Live imaging of altered period1 expression in the suprachiasmatic nuclei of Vipr2−/− mice1

Hughes, Alun; Guilding, Clare; Lennox, Laura; Samuels, Rayna E.; McMahon, Douglas G.; Piggins, Hugh D.

doi:10.1111/j.1471-4159.2008.05520.x

Cited by 55 publications

(68 citation statements)

References 43 publications

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“…When cells are coupled, they necessarily express similar periods, and coupling therefore involves adjustments in period. Because VIP-VPAC2 signaling is already thought to be important for coupling (2,6,17), the regulation of period and coupling mechanisms may be closely linked.…”

Section: Discussionmentioning

confidence: 99%

“…The 3 days of data beginning after the first full day following media change were analyzed for each 7-day period of recording (pretreatment: days 2-5; drug application: days 8 -11; and washout: days [15][16][17][18]. Baseline drift was subtracted using a polynomial curve equal to the number of days analyzed (three).…”

Section: Methodsmentioning

confidence: 99%

“…) lack normal circadian activity, probably because of loss of synchronization among SCN neurons and a loss of rhythmicity in individual cells (2,3,6,8,17,29). Moreover, SCN transplants that are successful in restoring rhythms express VIP (24, 34), suggesting that VIP is a possible SCN output signal.…”

mentioning

confidence: 99%

“…VIP in the SCN is rhythmically expressed in a light-dark cycle (LD) (1,38), and exposure to constant light decreases VIP peptide content (39). Knockout mice for VIP (vip Ϫ/Ϫ ) or its receptor (vpac 2 Ϫ/Ϫ ) lack normal circadian activity, probably because of loss of synchronization among SCN neurons and a loss of rhythmicity in individual cells (2,3,6,8,17,29). Moreover, SCN transplants that are successful in restoring rhythms express VIP (24,34), suggesting that VIP is a possible SCN output signal.…”

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confidence: 99%

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Chronic stimulation of the hypothalamic vasoactive intestinal peptide receptor lengthens circadian period in mice and hamsters

Pantazopoulos

Dolatshad

Davis

2010

American Journal of Physiology-Regulatory, Integrative and Comp

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) lack normal circadian activity, probably because of loss of synchronization among SCN neurons and a loss of rhythmicity in individual cells (2,3,6,8,17,29). Moreover, SCN transplants that are successful in restoring rhythms express VIP (24, 34), suggesting that VIP is a possible SCN output signal.In addition to possible roles in coupling and output, VIP-VIP receptor (VPAC2) signaling may be involved in transduction of photic input to SCN cells. Studies have shown that VIP pulses result in phase delays or phase advances of locomotor activity, depending on circadian time of administration (32). These effects are similar to the phase-shifting effects of light pulses. Electrophysiological investigations have shown that application of VIP, or a VPAC2 receptor agonist, have similar phase-shifting effects on the firing rates of SCN neurons (36). VIP pulses have also been shown to induce expression of the clock genes per1 and per2 (30), similar to the effect of light pulses on per gene expression.Taken together, these findings indicate that VIP mediates several important aspects of circadian rhythm regulation by the SCN. Whereas mice lacking VPAC2 or VIP show either shorter periods or complete loss of rhythmic activity (2, 7), the effect of chronic VPAC2 receptor activation has not been examined. Based on the evidence of a role for VIP-VPAC2 signaling in integrating light information to SCN neurons, together with disruptions in wheelrunning activity and synchrony of SCN neurons in vip Ϫ/Ϫ mice, we hypothesized that chronic stimulation of the VPAC2 receptor may result in lengthening of the period, similar to the effect of constant light (9). In addition, chronic stimulation of the VPAC2 receptor could result in increased or decreased synchrony among SCN cells. If synchrony is decreased, activity rhythms could be disrupted similar to knockout mice. If synchrony is increased, it is expected that the amplitude of a rhythm expressed by a population of rhythmic cells will increase. For example, this might be seen as higher peak expression of a key circadian regulatory gene, per2. Because VIP processes extend outside the SCN, VIP might also act as an output signal from the SCN. If so, chronic stimulation of the VPAC2 receptor in regions adjacent to the SCN through intraventricular infusion should affect activity levels. To test these hypotheses, we chronically infused a potent VPAC2 receptor agonist 44)] in the third ventricle of Syrian hamsters while monitoring wheel-running activity. In addition, we examined the effect of chronic application of BAY 55-9837 on period and amplitude of PER2 expression measured by bioluminescence in cultured SCN explants.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Chronic stimulation of the hypothalamic vasoactive intestinal peptide receptor lengthens circadian period in mice and hamsters

