Daily rhythm of body and auricle temperature in goats kept at two different ambient temperatures

In fluctuating environmental temperature, homeotherms are able to maintain stable their body temperature, which however reveals a rhythmic daily pattern as described in literature. Because of the importance of body temperature rhythmicity in the knowledge of thermal homeostasis and as a means to facilitate the study of biological rhythmicity in general, the aim of our study was to assess the influence of two different ambient temperature on the daily rhythmicity of body and auricle temperature in goat (Capra hircus). For our study 6 female adult Maltese goats (18 month old), not pregnant and clinically healthy were used. On each subject body and auricle temperature was recorded during two different periods, of 7 days each, every 3 hours for 24 hours from 07.00 to 04.00, at different environmental temperature (1^st period 18.25 ± 1.48°C, 2^nd period 28.25 ± 2.05°C). The analysis of the obtained result under two ambient temperature indicates the existence of a daily periodicity, with small differences in amplitude and acrophase between the two studied period, both in body and auricle temperature in Maltese breed goat so we can assume that environmental temperature can influence in a significant way the daily pattern of body and auricle temperature.     

Short- and long-term responses to fescue toxicosis at different ambient temperatures

Intake of endophyte-infected tall fescue by cattle results in fescue toxicosis, which is characterized by increased hyperthermia during heat stress and concomitant reductions in feed intake and growth. Rats were monitored at 21 or 31 °C for short- or long-term periods to determine temporal changes associated with the intake of endophyte-infected (E+) or uninfected (E−) fescue seed diets. Core temperature only changed in rats fed E+ diet at 31 °C. Intake of E+ diet reduced feed intake, daily gain, and serum prolactin. There were temporal and thermal differences in the response to endophytic toxins, with short-term changes diminishing over time at 21 °C, but increasing for certain parameters at 31 °C.     

Changes in ambient temperature at the onset of thermoregulatory responses in exercise-trained rats

Spontaneous running in a wheel has emerged as a useful method of exercise in rodents. We investigated how exercise training with a running wheel affects ambient temperatures (T _a) at the onset of thermoregulatory responses in rats. Female rats were allowed to run freely in the wheel for 6 months. Sedentary control rats did not exercise during the same period. After the exercise training period, they were loosely restrained and T _a values at the onset of tail skin vasodilation and cold- induced thermogenesis were determined by raising or lowering T _a. Resting levels of core temperature and heat production of the exercise-trained rats were significantly higher than those of the controls. T _a values at the onset of tail skin vasodilation and cold-induced thermogenesis of the exercise-trained rats were higher than those of the controls. The results suggest that, in rats, exercise training with a running wheel elevates ambient temperatures for heat loss and heat production, which may then contribute to maintaining the core temperature at a high level. Received: 20 August 1999 / Revised: 22 November 1999 / Accepted: 24 November 1999     

Interaction of MIF-I or alpha-MSH with D-amphetamine or chlorpromazine on thermoregulation and motor activity of rats maintained at different ambient temperatures

Administration of several doses of MIF-I or alpha-MSH did not modify colonic temperature or the level of motor activity of rats in ambient temperatures of 4 degree or 20 degrees C. However, the thermoregulatory but not motor effects of the interaction between MIF-I or alpha-MSH with d-amphetamine were dependent upon ambient temperature. At 4 degree C, 1.0 mg/kg of both peptides enhanced the d-amphetamine-induced hypothermia, but at 20 degrees C both peptides blocked the hyperthermic effects of d-amphetamine. The hypothermic effect of chlorpromazine (CPZ) at 4 degree C and 20 degrees C was blocked by 1.0 mg/kg MIF-I but not by 1.0 mg/kg alpha-MSH. No linear dose response relationships between various doses of MIF-I or alpha-MSH and thermal responses were found. Administration of melanin or the use of hypophysectomized rats did not alter the significant interactions observed after peripheral injections.     

