On the Chronobiology of Cohabitation

Paul, Matthew J.; Schwartz, William J.

doi:10.1101/sqb.2007.72.042

Cited by 20 publications

(16 citation statements)

References 45 publications

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“…There has been renewed interest in social stimuli as circadian zeitgebers [57]–[59], and the present results suggest that social synchrony can involve circadian oscillators outside of the light-entrainable SCN pacemaker. Comparative studies of scheduled mating and restricted feeding should reveal whether natural rewards affect a common circadian oscillator for anticipatory appetitive behaviors, or whether different populations of circadian clock cells are recruited by different reward stimuli.…”

Section: Discussionmentioning

confidence: 50%

Scheduled Daily Mating Induces Circadian Anticipatory Activity Rhythms in the Male Rat

et al. 2012

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Daily schedules of limited access to food, palatable high calorie snacks, water and salt can induce circadian rhythms of anticipatory locomotor activity in rats and mice. All of these stimuli are rewarding, but whether anticipation can be induced by neural correlates of reward independent of metabolic perturbations associated with manipulations of food and hydration is unclear. Three experiments were conducted to determine whether mating, a non-ingestive behavior that is potently rewarding, can induce circadian anticipatory activity rhythms in male rats provided scheduled daily access to steroid-primed estrous female rats. In Experiment 1, rats anticipated access to estrous females in the mid-light period, but also exhibited post-coital eating and running. In Experiment 2, post-coital eating and running were prevented and only a minority of rats exhibited anticipation. Rats allowed to see and smell estrous females showed no anticipation. In both experiments, all rats exhibited sustained behavioral arousal and multiple mounts and intromissions during every session, but ejaculated only every 2–3 days. In Experiment 3, the rats were given more time with individual females, late at night for 28 days, and then in the midday for 28 days. Ejaculation rates increased and anticipation was robust to night sessions and significant although weaker to day sessions. The anticipation rhythm persisted during 3 days of constant dark without mating. During anticipation of nocturnal mating, the rats exhibited a significant preference for a tube to the mating cage over a tube to a locked cage with mating cage litter. This apparent place preference was absent during anticipation of midday mating, which may reflect a daily rhythm of sexual reward. The results establish mating as a reward stimulus capable of inducing circadian rhythms of anticipatory behavior in the male rat, and reveal a critical role for ejaculation, a modulatory role for time of day, and a potential confound role for uncontrolled food intake.

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Section: Discussionmentioning

confidence: 50%

Scheduled Daily Mating Induces Circadian Anticipatory Activity Rhythms in the Male Rat

et al. 2012

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“…2C), confirming true entrainment. Of note, the free-running period in DD (τ) showed prominent aftereffects of the previous entraining cycle, i.e., it was relatively short in the 23.33-h T-cycle group (23.58 ± 0.03 h, n = 3) and relatively long in the 24.67-h T-cycle group (24.58 ± 0.04 h, n = 4) compared with the species-typical τ close to 24 h (as documented in the literature over the past few decades) (11,12). Interestingly, τ was statistically indistinguishable from the period of the previous T cycle for the 24.67-h animals (95% confidence interval for τ of 24.45-24.71 h) but not for the 23.33-h animals (23.45-23.70 h).…”

Section: Resultsmentioning

confidence: 81%

Distinct patterns of Period gene expression in the suprachiasmatic nucleus underlie circadian clock photoentrainment by advances or delays

