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 3H-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 (KD). 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 3H-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.
- β-adrenoceptor desensitization
ASJC Scopus subject areas
- Behavioral Neuroscience