20 - Alterations in Neonatal Sexual Differentiation Affect T-cell Maturation

Abstract

This chapter presents a study on how alterations in neonatal sexual differentiation affect T-cell maturation. Ten pregnant Albino Oxford (AO) rats were used for the purpose of this study, and litters were assigned randomly to an experimental condition, 5 to oil and 5 to testosterone-acetate (TA) treatment. On the second postpartum day, one group of female offspring was removed from their mothers and injected subcutaneously with 2.5 mg testosterone-acetate (TA) treatment in 50 μl vegetable oil. The study shows that in female rats androgenized by a single injection of TA on the second postnatal day and sacrificed at age either 30 or 75 days, the thymic yield was significantly reduced compared with age-matched controls. In the peripubertal TA-treated rats, the percentage of CD4+8+ double positive (DP) cells was reduced, whereas the percentages of CD4–8– double negative (DN) and CD4+8– single positive (SP) cells were increased. These data, coupled with an increase in the percentage of cells with high expression of TCRαβ, implicate an increase in the percentage of CD4+8– cells in a final stage of maturation. In adult TA-treated rats, a decrease in the percentages of both CD4+8– cells and thymocytes with high expression of TCRαβ+ was found. These findings suggest a reduction in the percentage of CD4+8– cells in a final stage of maturation, and changes in the development of hypothalamo-pituitary-gonadal (HHG) axis can affect the process of intrathymic T-cell maturation.