GABA release from suprachiasmatic nucleus terminals is necessary for the light-induced inhibition of nocturnal melatonin release in the rat

Kalsbeek, Andries; Cutrera, Rodolfo A.; Heerikhuize, J.J. van; Vliet, Jan van der; Buijs, Ruud M.

doi:10.1016/s0306-4522(98)00635-6

Cited by 87 publications

(52 citation statements)

References 81 publications

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“…They could also account for suppression of melatonin production during the (subjective) day. In a more recent report the same group [19]suggested the posterior two thirds of the PVH may be a major site where SCN-GABAergic projections mediate the suppressive effect of nocturnal light on melatonin production. Moreover, they raised the possibility of a complementary GABAergic projection from the DMH to the PVH, acting as a parallel pathway to potentiate SCN effects on the control of melatonin production.…”

Section: Discussionmentioning

confidence: 99%

“…In addition, Kalsbeek et al [18]suggested in 1996, on the basis of a series of microdialysis and microinfusion experiments, that the dorsal hypothalamus, and in particular the DMH, a known target of GABAergic inputs from the SCN, may be part of the neural circuit responsible for the low levels of diurnal melatonin production and for the suppressive effect of acute nocturnal exposure to light on pineal melatonin synthesis. In a more recent report, they also suggested [19]that the critical region for SCN-GABA inhibition of melatonin synthesis could be the posterior two thirds of the PVH, a region which contains the spinal-projecting parvocellular neurons considered to mediate central control of spinal autonomic functions [20]. A role for the DMH in this process, however, was not excluded, since it was suggested that DMH-GABAergic projections to the PVH may participate in the light-evoked GABA inhibition in that nucleus, enhancing the direct effect exerted by the SCN.…”

Section: Introductionmentioning

confidence: 99%

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Lesions of the Dorsomedial Hypothalamic Nucleus Do Not Influence the Daily Profile of Pineal Metabolism in Rats

et al. 2001

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The present study attempted to characterize the effects of electrolytic lesions of the hypothalamic dorsomedial nucleus on the daily profile of pineal metabolism as well as on the inhibition of pineal melatonin synthesis induced by acute light exposure during the night. Adult male Wistar rats (n = 107, 12:12 h light-dark cycle) were left intact (n = 47) or lesioned (n = 60). Lesioned rats and their respective controls were killed at six time points distributed throughout the light-dark cycle. At ZT (zeitgeber time) 18 the animals were killed either in the dark or after 15 min of light stimulation. Pineal glands were assayed using high-performance liquid chromatography with electrochemical detection (HPLC-ED). There was no difference in the amounts of pineal indoles between lesioned and control rats under any of the experimental situations tested. These results suggest that in rats, the hypothalamic dorsomedial nucleus does not participate in either the neural control of daily pineal metabolism or the nocturnal light-induced inhibition of the pineal metabolism.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lesions of the Dorsomedial Hypothalamic Nucleus Do Not Influence the Daily Profile of Pineal Metabolism in Rats

et al. 2001

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“…Pineal melatonin release is driven by the SCN via the paraventricular nucleus (PVN), superior cervical ganglion (SCG) and intermediolateral column of the spinal cord (IML) pathway [58,69]. Pharmacological infusions at the PVN have shown the involvement of nocturnal glutamate excitatory signalling and diurnal GABA (g-aminobutyric acid) inhibitory signalling to PVN neurons that both shape the melatonin signal to signal the length of the night [61][62][63][64][65].…”

Section: Adjustment To Changing Day Length As a Selection Force For Tmentioning

confidence: 99%

Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod

Hut

Beersma

2011

Phil. Trans. R. Soc. B

181

193

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Virtually all species have developed cellular oscillations and mechanisms that synchronize these cellular oscillations to environmental cycles. Such environmental cycles in biotic (e.g. food availability and predation risk) or abiotic (e.g. temperature and light) factors may occur on a daily, annual or tidal time scale. Internal timing mechanisms may facilitate behavioural or physiological adaptation to such changes in environmental conditions. These timing mechanisms commonly involve an internal molecular oscillator (a 'clock') that is synchronized ('entrained') to the environmental cycle by receptor mechanisms responding to relevant environmental signals ('Zeitgeber', i.e. German for time-giver). To understand the evolution of such timing mechanisms, we have to understand the mechanisms leading to selective advantage. Although major advances have been made in our understanding of the physiological and molecular mechanisms driving internal cycles (proximate questions), studies identifying mechanisms of natural selection on clock systems (ultimate questions) are rather limited. Here, we discuss the selective advantage of a circadian system and how its adaptation to day length variation may have a functional role in optimizing seasonal timing. We discuss various cases where selective advantages of circadian timing mechanisms have been shown and cases where temporarily loss of circadian timing may cause selective advantage. We suggest an explanation for why a circadian timing system has emerged in primitive life forms like cyanobacteria and we evaluate a possible molecular mechanism that enabled these bacteria to adapt to seasonal variation in day length. We further discuss how the role of the circadian system in photoperiodic time measurement may explain differential selection pressures on circadian period when species are exposed to changing climatic conditions (e.g. global warming) or when they expand their geographical range to different latitudes or altitudes.

