Circadian Rhythm Response Research Articles

Phase-dependent shift of free-running human circadian rhythms in response to a single bright light pulse.

Responsiveness of free-running human circadian rhythms to a single pulse of bright light was examined in a temporal isolation unit. Bright light (5000 lx) of either 3 or 6 h duration, applied during the early subjective day, produced phase-advance shifts in both the sleep-wake cycle and the rhythm of rectal temperature; the light pulse had essentially no effect on the phase of the circadian rhythms, when it was introduced during the late subjective day or the early subjective night. The results indicate that bright light can reset the human circadian pacemaker.

Influence of experimental design on the response of the rat testes to exogenous gonadotropins: Induced rhythms?∗

Abstract In order to investigate whether an alteration in experimental design would affect an apparent circadian rhythm in response of the rat testes to gonadotropins, two protocols were tested using prolactin plus LH or hCG. Time‐Variable Design: the time intervals between hypophysectomy, gonadotropin injection and autopsy were not held constant. Autopsy occurred 24 h after the morning treatment but 12 h following the evening treatment. Time‐Constant Design: all time intervals between procedures were a constant 24 h. Sex accessory tissue weights and serum testosterone were determined to assess responses. Our results show that a particular design (Time‐Variable) results in an apparent circadian response to LH and hCG when this periodicity is not actually present.

Organ transplantation and broader chronotherapy with lmplantable pump and computer programs for marker rhythm assessment

The effects of timing cyclosporine (Cs) administration were tested on nephrectomized dogs bearing an allografted kidney. 1.5 mg/kg of cyclosporine per day were given via an externally programmable implanted Medtronic pump at a continuous injection rate or with one of 6 changing rates, each involving 8 different doses, increasing and then decreasing sinusoidally every day, with the total dose per day equal to that in dogs infused at a constant rate. With both the constant and the sinusoidal rate, Cs prolonged graft function with statistical significance. Moreover, some sinusoidal infusion schedules were better than others. The assumption that the differences among dogs treated with different sinusoidal schedules varied randomly was rejected by the fit of a 24-hour cosine function. This approach demonstrated a statistically significant circadian rhythm in response to sinusoidal Cs treatment. The timing of the best schedule during the dark span is surprising in view of a similar timing found for the optimal Cs effect in nocturnal rats bearing heart or pancreas allografts. Further research will have to examine whether this similarity of timing is reproducible, as seems to be the case for melatonin in blood or urine of human beings and noctural rodents. The experimental design including the use of a programmable implantable pump and the procedures for cosinor analysis, in conjunction with diagnostic regression tests, represents an approach to chronotherapy that is more generally applicable. Although chronopharmacokinetic changes have also been explored here and their rhythmicity documented, this contribution is not likely to account fully for the results here obtained.

Circadian Responses of Gonads and Fat Stores to Handling of Gulf Killifish

Abstract When male gulf killifish Fundulus grandis were netted at a consistent time each day for 2–3 weeks, gonad weight and fat stores increased or decreased depending on the time of day the handling occurred. The phases, amplitudes, and patterns of these response rhythms may be influenced by day length and season. In spring, gonad responses were similar at temperatures of 20 and 28 C. In fall, when gulf killifish were placed on a 48-hour diel cycle (12 hours light, 36 hours darkness), fat-response rhythms recycled every 20 hours (for example, similar responses occurred at 0, 20, and 40 hours after the onset of light). Thus, daily photoperiod appears to entrain a circadian rhythm of responsiveness to handling similar to its entrainment of a circadian responsiveness to light.

Photoperiodic stimulation of pubertal development in male deer mice: involvement of the circadian system.

Pubertal development in prairie deer mice (Peromyscus maniculatus bairdii) is accelerated by exposure of juveniles to a long-day photoperiod, and, conversely, retarded by exposure to short days. The purpose of the present study was to evaluate the possible involvement of the circadian system in the photoperiodic regulation of puberty. Weanling males, previously housed on a short-day light cycle of 6L:18D, were subjected to a "resonance" protocol in which they received one of the following light cycles: 6L:18D, 6L:30D, 6L:42D, 6L:54D, or 16L:8D. Post-weaning exposure to cycles of 16L:8D, 6L:30D, and 6L:54D stimulated reproductive organ growth as measured at 6 weeks of age. Exposure to cycles of 6L:18D and 6L:42D failed to stimulate reproductive development. These data support the hypothesis that young male deer mice use a circadian rhythm of responsiveness to light to measure photoperiodic time and, consequently, regulate pubertal development.

