Does rapid-eye-movement sleep play a role in brain development?
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Animals↗
Biomedical subjects
M Mirmiran
Publications and source records attributed to M Mirmiran.
The function of fetal/neonatal rapid eye movement sleep.
The hypothesis is put forward that rapid eye movement (REM) sleep in early life serves as (1) an indicator for the degree of brain maturation and (2) the promoter of further brain development. This hypothesis, although not exclusive, differs (a) from the theory of Roffwarg et al. that REM sleep substitutes for 'wakefulness' during the period (early life) in which wakefulness is limited, (b) from the theory of Crick and Mitchson, i.e., the 'unlearning' hypothesis of REM sleep, (c) from the theory of Jouvet, i.e., that REM sleep is a time for genetic read-out and (d) from the theory of Freud, i.e., that dreams fulfil our wishes (in other words, activation of neuronal systems that were disproportionally activated during wakefulness).
Child↗
Effects of a novel melatonin analog on circadian rhythms of body temperature and activity in young, middle-aged, and old rats.
Circadian rhythms of body temperature and activity were recorded in young, middle-aged, and old rats. A new melatonin analog, S20242, was administered daily around the onset of darkness for a 2-week period. Compared to the young animals, there was a significant age-related reduction in the amplitude and stability of body temperature and activity in both the middle-aged and old rats. In these two groups there was an improvement of the circadian rhythm of body temperature as a result of daily application of the melatonin analog.
Aging↗
Hippocampal neuronal responsiveness to different neurotransmitters in the adult rat after neonatal interference with noradrenaline transmission.
In order to test the functional significance of noradrenergic neurotransmission for brain maturation, rat pups were injected daily with clonidine from 8-21 days of postnatal life. In adulthood, single cell responses to microiontophoretically applied neurotransmitters were studied in different layers of the hippocampus. No significant differences were found in neuronal responsiveness to glutamate, GABA, or acetylcholine in the hippocampus of clonidine-treated rats as compared with age-matched controls. However, there was a significantly stronger depression of glutamate-evoked activity of CA1 pyramidal neurons by noradrenaline in the clonidine-treated rats.
Acetylcholine↗
Circadian rhythms in early human development.
The body temperature, heart rate and rest-activity cycles of 12 low-risk preterm infants (29-35 weeks) were continuously recorded in the neonatal intensive care unit over a period of 1-2 weeks. Throughout the recordings the light was on continuously, the feeding was done intra-gastrically every 2 h and the incubator temperature was constant. Under such conditions a significant circadian rhythm was found in the body temperature and heart rate of more than 50% of the infants. These findings indicate the possible existence of an endogenous circadian rhythm in early human infancy. Since lights are continuously on in the neonatal intensive care unit, this might impair the time of emergence of day-night entrainment of the biological clock in preterm infants.
Body Temperature↗
Neurobehavioral teratogenic effects of clomipramine and alpha-methyldopa.
Neonatal treatment of rats with centrally acting drugs such as clomipramine was shown to affect adult body and brain weight, behavior and sleep. We made a further study of the effects of clomipramine and tested one dose of alpha-methyldopa. Male rats were treated twice daily with saline, 7.5 or 15 mg/kg clomipramine or 100 mg/kg alpha-methyldopa from postnatal day 2-14 and tested in adulthood for effects on acquisition of radial maze behavior, on problem solving behavior in Hebb-Williams mazes, sexual performance and sleep-wake patterns. Clomipramine-treated rats had reduced body weight. No effects of neonatal drug treatment were found on several measures in the two mazes. Ejaculating rats in all three treatment groups showed longer latencies for sexual behavior and clomipramine-treated rats showed fewer ejaculations. Clomipramine-treated rats spent more time sleeping than the controls during the 24 hr sleep-wake recordings in adulthood.
Animals↗
Vasoactive intestinal polypeptide neuron changes in the senile rat suprachiasmatic nucleus.
The suprachiasmatic nucleus (SCN) is thought to be the main neuronal oscillator underlying circadian rhythmicity of different biological phenomena such as sleep-wakefulness and body temperature. Although numerous studies in old rats showed that circadian organization is clearly disturbed in senescence, no decrease in total SCN cell number has been observed. However, in an earlier study we found a significant decrease of approximately 30% in the number of immunocytochemically-stained vasopressin (VP) neurons in the SCN of the old rat. The aim of the present study was to examine whether another group of SCN neurons, i.e., the vasoactive intestinal polypeptide (VIP) cells, shows age-related changes parallel with disturbances found in sleep/wake parameters. Immunocytochemical staining with antiVIP followed by morphometric analysis revealed a 36% decrease in the number of immunoreactive VIP neurons in the SCN of old rats as compared to young ones. The average size of the remaining VIP cells increased in aged rats. The rapid-eye-movement (REM)-sleep time was negatively correlated with the immunoreactive VIP cell number in the old animals. VP and VIP alterations in the SCN may constitute an anatomical substrate for the circadian disturbances observed in senescence.
Aging↗
Neurochemical and electrophysiological disturbances mediate developmental behavioral alterations produced by medicines.
Many centrally acting drugs which are prescribed for hypertension, depression, epilepsy, insomnia and asthma may also affect fetal brain neurotransmission and behavioral states. Nearly all these drugs enter the fetal circulation following maternal administration. The immaturity of the blood-brain barrier and greater accumulation in the developing brain make the fetal brain a major target of its mother's medication. Adverse effects that are seen in the fetus are not necessarily evident in its mother. We have shown that drugs like clonidine (an antihypertensive) and clomipramine (an antidepressant), which act on noradrenaline and serotonin neurotransmission in the brain, suppress rapid eye movement sleep in the developing rat. In adulthood, the neonatally treated rats showed hyperactivity, hyperanxiety, reduced sexual behavior, disturbed sleep patterns and reduced cerebral cortical size. Furthermore, such treatment induced an increase in voluntary alcohol consumption and a decreased adaptability of responses to changes in water deprivation in a Y-maze. Little is known about long-lasting consequences of centrally acting drugs used during late gestation in humans. Minor neurological disturbances, such as delayed visual motor performance, smaller head circumference, increased anxiety and disturbed sleep-wake patterns, have been reported in children born to hypertensive mothers treated with clonidine or alpha-methyl-dopa.
Aging↗
Survey of sleeping position after hospital discharge in healthy preterm infants.
OBJECTIVE: To evaluate the prevalence of nonprone (supine or side) versus prone sleeping position in healthy preterm infants. STUDY DESIGN: A questionnaire on sleeping position was mailed to mothers of 167 preterm infants discharged from the intermediate nursery at Packard Children's Hospital at Stanford. The prevalence of nonprone sleeping at 1 month (term corrected age) and 3 months (2 months corrected age) after nursery discharge was analyzed by an unpaired t test. RESULTS: Nonprone position sleeping occurred in 64% initially and dropped to 35% at 2 months corrected age. CONCLUSIONS: Overall, nonprone sleeping was widespread in our healthy preterm infants after hospital discharge but may not persist. A majority of these infants were sleeping prone during a high-risk period for sudden infant death syndrome.
Child Development↗