Estimation of the core temperature control during ambient temperature changes and the influence of circadian rhythm and metabolic conditions in mice

It has been speculated that the control of core temperature is modulated by physiological demands. We could not prove the modulation because we did not have a good method to evaluate the control. In the present study, the control of core temperature in mice was assessed by exposing them to various ambient temperatures (T_a), and the influence of circadian rhythm and feeding condition was evaluated. Male ICR mice (n=20) were placed in a box where T_a was increased or decreased from 27 °C to 40 °C or to −4 °C (0.15 °C/min) at 0800 and 2000 (daytime and nighttime, respectively). Intra-abdominal temperature (T_core) was monitored by telemetry. The relationship between T_core and T_a was assessed. The range of T_a where T_core was relatively stable (range of normothermia, RNT) and T_core corresponding to the RNT median (regulated T_core) were estimated by model analysis. In fed mice, the regression slope within the RNT was smaller in the nighttime than in the daytime (0.02 and 0.06, respectively), and the regulated T_core was higher in the nighttime than in the daytime (37.5 °C and 36.0 °C, respectively). In the fasted mice, the slope remained unchanged, and the regulated T_core decreased in the nighttime (0.05 and 35.9 °C, respectively), while the slopes in the daytime became greater (0.13). Without the estimating individual thermoregulatory response such as metabolic heat production and skin vasodilation, the analysis of the T_a–T_core relationship could describe the character of the core temperature control. The present results show that the character of the system changes depending on time of day and feeding conditions.     

Daily rhythm and seasonal pattern of lick use in sika deer (Cervus nippon) in China

Many ungulates are reported to use natural or artificial licks with seasonal patterns around the world. From December 2016 to August 2017, we used infrared camera to record the use of artificial licks in wild sika deer (Cervus nippon) in Zhejiang Qingliangfeng National Nature Reserve, China. We explored the daily rhythm, seasonal pattern and sex difference in lick utilization. In total, 12,043 videos and 22,901 pictures were collected. Our results showed that: (1) the lick visiting frequency was higher at night than that during daytime; (2) the difference in lick visiting frequency between females and males disappeared after taking into account of sex ratio; (3) the lick duration peaked in April during a year. These findings suggested that there were clear daily rhythm and seasonal pattern of lick use in sika deer. Seasonal change in lick use intensity was consistent with our prediction. These variations in lick use might be driven by both the physiological needs of the mineral elements in different life stages and the seasonal changes in climate and food. The reserve management authority should pay more attention to the supplement of licks in spring and summer to fulfill animal’s physiological needs.     

Daily and circadian rhythms in the activity of mixed function oxidases system in rats of different age

Abstract

An age‐associated alterations in daily and circadian changes of cytochrome P‐450‐linked monooxygenases system activity were studied using 1‐, 6‐ and 12‐months old male Wistar rats, in winter and in spring season. Cytochrome P‐450 and NADPH‐cytochrome P‐450 reductase showed 12h rhythm in all investigated age groups of animals. Cytochrome b₅ and NADH‐cytochrome b₅ reductase were characterized by a 12h daily rhythm in 1‐month old rats, but in older ones 24h circadian rhythm was found. There was not significant changes of the rhythm pattern in the activity of investigated MFO system ingredients in rats of different age, between spring and winter.     

Daily rhythms of nonshivering thermogenesis and responses to photoperiod manipulations in Apodemus mystacinus from two different ecosystems

Comparative physiology is an important tool for understanding adaptation to environment. Regulatory nonshivering thermogenesis (NST) is an essential mechanism in small mammals for coping with low ambient temperatures. Because of its geographical location and its sharp climatic changes across short distances, Israel offers conducting comparative studies between different populations of the same species. The aims of this study were: (1) to compare NST-capacity daily rhythms, between the two populations of the broad-toothed field mouse Apodemus Mystacinus—that of Mount Carmel (Mediterranean) and that of Mount Hermon (Subalpinic), (2) to compare the thermoregulatory daily rhythms response to photoperiod manipulations of mice from the two populations.

Mice were acclimated for at least 3 weeks to long scotophase (16D:8L-LS) and then to long photophase (16L:8D-LP) at a constant ambient temperature (T_a) of 24±1 °C. The following variables were compared at four different times of the day (06, 12, 18, 24 h): minimal body temperature (T_bMin), minimal oxygen consumption (VO₂Min) measured at the lower critical point and their response to noradrenaline (NA), 1.5 mg/1 kg.W_b injected s.c., (VO₂NA and T_bNA). NST-capacity was calculated as the ratio between VO₂NA and VO₂Min. The measurements were carried out at T_a of 28 °C and in light conditions matching those of acclimation. NA was injected after establishing VO₂Min and T_bMin. The values mean±SD are given for each measurement for n=6.

A three-way ANOVA revealed a significant difference between the two populations. Significant differences were revealed at different hours within populations under the different photoperiod regimes for different measured variables.     

