Glucocorticoid-catecholamine interplay within the composite thymopoietic regulatory network

This paper highlights the multiple putative thymic and extrathymic points of intersection and interaction between glucocorticoids (GCs) and catecholamines (CAs)-the end-point mediators of the major routes of communication between the brain and the immune system-in the context of intricate thymic T cell-developmental tuning. More specifically, we discuss in detail findings indicating that adrenal GCs can influence thymopoiesis by adjusting directly and/or indirectly (through modulation of pituitary and local ACTH synthesis) not only thymic GC synthesis, in a cell type-specific manner, but also thymic CA bioavailability (via altering CA outflow from sympathetic nerve endings and local CA synthesis), beta and alpha(1)-adrenoceptor (AR) expression, and/or AR-mediated intracellular signal transduction in thymic cells. In addition, this short review points to GC-and CA-sensitive stages along the multistep T cell-developmental journey and the possible effects of altered GC, and consequently CA signaling, on thymopoietic efficiency.