Body Temperature Dynamics in Small Mammals and Birds in 10-120-min Period Range

Association between Ultradian Rhythms of Body Temperature in Small Mammals and Earth's Crust Stress

Association was assessed between the data harvested by a long-baseline laser interference deformograph and the dynamics of body temperature (BT) in hamsters deprived of natural daily light-darkness changes. The power spectral data revealed the positive correlation between simultaneous time series of hamster BT and the Earth's crust deformation (ECD). The superposed epoch analysis established an association between abrupt upstrokes of hamster BT and ECD increments. Thus, the direct relationships between BT dynamics (reflecting predominance of sympathetic part of autonomic nervous system) and ECD (according to long-baseline laser interference deformography) were established. The study observed synchronization of the free-running circadian rhythm of hamster BT with the tidal stress in Earth's lithosphere. Further studies are needed to find the physical factor underlying the revealed relationships.

Effect of Heliogeophysical and Atmospheric Factors on the Degree of Synchronization of Ultradian Rhythms of Body Temperature in Mice

In a long-term (8 months) study, we examined the degree of synchronization of ultradian body temperature oscillations of two isolated groups of mice kept under constant dim illumination. In most cases, the periods of increased activity accompanied by rapid elevation of body temperature coincided in these groups of mice, but in some days, no significant synchronization between the examined parameters was observed. Analysis of the effects of environmental factors on the degree of synchronization of ultradian rhythms in mice revealed association of this parameter with the dynamics of atmospheric pressure (AtmP) and to a lesser extent with the vertical component of interplanetary magnetic field Bz. The loss in synchronicity of ultradian rhythms of mouse activity occurred after a rapid drop of AtmP or during pronounced negative Bz. Therefore, these factors can be viewed as desynchronizers of the biological ultradian rhythms.

Fluctuations in the Rate of Radioactive Decay of the Natural Potassium-40 Isotope Can Potentially Affect the Periodic "Spontaneous" Activity of Animals

Body temperature rhythms of C57Bl/6 laboratory mice and common greenfinches (Chloris chloris) and feeding periods of common starlings (Sturnus vulgaris) were compared with the intensity of fluctuations in ⁴⁰К radioactive decay. Body temperature changes in greenfinches and mice were found to positively correlate with the intensity of fluctuations in ⁴⁰K radioactive decay. Superposed epoch analysis showed that an increase in mouse body temperature, which reflects the start of the active phase in the sleep-wake cycle, and food intake in starlings coincide with an increase in the intensity of ⁴⁰K radioactive decay. Thus, animal activity in the ultradian range of periods may be related to external quasi-rhythmic physical influences, rather than being determined only by endogenous processes. Given the extremely low dose of natural ⁴⁰К exposure, a factor responsible for radioactivity fluctuations may act as a biotropic factor.

Possible External Factors Determining Ultradian (4-20-min) Rhythms of Body Temperature

The study examined the effect of passive magnetic shielding on the magnitude of rhythmic oscillations of body temperature (BT) with 4-20 min periods in mice and their correlation with similar oscillations in unshielded control group. A magnetic permalloy screen that 35-fold attenuates the total geomagnetic field and decreased the undulations of magnetic field with the periods of few minutes by 5 times, produced no effect on the mean amplitude of BT oscillations within the same period range, their spectral power, and the cross-spectral density of examined rhythms in comparison with the control (unshielded) mice. Thus, either the mice possess a very sensitive magnetic sensory system or there exists an external non-magnetic factor affecting rhythmicity of BT. The study advanced intensity of thermal neutron radiation near the Earth's surface known to reflect the flow of accelerated particles generated by the secondary cosmic rays as the external factor, which strongly correlates with BT rhythms revealed by cross-spectrum analysis.

Association between Rhythmic Variations of Mouse Body Temperature with 4-16-Minute Periods and Geomagnetic Undulations in Corresponding Frequency Range Pc5/Pi3

The rhythmic variations of body temperature in two groups of mice located in Moscow and Novosibirsk were compared with geomagnetic undulations within Pc5/Pi3 (1-5 mHz) range measured in Borok and Novosibirsk middle-latitude geophysical observatories located at the same longitudes as the examined mice. The spectral maxima of geomagnetic undulations and body temperature variations were observed with greatest probability at the frequencies of 1.6, 2.3, and 3.1 mHz. At this, the mean square of the distance between the frequencies of spectral maxima of simultaneous oscillations was smaller than that of random intervals favoring the hypothesis on geomagnetic undulations as the synchronizer of biorhythms. In both groups of mice, the share of intervals with a high spectral coherency between geomagnetic undulations and body temperature variations had common maximum in the pre-midnight sector of local time and it was higher for the large-scale geomagnetic undulations. Dependence of geomagnetic undulations on spatial scale suggests that body temperature is affected by electrotelluric field.

Changes in Body Temperature of Small Mammals and Birds in a Few Minutes Range as Reflection of Environmental Influences

The study examined the changes in intraperitoneal body temperature of laboratory mice, Jungar hamsters, European greenfinch Chloris chloris, and starlings. In a few minutes range, these changes significantly correlated not only between the animals of the same species, but also between the different classes such as birds and mammals, which were isolated from each other and maintained under different illumination regimen. This phenomenon indicates some external influence(s) on the central mechanisms of the thermal control system not related to illumination regiment. In 80% cases, the phases of most pronounced rhythms of body temperature oscillating with the periods of 8-9 and 12-13 min coincided with those of geomagnetic field within the accuracy of ±1 min. However, the amplitude of body temperature oscillations did not depend on the amplitude of geomagnetic field (GMF) oscillations. Synchronicity of the changes in body temperature and GMF was observed at the amplitude of GMF oscillation of 0.4 nT, which is extremely low value. In contrast, there was no reaction of body temperature to greater (6-10 nT) but irregular and abrupt perturbations of GMF.