Circadian actions of melatonin at the suprachiasmatic nucleus

Gillette, Martha U.; McArthur, Angela J.

doi:10.1016/0166-4328(96)00085-x

Cited by 107 publications

(58 citation statements)

References 35 publications

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“…During photic induction of nonresponsiveness, changes in coupling presumed to occur in the circadian system-both those that involve changes in τ′ E and τ′ M and those that are not associated with changes in oscillator period-are independent of the pineal gland and short duration nocturnal MEL secretion that accompanies exposure to inductive DLs. In several laboratory models, exogenous MEL influences specific metabolic activity of SCN tissue (Gillette and McArthur, 1995). In Siberian hamsters and other photoperiodic mammals, MEL secretion, the output of a circadian clock, mediates seasonal variation in immune function and hypothalamic neuroendocrine activity (Bartness et al, 1993;Demas and Nelson, 1997).…”

Section: Discussionmentioning

confidence: 99%

Pineal-Independent Regulation of Photo-Nonresponsiveness in the Siberian Hamster (Phodopus sungorus)

Prendergast

Freeman

1999

J Biol Rhythms

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The pineal hormone melatonin influences circadian rhythms and also mediates reproductive responses to photoperiod. The authors tested whether pinealectomy influences circadian oscillators responsible for induction of nonresponsiveness to short day lengths by preventing normal short-day patterns of circadian entrainment. Adult male Siberian hamsters were pinealectomized or sham operated, maintained in either 18 h light per day (18L) or 15L for 10 weeks, and then tested for responsiveness to 10L. Because pinealectomized hamsters do not show gonadal regression in short day lengths, responsiveness was assessed by measuring phase angle of entrainment and the length of the nightly activity period following transfer to 10L. The incidence of nonresponsiveness was significantly higher in 18L hamsters than in 15L hamsters but was unaffected by pineal status. Fully 88% of 18L hamsters failed to entrain to 10L in the normal short-day manner; the duration of nightly activity remained compressed, and the phase angle of entrainment was large and negative relative to lights off. The 15L hamsters entrained normally to 10L. Exposure to constant light after 10L treatment was equally effective in inducing arrhythmicity in pinealectomized and intact hamsters. Changes in the period of morning and evening circadian oscillators subsequent to 18L treatment did not predict circadian responsiveness to short photoperiod. Long-day induction of photo-nonresponsiveness, which prevents winter responses to short day lengths, occurs independently of pineal melatonin feedback on the circadian system.

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Section: Discussionmentioning

confidence: 99%

Pineal-Independent Regulation of Photo-Nonresponsiveness in the Siberian Hamster (Phodopus sungorus)

Prendergast

Freeman

1999

J Biol Rhythms

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“…In contrast to GRs (see above), high densities of MT1 and MT2 receptors in the SCN have been demonstrated (Gillette & McArthur 1996). In rodents, timed daily administration of high concentrations of exogenous melatonin can entrain the free-running endogenous rhythm under constant darkness conditions (Armstrong et al 1986, Redman & Armstrong 1988.…”

Section: Melatoninmentioning

confidence: 99%

Interactions between endocrine and circadian systems

Tsang¹,

Barclay

Oster

2013

Journal of Molecular Endocrinology

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In most species, endogenous circadian clocks regulate 24-h rhythms of behavior and physiology. Clock disruption has been associated with decreased cognitive performance and increased propensity to develop obesity, diabetes, and cancer. Many hormonal factors show robust diurnal secretion rhythms, some of which are involved in mediating clock output from the brain to peripheral tissues. In this review, we describe the mechanisms of clock-hormone interaction in mammals, the contribution of different tissue oscillators to hormonal regulation, and how changes in circadian timing impinge on endocrine signalling and downstream processes. We further summarize recent findings suggesting that hormonal signals may feed back on circadian regulation and how this crosstalk interferes with physiological and metabolic homeostasis.

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“…It is possible to show that the 24 h rhythm of electrical activity persists in vitro for several cycles and is phased in relation to the donor's previous light-dark cycle. Physiological concentrations of melatonin added to the cultures at different circadian times induce substantial phase advances according to a phase-response curve resembling that seen in intact animals using activity-rest as a circadian marker rhythm (Gillette and McArthur, 1996).…”

Section: Target Sites Of Melatonin Influencing Circadian Rhythmsmentioning

confidence: 99%

Melatonin and the pineal gland: influence on mammalian seasonal and circadian physiology

Arendt

1998

Reviews of Reproduction

309

184

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The pineal gland appears to serve the same function in all mammals studied to date. The pattern of secretion of its major hormone, melatonin, conveys information concerning light-dark cycles to the body physiology for the organization of seasonal and circadian rhythms (Arendt, 1995). Recently, much progress has been made in identifying, localizing and characterizing melatonin receptors. This review provides a brief summary of the important features of the production and effects of melatonin that impinge upon its circadian physiology and seasonal functions and that have proved of use in the general study of biological rhythms. Wherever possible, broad reference is made to reviews rather than the original literature. Where no citation is given to publications before 1994, references can be found in Arendt (1995) and other cited reviews.The pineal gland is part of the visual system and mammalian pinealocytes are derived evolutionarily from the pineal photoreceptors of lower vertebrates. The influence of the pineal gland on the circadian system appears to be more important in lower vertebrates than in mammals. In some reptiles and birds, the pineal appears to act as a central circadian rhythm generator. In house sparrows (Passer domesticus), pinealectomy leads to arrhythmicity which can be restored by transplanting a pineal from another bird (Menaker et al., 1981). The circadian phase of the donor bird is conveyed to the host with the transplant. It is possible to culture pineal explants and dispersed pineal cells from fish, lizards and birds, and these preparations retain their circadian melatonin production in vitro. In contrast, the mammalian pineal does not retain endogenous rhythmicity in culture.The retinae of lower vertebrates also generate melatonin rhythms in culture and the hamster retina (maintained at low temperature; Tosini and Menaker, 1996) can show the same phenomenon, which suggests that there may be a circadian pacemaker in the mammalian eye.In contrast to reptiles and birds, pinealectomy in mammals has rather more subtle effects on the circadian system. For example, the rate of resynchronization of rats to a phase shift of the light-dark cycle is faster in pinealectomized than in intact animals, and pinealectomy leads to disrupted circadian rhythms in rats kept in constant light (Armstrong, 1989;Cassone, 1992). The pineal, and indeed melatonin secretion, cannot be regarded as essential in the adult mammalian circadian system given that, in their absence, virtually normal function is maintained.In mammals, the ability to respond to changing artificial daylength in terms of seasonal functions is abolished by pinealectomy or denervation of the gland. In long-lived species, such as sheep and ferrets, pinealectomy leads to desynchronization of seasonal rhythms in reproductive function from the annual periodicity, which suggests that the pineal essentially synchronizes the endogenous cycle to a yearly periodicity. Production of melatoninMelatonin is synthesized within the pineal gland itself, in the ret...

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Circadian actions of melatonin at the suprachiasmatic nucleus

Cited by 107 publications

References 35 publications

Pineal-Independent Regulation of Photo-Nonresponsiveness in the Siberian Hamster (Phodopus sungorus)

Pineal-Independent Regulation of Photo-Nonresponsiveness in the Siberian Hamster (Phodopus sungorus)

Interactions between endocrine and circadian systems

Melatonin and the pineal gland: influence on mammalian seasonal and circadian physiology

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