Influence of Synchronized Sleep on the Biosynthesis of RNA in Two Nuclear Classes Isolated from Rabbit Cerebral Cortex

The biosynthesis of RNA during sleep has been studied in two purified nuclear fractions, separated from rabbit cerebral cortex after subarachnoidal injection of radioactive orotate. The biochemical parameters have been referred to the percent EEG synchronization recorded during the period of incorporation (1 hr). The content of radioactive RNA per nucleus increases significantly with percent synchronization in the fraction of large nuclei (of neuronal and astroglial origin). While sedimentation and electrophoretic analyses of this RNA are consistent with the hypothesis of an enhanced turnover of rRNA during wakefulness, the accumulation of labelled RNA which is observed during sleep may be due to a modified turnover of nuclear heterogeneous RNA. On the other hand, in the fraction of small nuclei (mostly of oligodendroglial origin) the content of radioactive RNA per nucleus and the pattern of sedimentation of labelled RNA show no dependence on the electrical state of the cortex. These data indicate that in the cerebral cortex the sleep-wakefulness transition is accompanied by a different cellular response in RNA turnover.