DETERMINATION OF NADPH IN THE RAT-BRAIN DURING SLEEP-WAKE STATES WITHAN OPTIC FIBER SENSOR AND TIME-RESOLVED FLUORESCENCE PROCEDURES

The present paper reports a nanosecond time-resolved fluorescence deri ved from the cortex and the area of the periaqueductal gray including the nucleus raphe dorsalis (PAG-nRD) in unanaesthetized freely moving rats. The measurements were acquired through a single optic fibre tran smitting a subnanosecond nitrogen laser pulse (337 nm, 15 Hz) and coll ecting the brain fluorescence occurring at 460 nm which might depend o n mitochondrial NADH (reduced form of nicotinamide adenine dinucleotid e). The fluorometric method was combined with polygraphic recordings, and this procedure allowed us to define, for the first time, variation s of the 460 nm signal occurring throughout the sleep-wake cycle. In t he PAG-nRD, the signal exhibited moderate heterogeneous variation in a mplitude during slow-wave as compared to the waking state. Constant in creases were observed during paradoxical sleep as compared to the waki ng state. For this state of sleep the magnitude of the variations depe nded on the optic fibre location. In the cortex and during either slow -wave sleep or paradoxical sleep, the signal presented moderate increa ses which were significant during paradoxical sleep. The magnitude of the redox variations observed either in the PAG-nRD or in the cortex m ight be ascribed to the oxidative energy balance which is related to s leep stales. (C) 1997 IBRO. Published by Elsevier Science Ltd.