Sympathetic Regulation of Circadian Rhythm of Serotonin <i>N</i>‐Acetyltransferase Activity in Pineal Gland of Infant Rat

Deguchi, Takao

doi:10.1111/j.1471-4159.1982.tb08700.x

Cited by 25 publications

(8 citation statements)

References 33 publications

(28 reference statements)

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“…These results are similar to those observed in adult [23] or preweanling [8,38] rats and suggest that retinal mechanisms (presumably, photoreceptive cells) appear to be essential in both adult and 7-day-old animals for mediating the light-induced suppression of nocturnal NAT activity.…”

Section: Discussionsupporting

confidence: 77%

“…Light:dark differences and the effect of nocturnal light exposure on NAT activity in developing rats was assessed by individually removing animals of different ages (2,3,4,5,6,7,8 or 60 days old) from their litters and (1) killing them during the middle of the light phase of the lighting cycle; (2) killing them during the middle o f the dark phase (unhandled controls) or placing them in the testing apparatus in dark ness for I min, returning them to their mothers/litters in darkness, and killing them 30 min later (dark-exposed controls), or (3) exposing them to light for 1 min, then returning them to their litters in darkness for 30 min until they were killed. Pineal glands were removed for assay of NAT activity.…”

Section: Methodsmentioning

confidence: 99%

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Light-Induced Changes in Pineal Gland N-Acetyltransferase Activity: Developmental Aspects

Bronstein

Haak²,

Torres³

et al. 1990

Neuroendocrinology

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In adult rats, light acting via a retino-pineal gland neural pathway influences pineal gland biochemistry in two ways: (1) it entrains endogenous circadian rhythms in melatonin biosynthesis to the environmental photoperiod and (2) exposure to even very brief periods of light during the nighttime rapidly suppresses the high levels of nocturnal melatonin production. The present studies were undertaken to determine precisely when photic stimulation first influences the enzymic activity of N-acetyltransferase (NAT), the pineal gland enzyme which rate-limits the overall biosynthesis of the hormone melatonin, and to examine some of the cellular mechanisms which might mediate light-induced effects in neonatal animals. Rats of different ages were either killed during the light phase or were exposed to darkness or light for 1 min during the dark phase of the lighting cycle, returned to their litters in darkness for 30 min and then killed. Pineal gland NAT activity in animals nocturnally exposed to 1 min of light was suppressed in animals 6 days of age or older. Nocturnal light exposure did not suppress enzyme activity in 3- to 5-day-old rats, even though these animals displayed clear light :dark differences in pineal gland NAT activity. Nocturnal light exposure also did not suppress nighttime levels of NAT activity in 7-day-old animals who had been bilaterally enucleated, suggesting that this effect is retinally mediated. Pretreatment of 7-day-old animals with the β-noradrenoceptor agonist drug, isoproterenol, prevented the nocturnal light-induced suppression of NAT activity. In experiments comparing the sensitivity of adult and neonatal rats to different illuminances or durations of nocturnal light exposure, we found that the duration or intensity of light exposure necessary to suppress nocturnal NAT activity was at least 5- to 10-fold greater in 7-day-old rats compared to adult animals. Taken together, these results suggest that the retino-pineal gland pathway appears to mediate light-induced changes in pineal glands of animals 6 days of age or older; however, this pathway does not function in an adult-like manner in neonatal animals.

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Section: Discussionsupporting

confidence: 77%

Section: Methodsmentioning

confidence: 99%

Light-Induced Changes in Pineal Gland N-Acetyltransferase Activity: Developmental Aspects

Bronstein

Haak²,

Torres³

et al. 1990

Neuroendocrinology

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“…In our experiments, exposure of 8-day-old blinded rats to sudden light at night did not affect the high NAT activity. Similarly, the nighttime increase of NAT activity in 12-dayold blinded rats is not affected by additional illumination until midnight [8]. Hence, as far as the pineal NAT rhythm is concerned, the retina is required for the light-induced suppression of the NAT activity in infant rats, just as in adult ones [9,23], and there is no indication for the presence of a non-retinal light perception in immature animals.…”

mentioning

confidence: 94%

Effect of Short and Long Photoperiods on Pineal N-Acetyltransferase Rhythm and on Growth of Testes and Brown Adipose Tissue in Developing Rats

Vanĕcek

Illnerová²

1985

Neuroendocrinology

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The effect of photoperiod on the rhythm in pineal N-acetyltransferase activity and on the growth of testes and of brown adipose tissue was studied in infant rats at the age of 5–15 days. After exposure to light at night, high N-acetyltransferase activity declined in 6-, 7-, and 8-day-old intact rats, but not in 5-day-old intact rats or in 8-day-old blinded rats. Hence, light might penetrate under closed eyelids and might be perceived by retinal photoreceptors in rats older than 6 days. In 15-day-old animals, the amplitude of the N-acetyltransferase rhythm was ten times higher than in 5-day-old rats. The pattern of the N-acetyltransferase rhythm, namely the duration of elevated nocturnal activity, was different under long and short photoperiod at least 1 week before opening of eyes. Photoperiod affected the growth of testes and of interscapular brown adipose tissue already in the preweaning period. In 15-day-old rats, immediately after opening of eyes, the weight of testes was significantly higher and the weight of brown fat lower under long than under short photoperiod. Photoperiodic regulation thus occurs before rats open their eyelids.

