Ultradian and Circadian Rhythms in the Plasma Concentration of Cortisol in Sheep

Fulkerson, WJ; Tang, Biao

doi:10.1677/joe.0.0810135

Cited by 117 publications

(69 citation statements)

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“…A similar feature was also noted by Ravault and Ortavant (1977) The pattern of cortisol spikes showed that the main difference between the two photoperiods was in the size of the peaks rather than in their frequency. The mean number of episodes compares closely with that observed by Fulkerson and Tang (1979) Forbes, 1982) and active immunisation against prolactin depresses growth (Ohlson et al, 1981) there has been a report of a photoperiodic effect on growth in cattle in which prolactin was very low due to low environmental temperatures (Peters et al, 1980 …”

supporting

confidence: 70%

“…Cortisol shows marked, frequent peaks and secretory spikes were defined using criteria similar to those described by Fulkerson and Tang (1979) for ovine cortisol secretion, that is when the plasma concentration in a sample was as least 10 nmol/I higher than that of the previous sample and the following sample also showed a level which was above the initial one. The end of an episode was when the concentration fell to at least as low as the pre-peak level in two consecutive samples.…”

mentioning

confidence: 99%

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The effect of short and skeleton long photoperiods on the plasma concentrations of prolactin and cortisol in sheep

Brinklow¹,

Forbes²

1984

Reprod. Nutr. Dévelop.

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SummarySuffolk-cross lambs, aged eight weeks, were exposed to either short photoperiods (8L : 16D, SP ; 7 castrated males and 6 females) or skeleton long photoperiods (7L : 10D : 1 L : 6D, SLP ; 6 castrated males and 7 females). They were fed individually on a complete pelleted diet at 70 g/kg live weight 0.75/day. Blood samples were taken monthly by jugular puncture for three months and, after 39 days on experiment, jugular catheters were inserted for frequent sampling over a 24 h period. The samples were assayed for prolactin using radioimmunoassay and for cortisol by competitive protein binding.SLP caused a large and significant increase in plasma prolactin throughout the experiment, with no effect of sex. During the 24 h period there were consistent peaks of prolactin at the start of both dark phases under SLP, with lower levels around the start of both light phases ; under SP, prolactin tended to be higher in the middle of the light phase and the midde of the dark phase than at other times.Considerable hourly fluctuations were observed in cortisol levels but an obvious 24 h rhythm was not. Mean levels were, however, significantly higher under SP (38.3 nmol/I) than under SLP (26.8 nmol/1).Introduction.

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supporting

confidence: 70%

mentioning

confidence: 99%

The effect of short and skeleton long photoperiods on the plasma concentrations of prolactin and cortisol in sheep

Brinklow¹,

Forbes²

1984

Reprod. Nutr. Dévelop.

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“…This is further supported by our observations of the willingness of the ewes to enter the milking parlor, the lack of cluster falls, and the presence of rumination during machine milking. The increase of basal levels during the day could be a result of increasing stress of manipulation, however it is more likely due to a nycthemeral rhythm already described in ewes [6,21].…”

Section: Discussionmentioning

confidence: 84%

The effect of a mixed-management system on the release of oxytocin, prolactin, and cortisol in ewes during suckling and machine milking

Marnet¹,

Negrão²

2000

Reprod. Nutr. Dev.

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-Milk yield and plasma oxytocin (OT), prolactin (PRL), and cortisol (CORT) during suckling and machine milking were measured in multiparous ewes subjected to a mixed management system of 3 sucklings and two daily milkings. Peak hormones were significantly increased and were similar during suckling and milking for PRL (181 vs. 163.3 ng·mL -1 ) and CORT (12.5 vs. 11.5 ng·mL -1 ). During the period of exclusive suckling, OT was always significantly released (90.3 pg . mL -1 ); however, during the period of mixed management, OT concentrations only increased during suckling compared to milking (91.7 vs. 13.1 pg·mL -1 ). The mean volume of milk obtained during suckling (632 mL) was significantly higher than during milking (255 mL). Thus, during a mixed management system, oxytocin and prolactin releases are not under similar central regulation. A mixed system, without OT release during milking, does not contribute to accelerate the conditioning of ewes for machine milking.

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“…In ruminants, it was described in sheep (Fulkerson and Tang, 1979;Mesbah and Brudieux, 1982) but it is not very pronounced in cattle and some studies failed to show any diurnal rhythm (see Mormede et al, 2007 for discussion). In the present study with goats, there was no clear-cut diurnal cycle, as previously shown by others (Kokkonen et al, 2001;Alila-Johansson et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Seasonal effects on plasma cortisol concentrations in the Bedouin buck: circadian studies and response to ACTH

Chergui¹,

Mormède²,

Foury³

et al. 2017

Animal

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Our work aims at the exploration of cortisol secretion in the Bedouin goat, native to the Algerian Sahara desert, to understand the mechanisms of adaptation to extreme hot climates. In the present study, diurnal and seasonal variations of cortisol concentrations were measured in basal conditions, as well as the response to ACTH stimulation tests across seasons in bucks. The plasma concentrations of cortisol showed no diurnal cycle but a large variation across seasons. The highest levels occurred in summer and winter when the environmental conditions are at their extreme levels. The rectal temperature showed nychthemeral and seasonal variations, and BW was also different across seasons with highest values in summer and lowest in winter. The results obtained after administration of two doses (2 or 10 μg/kg BW) of synthetic ACTH to three different age groups (kids, adults and elderly animals) showed a strong increase in plasma cortisol concentrations under all conditions with maximum levels achieved between 15 and 120 min. The analysis of the area under the cortisol curve showed no significant difference between the responses to the two doses of ACTH and between age groups, but showed seasonal variations with the lowest response in autumn than in other seasons. We conclude that season significantly affects secretion of cortisol in both basal state and under ACTH stimulation. However, the variation of adrenal reactivity to ACTH is not sufficient to explain seasonal differences, and in particular the summer peak in basal circulating cortisol concentrations. Further research should focus on the respective contribution of environmental factors (such as day length, temperature, humidity) and the mechanisms involved in cortisol regulation.

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Ultradian and Circadian Rhythms in the Plasma Concentration of Cortisol in Sheep

Cited by 117 publications

References 0 publications

The effect of short and skeleton long photoperiods on the plasma concentrations of prolactin and cortisol in sheep

The effect of short and skeleton long photoperiods on the plasma concentrations of prolactin and cortisol in sheep

The effect of a mixed-management system on the release of oxytocin, prolactin, and cortisol in ewes during suckling and machine milking

Seasonal effects on plasma cortisol concentrations in the Bedouin buck: circadian studies and response to ACTH

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