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  • 1
    Electronic Resource
    Electronic Resource
    Social stimuli fail to act as entraining agents of circadian rhythms in the golden hamster (1992)
    Springer
    Journal of comparative physiology 170 (1992), S. 181-187 
    Details
    ISSN: 1432-1351
    Keywords: Circadian rhythm ; Entrainment ; Social interaction ; Locomotor activity ; Body temperature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ability of social stimuli to act as entraining agents of circadian rhythms was investigated in golden hamsters (Mesocricetus auratus). In a first experiment, pairs of male hamsters (one of them enucleated and the other intact) were maintained under a light-dark (LD) cycle with a period of 23.3 h. Running-wheel activity was recorded to determine the effect of social interaction on the free-running circadian rhythm of activity. In several pairs, general activity and body temperature were also recorded. In all pairs the intact animals entrained to the LD cycle, whereas the activity rhythms of the enucleated animals free-ran with periods of approximately 24 h and showed no apparent sign of synchronization or relative coordination with the other member of the pair. In a second experiment, male hamsters maintained in constant darkness received pulses of social interaction, which have been reported to induce phase shifts of the activity rhythm. Consistent phase shifts in the running-wheel activity rhythm were not induced by the social pulses in our experiment. These results suggest strongly that social stimuli are not effective entraining agents of circadian rhythms in the golden hamster.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196900
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  • 2
    Electronic Resource
    Electronic Resource
    Peripheral nervous control of cold-induced reduction in the respiratory quotient of the rat (1990)
    Springer
    International journal of biometeorology 34 (1990), S. 24-27 
    Details
    ISSN: 1432-1254
    Keywords: Cold-induced thermogenesis ; Peripheral nervous system ; Respiratory quotient ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Cold-exposed rats show a reduction in the respiratory quotient which is indicative of a relative shift from carbohydrates to lipids as substrates for oxidative metabolism. In the present study, the effects of food deprivation and cold exposure on the respiratory quotient were observed. In addition, the involvement of the three main branches of the peripheral nervous system (sympathetic, parasympathetic, and somatic) was investigated by means of synaptic blockade with propranolol, atropine, and quinine, respectively. Both propranolol and quinine blocked the cold-induced decrease in respiratory quotient and increase in heat production, whereas atropine had only minor and very brief effects. It is concluded that both the sympathetic and somatic branches are involved in the metabolic changes associated with cold-induced thermogenesis and that the increase in metabolic heat production involves a shift from carbohydrate to lipid utilization irrespective of which of the two branches is activated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01045816
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of Early Environment on the Circadian Period of the Tau-Mutant Hamster (1998)
    Springer
    Behavior genetics 28 (1998), S. 153-158 
    Details
    ISSN: 1573-3297
    Keywords: Circadian rhythms ; golden hamster ; development ; tau gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract The role of the period of the environmental cycle during gestation and infancy on the circadian period of adult hamsters was studied. Tau-mutant hamsters of all three genotypes (+/+, 24-h circadian period; +/tau, 22-h period; tau/tau, 20-h period) were conceived and raised under either a 20-h light-dark cycle or a 24-h cycle. The circadian period in constant darkness was determined at 2 months of age by inspection of records of running-wheel activity. Differences in circadian period of up to 1.2 h were observed. However, changes of the same magnitude were also observed in animals conceived and raised under a 24-h cycle and exposed to a 20-h cycle at 8 months of age. Therefore, it is concluded that the aftereffects of entrainment can account for the apparent influence of the early environment. The free-running period of the circadian pacemaker seems to be under complete genetic control and not to be influenced by the period of the environmental cycle under which the animal is raised.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021428209122
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    Paper (German National Licenses)
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