The sleep of artificially reared newborn rats, effect of alpha-methyl-DOPA treatment on paradoxical sleep and on adult behaviour.

The development of paradoxical sleep was studied in newborn rats separated from their mothers immediately after birth and then fed artificially by an indwelling stomach tube. Development of PS in these animals was qualitatively similar but quantitatively it differed from that of animals remaining with their mother, the daily amount of PS being reduced. The PS depriving effect of alpha-methyl-dopa was studied after single and multiple doses. A 500 mg/kg dose daily led to a 75% continuous reduction. Rats remaining with their mother were injected with alpha-methyl-dopa during the three postnatal weeks. Subsequent tests revealed an increased locomotor activity and a higher rate of acquisition but no disturbance in shuttle-box conditioning. The norepinephrine, dopamine and serotonin content of the whole brain was not affected.