GLUCOCORTICOID RECEPTORS IN HUMAN PERIPHERAL-BLOOD MONONUCLEAR-CELLS IN RELATION TO AGE AND TO SPORT ACTIVITY

Glucocorticoid receptors (GR) are ubiquitous molecules and are present also in the hippocampus and in several other nervous and immune tissu es. Peripheral blood mononuclear cells (PBMCs) are a good model for st udies of GR in humans. Glucocorticoids are important for maintaining c ellular and humoral homeostasis and are key mediators of neuroendocrin e-immune regulatory interactions. The increase of cortisol is immunosu ppressive and reduces GR concentration both in nervous and immune syst ems. Variation of glucocorticoids in healthy aged subjects and athlete s has been shown. Prompted by these results, we have investigated in m an a possible relationship between GR binding capacity in the PBMCs an d age, in relation also to plasma testosterone and cortisol. The same parameters have been examined in a group of soccer players for compari son with the sedentary group. GR binding capacity was higher in younge r subjects than in older ones, and lower in the group of athletes than in the younger and older sedentary subjects. In the sedentary group a negative correlation was present between GR binding capacity and age. Plasma cortisol was higher and testosterone lower in the athletes; th ey were negatively correlated in athletes and positively correlated in the sedentary subjects. The results for athletes agree with their low er anabolic/catabolic balance. The mechanism of reduced GR levels in r elation to age and sport activity could involve a loss or an involutio n of receptor synthesis. However other possibilities, such as altered distribution of lymphocyte subpopulations with different receptor conc entrations and with different cytokine production, cannot be excluded. Several neuroendocrine-immune interactions could be responsible for r educed GR levels with age and sport activity in man.