Daily rhythms of oxygen consumption, body temperature, activity and melatonin in the Norwegian lemming Lemmus lemmus under northern summer photoperiod

Rodents inhabiting high latitudes, close to the Arctic Circle or above it, are exposed to near 24 h daylight during the summer season. An example to such rodent species is the Norwegian lemming Lemmus lemmus, which is distributed in northern Fennoscandia. We measured daily rhythms of heat production (VO₂), body temperature (T_b), motor activity and melatonin secretion (measured from its metabolite 6-sulfatoximelatonin 6-SMT) in individuals exposed to natural day light, Oulu Finland, in August 1997 and at a controlled ambient temperature of 22 °C. Our results show a daily rhythm of VO₂ with an acrophase at 04:00 h and minimal values measured at 16:00 h, with a significant difference (p<0.001) between mean day and night values. 6-SMT also shows a daily rhythm with maximal secretion during the dark phase 24:00 and 06:00 h in which total 6-SMT values were 2.92±1.1 and 3.87±1.2 ng, respectively. The lowest values were recorded at 12:00 h; 0.86±0.63 ng. These results suggest that lemmings show a VO₂ and melatonin daily rhythms, which seem to correlate with each other and it appears that melatonin secretion increases heat production.     

The effects of acute hypoxia and hypercapnia on oxygen consumption of the freshwater European eel

When exposed to hypoxia, eels Anguilla anguilla were able to regulate and maintain Vo₂ down to a water oxygen tension ( Pwo₂ ) of about 25 mmHg, a value far below those reported in other studies. When exposed to hypercapnia, eels showed a depression in Vo₂ as water carbon dioxide tension ( Pwco₂ ) increased. Faced with combined hypoxia-hypercapnia, eels showed an increase in their sensitivity to hypoxia, and the critical oxygen tension increased to 40–45 mmHg. The possible mechanisms underlying these responses were discussed, and the implications of such findings for extensive culture of eels were highlighted.     

Effects of beta-endorphin on body temperature in mice at different ambient temperatures

The effect of intracerebroventricular injection of beta-endorphin (beta-END) on body temperature of mice was studied at ambient temperatures (Ta) of 10 degrees, 20 degrees and 31 degrees C. Doses between 0.1 and 10.0 microgram/mouse were studied. The lower (less than 1 microgram) doses of beta-END produced a hyperthermia at all Ta's studied. The higher doses of beta-END produced hyper- or hypothermia depending on the Ta. The subcutaneous injection of naloxone (1 mg/kg) antagonized the high dose hypothermic effects, but not the hyperthermic effect of beta-END. These data suggest that there may be different receptors and/or sites of action for high and low doses of beta-END.     

Plasma osmolality and oxygen consumption of perch Perca fluviatilis in response to different salinities and temperatures

The present study determined the blood plasma osmolality and oxygen consumption of the perch Perca fluviatilis at different salinities (0, 10 and 15) and temperatures (5, 10 and 20° C). Blood plasma osmolality increased with salinity at all temperatures. Standard metabolic rate (SMR) increased with salinity at 10 and 20° C. Maximum metabolic rate (MMR) and aerobic scope was lowest at salinity of 15 at 5° C, yet at 20° C, they were lowest at a salinity of 0. A cost of osmoregulation (SMR at a salinity of 0 and 15 compared with SMR at a salinity of 10) could only be detected at a salinity of 15 at 20° C, where it was 28%. The results show that P. fluviatilis have capacity to osmoregulate in hyper‐osmotic environments. This contradicts previous studies and indicates intraspecific variability in osmoregulatory capabilities among P. fluviatilis populations or habitat origins. An apparent cost of osmoregulation (28%) at a salinity of 15 at 20° C indicates that the cost of osmoregulation in P. fluviatilis increases with temperature under hyperosmotic conditions and a power analysis showed that the cost of osmoregulation could be lower than 12·5% under other environmental conditions. The effect of salinity on MMR is possibly due to a reduction in gill permeability, initiated to reduce osmotic stress. An interaction between salinity and temperature on aerobic scope shows that high salinity habitats are energetically beneficial during warm periods (summer), whereas low salinity habitats are energetically beneficial during cold periods (winter). It is suggested, therefore, that the seasonal migrations of P. fluviatilis between brackish and fresh water is to select an environment that is optimal for metabolism and aerobic scope.     

