Circadian rhythmic changes of neuronal activity in the suprachiasmatic nucleus of the rat hypothalamic slice

Shibata, Shigenobu; Osuga, Yutaka; Kita, Hitoshi; Hattori, Katsumi

doi:10.1016/0006-8993(82)91041-1

Cited by 259 publications

(112 citation statements)

References 14 publications

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“…These biochemical changes are reflected in electrophysiological observations found for s.c.n. neurones, notably a reduced mean discharge rate (Groos & Hendricks, 1982;Green & Gillette, 1982;Shibata, Oomura, Kita & Hattori, 1982). Concomitant with the lower firing rate is a decrease in glucose utilization (Schwartz, Davidsen & Smith, 1980) in the s.c.n.…”

Section: Discussionmentioning

confidence: 99%

Circadian variation in sensitivity of suprachiasmatic and lateral geniculate neurones to 5‐hydroxytryptamine in the rat.

Mason¹

1986

The Journal of Physiology

104

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SUMMARY1. Extracellular single-unit recordings were obtained from neurones in the suprachiasmatic nuclei (s.c.n.) of the rat (a putative circadian pace-maker), the ventral lateral geniculate nucleus (v.l.g.n.) and the hippocampus. These areas receive a 5-hydroxytryptamine (5-HT) innervation from the raphe nuclei. Recording of neuronal activity in the s.c.n., v.l.g.n. and the hippocampus revealed a diurnal variation in the response to the ionophoresis of 5-HT. This variation was manifest as a 2-3-fold increase in post-synaptic sensitivity to 5-HT during the subjective dark (active) phase of the circadian cycle. In contrast there was no apparent circadian variation in the sensitivity of s.c.n., v.l.g.n. or hippocampal neurones to ionophoresed y-aminobutyric acid (GABA).2. Neuronal activity recorded in the s.c.n., v.l.g.n. and hippocampus also exhibited a circadian variation in the recovery from 5-HT-induced suppression of firing. This may reflect reuptake processes as recovery can be prolonged by ionophoresis of uptake blockers (imipramine or fluoxetine).3. Rats (n = 15) expressing circadian arrhythmicity in theirrest-activity behaviour induced by long-term continuous illumination (150-200 lx) showed no apparent circadian variation in 5-HT sensitivity. This loss was accompanied by either the development of (i) a 5-6-fold subsensitivity to ionophoresed 5-HT (eleven out of fifteen rats) or (ii) a 2-3-fold supersensitivity to ionophoresed 5-HT (four out of fifteen rats).4. A similar loss of circadian variation and the development of a subsensitivity to ionophoresed 5-HT was also found in three rats sustaining complete electrolytic lesions of the s.c.n. These changes were not found in rats (n = 4) with partial s.c.n. lesions.5. These results implicate the s.c.n., or fibres passing through it, in the circadian modulation of 5-HT sensitivity in neurones both intrinsic to the s.c.n. circadian pace-maker itself and in the hippocampus and lateral geniculate nucleus (regions remote from the s.c.n.).

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Section: Discussionmentioning

confidence: 99%

Circadian variation in sensitivity of suprachiasmatic and lateral geniculate neurones to 5‐hydroxytryptamine in the rat.

Mason¹

1986

The Journal of Physiology

104

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“…Ablation of the SCN produces a loss of circadian rhythmicity at the whole-animal level (Moore and Eichler 1972;Stephan and Zucker 1972), with no recovery of function irrespective of the age at which the lesion is made (Mosko and Moore 1979). The SCN oscillates in the absence of input from the rest of the brain both in vivo (Inouye and Kawamura 1979) and in vitro (Green and Gillette 1982;Groos and Hendriks 1982;Shibata et al 1982). Within the SCN, circadian oscillations can be measured in gene expression, electrical activity, metabolic activity, and neuropeptide release (Reppert and Weaver 2001).…”

