Rise In Cortisol Concentrations Research Articles

Is the growth hormone concentration regulated by the morning rise in the plasma cortisol concentration?

Exogenous steroids affect plasma growth hormone (GH) concentrations and hypothalamic somatostatin levels either directly, by stimulating the anterior pituitary gland, or indirectly by partially inhibiting the response of the pituitary gland to stimuli. The effect of the circadian rhythm of cortisol on plasma GH concentrations is unknown. In normal subjects, highest plasma GH concentrations are recorded within the first two hours of onset of sleep. During the early morning the plasma GH concentration decreases and the plasma cortisol concentration increases. We investigated the effect of the early morning rise in plasma cortisol concentration on plasma GH concentrations. We studied 12 healthy volunteers on two occasions. On one occasion the early morning rise in plasma cortisol concentrations was reduced by administering metyrapone (750 mg, 4 hourly from 03.00), while on the other occasion no intervention was made. Plasma GH and cortisol concentrations were measured every 30 and 60 minutes respectively from 22.00 until 14.00. Metyrapone caused a significant reduction in the rise of plasma cortisol concentration, but the GH concentration was identical on both occasions. We conclude that the morning rise in cortisol concentration has no acute regulatory effect on the plasma GH concentration.

Cortisol responses of calves to two methods of disbudding used with or without local anaesthetic

Cattle are disbudded or dehorned using a variety of methods. In this study, plasma cortisol concentrations were used to monitor distress in 6-week-old Friesian calves during the 9 hours following disbudding. Disbudding was carried out with a cautery iron or a dehorning scoop, with or without local anaesthetic. Cautery caused a transient rise in cortisol concentrations which returned to control values within 3 hours. The cortisol response to the scoop was more prolonged, as the plasma cortisol concentrations did not return to control levels until 7.5 hours after disbudding. The administration of a local anaesthetic reduced the cortisol response during the first 2 hours after scoop dehorning. This reduced response was followed by a delayed rise in cortisol concentrations between 2 and 7.5 hours. Cautery caused less distress than the scoop. The administration of local anaesthetic had little effect in alleviating distress in calves disbudded using the cautery iron.

Effects of Sexual Stimulation, with and without Ejaculation, on Serum Concentrations of LH, FSH, Testosterone, Cortisol and Prolactin in Stallions

Six lighthorse stallions with previous sexual experience were used to determine the short-term effects of sexual stimulation (SS; 5 min exposure to an estrous mare), SS plus ejaculation (SSE), and no stimulation (control) on serum concentrations of LH, FSH, testosterone, cortisol and prolactin. Stallions received one treatment per day on d 1, 4 and 7. Treatments were assigned such that each stallion 1) received each treatment once and 2) experienced a unique sequence of treatments. Neither SS nor SSE had any consistent effects on LH or FSH concentrations. Testosterone concentrations during control bleedings increased (P less than .05) with time. This increase was suppressed (P less than .05) by both SS and SSE. Cortisol concentrations increased (P less than .05) immediately after SS and SSE. Cortisol concentrations also tended to increase during the control bleedings, but only in stallions that previously had been exposed to SS or SSE. Prolactin concentrations increased (P less than .05) immediately after SS and SSE and tended to rise during control bleedings in stallions previously exposed to SS or SSE. We conclude that 1) prolactin and cortisol were secreted rapidly in response to SS and SSE, 2) the rise in cortisol concentrations likely suppressed testosterone secretion within the next hour, and 3) stallions appeared to associate the distant sounds of other stallions with their own previous exposure to SS and SSE, resulting in a cortisol response (and perhaps a prolactin response) even in the absence of direct stimulation.

Adrenocortical response to one-leg and two-leg exercise on a bicycle ergometer.

