DIFFERENTIAL-EFFECTS OF CASTRATION IN SEXUALLY IMMATURE AND MATURE RATS ON THE PHENOTYPIC PROFILE OF THYMOCYTES

In order to assess the influence of gonadal hormones on the process of intrathymic T cell-maturation, peripubertal(30 days old) and young ad ult (60 days old) rats were castrated and the total thymic cellularity as well as the cellularity of the main thymocyte subpopulations defin ed by the expression of CD4 and CD8 molecules, and TCRab were analyzed in adult (75 days old) rats. The total yield of thymocytes was signif icantly increased in adults castrated at day 30 over the controls. Als o, the total number of CD4+/CD8+ double positive (DP) thymocytes as we ll as the total number of both the CD4+/CD8- and CD4-/CD8+ single posi tive (SP) and TCR alpha beta positive thymocytes were significantly in creased in these rats. However, castration performed in young adult ra ts affected neither the total thymic cellularity nor the cellularity o f the main thymocyte subpopulations. Results clearly indicate that: a) castration performed before sexual maturity affects the process of in trathymic T cell maturation in adults and b) the process of intrathymi c T cell development is not altered in adults of the same age castrate d in very early adulthood.