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“…The paraventricular nucleus of the hypothalamus receives extensive SCN projections, and the neurotransmitter GABA may form a necessary link in this pathway (36,37). The circuit is completed by paraventricular nucleus projections to preganglionic neurons of the sympathetic nervous sys-tem (in the intermediolateral column of the spinal cord) and postganglionic cell bodies in the superior cervical ganglion that noradrenergically synapse in the pineal gland.…”

Section: Converting Multiple Pacemaker Output Mechanisms Into Temporamentioning

confidence: 99%

Invited Review: A neural clockwork for encoding circadian time

Herzog

Schwartz

2002

Journal of Applied Physiology

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Many daily biological rhythms are governed by an innate timekeeping mechanism or clock. Endogenous, temperature-compensated circadian clocks have been localized to discrete sites within the nervous systems of a number of organisms. In mammals, the master circadian pacemaker is the bilaterally paired suprachiasmatic nucleus (SCN) in the anterior hypothalamus. The SCN is composed of multiple single cell oscillators that must synchronize to each other and the environmental light schedule. Other tissues, including those outside the nervous system, have also been shown to express autonomous circadian periodicities. This review examines 1) how intracellular regulatory molecules function in the oscillatory mechanism and in its entrainment to environmental cycles; 2) how individual SCN cells interact to create an integrated tissue pacemaker with coherent metabolic, electrical, and secretory rhythms; and 3) how such clock outputs are converted into temporal programs for the whole organism. suprachiasmatic nucleus; period; oscillator; pacemaker; photoperiod THE EARTH'S DAILY ROTATION about its axis has imposed potent selective pressures on organisms. The fundamental adaptation to the environmental day-night cycle is an endogenous 24-h clock that regulates biological processes in the temporal domain. This clock coordinates physiological events around local (geophysical) time, optimizing the economy of biological systems and allowing for a predictive, rather than purely reactive, homeostatic control. Circadian clocks contribute to the regulation of sleep and reproductive rhythms, seasonal behaviors, and celestial navigation. The practical importance of human circadian rhythmicity, as well as its consequences for health and disease, is now being realized. INVESTIGATING CIRCADIAN RHYTHMICITY AND LOCALIZING A PACEMAKER TO MAMMALIAN BRAINMany biological activities are restricted to specific times of day. In the absence of external timing cues, some of these processes remain rhythmic ("free run") with ϳ24-h (circadian) periods. The features of these self-sustaining oscillations have suggested the existence of an endogenous timekeeping mechanism. The circadian pacemaker receives input (afferent) pathways for synchronization (entrainment) to light-dark cycles and expresses its rhythmicity through output (efferent) pathways. The pacemaker works as a clock because its endogenous period is adjusted to the external 24-h period, primarily by light-induced phase shifts that reset the pacemaker's oscillation. Advances or delays occur because the pacemaker is differentially sensitive to light exposure at different times in its free-running circadian cycle; this rhythm of light sensitivity can be quantified as a "phase-response curve" (PRC). Variations in photic sensitivity, in concert with changes in the pacemaker's endogenous period and amplitude, can dramatically affect the temporal sequencing of clock-controlled events.In mammals, a circadian pacemaker has been localized to the suprachiasmatic nucleus (SCN). The body of evidence identi...

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GABA release from suprachiasmatic nucleus terminals is necessary for the light-induced inhibition of nocturnal melatonin release in the rat

Cited by 87 publications

References 81 publications

Lesions of the Dorsomedial Hypothalamic Nucleus Do Not Influence the Daily Profile of Pineal Metabolism in Rats

Lesions of the Dorsomedial Hypothalamic Nucleus Do Not Influence the Daily Profile of Pineal Metabolism in Rats

Evolution of time-keeping mechanisms: early emergence and adaptation to photoperiod

Invited Review: A neural clockwork for encoding circadian time

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