Autoradiographic analysis of D1 and D2 dopaminergic receptors in rat brain after paradoxical sleep deprivation.

Previous work had shown that paradoxical sleep deprivation (PSD) results in potentiation of several apomorphine-induced behaviors, leading to the suggestion that PSD induces an upregulation of brain dopamine receptors. In this study, quantitative receptor autoradiography was used to verify whether PSD does, in fact, induce alterations in D1 or D2 receptor binding, and to investigate the regional brain specificity of such effects. After 96 h of PSD, [3H]SCH-23390 binding to D1 receptors was examined in 30 different brain areas of 10 experimental and 10 cage control rats. [3H]Spiperone was used to label D2 sites in adjacent tissue sections. Results revealed a 39% increase in [3H]SCH-23390 binding in the entorhinal cortex of PSD rats (p < 0.05), but no other changes in any of the remaining 29 brain areas examined. In contrast, [3H]spiperone binding was significantly elevated in the n. accumbens (+45%) and in all subregions of the caudate-putamen (range: +13% to +23%). These results, thus, provide evidence that PSD increases D2 but not D1 receptor binding in brain. The present results also suggest that upregulated D2 receptors can account for the previously reported changes in apomorphine-induced behaviors after PSD.