Increase of dopamine D2(High) receptors in the striatum of rats sensitized to caffeine motor effects.

It has been previously demonstrated how rats can develop behavioral dopamine supersensitivity after long-term administration of caffeine. Since behavioral dopamine supersensitivity in rats is usually accompanied by an elevation in striatal dopamine D2(High) receptors, we examined whether alterations in D2(High) receptors occurred in the striatum of rats administered caffeine according to a regimen capable of eliciting behavioral dopamine supersensitivity (15 mg/kg i.p. every other day for 14 days). An increase of 126% in striatal D2(High) receptors was found in caffeine-sensitized rats. This marked elevation in D2(High) receptors may account for the caffeine-induced behavioral dopamine supersensitivity and may help elucidate the interactions between caffeine and dopamine neurotransmission. (c) 2008 Wiley-Liss, Inc.