Elsevier

Physiology & Behavior

Volume 63, Issue 5, March 1998, Pages 837-843
Physiology & Behavior

Original Articles
Diurnally Changing Effects of Locomotor Activity on Body Temperature in Laboratory Mice

https://doi.org/10.1016/S0031-9384(97)00546-5Get rights and content

Abstract

In mice circadian body temperature curves are masked due to the effect of motor activity. However, body temperature will not immediately reflect activity, but rather the integrated activity over IT minutes (integration time) and after a certain delay (lag), and the sensitivity to such masking may change throughout the circadian cycle. The aims of the present investigation were to estimate IT and lag, to quantify the effect of motor activity on body temperature at different times of the day, and, using these results, to draw temperature curves that are closer to the endogenous one. Activity and body temperature of adult male laboratory mice were recorded telemetrically at 10-min intervals. Animals were housed in air-conditioned rooms (T = 22 ± 2°C; relative humidity: 55–65%) with a light–dark cycle of 12 h:12 h (light from 0700 to 1900 hours) and food and water available ad lib. The diurnal activity and body temperature rhythms were similar with a main maximum during the dark time and a secondary maximum immediately following lights-on. Nearly all changes of activity were reflected in body temperature. IT and lag were established on the basis of the best correlation between body temperature and activity (overlapping 4-h sections of 12 days) for all combinations of IT from 10 to 90 min and lag from 0 to 50 min (10-min steps each). The overall means of IT and lag were 40 and 0 min, respectively. During the dark time the values were somewhat larger, but not significantly so. The correlation between activity and body temperature was significantly better in the light time compared to the dark time. The sensitivity of the body temperature to changes in activity was investigated by linear regression analysis for every hour over 12 days (IT = 40 min, lag = 0 min). The gradients assessed by regression analysis showed a diurnal pattern with maximal values during the light time (p < 0.01). Thus, body temperature was raised by activity more during the light time (minimum of body temperature and activity) than during the dark time. The intercepts showed a nearly sinusoidal diurnal pattern with maximal values in the middle of the dark time. Accepting that the intercepts correspond to zero activity at a certain time of day, one might use them to get a curve that is closer to the endogenous body temperature rhythm. Mechanisms (circadian and thermoregulatory) that might cause the diurnally changing sensitivity of body temperature to activity are discussed.

Section snippets

Materials and Methods

Investigations were carried out on adult male laboratory mice of our own outbred stock (Haz:ICR), which is chronobiologically well characterized [for review, see [24]]. Animals were housed in air-conditioned rooms at an ambient temperature of 22 ± 2°C and a relative humidity of 55–65%. They were exposed to an artificial light–dark cycle (LD) of 12 h:12 h with lights on from 0700 to 1900 hours Central European Time. The illumination intensity during light time was about 150 lux. Standardized

1. Diurnal Activity and Body Temperature Rhythms

Fig. 1 shows typical diurnal changes of locomotor activity and core temperature in a male mouse with a main maximum in the dark time and a secondary maximum immediately following lights-on. The Fig. 1 illustrates the effect of activity on temperature. Nearly all changes of activity were reflected in a temperature change.

In an additional study, in which measurements were performed every minute, the relationship between locomotor activity and body temperature could be investigated in more

Discussion

The overt diurnal/circadian rhythm of body temperature consists of an endogenous and an exogenous component. The endogenous component is under the control of a circadian clock 4, 16. The exogenous component is mainly due to the activity behavior. Since motor activity produces heat, body temperature will be raised. This can be seen very clearly when comparing the diurnal patterns of locomotor activity and body temperature (Fig. 1, Fig. 2).

Others have tried to quantify the effect of activity on

References (24)

  • J. Aschoff et al.

    Human circadian rhythmsA multioscillatory system

    Fed. Proc.

    (1976)
  • P. Franken et al.

    Sleep and waking have a major effect on the 24-hr rhythm of cortical temperature in the rat

    J. Biol. Rhythms

    (1992)
  • Cited by (120)

    • Flexibility in body temperature rhythms of free-living natal mole-rats (Cryptomys hottentotus natalensis)

      2021, Journal of Thermal Biology
      Citation Excerpt :

      Field Tb measurements can provide invaluable information regarding the thermoregulatory abilities of animals in their natural habitat and may also be used as a proxy for locomotor activity. Increased physical activity leads to an increase in Tb and changes in these two parameters are usually closely correlated (Refinetti, 1997, 1999, 1999; Refinetti and Kenagy, 2018; Tachinardi et al., 2014; Weinert and Waterhouse, 1998, 1999). In the laboratory, the daily rhythmicity in locomotor activity of Natal mole-rats (Hart et al., 2004) and several other mole-rat species (Ackermann et al., 2017; de Vries et al., 2008; Oosthuizen and Bennett, 2015; Oosthuizen et al., 2003; Schöttner et al., 2006; Vasicek et al., 2005) have been well documented.

    • Analgesic effect of dimethyl trisulfide in mice is mediated by TRPA1 and sst<inf>4</inf> receptors

      2017, Nitric Oxide - Biology and Chemistry
      Citation Excerpt :

      However, in the respirometry setup the mice were loosely restrained and they were unable to use an important natural thermoeffector, general locomotor activity. Since fluctuations of locomotor activity are often reflected in parallel changes of Tb in small rodents, we were also interested in thermoregulatory effects of DMTS in freely-moving mice [14,29,64]. As shown by the Tb and locomotor activity curves representing the difference between DMTS and vehicle treatment in Fig. 6, administration of DMTS (500 μmol/kg, i.p.) to TRPA1 WT and KO mice in the telemetry setup evoked a significant fall of over 4 °C in their deep Tb.

    View all citing articles on Scopus
    View full text