CHRONIC CAFFEINE ALTERS THE DENSITY OF ADENOSINE, ADRENERGIC, CHOLINERGIC, GABA, AND SEROTONIN RECEPTORS AND CALCIUM CHANNELS IN MOUSE-BRAIN

1. Chronic ingestion of caffeine by male NIH strain mice alters the de nsity of a variety of central receptors. 2. The density of cortical A1 adenosine receptors is increased by 20%, while the density of striata l A2A adenosine receptors is unaltered. 3. The densities of cortical b eta1 and cerebellar beta2 adrenergic receptors are reduced by ca. 25%, while the densities of cortical alpha1 and alpha2 adrenergic receptor s are not significantly altered. Densities of striatal D1 and D2 dopam inergic receptors are unaltered. The densities of cortical 5 HT1 and 5 HT2 serotonergic receptors are increased by 26-30%. Densities of cort ical muscarinic and nicotinic receptors are increased by 40-50%. The d ensity of cortical benzodiazepine-binding sites associated with GABA(A ) receptors is increased by 65%, and the affinity appears slightly dec reased. The density of cortical MK-801 sites associated with NMDA-glut aminergic receptors appear unaltered. 4. The density of cortical nitre ndipine-binding sites associated with calcium channels is increased by 18%. 5. The results indicate that chronic ingestion of caffeine equiv alent to about 100 mg/kg/day in mice causes a wide range of biochemica l alterations in the central nervous system.