Growth and food consumption of 0+ Arctic charr fed pelleted or natural food at six different temperatures

The effects of temperature and diet on the specific growth rate and food consumption of 1-summer-old Arctic charr Salvelinus alpinus were studied. Fish were reared singly in aquaria at six different constant temperatures (5, 9, 13, 16, 18 and 20°C). They were fed Neomysis integer or commercial pelleted food for 2 weeks and growth and food consumption were measured. In both experiments, growth rate increased to an optimum at 15°C. Growth rates were high in the range 13–18°C, with no significant ( P >0·05) differences between temperatures. No significant ( P> 0·05) differences in growth were found between fish at 9 and 20°C. There were no effects of diet on size-adjusted growth rates. The growth efficiency decreased with increasing temperature in both treatments, but the decrease was faster in the Neomysis treatment. Charr seemed to compensate for the high water content (79·5%) of Neomysis by having a higher food intake.     

Oxygen consumption and sulfide detoxification in the lugworm Arenicola marina (L.) at different ambient oxygen partial pressures and sulfide concentrations

The lugworm Arenicola marina is a typical inhabitant of intertidal flats. In its L-shaped burrow the animal is exposed to varying concentrations of O₂ and toxic sulfide depending on the tides. The lugworm is able to detoxify sulfide through its oxidation to thiosulfate. When exposed to declining O₂ tensions Arenicola marina reacted as an oxyconformer. In the presence of 25 μmol · l⁻¹ sulfide the respiration was not affected. In contrast, the lugworm consumed significantly less O₂ at any Po₂ in the presence of 200 μmol · l⁻¹ sulfide. Without sulfide anaerobic metabolism started at a Po₂ of approximatedly 10 kPa. Even at high O₂ tensions animals exposed to sulfide produced significantly more anaerobic metabolites compared with the controls. Accordingly the critical value Pc_M, the ambient Po₂ below which anaerobic metabolism starts, was shifted towards normoxia. Since O₂ supply was sufficient for aerobic metabolism, anaerobiosis was induced by sulfide. An influx of sulfide was observed at 25 as well as at 200 μmol · l⁻¹ sulfide. The main product of sulfide detoxification in the lugworm was thiosulfate. Its synthesis increased with ambient Po₂ and depended on the sulfide concentration. Sulfide and thiosulfate were detected in the coelomic fluid, the blood, and the body wall of Arenicola marina. Only about 2% of the ambient O₂ was used for sulfide detoxification at 25 μmol · l⁻¹ sulfide and about 50% at 200 μmol · l⁻¹ sulfide, respectively. Even at the low sulfide concentration Arenicola marina's capacity to detoxify sulfide was too low to maintain a complete aerobic metabolism. Accepted: 19 February 1997     

Effects of ambient Lake Mohave temperatures on development,oxygen consumption,and hatching success of the razorback sucker

Synopsis Spawning of razorback suckers,Xyrauchen texanus, in Lake Mohave occurred from 10–22°C and larvae were collected at water temperatures from 10–15°C in 1982 and 1983. In the laboratory, hatching success was similar from 12–20°C, but reduced hatching success was found at 10°C while none hatched a 8°C. Development rate and oxygen consumption were positively related to incubation temperature. Direct effects of ambient Lake Mohave water temperatures on hatching success of razorback sucker embryos are considered minimal. Historical spawning temperatures for the species are hypothesized based upon successful incubation temperatures and comparison to the white sucker,Catostomus commersoni.     

Role of SCN in Daily Rhythms of Plasma Glucose,FFA, Insulin and Glucagon

The daily changes in plasma glucose, FFA, insulin and glucagon concentrations in rats under 12 hr-12 hr light-dark conditions, and the role of the suprachiasmatic nucleus (SCN) of the hypothalamus in these changes were examined. In sham-operated rats, the four parameters showed significant daily rhythms. However, after bilateral lesions of the SCN, daily rhythms could not be detected in these parameters under the present experimental conditions. Furthermore, after the SCN lesions the plasma glucose concentration remained at the minimum level of that in sham-operated rats, while the plasma insulin and glucagon concentrations reduced to approximately the mean level and about half the minimum level of sham-operated rats, respectively, and the FFA concentration lowered to somewhat below the minimum level. Gradual increase in the plasma insulin concentration at the end of the light period was observed in intact rats even after starvation for 24 hr. These findings suggest that the SCN is essential for generation of the daily changes in the plasma glucose, FFA, insulin and glucagon concentrations and also that it plays critical roles in regulation of the secretion of pancreatic hormones. The gradual increase in the plasma insulin level observed at the end of the light period is discussed in connection with initiation of spontaneous feeding behaviour.