Stress induced desensitization of lymphocyte β-adrenoceptors in young and aged rats

Abstract The effects of different times of immobilization stress on intact lymphocyte β-adrenoceptors and plasma corticosterone were compared in 3-month and 24-month-old rats. In young animals after 30 min restraint 3 H-dihydroalprenolol specific binding was significantly reduced (61% of control value) and plasma corticosterone significantly raised (186% of control). The effect on β-adrenoceptors was due to changes in receptor number (Bmax) without any effect on affinity (K D ). In aged rats both effects were only seen after 180 min restraint and were less pronounced. Isoproterenol treatment in vitro reduced β-adrenoceptors on lymphocytes. This effect was less pronounced in lymphocytes from aged rats. Corticosterone in vitro increased 3 H-dihydroalprenolol specific binding. We therefore suggest that the decrease of β-adrenoceptors reflects an adaptive response to the stress-induced catecholamine release and that corticosterobe could play a role in reversing this effect. This adaptive response to stress seems to be impaired in aged animals.