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“…We next examined the effect of maternal SCN lesions on the rhythm of pineal NAT activity in lo-d-old pups; the pineal NAT rhythm is one of the first circadian rhythms overtly expressed in rats (Reppert, 1982), and it accurately reflects circadian output from the developing SCN (Deguchi, 1982). Sham and SCN-lesioned pregnant rats were housed in LD throughout pregnancy.…”

Section: Maternal Scn Lesionsmentioning

confidence: 99%

Maternal suprachiasmatic nuclei are necessary for maternal coordination of the developing circadian system

Reppert¹,

Schwartz²

1986

J. Neurosci.

150

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During late fetal and early neonatal life, the maternal circadian system coordinates the timing of a circadian clock in the hypothalamic suprachiasmatic nuclei (SCN) to the prevailing lightdark cycle, The role of the maternal SCN in the process of maternal coordination was investigated in rats. Complete lesions of the maternal SCN on day 7 of gestation disrupted rhythms of SCN glucose utilization in fetuses and pineal IV-acetyltransferase activity in lo-d-old pups. This disruption was probably due to the desynchronization of individually oscillating fetal SCN, because individual pups born to and reared by SCN-lesioned dams under constant conditions exhibited normal circadian rhythms in drinking behavior. Cross-foster studies showed that the maternal circadian system can coordinate developing circadian rhythmicity during either the pre-or postnatal period. The results indicate that the maternal SCN are a necessary component of the mechanism of maternal coordination during both the pre-and postnatal periods.In mammals, the suprachiasmatic nuclei (SCN) of the anterior hypothalamus contain a circadian pacemaker (biological clock) that controls the rhythmic expression ofnumerous physiological processes (Moore, 1983;Rusak and Zucker, 1979). The daily light-dark cycle entrains the SCN pacemaker to the 24 hr day primarily through a monosynaptic retinohypothalamic pathway to the nuclei (Moore, 198 1).We recently used the '%-labeled deoxyglucose (dG) autoradiographic method to examine the functional activity of the SCN clock during fetal development. The results of our dG experiments in rats show that the SCN are already oscillating during late prenatal life Schwartz, 1983, 1984); the fetal nuclei manifest a daily rhythm of glucose utilization (energy metabolism) with high activity during the day and low activity at night. We also showed that the fetal SCN are not directly synchronized by light that penetrates the maternal abdomen and uterus. Instead, it is the maternal circadian system that coordinates the timing (phase) ofthe fetal SCN to prevailing lighting conditions. The maternal circadian system continues to coordinate the developing circadian system during the early postnatal period (Reppert, 1985). Maternal coordination wanes after the first week of life Takahashi and Deguchi, 1983) as the neonatal rat begins to respond to light directly through its own retinohypothalamic pathway (Reppert, 1984).Received Nov. 7, 1985; revised Feb. 18, 1986; accepted Feb. 20, 1986. We thank Robert Coleman, Matthew Morton, and Mark Banister for technical assistance, and Dr. The present studies were designed to examine the role of the maternal SCN in the mechanism of maternal coordination. For these studies, lesions of the maternal nuclei were performed on day 7 of gestation, and the subsequent effects on 3 parameters of circadian development in the offspring were monitored, SCN glucose utilization was examined during prenatal life, while pineal N-acetyltransferase (NAT) activity and drinking behavior were monitored during the postn...

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Sympathetic Regulation of Circadian Rhythm of Serotonin N‐Acetyltransferase Activity in Pineal Gland of Infant Rat

Cited by 25 publications

References 33 publications

Light-Induced Changes in Pineal Gland N-Acetyltransferase Activity: Developmental Aspects

Light-Induced Changes in Pineal Gland N-Acetyltransferase Activity: Developmental Aspects

Effect of Short and Long Photoperiods on Pineal N-Acetyltransferase Rhythm and on Growth of Testes and Brown Adipose Tissue in Developing Rats

Maternal suprachiasmatic nuclei are necessary for maternal coordination of the developing circadian system

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