Twelve healthy male subjects exercised for 30 min on a bicycle ergometer, using only one leg, at a work load that was nearly exhausting. Nine subjects (group A) showed a marked rise in plasma cortisol concentration (240 +/- 50 nmol x l-1), but in three subjects no such rise occurred (group B). All group B subjects had elevated cortisol levels prior to the period of exercise, which may have inhibited the adrenocortical response. Seven subjects of group A also performed the same work load using both legs. Under this regime, increases in plasma cortisol and aldosterone levels, blood lactate level and heart rate, but not plasma potassium, were significantly smaller than for one-leg exercise. These findings are consistent with the hypothesis that activation of the hypothalamic-pituitary-adrenal (HPA) system during exercise could be mediated through the stimulation of chemoreceptors in the exercising muscles. This effect could be reinforced by HPA stimulation in response to the greater acceleration of heart rate in one-leg exercise. The marked rises in plasma potassium levels might be responsible for the elevation of plasma aldosterone concentration particularly in those experiments when this occurs earlier than, or in the absence of, rises in cortisol concentration.

Studies on certain aspects of progesterone and cortisol dynamics before, during and after labour.

SUMMARYConcentrations of progesterone, cortisol, free (unbound) progesterone and cortisol binding capacity (CBG) in blood samples were measured serially from 3 weeks preceding delivery to 5 days post partum. There was no change in total plasma progesterone in the last few weeks of pregnancy or during labour but after delivery the concentration of progesterone decreased significantly. Cortisol concentrations showed no change in the last 3 weeks of pregnancy but increased considerably (by 67%) during labour and remained at this high level until at least 2 h post partum, decreasing thereafter. At 5 days post partum the cortisol concentrations were significantly lower than those found a few weeks before labour. The fraction of free progesterone did not change during labour but there was a significant rise in percentage free progesterone 2 h post partum. This rise in percentage free progesterone coincided with the highest concentration of plasma cortisol and a relatively low plasma progesterone. The fraction of free progesterone decreased 1 day post partum to levels that were similar to or slightly lower than those existing before delivery. There was no change in the concentration of CBG before or during labour or at least until 5 days post partum. These results generally support the suggestion that the rise in cortisol concentration during labour can lead to an increase in the fraction of free progesterone.

Adrenal response to physical stress and the effect of adrenocorticotropic hormone in newborn infants

Serial plasma cortisol concentrations were determined in a group of normal newborn infants during the first three days of life; similar measurements were made in neonates experiencing physical stress in the prenatal or postnatal period. No statistically significant differences between these groups were noted. The possibility that the adrenal gland of stressed neonates may be relatively insensitive to ACTH was then investigated: Intramuscular administration of 5 units of a soluble ACTH preparation to these subjects resulted in a substantial rise in cortisol concentration.

Effects of stanniectomy and hypophysectomy on total plasma cortisol levels in the eel ( Anguilla anguilla L.)

Total plasma cortisol levels were estimated in freshwater (FW) and seawater (SW) adapted eels following stanniectomy and hypophysectomy. After 2 wk in calcium-enriched SW, lowered cortisol concentrations of staniectomized eels were associated with marked hypercalcemia. In one group of FW eels, however, there were elevated cortisol levels 10 days after stanniectomy, this initial rise in cortisol levels occurring before the development of significant hypercalcemia. When hypercalcemia had developed in stanniectomized FW eels, cortisol titers were not raised. Ten days after hypophysectomy, plasma cortisol levels had fallen in both FW and SW adapted fish. When the pituitary gland of SW eels was left intact, all wounding provoked a rise in cortisol concentrations. Plasma calcium levels remained unchanged 10 days after the corpuscles of Stannius were excised from their position on the mesonephros and grafted into the pronephric tissue. The role of the corpuscles of Stannius is discussed in relation to the interrenal gland and ionic regulation.

Adrenocortical function in the aged, assessed by the rapid corticotrophin test (Synacthen).

ABSTRACT 15 aged subjects, average age 81 years, were exposed to maximum corticotrophin stimulation. A single intravenous dose of 250 μg Synacthen was administered, and the changes in the plasma cortisol level were measured over the next 4 hours. 10 young subjects were included as controls. Both absolutely and relatively, the aged showed a completely adequate response. The maximum rise in cortisol concentration was observed 120 min after stimulation and was amounted to 24 μg/100 ml in the aged and 20.2 μg/100 ml in the young subjects. A significant difference in the level of the stimulation curve in the two age groups could not be demonstrated. The question is discussed whether the uniform rise in the plasma cortisol concentration in the young and the aged can be taken to support the theory of a reduced cortisol synthesis in the latter group.