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Photic and pineal modulation of food anticipatory circadian activity rhythms in rodents.

Patton DF, Parfyonov M, Gourmelen S, Opiol H, Pavlovski I, Marchant EG, Challet E, Mistlberger RE - PLoS ONE (2013)

Bottom Line: Nonetheless, light could reduce the duration or magnitude of FAA.In both species, FAA was significantly and reversibly enhanced in the skeleton photoperiod compared to the full photoperiod.These results indicate that procedures affecting behavioral responses to light can significantly alter the magnitude of food anticipatory rhythms in rodents.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada.

ABSTRACT
Restricted daily feeding schedules entrain circadian oscillators that generate food anticipatory activity (FAA) rhythms in nocturnal rodents. The location of food-entrainable oscillators (FEOs) necessary for FAA remains uncertain. The most common procedure for inducing circadian FAA is to limit food access to a few hours in the middle of the light period, when activity levels are normally low. Although light at night suppresses activity (negative masking) in nocturnal rodents, it does not prevent the expression of daytime FAA. Nonetheless, light could reduce the duration or magnitude of FAA. If so, then neural or genetic ablations designed to identify components of the food-entrainable circadian system could alter the expression of FAA by affecting behavioral responses to light. To assess the plausibility of light as a potential mediating variable in studies of FAA mechanisms, we quantified FAA in rats and mice alternately maintained in a standard full photoperiod (12h of light/day) and in a skeleton photoperiod (two 60 min light pulses simulating dawn and dusk). In both species, FAA was significantly and reversibly enhanced in the skeleton photoperiod compared to the full photoperiod. In a third experiment, FAA was found to be significantly attenuated in rats by pinealectomy, a procedure that has been reported to enhance some effects of light on behavioral circadian rhythms. These results indicate that procedures affecting behavioral responses to light can significantly alter the magnitude of food anticipatory rhythms in rodents.

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Food anticipatory activity in mice recording under a full photoperiod and skeleton photoperiods.A. Group mean (± sem) waveforms of wheel running activity in food restricted mice entrained, to a full photoperiod (blue dashed curve), a skeleton photoperiod (red solid curve) and again a full photoperiod (black dashed curve), in successive two week blocks. The waveforms were obtained by averaging the second week on each LD schedule. The 6-h daily mealtime is denoted by green shading. The LD cycle during the full photoperiod is indicated by the horizontal yellow and black bars along the horizontal axis. Light exposure during the skeleton photoperiod is indicated by the vertical yellow bars. Time is plotted in 10 min bins, from the beginning of the lights on (Zeitgeber time 0). B. Group mean (± sem) food anticipatory activity ratios calculated for each day of food restriction, by dividing activity during the 2h prior to mealtime (ZT4-6) by activity from ZT12-24.
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pone-0081588-g004: Food anticipatory activity in mice recording under a full photoperiod and skeleton photoperiods.A. Group mean (± sem) waveforms of wheel running activity in food restricted mice entrained, to a full photoperiod (blue dashed curve), a skeleton photoperiod (red solid curve) and again a full photoperiod (black dashed curve), in successive two week blocks. The waveforms were obtained by averaging the second week on each LD schedule. The 6-h daily mealtime is denoted by green shading. The LD cycle during the full photoperiod is indicated by the horizontal yellow and black bars along the horizontal axis. Light exposure during the skeleton photoperiod is indicated by the vertical yellow bars. Time is plotted in 10 min bins, from the beginning of the lights on (Zeitgeber time 0). B. Group mean (± sem) food anticipatory activity ratios calculated for each day of food restriction, by dividing activity during the 2h prior to mealtime (ZT4-6) by activity from ZT12-24.

Mentions: FAA in wheel counts summed from ZT4 to ZT6 prior to mealtime was significantly increased in the skeleton photoperiod compared to both the preceding and the following full photoperiods (FPP1: 1069±367, SPP: 2921±691, and FPP2: 1006±396 wheel revolutions; F(2,8)  = 7.2, p = .017; Fig. 4a). Both the duration and the peak of FAA were higher in the skeleton photoperiod condition. FAA ratios were also much higher in the skeleton photoperiod compared to FPP1 and FPP2 (18.6±3.3 vs. 5.4±2.2 and 5.8±1.8%, respectively; F(2,8)  = 9.7, p<.01; Fig. 4b). Food intake was not significantly changed in the skeleton photoperiod group (3.2±0.1 g) by comparison to the first (3.3±0.1 g) and the second full photoperiods (3.2±0.2 g; F(2,8)  = 1.8, p = .22). By contrast, body weight during restricted feeding was significantly changed according to the successive photoperiodic conditions (FPP1: 21.3±0.6, SPP: 22.0±0.4, and FPP2: 22.3±0.5 g; F(2,8)  = 9.4, p = .008). Because the increase in body weight during the skeleton photoperiod was not reversed in subsequent full photoperiod, but instead was enhanced, this gain in body weight is likely due to the effect of time.


Photic and pineal modulation of food anticipatory circadian activity rhythms in rodents.

