Free-running periods of endogenous circannian rhythms in the golden mantled ground squirrel, Citellus lateralis

Pengelley, Eric T.; Asmundson, Sally M.

doi:10.1016/0010-406x(69)91312-7

Cited by 63 publications

(21 citation statements)

References 13 publications

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“…This suggests that food intake regulation is not affected by the T a at which the animal is maintained. However, the presence or absence of food did influence the length of the hibernation period: when provided with ad libitum food during the hibernation season, animals maintained at 0°C remained aphagic and heterothermic for much longer than animals maintained at 22°C, which ate the provided food when their body mass dropped below a certain point, and returned to stable euthermia at an earlier date than those animals kept at 0°C (Pengelley 1974;Pengelley et al 1976).…”

Section: Behavioral Observations Of Food Intakementioning

confidence: 88%

“…For example, analysis of feeding patterns of the golden-mantled ground squirrel (GMGS, Callospermophilus lateralis) during the hyperphagic period demonstrated that these animals spent roughly 57% of their active hours feeding, and that food consumption and meal frequency increased roughly twofold when compared with earlier summer levels (Mrosovsky and Boshes 1986). Pengelley and Asmundson (1969) and Pengelley (1974) have demonstrated that GMGS have a circannual rhythm of food intake. When animals are kept at a high T a that makes entry into torpor impossible (T a = 35°C), GMGS still manifest a significant decline in food intake during the winter hibernation period.…”

Section: Behavioral Observations Of Food Intakementioning

confidence: 97%

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The regulation of food intake in mammalian hibernators: a review

Florant

Healy

2011

J Comp Physiol B

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One of the most profound hallmarks of mammalian hibernation is the dramatic reduction in food intake during the winter months. Several species of hibernator completely cease food intake (aphagia) for nearly 7 months regardless of ambient temperature and in many cases, whether or not food is available to them. Food intake regulation has been studied in mammals that hibernate for over 50 years and still little is known about the physiological mechanisms that control this important behavior in hibernators. It is well known from lesion experiments in non-hibernators that the hypothalamus is the main brain region controlling food intake and therefore body mass. In hibernators, the regulation of food intake and body mass is presumably governed by a circannual rhythm since there is a clear seasonal rhythm to food intake: animals increase food intake in the summer and early autumn, food intake declines in autumn and actually ceases in winter in many species, and resumes again in spring as food becomes available in the environment. Changes in circulating hormones (e.g., leptin, insulin, and ghrelin), nutrients (glucose, and free fatty acids), and cellular enzymes such as AMP-activated protein kinase (AMPK) have been shown to determine the activity of neurons involved in the food intake pathway. Thus, it appears likely that the food intake pathway is controlled by a variety of inputs, but is also acted upon by upstream regulators that are presumably rhythmic in nature. Current research examining the molecular mechanisms and integration of environmental signals (e.g., temperature and light) with these molecular mechanisms will hopefully shed light on how animals can turn off food intake and survive without eating for months on end.

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Section: Behavioral Observations Of Food Intakementioning

confidence: 88%

Section: Behavioral Observations Of Food Intakementioning

confidence: 97%

The regulation of food intake in mammalian hibernators: a review

Florant

Healy

2011

J Comp Physiol B

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“…Besides color change, Calomys laucha also presented an apparently endogenous body weight variation as it seems to happen in squirrels, minks and European hamsters (Pengelley and Asmundson 1969, Martinet et al 1992, Masson-Pevet et al 1994, since Wt animals were heavier than St animals, even without contact with the natural environment.…”

Section: Discussionmentioning

confidence: 99%

“…Minks and squirrels present an endogenous rhythm of molt which is strongly influenced by changes in photoperiod (Martinet et al 1992) or temperature (Joy and Mrosovsky 1985). Both species also possess endogenous annual rhythms in body weight (Martinet et al 1992, Pengelley andAsmundson 1969) as do European hamsters (Masson-Pevet et al 1994) and dormice (Mrosovsky 1977).…”

Section: Introductionmentioning

confidence: 99%

Seasonal pelage color change: news based on a South American Rodent

Camargo

Colares

Castrucci

2006

An. Acad. Bras. Ciênc.

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Mammalian seasonalmolting and color change are known to be influenced by photoperiod changes. Calomys laucha, a South American rodent, exhibits seasonal pelage color change; however, unlike Northern hemisphere rodents, which present a gray or brown color during summer and a whitish color during winter, C. laucha pelage changes from an orange color during summer to a dark gray color during winter. Animals maintained for over a year in stationary photoperiod (LD 12:12h, 22 • C) presented orange pelage color during the summer corresponding month (January), and gray color during the winter corresponding month (July). Same age animals were evaluated during summer or winter months, and also showed different colors. Animals exposed for 12 weeks to summer or winter artificial conditions displayed color change, not according to the environmental conditions, as expected, but similar to that of animals maintained in stationary photoperiod. These results suggest that pelage color change in C. laucha is controlled by an endogenous circannual rhythm. The adaptive function of C. laucha color change is discussed.

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“…Circannual rhythms have been found to persist for several cycles in both birds and mammals, suggesting that a circannual clock can function throughout the life of an individual (Pengelley and Asmundson, 1969;Pengelley and Asmundson, 1974;Richter, 1978;Gwinner, 1986). The most compelling evidence for circannual rhythms comes from experiments in which captive birds kept on constant and 'neutral' photoperiods (e.g.…”

Section: Introductionmentioning

confidence: 99%

Persistence of circannual rhythms under constant periodic and aperiodic light conditions: sex differences and relationship with the external environment

Budki

Rani

Kumar

2012

Journal of Experimental Biology

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SUMMARYThe timing and duration of gonadal phases in the year indicates that breeding cycles are regulated by endogenous mechanisms. The present study on tropical spotted munia (Lonchura punctulata) investigates whether such mechanisms are based on circannual rhythms, and whether circannual rhythms between sexes differ in their relationship with the light environment. Birds were subjected to 12h light per day (12L:12D), alternate days of light and darkness (24L:24D, LL/DD) and continuous light (LL), with L22lx and D≤1lx, for 28months at constant temperature (18±1°C). Groups kept on natural day lengths (NDL) served as controls. Measurement of body mass, gonads and molts of the primary wing feathers and body plumage at regular intervals showed that birds underwent repeated cycles in gonads and molt, but not in body mass. Under NDL, gonadal phases in both sexes cycled with 12month periods. Under other conditions, males cycled with similar periods of ~11months, but females cycled with relatively large period variations, ~10-13months. Gonadal recrudescence-regression phase was longer in males than in females and, in both sexes, longer in the second year compared with the first year. The molt of wing primaries was more closely coupled to gonadal maturation in groups on NDL and 12L:12D than in groups on LL and LL/DD, but this relationship drifted apart in the second year. Body plumage molts were relatively more highly variable in both frequency and pattern in females than in males. It is suggested that annual breeding cycle in spotted munia is regulated by the self-sustained circannual rhythms, which probably interact with the annual photoperiodic cycle to synchronize breeding cycles to calendar year. Both sexes seem to have independent timing strategies, but females appear to share a greater role in defining the reproductive season in relation with the environment. Supplementary material available online at

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Free-running periods of endogenous circannian rhythms in the golden mantled ground squirrel, Citellus lateralis

Cited by 63 publications

References 13 publications

The regulation of food intake in mammalian hibernators: a review

The regulation of food intake in mammalian hibernators: a review

Seasonal pelage color change: news based on a South American Rodent

Persistence of circannual rhythms under constant periodic and aperiodic light conditions: sex differences and relationship with the external environment

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