12 mg dose mtx. the total count includes small, medium and large sized agnors. a statistically high significant difference was found from normal to 12 mg dose mtx as well as between the doses. in conclusion, the genotoxicity in rats is well documented with high dose of methotrexate (12 mg/kg) compared to low dose (8 mg/kg). methotrexate treatment reduces the transcription rate and ploidy. methotrexate reduces the cell proliferation. thus it reduces the count.