Effects of L-erythro-3, 4-dihydroxyphenylserine on sleep-wakefulness patterns and concentrations of brain catecholamines and serotonin in rats.

The effects of 3,4-dihydroxyphenylserine (DOPS), a nonnatural precursor of noradrenaline, on the sleep-wakefulness patterns of rats were studied. When the animals received an intraperitoneal injection of L-erythro-DOPS (200 mg/kg), a significant increase in slow wave sleep and a tendency to decrease wakefulness were observed during the first 2 hours after the injection. Paradoxical sleep increased 4-8 hours after the treatment. A simultaneous injection of benserazide (20 mg/kg) enhanced these effects. L-threo-DOPS (200 mg/kg, i.p.) had no effect on the sleep-wakefulness patterns. The effects of DOPS on the concentrations of brain catecholamines and serotonin in rats were also examined. An intraperitoneal injection of L-erythro-DOPS markedly increased the concentration of noradrenaline (probably the d-form) and decreased that of serotonin and dopamine. L-threo-DOPS had no effect on the brain monoamine levels of the rats in the present experimental condition. The effects of L-erythro-DOPS on the neurons containing noradrenaline in the rats were examined by fluorescence histochemistry. Fluorescence in the neuronal perikarya and fibers containing noradrenaline markedly increased in the n. coeruleus, n. paraventricularis and cerebral cortex after an intraperitoneal injection of amino acid. Fibers containing the fluorescence also increased in the second two areas.