Section: The Scn and Its Functionmentioning

confidence: 99%

Exploring Spatiotemporal Organization of SCN Circuits

Yan

Karatsoreos

LeSauter

et al. 2007

Cold Spring Harbor Symposia on Quantitative Biology

105

111

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Suprachiasmatic nucleus (SCN) neuroanatomy has been a subject of intense interest since the discovery of the SCN's function as a brain clock and subsequent studies revealing substantial heterogeneity of its component neurons. Understanding the network organization of the SCN has become increasingly relevant in the context of studies showing that its functional circuitry, evident in the spatial and temporal expression of clock genes, can be reorganized by inputs from the internal and external environment. Although multiple mechanisms have been proposed for coupling among SCN neurons, relatively little is known of the precise pattern of SCN circuitry. To explore SCN networks, we examine responses of the SCN to various photic conditions, using in vivo and in vitro studies with associated mathematical modeling to study spatiotemporal changes in SCN activity. We find an orderly and reproducible spatiotemporal pattern of oscillatory gene expression in the SCN, which requires the presence of the ventrolateral core region. Without the SCN core region, behavioral rhythmicity is abolished in vivo, whereas low-amplitude rhythmicity can be detected in SCN slices in vitro, but with loss of normal topographic organization. These studies reveal SCN circuit properties required to signal daily time.

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“…Importantly, rhythms are restored with the period of the donor SCN, indicating that the transplanted tissue does not act by restoring host brain function but that the "clock" is contained in the transplanted tissue. Further evidence that clock function is contained within the SCN comes from studies demonstrating that circadian rhythms in neural firing rate persist in isolated SCN tissue maintained in culture (Green and Gillette, 1982;Groos and Hendriks, 1982;Shibata et al, 1982). An excellent overview of these studies in historical perspective is available (Weaver, 1998).…”

Section: Identification Of a Brain "Clock": From Tissue To Genementioning

confidence: 99%

The regulation of neuroendocrine function: Timing is everything

Kriegsfeld

Silver

2006

Hormones and Behavior

130

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Hormone secretion is highly organized temporally, achieving optimal biological functioning and health. The master clock located in the suprachiasmatic nucleus (SCN) of the hypothalamus coordinates the timing of circadian rhythms, including daily control of hormone secretion. In the brain, the SCN drives hormone secretion. In some instances, SCN neurons make direct synaptic connections with neurosecretory neurons. In other instances, SCN signals set the phase of "clock genes" that regulate circadian function at the cellular level within neurosecretory cells. The protein products of these clock genes can also exert direct transcriptional control over neuroendocrine releasing factors. Clock genes and proteins are also expressed in peripheral endocrine organs providing additional modes of temporal control. Finally, the SCN signals endocrine glands via the autonomic nervous system, allowing for rapid regulation via multisynaptic pathways. Thus, the circadian system achieves temporal regulation of endocrine function by a combination of genetic, cellular, and neural regulatory mechanisms to ensure that each response occurs in its correct temporal niche. The availability of tools to assess the phase of molecular/cellular clocks and of powerful tract tracing methods to assess connections between "clock cells" and their targets provides an opportunity to examine circadian-controlled aspects of neurosecretion, in the search for general principles by which the endocrine system is organized. KeywordsCircadian; Diurnal; Endocrinel; Neurosecretion; Clock genes; Suprachiasmatic Circadian aspects of reproductionThe importance of circadian (about a day) timing in hormone production/secretion has been known since the 1950s when Everett and Sawyer determined that a stimulatory signal occurring during a narrow temporal window on the afternoon of proestrus is necessary for induction of ovulation later that night (Everett and Sawyer, 1950). Such close temporal organization is important for successful reproduction, as numerous hormone-dependent behavioral and physiological processes must be coordinated. If optimal temporal relationships are disrupted, pronounced deficits in fertility can result. For example, ovulation, behavioral estrus, fertilization, and pregnancy maintenance require a specific

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Circadian rhythmic changes of neuronal activity in the suprachiasmatic nucleus of the rat hypothalamic slice

Cited by 259 publications

References 14 publications

Circadian variation in sensitivity of suprachiasmatic and lateral geniculate neurones to 5‐hydroxytryptamine in the rat.

Circadian variation in sensitivity of suprachiasmatic and lateral geniculate neurones to 5‐hydroxytryptamine in the rat.

Exploring Spatiotemporal Organization of SCN Circuits

The regulation of neuroendocrine function: Timing is everything

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