Olfactory bulb neurons express functional, entrainable circadian rhythms

Granados‐Fuentes, Daniel; Saxena, Mohit; Prolo, Laura M.; Aton, Sara J.; Herzog, Erik D.

doi:10.1111/j.0953-816x.2004.03117.x

Cited by 104 publications

(98 citation statements)

References 42 publications

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“…These in vitro oscillations are sustained (Granados-Fuentes et al 2004;Yoo et al 2004), although overall amplitude may dampen as the rhythms of individual cells desynchronize ( Nagoshi et al 2004;Welsh et al 2004). The physiological significance of the cycling of such genes in extra-SCN tissues is not known, but they may be autonomous 'slave' oscillators whose phase is set by the 'master' oscillator within the SCN.…”

Section: On the Location Of Interval Timers And Circannual Clocksmentioning

confidence: 99%

Tracking the seasons: the internal calendars of vertebrates

Paul

Zucker

Schwartz

2007

Phil. Trans. R. Soc. B

175

152

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Animals have evolved many season-specific behavioural and physiological adaptations that allow them to both cope with and exploit the cyclic annual environment. Two classes of endogenous annual timekeeping mechanisms enable animals to track, anticipate and prepare for the seasons: a timer that measures an interval of several months and a clock that oscillates with a period of approximately a year. Here, we discuss the basic properties and biological substrates of these timekeeping mechanisms, as well as their reliance on, and encoding of environmental cues to accurately time seasonal events. While the separate classification of interval timers and circannual clocks has elucidated important differences in their underlying properties, comparative physiological investigations, especially those regarding seasonal prolactin secretions, hint at the possibility of common substrates.Keywords: seasonality; photoperiodism; circannual; interval timers While the Earth remaineth, seedtime and harvest, and cold and heat, and summer and winter, and day and night shall not cease.Genesis 8: 22, King James Version (1611) As the Earth makes its yearly orbit around the Sun, the planet's 23.58 axial tilt leads to the cyclical environmental changes that we call the seasons. Recurrent challenges to the survival of organisms and their offspring arise with the dawning of each new season, and animals have evolved seasonally induced changes in phenotype that adapt them to these predictable events. For example, in many temperate environments, winter is generally characterized by severe decreases in ambient temperature and food availability, leading to increased energetic demands at a time when resources are diminished. Because energy requirements of female mammals typically increase markedly during lactation (Bronson 1989) and newly weaned offspring are particularly vulnerable to environmental perturbations (Hill 1992), raising offspring during this time of year is often futile. Thus, many temperate species have evolved winter-specific behaviours and physiology to conserve energy (e.g. hibernation, a more insulative pelage, huddling) or provide for escape (e.g. migration). Many species also increase the chances of offspring survival by timing their mating behaviours so that parturition occurs during energetically favourable times of year.

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Section: On the Location Of Interval Timers And Circannual Clocksmentioning

confidence: 99%

Tracking the seasons: the internal calendars of vertebrates

Paul

Zucker

Schwartz

2007

Phil. Trans. R. Soc. B

175

152

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“…To test whether the circadian patterns of gene expression and firing rate in the cultured OB (Abe et al, 2002;Granados-Fuentes et al, 2004b) relate to olfactory function in vivo, we counted c-Fos-immunoreactive (c-Fos-IR) cells in the olfactory system of mice after stimulation with cedar oil at different times of the day. In constant darkness, cedar oil induced similar daily rhythms in the number of c-Fos-IR cells of the OB and PC (Fig.…”

Section: Odor-evoked C-fos Is Circadian In the Ob And Pcmentioning

confidence: 99%

A Circadian Clock in the Olfactory Bulb Controls Olfactory Responsivity

Granados‐Fuentes¹,

Tseng²,

Herzog³

2006

J. Neurosci.

144

127

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Recently, it has been shown that multiple mammalian cell types express daily rhythms in vitro. Although the suprachiasmatic nucleus (SCN) of the hypothalamus is known to regulate a wide range of circadian behaviors, the role for intrinsic rhythmicity in other tissues is unknown. We tested whether the main olfactory bulb (OB) of mice mediates daily changes in olfaction. We found circadian rhythms in cedar oil-induced c-Fos, a protein marker of cellular excitation, in the mitral and granular layers of the OB and in the piriform cortex (PC). These oscillations persisted in constant darkness with a fourfold change in amplitude and a peak ϳ4 h after the onset of daily locomotor activity. Electrolytic lesions of the SCN abolished circadian locomotor rhythms, but not odor-induced c-Fos rhythms in the OB or PC. Furthermore, removal of the OB abolished spontaneous circadian cycling of c-Fos in the PC, shortened the free-running period of locomotor rhythms, and accelerated re-entrainment after a 6 h advance and slowed re-entrainment after a 6 h delay in the light schedule. OB ablation or odorant altered the amplitude of c-Fos rhythms in the SCN and ablation of one OB abolished c-Fos rhythms in the ipsilateral PC, but not in the contralateral OB and PC. We conclude that the OB comprises a master circadian pacemaker, which enhances olfactory responsivity each night, drives rhythms in the PC, and interacts with the SCN to coordinate other daily behaviors.

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“…For instance, rhythmic expression of Per1 and Per2 mRNA is observed in forebrain structures such as olfactory bulbs, piriform and cerebral cortices, hippocampus, paraventricular and arcuate hypothalamic nuclei (Asai et al, 2001;Wakamatsu et al, 2001;Abe et al, 2002;Granados-Fuentes et al, 2004). PER2 expression has also been reported in limbic structures, such as amygdala and bed nucleus of the stria terminalis (Amir et al, 2004;Lamont et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Forebrain oscillators ticking with different clock hands

Feillet

Mendoza

Albrecht

et al. 2008

Molecular and Cellular Neuroscience

135

113

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Clock proteins like PER1 and PER2 are expressed in the brain, but little is known about their functionality outside the main suprachiasmatic clock. Here we show that PER1 and PER2 were neither uniformly present nor identically phased in forebrain structures of mice fed ad libitum. Altered expression of the clock gene Cry1 was observed in respective Per1 or Per2 mutants. In response to hypocaloric feeding, PERs timing was not markedly affected in few forebrain structures (hippocampus). In most other forebrain oscillators, including those expressing only PER1 (e.g., dorsomedial hypothalamus), PER2 (e.g., paraventricular hypothalamus) or both (e.g., paraventricular thalamus), PER1 was up-regulated and PER2 largely phase-advanced. Cry1 expression was selectively modified in the forebrain of Per mutants challenged with hypocaloric feeding. Our results suggest that there is not one single cerebral clock, but a system of multiple brain oscillators ticking with different clock hands and differentially sensitive to nutritional cues.

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Olfactory bulb neurons express functional, entrainable circadian rhythms

Cited by 104 publications

References 42 publications

Tracking the seasons: the internal calendars of vertebrates

Tracking the seasons: the internal calendars of vertebrates

A Circadian Clock in the Olfactory Bulb Controls Olfactory Responsivity

Forebrain oscillators ticking with different clock hands

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