Restoration of paradoxical sleep by cerebrospinal fluid transfer to PCPA pretreated insomniac cats.

In p-chlorophenylalanine (PCPA) pretreated insomniac cats, the intraventricular (i.v.t.) injection of artificial cerebrospinal fluid (CSF) did not impair the insomnia. CSF transfer from normal cats was followed in 4 out of 9 cats by the restoration of paradoxical sleep (PS). However, CSF transfer from paradoxical sleep deprived cats did result in 12 out of 13 experiments in a significant increase in slow wave sleep (SWS) and the induction of PS. Biochemical analysis of the CSF from normal or PS deprived cat has shown that the highest quantity of indolamines was at least 1000 times smaller than the threshold dose of 5-HTP (200 microgram) which has been shown to be able to restore sleep by i.v.t. injection in PCPA pretreated insomniac cats. These experiments provide evidence that the transfer of a small quantity of CSF (250 microliter) from a previously paradoxical sleep deprived cat can restore paradoxical sleep in an insomniac PCPA pretreated cat in bypassing the biosynthesis of serotonin (5-HT). These results suggest that a 'paradoxical sleep inducing factor' may be stored in the central nervous system during sleep deprivation.