Patton DF, Parfyonov M, Gourmelen S, Opiol H, Pavlovski I, Marchant EG, Challet E, Mistlberger RE - PLoS ONE (2013)

Food anticipatory activity in mice recording under a full photoperiod and skeleton photoperiods.A. Group mean (± sem) waveforms of wheel running activity in food restricted mice entrained, to a full photoperiod (blue dashed curve), a skeleton photoperiod (red solid curve) and again a full photoperiod (black dashed curve), in successive two week blocks. The waveforms were obtained by averaging the second week on each LD schedule. The 6-h daily mealtime is denoted by green shading. The LD cycle during the full photoperiod is indicated by the horizontal yellow and black bars along the horizontal axis. Light exposure during the skeleton photoperiod is indicated by the vertical yellow bars. Time is plotted in 10 min bins, from the beginning of the lights on (Zeitgeber time 0). B. Group mean (± sem) food anticipatory activity ratios calculated for each day of food restriction, by dividing activity during the 2h prior to mealtime (ZT4-6) by activity from ZT12-24.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3852709&req=5

pone-0081588-g004: Food anticipatory activity in mice recording under a full photoperiod and skeleton photoperiods.A. Group mean (± sem) waveforms of wheel running activity in food restricted mice entrained, to a full photoperiod (blue dashed curve), a skeleton photoperiod (red solid curve) and again a full photoperiod (black dashed curve), in successive two week blocks. The waveforms were obtained by averaging the second week on each LD schedule. The 6-h daily mealtime is denoted by green shading. The LD cycle during the full photoperiod is indicated by the horizontal yellow and black bars along the horizontal axis. Light exposure during the skeleton photoperiod is indicated by the vertical yellow bars. Time is plotted in 10 min bins, from the beginning of the lights on (Zeitgeber time 0). B. Group mean (± sem) food anticipatory activity ratios calculated for each day of food restriction, by dividing activity during the 2h prior to mealtime (ZT4-6) by activity from ZT12-24.
Mentions: FAA in wheel counts summed from ZT4 to ZT6 prior to mealtime was significantly increased in the skeleton photoperiod compared to both the preceding and the following full photoperiods (FPP1: 1069±367, SPP: 2921±691, and FPP2: 1006±396 wheel revolutions; F(2,8)  = 7.2, p = .017; Fig. 4a). Both the duration and the peak of FAA were higher in the skeleton photoperiod condition. FAA ratios were also much higher in the skeleton photoperiod compared to FPP1 and FPP2 (18.6±3.3 vs. 5.4±2.2 and 5.8±1.8%, respectively; F(2,8)  = 9.7, p<.01; Fig. 4b). Food intake was not significantly changed in the skeleton photoperiod group (3.2±0.1 g) by comparison to the first (3.3±0.1 g) and the second full photoperiods (3.2±0.2 g; F(2,8)  = 1.8, p = .22). By contrast, body weight during restricted feeding was significantly changed according to the successive photoperiodic conditions (FPP1: 21.3±0.6, SPP: 22.0±0.4, and FPP2: 22.3±0.5 g; F(2,8)  = 9.4, p = .008). Because the increase in body weight during the skeleton photoperiod was not reversed in subsequent full photoperiod, but instead was enhanced, this gain in body weight is likely due to the effect of time.

Bottom Line: Nonetheless, light could reduce the duration or magnitude of FAA.In both species, FAA was significantly and reversibly enhanced in the skeleton photoperiod compared to the full photoperiod.These results indicate that procedures affecting behavioral responses to light can significantly alter the magnitude of food anticipatory rhythms in rodents.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, Simon Fraser University, Burnaby, British Columbia, Canada.

ABSTRACT
Restricted daily feeding schedules entrain circadian oscillators that generate food anticipatory activity (FAA) rhythms in nocturnal rodents. The location of food-entrainable oscillators (FEOs) necessary for FAA remains uncertain. The most common procedure for inducing circadian FAA is to limit food access to a few hours in the middle of the light period, when activity levels are normally low. Although light at night suppresses activity (negative masking) in nocturnal rodents, it does not prevent the expression of daytime FAA. Nonetheless, light could reduce the duration or magnitude of FAA. If so, then neural or genetic ablations designed to identify components of the food-entrainable circadian system could alter the expression of FAA by affecting behavioral responses to light. To assess the plausibility of light as a potential mediating variable in studies of FAA mechanisms, we quantified FAA in rats and mice alternately maintained in a standard full photoperiod (12h of light/day) and in a skeleton photoperiod (two 60 min light pulses simulating dawn and dusk). In both species, FAA was significantly and reversibly enhanced in the skeleton photoperiod compared to the full photoperiod. In a third experiment, FAA was found to be significantly attenuated in rats by pinealectomy, a procedure that has been reported to enhance some effects of light on behavioral circadian rhythms. These results indicate that procedures affecting behavioral responses to light can significantly alter the magnitude of food anticipatory rhythms in rodents.

Show MeSH
Related in: MedlinePlus