Active immunization against gonadotropin-releasing hormone affects thymic T cell production, migration, and colonization in male rat lymphoid tissue.

Active immunization against gonadotropin-releasing hormone (GnRH) inhibits animal reproduction and has become a friendly alternative to surgical castration, which has been reported to affect the proportion of thymic T cell subpopulations. The effects of active immunization against GnRH on T cell migration from the thymus to the periphery and T cell distribution in lymphoid tissues remain unclear. Here, we showed that active immunization against GnRH increased thymic size and weight, enlarged the number of thymocytes, and enhanced CD4 recent thymic emigrants (RTEs) and CD8 RTEs migration to the blood and spleen. Active immunization against GnRH had no significant effect on naïve CD4, naïve CD8, CD4 memory/activated, or CD8 memory/activated T cells. In addition, active immunization against GnRH increased the proportion of CD3 T cells in the spleen and lymph nodes. The percentages of CD3CD4 and CD3CD8 T cells in the blood, spleen, and lymph nodes were not significantly affected by GnRH immunization. Overall, these results enhance our understanding of thymic T cell production, migration, and colonization in rat lymphoid tissues affected by GnRH immunization.