ABSTRACT
Spleen is an organ that plays a major role in body's immune system and can affect some medicines on it. The purpose of this study is to examine the chronic effect of Methylphenidate on plasma cells and the morphometric and histomorphometric changes in spleen. In this study, a total of 18 adult male mice were divided into one control and two experimental groups. The experimental groups received Methylphenidate 2 and 10 mg/kg body weight, daily by gavage for 40 days. After the treatment, the number of plasma cells, morphometric and histomorphometric changes in spleen and also the weights of mice were studied. The results showed that there is a significant statistical difference between the control and experimental groups in the number of plasma cells, morphometric and histomorphometric structures of spleen and also in the body weight [p<0.05]. The results of this study indicate the harmful effect of Methylphenidate on spleen - an organ that has a major role in body's immune system