Parallelism of circadian rhythmicity of salivary and serum cortisol concentration in normal dogs (original) (raw)
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Monitoring the circadian rhythm of serum and salivary cortisol concentrations in the horse
Domestic animal endocrinology
Daily fluctuations of cortisol concentration in the blood or saliva have been repeatedly reported. However, several contradictions in the existing literature appear on this subject. The present study was performed to definitively establish options for testing adrenocortical function. To the best of our knowledge, this is the first study to evaluate parallel circadian rhythms in salivary and serum cortisol concentrations during a 24-h period. Twenty horses were examined under the same conditions. Blood and saliva samples were taken every 2 h for 24 h to determine the daily changes in cortisol concentrations of saliva and serum at rest and to determine the relationship between salivary and serum cortisol levels. Cosinor analysis of group mean data confirmed a significant circadian component for both serum and salivary cortisol concentrations (P < 0.001 in both cases). The serum cortisol circadian rhythm had an acrophase at 10:50 AM (95% CI, 10:00 AM-11:40 AM), a MESOR of 22.67 ng/m...
The Circadian Rhythm of Cortisol in the Saliva of Young Pigs
Physiology & Behavior, 1996
The circadian rhythm of cortisol in the saliva of young pigs. PHYSIOL BEHAV 60(3) 985-989, 1996.-Single and population-mean cosinor analyses document a circadian rhythm in salivary cortisol of pigs (p < 0.001). The midline estimated statistic of rhythm, the MESOR (M), is 1.50 +_ 0.07 ng/ml. For the group of 14 pigs studied there was a predictable variation of 64% around this mean in salivary cortisol within a day: the double circadian amplitude, 2A, was 0.96 nglml, with a 95% confidence interval ranging from 0.60 to 1.32 ng/ml. A measure of timing, the acrophase, 4~, was 10 h 52 rain from the phase reference (0030, the middle of the daily dark span of the 24-h light-dark cycle in which the pigs were kept). The 95% confidence interval of th extended from 9 h 48 min to 12 h 12 min from the reference time. The chronobiologic approach provides indispensable quantitive characteristics as reference standards for future basic or applied work. Pigs Salivary cortisol Chronobiology Circadian rhythmicity
The Circadian Rhythm of Salivary Cortisol in Growing Pigs: Effects of Age, Gender, and Stress
Physiology & Behavior, 1997
The circadian rhythm of salivary cortisol in growing pigs: effects of age, gender and stress. PHYSIOL BEHAV 62(3) 623-630, 1997.-This experiment was designed to examine circadian rhythmicity of cortisol in saliva of growing pigs, in relation to age, gender, and (time of) stressor application. Additionally, the acute cortisol response to a stressor was studied. Five groups, each consisting of 3 barrows and 3 gilts, were involved in the experiment. In a Control Group, saliva samples were taken at 1-h intervals at 12, 16, 20, and 24 weeks of age. Within 1 week, rhythmicity of cortisol was assessed during two 24-h spans (Monday and Friday). Rhythm characteristics were evaluated by cosinor analysis, describing the rhythm by several parameters. In 2 groups at 12 weeks and 2 other groups at 20 weeks of age, a stressor was applied (4 h of isolation) on Thursday morning or evening. Again, rhythmicity was assessed on Monday and Friday by sampling at 2-h intervals. Acute cortisol effects were studied by sampling at several time-points during isolation. Between 12 and 24 weeks of age, basal cortisol concentrations decreased and a rather stable and adult circadian rhythm was reached at 20 weeks of age. Average basal cortisol concentrations were higher in barrows than in gilts. Furthermore, after isolation, the amplitude of the rhythm was increased in barrows but was unchanged in gilts. The rhythm was more unstable and the maximum value tended to shift only after evening isolation. Stressor timing, but also age, was found to affect average cortisol concentrations. Moreover, stressor timing was important for the acute cortisol response: the increase was higher in the morning. The results of this study emphasize the importance of considering the circadian rhythmicity of cortisol, in relation to age, gender, and (time of) stressor application, when studying the cortisol response of animals to stressors.
2011
Knowledge of whole body circadian phase is important for the evaluation of physiological processes and for planning time-qualified therapy. The nightly peak in melatonin secretion and the morning peak in cortisol secretion are well-known, prominent circadian rhythmic phenomena in health. Due to their high-amplitude oscillation and relative stability of phase under standardized light-dark conditions, both hormones, either by frequent, dense sampling for melatonin near the onset and/or offset of sleep, morning vs. evening sampling for cortisol, or around-the-clock dense sampling of either, have been suggested for use as a 24 h marker rhythm. Our study evaluated a feasible sampling protocol of collecting six blood samples over 24 h to individually determine whole body circadian phase (i.e., the acrophase, aØ) from each hormone and therein establish synchronization to the light-dark schedule. Cortisol and melatonin serum levels were measured in peripheral blood samples collected every 4 h for 24 h from 11 healthy men, ages 35-53 years, with the sleep/dark span from 23:00-07:00 h. Circadian changes were evaluated by ANOVA and 24 h cosine fitting for original serum levels and also for the fractional variation (FV) that was calculated to evaluate the dynamics (percentage change) of the rise and fall in serum levels between 4 h sampling times. A significant time-effect and 24 h rhythm was detected for both serum melatonin (aØ = 01:35 h) and cortisol (aØ = 07:48 h), confirming synchronization by the subjects as a group to their 24 h environmental light-dark (sleep-wake) schedule, with the anticipated peak for melatonin during darkness and for cortisol in the morning. Overall 4 h FV levels for melatonin and cortisol also showed prominent 24 h rhythms, with highest values prior to darkness onset for melatonin (aØ = 22:29 h) and near mid-dark for cortisol (aØ = 02:12 h), which preceded maximal serum levels by ∼3 h for melatonin and ∼5 h for cortisol. On an individual basis, all 11 subjects showed an unmistakable peak in serum melatonin levels at 02:00 h, while eight subjects showed a clear peak in serum cortisol levels at 06:00 h, one subject showed a delayed peak at 10:00 h, and two subjects showed a broad peak between 02:00 h and 14:00 h. The aØ spread was 5 h 18 min for melatonin (23:54 h to 05:12 h) and 7 h 11 min for cortisol (04:54 h to 12:05 h). These results show that 4 h sampling over 24 h, in lieu of more frequent sampling, can be useful for determining whole body circadian phase and light-dark synchronization, especially when using melatonin, since cortisol can be more easily influenced by external factors involving stress, thereby resulting in a larger spread in peak times. Calculating fractional variations over 4 h intervals also helps to describe the complex dynamics of hormone secretion rates over 24 h. It is thus possible to describe circadian characteristics of hormone secretion with a sampling and data analysis protocol that allows the definition of both temporal characteristics (by cosine fitting) and dynamics (percentage change) using samples obtained every 4 h over 24 h. This protocol may be useful in the study of hormone secretion levels and dynamics in disease and to guide therapeutic and other interventions by defining whole body circadian phase on an individual basis using melatonin or cortisol.
