Thymocyte apoptosis and proliferation modeling during rat thymic involution is influenced by ovarian hormones in a thymocyte subset-specific manner

• Main Authors: Arsenović-Ranin Nevena, Nacka-Aleksić Mirjana, Đikić Jasmina, Perišić Milica, Kosec D., Pilipović I., Stojić-Vukanić Zorica, Leposavić Gordana
• Format: Article
• Language: English
• Published: Sciendo 2013-01-01
• Series: Acta Veterinaria
• Subjects: ovariectomy; thymic involution; thymocyte apoptosis; thymocyte proliferation
• Online Access: http://www.doiserbia.nb.rs/img/doi/0567-8315/2013/0567-83151301003A.pdf

The study was aimed to define the putative role of ovarian hormones in shaping thymocyte apoptosis and proliferation during thymic involution. Thymocytes from young adult and middle-aged rats ovariectomized (Ox) before puberty were examined for apoptosis and proliferation. Apoptosis and proliferation were measured in fresh thymocyte suspensions and in their 18-hour cultures, and fresh thymocyte suspensions, respectively. The thymocyte population and the major thymocyte subsets were analyzed following triple staining using anti-CD4 and anti-CD8 monoclonal antibodies and 7-AAD to label apoptotic or proliferating cells. The frequency of apoptotic cells was lower in thymocyte suspensions and cultures from Ox rats of both ages. This reflected in a diminished frequency of apoptotic cells amongst CD4+CD8+ double positive (DP) and CD4+CD8- single positive (SP), and DP cells in young and middle-aged Ox rats, respectively. Additionally, in thymocyte cultures from Ox rats the frequency of apoptotic cells amongst CD4+CD8- and CD4-CD8+ SP cells decreased with age, but increased within DP and CD4-CD8- double negative (DN) subsets, reaching in the former subset from middle-aged Ox rats higher values than in age-matched controls. The frequency of proliferating cells was also lower in Ox rats than in controls. This reflected the lower frequency of cycling cells amongst CD4+CD8- SP and CD4-CD8+ SP thymocytes in young rats, and DP and CD4-CD8+ SP thymocytes in middle-aged rats. Besides, in both SP and DP thymocyte subsets from Ox rats the frequency of proliferating cells declined with age. In conclusion, thymocyte apoptosis and proliferation exhibit ovarian hormone-dependent thymocyte subset specific alterations during thymic involution. [Projekat Ministarstva nauke Republike Srbije, br. 175050]