Effect of feeding on the diurnal rhythm of plasma cortisol and adrenocorticotrophic hormone concentrations in the pregnant ewe and sheep fetus

Simonetta, Giuseppe; Walker, DW; McMillen, I. C.

doi:10.1113/expphysiol.1991.sp003488

Cited by 35 publications

(29 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…4–10 n M ), the free concentration is similar to that at the circadian nadir in humans [33]. In sheep there is no circadian rhythm in cortisol [34, 35], which is not surprising for a species with no pronounced day/night differences in feeding or sleep/wake behavior. A diurnal pattern can be induced by restricted feeding; in this case levels at the time of the morning feeding would high enough for saturation of MR.…”

Section: Discussionmentioning

confidence: 89%

Pharmacology and Physiology of Ovine Corticosteroid Receptors

Richards¹,

Hua

Keller‐Wood³

2003

Neuroendocrinology

View full text Add to dashboard Cite

The aim of these studies was to characterize the ovine corticosteroid receptors (MR, mineralocorticoid receptors and GR, glucocorticoid receptors) in ovine hippocampus and brainstem. Adrenal-intact and adrenalectomized ewes were studied; adrenalectomized ewes were killed 47 ± 9 h after steroid withdrawal, when symptoms of hypotension and/or hyperkalemia became evident. RT-PCR, immunoblotting and pharmacologic studies indicated the presence of both MR and GR in hippocampus and brainstem. Competitive binding studies using ³H-cortisol in brain tissue showed that the ovine MR binds cortisol, aldosterone and progesterone with equal affinity. Differences in receptor availability in intact and adrenalectomized ewes, along with determination of the binding affinity (K_d) of MR and GR, suggested that MR occupancy is about 90%, whereas GR occupancy is about 30%, in normal animals. There was a significant increase in protein level of MR in brainstem, and the appearance of a higher molecular weight band for MR in hippocampus following steroid withdrawal, however no significant change in mRNA was detected by semiquantitative RT-PCR for either MR or GR in hippocampus or brainstem following steroid withdrawal. These studies suggest that physiological ligands of MR in the sheep brain include progesterone and cortisol, and that, as in other species, affinity of MR for cortisol is greater than that of GR.

show abstract

Section: Discussionmentioning

confidence: 89%

Pharmacology and Physiology of Ovine Corticosteroid Receptors

Richards¹,

Hua

Keller‐Wood³

2003

Neuroendocrinology

View full text Add to dashboard Cite

show abstract

“…For example, primary or secondary peaks in plasma cortisol have been observed in sheep at, or just prior to, the time of feeding (Keller-Wood et al 1988). Moreover, there was a diurnal rhythm in plasma concentrations of cortisol in pregnant ewes fed once daily, with the levels being highest just before food presentation, whereas there was no such rhythm in ewes that were fed at frequent intervals throughout the day (Simonetta et al 1991). Furthermore, peaks in the plasma concentrations of cortisol have been observed in sheep in the morning when human activity may have been increased (McNatty et al 1972).…”

Section: No Stress Stressmentioning

confidence: 99%

Suppression of the secretion of luteinizing hormone due to isolation/restraint stress in gonadectomised rams and ewes is influenced by sex steroids

Tilbrook

Canny²,

Serapiglia³

et al. 1999

Journal of Endocrinology

View full text Add to dashboard Cite

In this study we used an isolation/restraint stress to test the hypothesis that stress will affect the secretion of LH differently in gonadectomised rams and ewes treated with different combinations of sex steroids. Romney Marsh sheep were gonadectomised two weeks prior to these experiments. In the first experiment male and female sheep were treated with vehicle or different sex steroids for 7 days prior to the application of the isolation/restraint stress. Male sheep received either i.m. oil (control rams) or 6 mg testosterone propionate injections every 12 h. Female sheep were given empty s.c. implants (control ewes), or 2 1 cm s.c. implants containing oestradiol, or an intravaginal controlled internal drug release device containing 0·3 g progesterone, or the combination of oestradiol and progesterone. There were four animals in each group. On the day of application of the isolation/ restraint stress, blood samples were collected every 10 min for 16 h for the subsequent measurement of plasma LH and cortisol concentrations. After 8 h the stress was applied for 4 h. Two weeks later, blood samples were collected for a further 16 h from the control rams and ewes, but on this day no stress was imposed. In the second experiment, separate control gonadectomised rams and ewes (n=4/ group) were studied for 7 h on 3 consecutive days, when separate treatments were applied. On day 1, the animals received no treatment; on day 2, isolation/restraint stress was applied after 3 h; and on day 3, an i.v. injection of 2 µg/kg ACTH 1-24 was given after 3 h. On each day, blood samples were collected every 10 min and the LH response to the i.v. injection of 500 ng GnRH administered after 5 h of sampling was measured. In Experiment 1, the secretion of LH was suppressed during isolation/ restraint in all groups but the parameters of LH secretion (LH pulse frequency and amplitude) that were affected varied between groups. In control rams, LH pulse amplitude, and not frequency, was decreased during isolation/restraint whereas in rams treated with testosterone propionate the stressor reduced pulse frequency and not amplitude. In control ewes, isolation/restraint decreased LH pulse frequency but not amplitude. Isolation/restraint reduced both LH pulse frequency and amplitude in ewes treated with oestradiol, LH pulse frequency in ewes treated with progesterone and only LH pulse amplitude in ewes treated with both oestradiol and progesterone. There was no change in LH secretion during the day of no stress. Plasma concentrations of cortisol were higher during isolation/restraint than on the day of no stress. On the day of isolation/restraint maximal concentrations of cortisol were observed during the application of the stressor but there were no differences between groups in the magnitude of this response. In Experiment 2, isolation/restraint reduced the LH response to GnRH in rams but not ewes and ACTH reduced the LH response to GnRH both in rams and ewes. Our results show that the mechanism(s) by which isolation/restraint stress s...