Chapter 46 Circadian rhythmicity: from basic science to clinical approach
Supplements to Clinical neurophysiology
Knowledge on mechanisms underlying the mammalian circadian system, on the effect of light and season of the year on the system and on the role of melatonin improves the understanding of daily rhythms or of chronobiological disorders and leads to new therapies. Many biochemical, physiological, and behavioral processes in mammals including humans exhibit circadian rhythms. Among them are endocrine rhythms in melatonin, adrenocorticotropic hormone (ACTH), corticosteroids, growth hormone, and prolactin as well as rhythms in the rest-activity and sleep–wake cycle, in body temperature, and many other variables. The rhythms are controlled by a circadian pacemaker located in the suprachiasmatic nuclei (SCN) of the hypothalamus. In a non-periodic environment, the pacemaker free-runs with a period close to, but not equal to 24 hour. To the 24-hour day, the phase and period of the circadian pacemaker are entrained mainly by alternation of environmental light and darkness—namely, by the light p...
Life Sciences, 2003
Plasma melatonin and cortisol are characterized by a marked circadian rhythm, but little information is available about the reproducibility and stability of these rhythms over several weeks in the same subjects. This study examined the characteristics of these rhythms in 31 healthy human subjects 20 to 30 years of age. They were synchronized with a diurnal activity from 0800 to 2300 and nocturnal rest. They participated in three 24-hour sessions (S1, S2, and S3): S2 took place two weeks after S1 and S3 4 weeks after S2. Blood samples were taken during each session at 3-hour intervals from 1100 to 2000 and hourly from 2200 to 0800. Comparison of the circadian rhythms between groups used repeated measures 2-way ANOVA, the cosinor method, and Bingham's test. Intraindividual variations were compared by the cosinor method and Bingham's test. The groups did not differ, but a slight difference in the amplitude or acrophase of individual circadian rhythms was observed in 5 of 31 subjects for melatonin and 1 of 31 for cortisol. The circadian means did not differ over the three sessions. These results show that the circadian profile of cortisol and melatonin are highly reproducible over a six-week period, in both individuals and groups. Our study clearly shows that these hormones can be considered to be stable markers of the circadian time structure and therefore useful tools to validate rhythms' synchronisation of human subjects.
Biological Rhythm Research, 2012
To investigate the daily rhythm of rectal and vaginal temperature, we used six mongrel dogs with a mean body weight of 15±3 kg, aged between 2 and 3 years old. Rectal and vaginal temperatures were recorded every 3 h over 48-h period during three different lighting regimes: natural light/dark (L/D) cycle (sunrise 06:25, sunset 17:05), constant light (L/L) and constant darkness (D/D). A daily rhythm of rectal temperature was observed in both days of monitoring in all experimental conditions. Vaginal temperature showed a daily rhythmicity in L/D and D/D cycle. During the L/L cycle, daily rhythm was disrupted. Rhythmic parameters (MESOR, amplitude, acrophase and robustness) did not change between the different photoperiod and the site of temperature collection. In conclusion, the monitoring of vaginal temperature can be considered a valid alternative to the monitoring of body temperature as well as rectal temperature under natural lighting conditions in canine medicine.
2001
Free cortisol measured in saliva has been shown to have the same diurnal rhythm as serum cortisol, one that typically declines rapidly throughout the waking day. A recent study showed that over 15% of a sample of community individuals who were monitored over two days did not show the typical diurnal rhythm. The present study specifically tested the hypothesis that there is significant between-subject variation (individual differences) in diurnal rhythms using multi-level, random regression models.
The goal of the present study was to investigate the daily pattern of serum cortisol rhythm in relation to the total locomotor activity in horses housed in an individual box under a 12-hour light-dark cycle. Blood samples were collected at 3-hour intervals over a 48-hour period via an intravenous cannula inserted into the jugular vein in 5 Italian Saddle horses. In addition, the horses were equipped with Actiwatch Mini, actigraphy-based data loggers that record a digitally integrated measure of motor activity. The application of cosinor rhythmometry showed a daily rhythmicity of serum cortisol levels and locomotor activity. Both parameters showed a diurnal acrophase, at the beginning of photophase for cortisol anticipates of about 5 hours with respect to the acrophase of locomotor activity. The data on the distribution of acrophases have implications for the issue of causation. In conclusion, we found no influence of the rhythm of locomotor activity with the rhythm of serum cortisol.