Caffeine down-regulates β adrenoreceptors in rat forebrain

Abstract We studied the influence of caffeine treatment (50 mg/kg for 3 doses) on catecholamine utilization and adrenergic receptor binding in female rats. Caffeine enhanced the reduction in forebeain norepinephrine levels following α -methyl- p -tyrosine without altering the reduction in dopamine levels. Caffeine reduced the apparent number of β receptors in forebrain as measured by the B max for [ 3 H]dihydroalprenolol binding. No changes in α 1 or α 2 receptor binding, as measured with [ 3 H]prazosin and [ 3 H]clonidine, respectively, were noted. These data show that caffeine selectively increases the rate of norepinephrine utilization in rat forebrain and that this is associated with a small, but significant, reduction in β receptor density in this brain area.