Gene differences modify Aschoff's rule in mice

Nocturnal animals typically display an increase in the free running period of circadian rhythms in response to light in direct proportion to intensity. Here we show that gene differences among inbred strains of mice ( Mus musculus) modify the effect of constant bright light on the free running period of a circadian rhythm for wheel running activity. Individuals with the shortest free running periods in dim red light showed the greatest increases in period following exposure to bright light. These effects may be due to gene-imposed differences in the response of a circadian pacemaker to light, or they may be due to gene-imposed differences in visual system function that alter perception of light intensity.

Two mechanisms of rephasal of circadian rhythms in response to a 180° phase shift (simulated 12‐hr time zone change)

A model developed by Wever (1966) is considered. The model describes the behavior of circadian rhythms in response to photoperiod phase shifts simulating time zone changes, as a function of endogenous periodicity, light intensity, and direction of phase shift. A description is given of an investigation conducted to test the model upon the deep body temperature rhythm in unrestrained subhuman primates. An evaluation is conducted regarding the applicability of the model in predicting the type and duration of desynchronization induced by simulated time zone changes as a function of endogenous periodicity.

Effects of a synchronizer phase shift on circadian rhythms in response of mice to ethanol or ouabain.

The percentage of mice dying from a toxic dose of ethanol or ouabain was determined at 4-hour intervals during the first 3 days after inversion of an LD(12:12) lighting regimen. In comparison to unshifted control animals at similar stages of the synchronizer schedule, spans of relative advantage alternated with spans of relative disadvantage due to a gradual phase-shift of the circadian susceptibility rhythm. Overall mortality, determined for an integral number of day, was not obviously affected by the regimen-shift.

The persistence of a circadian rhythm in histamine response in guinea pigs maintained under continuous illumination.

AbstractAdult guinea pigs were carefully standardized for at least seven days prior to each experiment; this included an artificial light‐dark cycle with light extending from 0600 to 1800. On three experimental days, eight animals were injected subcutaneously with 300 μg of histamine at six‐hour intervals over a 24‐hour period; each animal received four injections during one day. The size of the erythema produced each time was measured. In all three experiments a prominent group rhythm was demonstrated with maximum response occurring during the dark phase; minimum response always occurred during the latter part of the light phase. Such results indicate a strong synchronization among the animals of the group.Two additional, similar studies were performed on animals standardized in one case for 21 days and in the second for 35 days under continuous illumination. The group rhythms of histamine response under these conditions, when compared to the light‐dark adapted group rhythm, were greatly modified in phasing and profile. The circadian rhythm in response to histamine persisted in each individual animal. The change in the phasing and profile of the group rhythm was due to a partial desynchronization among the individual animals subjected to continuous illumination.

Circadian rhythm of responsiveness in crayfish visual units.

AbstractMetal microelectrodes were implanted in the optic nerve of the crayfish, Procambarus clarki, and the activity of the sustaining fibers (units which react tonically to changes in illumination) was continuously recorded over periods up to 8 weeks. In animals kept in darkness, the response to periodic test light pulses was found to vary in a circadian manner. The duration of the cycles varied between 22 24 hr, with a phase of high responsiveness during the subjective night, which abruptly changed to one of low responsiveness at subjective dawn. The phase, amplitude, and shape of the cycles were modifiable by light pulses. The spontaneous activity of these units in darkness showed a similar fluctuation, and so did the electroretinogram amplitude, the spontaneous motor activity of the animal, as indicated by records from mechanoreceptive and activity fibers (units which are activated, directly or indirectly by body movements), and the motor responsiveness to light. The time course of these cycles suggests that they are driven by a common “clock,” through humoral mechanisms.

