Caffeine down-regulates beta adrenoreceptors in rat forebrain.
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 forebrain norepinephrine levels following alpha-methyl-p-tyrosine without altering the reduction in dopamine levels. Caffeine reduced the apparent number of beta receptors in forebrain as measured by the Bmax for [3H]dihydroalprenolol binding. No changes in alpha1 or alpha2 receptor binding, as measured with [3H]prazosin and [3H]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 beta receptor density in this brain area.
D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D001921:Brain / Q000187:drug effects*; D002110:Caffeine / Q000494:pharmacology*; D003000:Clonidine / Q000378:metabolism; D004082:Dihydroalprenolol / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism; D005260:Female; D008781:Methyltyrosines / Q000494:pharmacology; D009638:Norepinephrine / Q000378:metabolism; D011224:Prazosin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000187:drug effects*; D011943:Receptors, Adrenergic, beta / Q000187:drug effects*; D009435:Synaptic Transmission / Q000187:drug effects*; D019805:alpha-Methyltyrosine
D008781:Methyltyrosines; D011941:Receptors, Adrenergic; D011943:Receptors, Adrenergic, beta; D002110:Caffeine; D004082:Dihydroalprenolol; D019805:alpha-Methyltyrosine; D003000:Clonidine; D004298:Dopamine; D009638:Norepinephrine; D011224:Prazosin