Cellular mechanism of estrogen-induced thymic involution in wall lizard: caspase-dependent action

Journal of Experimental Zoology. Part A, Comparative Experimental Biology
B Hareramadas, U Rai

Abstract

The present study, for the first time in an ectothermic vertebrate, demonstrates the cellular mechanism of estrogen-induced thymic involution. Ovariectomy in lizards during the preparatory phase of the reproductive cycle resulted in distinct differentiation of cortico-medullary regions and increase in cellularity, especially in the cortical region. The ovariectomy-induced changes were reversed following administration of 17-estradiol (E2), suggesting a primary role of E2 in causing thymic atrophy. To understand the cellular mechanism of E2-induced thymic atrophy, in vitro effect of E2 was investigated on thymocyte proliferation and apoptosis. E2 decreased the uptake of tritiated thymidine (3H-TdR) by thymocytes in a dose-dependent manner, suggesting that estrogen directly inhibits the thymocyte proliferation. Unlike proliferation, E2 did not have any direct effect on thymocyte apoptosis, as evident by DNA gel electrophoretic, flow cytometric or fluorescence microscopic studies. However, in the presence of thymic epithelial cell-rich stromal components (TEC), E2 treatment at low or high concentrations resulted in depolarization of plasma membrane, DNA fragmentation and decrease in DNA content. This suggests that E2 indirectly, t...Continue Reading

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Citations

Aug 31, 2012·The Anatomical Record : Advances in Integrative Anatomy and Evolutionary Biology·Stephanie Lynn DelormeMatthew Kenneth Vickaryous
Jul 13, 2016·Developmental and Comparative Immunology·Helmut SegnerMagdalena Chadzinska
Apr 2, 2021·The Journal of Experimental Biology·Matthieu PaiolaTiphaine Monsinjon
Jun 12, 2021·Frontiers in Immunology·Mingli LuoXi Sun
Aug 24, 2021·The Journal of Experimental Biology·Matthieu PaiolaTiphaine Monsinjon

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