The Biology of Trichoplusia ni (Lepidoptera: Noctuidae). IV. Environmental Control of Mating12

Among adults of Trichoplusia ni (Hubner) exposed to naturally fluctuating environmental conditions, few matings occurred on nights when the midnight temperature was less than 14°C. In the laboratory, T. ni adults mated at temperatures as low as 10°C, after having been held for 4 days at 26±1°C. The threshold-temperature range for mating in the laboratory was similar to the threshold-temperature range for male responses to female sex pheromone extracts. Light influenced both the occurrence and the timing of mating. Mating was inhibited at light intensities greater than 0.3 lux. The mean time of mating in the field and in the laboratory was after midnight. Although the timing of mating was found to be influenced slightly by the circadian rhythm of responsiveness in the male, the timing was primarily controlled by a light: dark-cycle-entrained rhythm in the female.

Miniature long-life temperature telemetry system.

ArticleMiniature long-life temperature telemetry system.T B Fryer, G J Deboo, and C M WingetT B Fryer, G J Deboo, and C M WingetPublished Online:01 Jan 1966https://doi.org/10.1152/jappl.1966.21.1.295MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByEEG measurements by means of radiotelemetry after intracerebroventricular (ICV) cannulation in rodentsJournal of Neuroscience Methods, Vol. 118, No. 1Analysis of the circadian rhythm of body temperatureBehavior Research Methods, Instruments, & Computers, Vol. 24, No. 1Ein Radiotelemetriesystem zur langfristigen, kontinuierlichen Registrierung der Körperkerntemperatur von kleinen Versuchstieren*13 May 2010 | Journal of Veterinary Medicine Series A, Vol. 35, No. 1-10Implantable long-life temperature telemetry system with interference suppressionMedical and Biological Engineering and Computing, Vol. 18, No. 5The Advantages of Short Range Telemetry through the Intact Skin for Physiological Measurements in Both Animals and ManTelemetry Measured Body Temperature of Domestic Fowl at Various Ambient TemperaturesPoultry Science, Vol. 57, No. 4Biotelemetry from free-ranging animalsTwo mechanisms of rephasal of circadian rhythms in response to a 180° phase shift (simulated 12‐hr time zone change)Journal of Interdisiplinary Cycle Research, Vol. 7, No. 4Ovulation and equine body temperature and heart rate circadian rhythmsJournal of Interdisiplinary Cycle Research, Vol. 7, No. 1A Linear Temperature-to-Frequency ConverterIEEE Transactions on Instrumentation and Measurement, Vol. 24, No. 3A portable external two-channel radiotelemetrical GM-detector unit, for measurements of radionuclide-tracers in vivoThe International Journal of Applied Radiation and Isotopes, Vol. 25, No. 4The Application of Aerospace Technology to Patient MonitoringIEEE Transactions on Biomedical Engineering, Vol. BME-20, No. 3Noradrenergic control of circadian rhythms inCebus albifronsAmerican Journal of Physical Anthropology, Vol. 38, No. 2Implantable Telemetry Systems for Use in Animal Monitoring11 July 2009 | Biomaterials, Medical Devices, and Artificial Organs, Vol. 1, No. 2A radiotelemetrical measuring device, implantable on animals, for long term measurements of radionuclide-tracersThe International Journal of Applied Radiation and Isotopes, Vol. 23, No. 11A telemetry system for recording body temperature of large numbers of caged rodentsMedical & Biological Engineering, Vol. 10, No. 5A system for recording the body temperature of several animals simultaneouslyMedical & Biological Engineering, Vol. 10, No. 1Radiotelemetrical equipment for continous subcutaneous measurements of the circadian temperature rhythm in ratsPfl�gers Archiv European Journal of Physiology, Vol. 328, No. 2Radio Telemeters for Temperature and BiopotentialsPoultry Science, Vol. 49, No. 6Response of monkey biorhythms to changing photoperiodsComparative Biochemistry and Physiology, Vol. 30, No. 4Thermally Stable Telemeter for Thermoregulation StudiesScience, Vol. 161, No. 3841The Significance of Circadian Rhythms in the Search for the Moment of Ovulation in PrimatesFertility and Sterility, Vol. 19, No. 2A Radio Transmitter for Telemetering Body Temperatures of ChickensPoultry Science, Vol. 47, No. 2 More from this issue > Volume 21Issue 1January 1966Pages 295-8 https://doi.org/10.1152/jappl.1966.21.1.295PubMed5903929History Published online 1 January 1966 Published in print 1 January 1966 Metrics