Early postnatal castration affects thymic and thymocyte noradrenaline levels and beta-adrenoceptor-mediated influence on the thymopoiesis in adult rats

Abstract

The interactions among the nervous, endocrine and immune system were studied by examining: i) thymic and thymocyte catecholamine levels in adult rats castrated (Cx) at postnatal day 3 and ii) effects of 14-day-long propranolol (P) treatment on main thymocyte differentiational molecule expression in adult non-Cx and Cx rat. The results demonstrated that castration in early postnatal period lowers levels of both neurally- and thymocyte-derived noradrenaline in adult rats, and thereby diminishes beta-adrenoceptor-mediated fine tuning of the T-cell differentiation/maturation. In non-Cx rats P affected TCR alpha beta-dependent stages of thymocyte differentiation/maturation decreasing frequency of CD4+8+ double positive (DP) TCR alpha beta(low) low cells entering selection processes and increasing relative number of positively selected DP TCR alpha beta(high) (most likely due to an increased thymocyte surface density of Thy-1 that is involved in negative control of TCR alpha beta-mediated signaling/selection thresholds) and the most mature CD4+8- TCR alpha beta(high) cells (including CD4+25+ regulatory cells). However, in Cx rats P failed to produce any significant changes in thymocyte subset composition.