Pantazopoulos

Dolatshad

Davis

2010

American Journal of Physiology-Regulatory, Integrative and Comp

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“…It should in this context also be mentioned that luminescence imaging is nowadays possible with highly sensitive CCD cameras 11 , allowing recordings even in single SCN neurons (~ 6-10 μm) and other cell types, utilized by major laboratories studying circadian rhythms. Finally, several circadian investigators commonly use monitoring of molecular expression using other reporters, such as the Green Fluorescent Protein, in order to study clock gene/protein oscillations [16][17][18][19] .…”

Section: Benefits and Disadvantages With Luciferase Reporter Technologymentioning

confidence: 99%

Slice Preparation, Organotypic Tissue Culturing and Luciferase Recording of Clock Gene Activity in the Suprachiasmatic Nucleus

Savelyev¹,

Larsson²,

Johansson³

et al. 2011

JoVE

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A central circadian (~24 hr) clock coordinating daily rhythms in physiology and behavior resides in the suprachiasmatic nucleus (SCN) located in the anterior hypothalamus. The clock is directly synchronized by light via the retina and optic nerve. Circadian oscillations are generated by interacting negative feedback loops of a number of so called "clock genes" and their protein products, including the Period (Per) genes. The core clock is also dependent on membrane depolarization, calcium and cAMP 1 . The SCN shows daily oscillations in clock gene expression, metabolic activity and spontaneous electrical activity. Remarkably, this endogenous cyclic activity persists in adult tissue slices of the SCN [2][3][4] . In this way, the biological clock can easily be studied in vitro, allowing molecular, electrophysiological and metabolic investigations of the pacemaker function.The SCN is a small, well-defined bilateral structure located right above the optic chiasm 5 . In the rat it contains ~8.000 neurons in each nucleus and has dimensions of approximately 947 μm (length, rostrocaudal axis) x 424 μm (width) x 390 μm (height) 6 . To dissect out the SCN it is necessary to cut a brain slice at the specific level of the brain where the SCN can be identified. Here, we describe the dissecting and slicing procedure of the SCN, which is similar for mouse and rat brains. Further, we show how to culture the dissected tissue organotypically on a membrane 7 , a technique developed for SCN tissue culture by Yamazaki et al. 8 . Finally, we demonstrate how transgenic tissue can be used for measuring expression of clock genes/proteins using dynamic luciferase reporter technology, a method that originally was used for circadian measurements by Geusz et al. 9. We here use SCN tissues from the transgenic knock-in PERIOD2::LUCIFERASE mice produced by Yoo et al. 10. The mice contain a fusion protein of PERIOD (PER) 2 and the firefly enzyme LUCIFERASE. When PER2 is translated in the presence of the substrate for luciferase, i.e. luciferin, the PER2 expression can be monitored as bioluminescence when luciferase catalyzes the oxidation of luciferin. The number of emitted photons positively correlates to the amount of produced PER2 protein, and the bioluminescence rhythms match the PER2 protein rhythm in vivo 10 . In this way the cyclic variation in PER2 expression can be continuously monitored real time during many days. The protocol we follow for tissue culturing and real-time bioluminescence recording has been thoroughly described by Yamazaki and Takahashi 11 .

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Coupled network of the circadian clocks: a driving force of rhythmic physiology

2020

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The circadian system is composed of coupled endogenous oscillators that allow living beings, including humans, to anticipate and adapt to daily changes in their environment. In mammals, circadian clocks form a hierarchically organized network with a ‘master clock’ located in the suprachiasmatic nucleus of the hypothalamus, which ensures entrainment of subsidiary oscillators to environmental cycles. Robust rhythmicity of body clocks is indispensable for temporally coordinating organ functions, and the disruption or misalignment of circadian rhythms caused for instance by modern lifestyle is strongly associated with various widespread diseases. This review aims to provide a comprehensive overview of our current knowledge about the molecular architecture and system‐level organization of mammalian circadian oscillators. Furthermore, we discuss the regulatory roles of peripheral clocks for cell and organ physiology and their implication in the temporal coordination of metabolism in human health and disease. Finally, we summarize methods for assessing circadian rhythmicity in humans.

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Live imaging of altered period1 expression in the suprachiasmatic nuclei of Vipr2^−/− mice¹

Cited by 55 publications

References 43 publications

Chronic stimulation of the hypothalamic vasoactive intestinal peptide receptor lengthens circadian period in mice and hamsters

Chronic stimulation of the hypothalamic vasoactive intestinal peptide receptor lengthens circadian period in mice and hamsters

Slice Preparation, Organotypic Tissue Culturing and Luciferase Recording of Clock Gene Activity in the Suprachiasmatic Nucleus

Coupled network of the circadian clocks: a driving force of rhythmic physiology

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