Schwartz¹,

Tavakoli-Nezhad²,

Lambert

et al. 2011

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

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The circadian clock in the mammalian hypothalamic suprachiasmatic nucleus (SCN) is entrained by the ambient light/dark cycle, which differentially acts to cause the clock to advance or delay. Light-induced changes in the rhythmic expression of SCN clock genes are believed to be a critical step in this process, but how the two entrainment modalities-advances vs. delays-engage the molecular clockwork remains incompletely understood. We investigated molecular substrates of photic entrainment of the clock in the SCN by stably entraining hamsters to T cycles (non-24-h light/ dark cycles) consisting of a single 1-h light pulse repeated as either a short (23.33-h) or a long (24.67-h) cycle; under these conditions, the light pulse of the short cycle acts as "dawn," whereas that of the long cycle acts as "dusk." Analyses of the expression of the photoinducible and rhythmic clock genes Period 1 and 2 (Per1 and Per2) in the SCN revealed fundamental differences under these two entrainment modes. Light at dawn advanced the clock, advancing the onset of the Per1 mRNA rhythm and acutely increasing mRNA transcription, whereas light at dusk delayed the clock, delaying the offset of the Per2 mRNA rhythm and tonically increasing mRNA stability. The results suggest that the underlying molecular mechanisms of circadian entrainment differ with morning (advancing) or evening (delaying) light exposure, and such differences may reflect how entrainment takes place in nocturnal animals under natural conditions. circadian synchronization | circadian clock resetting | light entrainment A fundamental feature of the circadian clock that regulates daily behavioral and physiological rhythmicity is its entrainment to the environmental cycle of light and darkness. By matching the clock's endogenous ("free-running") period to that of the ambient day/night cycle, entrainment ensures that the phase relationship between clock and external day remains stable over time, thereby synchronizing body rhythms to local time. Light is the clock's preeminent entraining cue (Zeitgeber), and the clock responds to light by changing its angular velocity and shifting its phase. To match its oscillation to that of the Zeitgeber, the clock can increase its velocity and advance its phase if the clock's freerunning period is too long, or it can decrease its velocity and delay its phase if its free-running period is too short (1, 2).In mammals, the master circadian clock is located in the suprachiasmatic nucleus (SCN) in the anterior hypothalamus (3). The SCN is composed of multiple, coupled single-cell circadian oscillators (4), and analyses of induced and spontaneous mutations, gene sequence homologies, and protein-protein interactions have identified candidate regulatory molecules and biochemical processes that are likely to constitute the basic intracellular oscillatory mechanism (5). Genes at the core of the clock function within autoregulatory feedback loops, with proteins rhythmically suppressing the transcription of their own mRNAs. When the basic helix-loop-hel...

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“…Other important factors are social cues or influence of the group activity that may synchronize slightly divergent internal clocks of individual rats [11]–[13]. As the research on circadian rhythms has been variably performed on singly-housed and group-housed animals, this factor must also be taken into account when discussing mechanisms of circadian cycle of activity [14].…”

Section: Introductionmentioning

confidence: 99%

Circadian Rhythm of Outside-Nest Activity in Wild (WWCPS), Albino and Pigmented Laboratory Rats

et al. 2013

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The domestication process of the laboratory rat has been going on for several hundred generations in stable environmental conditions, which may have affected their physiological and behavioural functions, including their circadian system. Rats tested in our ethological experiments were laboratory-bred wild Norway rats (WWCPS), two strains of pigmented laboratory rats (Brown Norway and Long Evans), and two strains of albino rats (Sprague-Dawley and Wistar). Rats were placed in purpose-built enclosures and their cycle of activity (time spent actively outside the nest) has been studied for one week in standard light conditions and for the next one in round-the-clock darkness. The analysis of circadian pattern of outside-nest activity revealed differences between wild, pigmented laboratory, and albino laboratory strains. During daytime, albino rats showed lower activity than pigmented rats, greater decrease in activity when the light was turned on and greater increase in activity when the light was switched off, than pigmented rats. Moreover albino rats presented higher activity during the night than wild rats. The magnitude of the change in activity between daytime and nighttime was also more pronounced in albino rats. Additionaly, they slept outside the nest more often during the night than during the day. These results can be interpreted in accordance with the proposition that intense light is an aversive stimulus for albino rats, due to lack of pigment in their iris and choroid, which reduces their ability to adapt to light. Pigmented laboratory rats were more active during lights on, not only in comparison to the albino, but also to the wild rats. Since the difference seems to be independent of light intensity, it is likely to be a result of the domestication process. Cosinor analysis revealed a high rhythmicity of circadian cycles in all groups.

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On the Chronobiology of Cohabitation

Cited by 20 publications

References 45 publications

Scheduled Daily Mating Induces Circadian Anticipatory Activity Rhythms in the Male Rat

Scheduled Daily Mating Induces Circadian Anticipatory Activity Rhythms in the Male Rat

Distinct patterns of Period gene expression in the suprachiasmatic nucleus underlie circadian clock photoentrainment by advances or delays

Circadian Rhythm of Outside-Nest Activity in Wild (WWCPS), Albino and Pigmented Laboratory Rats

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