PARADOXICAL SLEEP-DEPRIVATION INCREASES THE CONTENT OF GLUTAMATE AND GLUTAMINE IN RAT CEREBRAL-CORTEX

We investigated the influence of the sleep/waking cycle, the effects o f paradoxical sleep deprivation (PSD) and of the vigilance-promoting d rug modafinil on the amino acid contents of rat brain cortex. No signi ficant nycthemeral variations in amino acid levels could be detected. PSD (12-24 hours), using the water tank method, significantly increase d the levels of glutamate and glutamine. The increase was still observ ed after the sleep rebound period. gamma-Aminobutyric acid (GABA) leve ls did not change significantly during the instrumental sleep deprivat ion but increased during the rebound period. Control experiments indic ate that the increase in glutamate and glutamine levels is due to PSD rather than to the stress associated with the experimental procedure. The increase in glutamate content cannot arise only from transaminatio n reactions, because the levels of other amino acids (such as aspartat e) did not decrease. Modafinil treatment did not significantly modify the brain cortex content of any of the amino acids tested.