The visual properties of rat and cat suprachiasmatic neurones

Groos, G. A.; Mason, Robert J.

doi:10.1007/bf00657651

Cited by 110 publications

(76 citation statements)

References 21 publications

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“…This convergence is consistent with previous observations that SCNprojecting RGCs have receptive fields of only 2-5° (Pu, 2000), whereas light-responsive SCN neurons have large receptive fields often exceeding 20°in diameter (Groos and Mason, 1980). Signals from inner and outer retinal channels combine to shape the photic response of the SCN Our results show that SCN neurons receive a complex photic signal in which the response kinetics, response to irradiance, and resistance to bleaching are typical for channels involving both classical photoreceptors and melanopsin ipRGCs (Fig.…”

Section: Neuronal Response Classes In the Scnsupporting

confidence: 93%

Responses of Suprachiasmatic Nucleus Neurons to Light and Dark Adaptation: Relative Contributions of Melanopsin and Rod–Cone Inputs

Drouyer¹,

Rieux²,

Hut³

et al. 2007

J. Neurosci.

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Section: Neuronal Response Classes In the Scnsupporting

confidence: 93%

Responses of Suprachiasmatic Nucleus Neurons to Light and Dark Adaptation: Relative Contributions of Melanopsin and Rod–Cone Inputs

Drouyer¹,

Rieux²,

Hut³

et al. 2007

J. Neurosci.

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“…Thus, in this strain of albino rat, the regulation of immunoreactive Fos by light appears selective for the visual system for photic entrainment of circadian rhythms; no change in the low levels of Fos expression was detected in other retino-recipient areas responsible for reflex oculomotor function and image formation. Of note, the mammalian entrainment system is characterized by several additional special features that distinguish it from other visual systems, including its photoreceptive properties (33), lack of retinotopic organization (34), and electrophysiological characteristics of SCN neurons (35,36). Dark On 32 ± 5* Labeled cell nuclei in the ventrolateral SCN, irrespective of the intensity of staining, were counted without knowledge of lighting conditions.…”

Section: Discussionmentioning

confidence: 99%

Light regulates expression of a Fos-related protein in rat suprachiasmatic nuclei.

Aronin

Sagar

Sharp

et al. 1990

Proc. Natl. Acad. Sci. U.S.A.

207

107

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Mammalian circadian rhythmicity is endogenously generated by a pacemaker in the suprachiasmatic nuclei and precisely entrained to the 24-hr day/night cycle by periodic environmental light cues. We show that light alters the immunoreactive levels of a transcriptional regulatory protein, Fos, in the suprachiasmatic nuclei of albino rats. Photic regulation of Fos immunoreactivity does not occur in other retino-recipient brain areas except for the intergeniculate leaflet, which appears to be involved in mediating some of the complex effects of light on expressed circadian rhythms. Our results point to a promising new functional marker for the cellular effects of light and suggest that the expression of Fos or a related nuclear protein may be part of the mechanism for photic entrainment of the circadian clock to environmental light/dark cycles.(12, 13) stimulation, and water deprivation (10). Recently, exposure of rats to flashing lights was reported to increase immunoreactive Fos in some cells of the inner nuclear and ganglion cell layers of the retina (14). To determine whether regional brain Fos expression might also be modulated by light, we used an affinity-purified antibody against a synthetic peptide of Fos (amino acids 132-154, a sequence that includes the probable DNA-binding domain) to perform immunohistochemistry on sections from the brains of Sprague-Dawley rats. We now report that light increases the levels of immunoreactive Fos in the SCN and hypothesize that events at the transcriptional level are part of the mechanism for photic entrainment of circadian rhythms to environmental light/ dark cycles. Some of these data have been reported previously in abstract form (15).Light-responsive neurons in the mammalian brain are organized into discrete circuits that are functionally, physiologically, and anatomically distinct. Thus, direct retinal projections to the superior colliculi are responsible for visually guided eye movements; visual inputs to the pretectum drive reflex pupillary function; and the optic pathway to the lateral geniculate nuclei relays information required for image formation. In addition to these classic connections, some retinal ganglion cells monosynaptically innervate the suprachiasmatic nuclei (SCN) in the anterior hypothalamus, site of an endogenous circadian clock (1). Activation of this retinohypothalamic tract appears to be both necessary and sufficient for precise entrainment of the period and phase of overt circadian rhythms to the natural day/night cycle (2). Such entrainment is achieved by light-induced phase shifts of the endogenous oscillation of the circadian pacemaker in the SCN; permanent advances or delays occur because the oscillator is differentially sensitive to light exposure at different phases of its free-running circadian cycle (3). The cellular mechanism of photic entrainment is unknown, but the search is underway (predominantly in organisms simpler than mammals) for molecular candidates at the membrane, cytoplasmic, and nuclear levels that might be a par...

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“…Suprachiasmatic and geniculate neurones were identified according to their response to visual stimuli (Hale & Sefton, 1978;Groos & Mason, 1980;Meijer et al 1984). The responsiveness of neurones to 5-HT was estimated from the ionophoretic charge (i.e.…”

Section: Methodsmentioning

confidence: 99%

“…was included as a representative site of an extra-hypothalamic region in receipt ofserotonergic innervation and additionally because ofits possible involvement in s.c.n. physiology (Rusak & Zucker, 1979;Groos & Mason, 1980. A division within the v.l.g.n., the intergeniculate leaflet (i.g.l.…”

mentioning

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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The visual properties of rat and cat suprachiasmatic neurones

Cited by 110 publications

References 21 publications

Responses of Suprachiasmatic Nucleus Neurons to Light and Dark Adaptation: Relative Contributions of Melanopsin and Rod–Cone Inputs

Responses of Suprachiasmatic Nucleus Neurons to Light and Dark Adaptation: Relative Contributions of Melanopsin and Rod–Cone Inputs

Light regulates expression of a Fos-related protein in rat suprachiasmatic nuclei.

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

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