Article Response of thymus lymphocytes to streptozotocin-induced diabetes and exogenous vitamin C administration in rats † Dils ¸ ad Ozerkan, 1, *, Nesrin Ozsoy 2 , and Suna Cebesoy 2 1 Department of Biology, Faculty of Arts and Sciences, Kastamonu University, 37100, Kastamonu, Turkey, and 2 Department of Biology, Faculty of Science, Ankara University, 06100, Tandogan/Ankara, Turkey *To whom correspondence should be addressed. E-mail: dilsadokan@gmail.com † Presented in part as an abstract at the 34th Federation of European Biochemical Societies (FEBS) Congress, Prague, Czech Republic, 4–9 July 2009. Received 22 December 2013; Accepted 27 July 2014 Abstract Diabetes causes oxidative stress, which in turn generates excessive free radicals resulting in cellular damage. Vitamin C is an antioxidant that protects tissues and organs from oxidative stress. The thymus is one of the most important lymphoid organs, which regu- lates T-lymphocyte proliferation and maturation. The aim of this study is to investigate the protective effects of vitamin C on the thymus of streptozotocin (STZ)-induced diabetic rats. The mitotic activity and cell integrity of thymic lymphocytes were explored. Wistar Albino rats were divided into three groups: control (Group 1), STZ-diabetes (Group 2) and vitamin C-treated STZ-diabetics (Group 3). Rats received a single intraperitoneal injection of 45 mg/kg STZ to induce diabetes. Vitamin C (20 mg/kg) was administered intragastrically. Semithin and ultrathin sections were examined under a light or an electron microscope, respectively. Considerable numbers of mitotic lymphocytes were observed in the thymus of control rats. In the diabetic rats, however, numbers of mitotic lymphocytes decreased to ∼57% of controls, and cell division abnormalities were observed. Additionally, diabetic rats showed degeneration in the structure of the thymus including trabecular thickening, accumulation of lipid vacuoles, heterochromatic nuclei and loss of mitochondrial cristae. Degradation of medullar and cortical integrity was also detected. In the vitamin C-treated STZ-diabetic group, the structure of the thymus and mitotic activity of the lymphocytes were similar to the control group. These results suggest that vitamin C protects the thymus against injury caused by diabetes and restores thymocyte mitotic activity. Key words: thymus, vitamin C, diabetes, electron microscope, mitotic activity Microscopy, 2014, 409–417 doi: 10.1093/jmicro/dfu029 Advance Access Publication Date: 21 August 2014 © The Author 2014. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com 409 by guest on January 6, 2016 http://jmicro.oxfordjournals.org/ Downloaded from