show abstract

“…In sheep, cattle, and deer, episodic fluctuations of cortisol levels dominate and no daily rhythm has been found, or the peaks and troughs have been detected at varying times of the day depending on the conditions (Abilay and Johnson, 1973;Barrell and Lapwood, 1978;Basset, 1974;Bubenik et al, 1977;1983;Fulkerson and Tang, 1979;Fulkerson et al, 1980;Hudson et al, 1975;Ingram et al, 1999;Kennaway et al, 1981;Lefcourt et al, 1993;Lincoln et al, 1982;MacAdam and Eberhart, 1972;McMillen et al, 1987;McNatty et al, 1972;Monfort et al, 1993;Paape et al, 1974;Simonetta et al, 1991;Thun et al, 1981;Wagner and Oxenreider, 1972). Although serum cortisol concentrations of goats have frequently been measured in investigations of stress responses (e.g., Greenwood and Shutt, 1992;Kannan et al, 2000), there are only two descriptions of the basic daily cortisol profile.…”

Section: Introductionmentioning

confidence: 96%

Serum Cortisol Levels in Goats Exhibit Seasonal But Not Daily Rhythmicity

Alila-Johansson

Eriksson

Soveri³

et al. 2003

Chronobiology International

View full text Add to dashboard Cite

The aim of the study was to find out whether there is a daily rhythm in goat serum cortisol concentrations, whether the concentration profiles differ between normal light:dark and constant dark conditions, and whether any seasonal variations might be detected in daily cortisol secretion patterns. Seven Finnish landrace goats were kept at indoor temperature (18-23 degrees C) under artficial lighting that approximately simulated the annual changes of daylength at 60 degrees N. Blood samples were collected for cortisol measurements by radioimmunoassay at 2h intervals during six times of the year: winter (light:dark 6:18h), early spring (10:14h), late spring (14:10h), summer (18:6h), early fall (14:10h), and late fall (10:14h). Cortisol profiles were determined for two consecutive days, first in light:dark (LD) conditions and then in continuous darkness (DD). There was no significant daily rhythm in serum cortisol levels in any time of the year, nor did the profiles in LD and DD conditions show any differences. A significant seasonal variation was, however, detected among the overall cortisol levels. In winter, the concentrations were higher than in any other season, and from early spring to summer they were at their lowest. Under equal photoperiods, the cortisol levels were higher in fall than spring. The difference between winter and summer was confirmed the following year in LD conditions. There was on correlation between serum cortisol and progesterone levels. The results suggest that the possible circadian variation of cortisol secretion in goats is completely masked by external factors, and lighting conditions do not have immediate effects on the daily secretion patterns. The seasonal variation in the overall cortisol levels is most probably related to the changes in photoperiod, because other conditions were relatively constant during the experiment.

show abstract

Effect of feeding on the diurnal rhythm of plasma cortisol and adrenocorticotrophic hormone concentrations in the pregnant ewe and sheep fetus

Abstract: SUMMARYThe effects of two different feeding regimes on the 24 h profiles of maternal and fetal plasma cortisol and adrenocorticotrophic hormone (ACTH) concentrations were studied in eight pregnant ewes between 123 and 144 days of gestation. Once daily-fed ewes (n = 4) received

Cited by 35 publications

References 12 publications

Pharmacology and Physiology of Ovine Corticosteroid Receptors

Pharmacology and Physiology of Ovine Corticosteroid Receptors

Suppression of the secretion of luteinizing hormone due to isolation/restraint stress in gonadectomised rams and ewes is influenced by sex steroids

Serum Cortisol Levels in Goats Exhibit Seasonal But Not Daily Rhythmicity

Contact Info

Product

Resources

About