Determination Of Cortisol Research Articles

Hypothalamic-pituitary-adrenal axis in mechanically ventilated critically ill patients: incidence of hyporesponsiveness to stimulation and relationship to cytokine levels

The incidence of hypothalamic-pituitary-adrenal (HPA) axis hypo-responsiveness to stimulation and its relationship to cytokine levels in mechanically ventilated critically ill patients remain controversial. To further clarify these issues, 42 patients (33 men) with a median age of 57 years (range: 16–81 years) were enrolled. Underlying diagnoses included postoperative cases (n = 20), multiple trauma without head injury (n = 12), pancreatitis (n = 4), and miscellaneous (n = 8). Endocrine testing was performed 3–14 days (median: 6 days) after ICU admission. The median APACHE II score at the day of endocrine testing was 15 and the mean SOFA score was 9 ± 4. Morning blood samples were collected for the determination of baseline cortisol, corticotropin (ACTH), and cytokines including IL-8, IL-1, IL-6, IL-12p70 and TNF-α. Immediately after, a low-dose stimulation test (LDST) was performed: 1 μg freshly prepared tetra-cosactrin (1–24) was administered as an intravenous bolus and 30 min later a second blood specimen was obtained to measure stimulated cortisol. Patients having stimulated cortisol levels less than 20 μg/dl were defined as nonresponders to the LDST. The mean baseline cortisol was 16 ± 6 μg/dl (range: 3–32 μg/dl). The mean stimulated cortisol and the increment in cortisol were and 21 ± 6 μg/dl (range: 11–42 μg/dl) and 6 ± 4 μg/dl (range: 0–20 μg/dl), respectively. The median ACTH was 19.0 pg/ml (range: 2–300 pg/ml). Fifteen patients (36%) were nonresponders to the LDST. In the entire patient population median cytokine levels were as follows: IL-8 = 133 pg/ml (range: 11–1010 pg/ml); IL-1 = 51 pg/ml (range: 0–282 pg/ml); TNF-α = 1 pg/ml (range: 0–16 pg/ml); and IL-12p70 = 8 pg/ml (range: 0–47 pg/ml). Nonresponders to the LDST had higher values for IL-1 (45 pg/ml vs 16 pg/ml, P < 0.05) and IL-12p70 (11 pg/ml vs 3 pg/ml, P < 0.05) compared with responders. The two groups did not differ with regard to the other cytokine concentrations. In conclusion, adrenal cortisol secretion after dynamic stimulation is deficient in about two-thirds of critically ill patients; this disorder is associated with higher IL-1 and IL-12p70 levels.

Multi-faceted effects of positive incidents on stress system functioning in a patient with systemic lupus erythematosus

This study on a patient with systemic lupus erythematosus (SLE) investigated the impact of positive emotionally pleasing incidents on hypothalamus-pituitary-adrenal (HPA) axis and cellular immune system activity under complex everyday conditions. A 52 year-old woman collected her entire urine for 56 days in 12-h intervals for the determination of cortisol and neopterin, a cellular immune parameter. Psychological variables were based on daily questionnaires and weekly interviews. Time series analysis consisted of ARIMA modeling and cross-correlational analysis. Positive everyday incidents were associated with three distinct emotional reactions: short-term positive reactions, anticipatory negative reactions, and long-term negative reactions. Short-term positive reactions were associated with a decrease in urine cortisol after 36 h and an increase after a total of 48 h, while urine neopterin increased 24 h after the incidents and decreased after a total of 84 h. Anticipatory negative reactions were associated with an initial increase in urine cortisol 24 h before the incident occurred and with a subsequent decrease a total of 12 h following the incident. Long-term negative reactions were associated with an ultimate increase in urine neopterin 144 h after the incidents. These findings empirically demonstrate that one specific category of positive everyday incidents can be associated with multiple emotional reactions that differ in valence (positive/negative) and duration (short-term/long-term), and also depend on whether an incident was expected (anticipated/not anticipated). This calls for a careful categorization of positive incidents when testing stress system functioning under complex everyday life conditions. Copyright © 2006 John Wiley & Sons, Ltd.

Influence of repeated treadmill exercise on quality and freezability of stallion semen

The objective of this study was to investigate changes of quality and freezability of stallion semen in response to repeated acute treadmill exercise. Ejaculates from 11 stallions were collected, evaluated and frozen weekly during four periods of 4 weeks each defined as before (period 1), during (period 2) and after (periods 3 and 4) intense exercise. In fresh semen the gel-free volume, sperm concentration, motility, normal sperm and sperm with major defects (acrosome defects, nuclear vacuoles, abnormal heads, midpiece defects and proximal droplets) were evaluated. In frozen–thawed semen, motility as well as viability (SYBR-14/PI) were examined. In period 2, all stallions were exercised on an indoor high speed treadmill twice a week (total of eight sessions) using an incremental workload test. Heart rate was monitored telemetrically during exercise and blood samples were taken for determination of cortisol, testosterone and lactate. Results of our investigation demonstrate that heart rate and the plasma concentrations of cortisol, testosterone and lactate significantly ( P < 0.05) increased during each exercise session. Furthermore, significantly more major sperm defects were present in periods 3 (69.5 ± 2.1%) and 4 (66.8 ± 2.1%) than in periods 1 (62.2 ± 2.4%) and 2 (62.5 ± 2.2%). Acrosome defects increased towards the end of exercise but improved 3 weeks later to values observed before exercise. In frozen–thawed semen, motility was significantly lower in period 2 (45.4 ± 2.3%) compared to period 4 (51.6 ± 1.7%) and viability was significantly lower in period 2 (49.2 ± 2.0%) than in periods 1 (53.8 ± 2.1%) and 4 (53.7 ± 1.6%). Our results clearly demonstrate that in the stallion repeated strenuous treadmill exercise can negatively influence semen quality and freezability.

Simultaneous determination of 6β-hydroxycortisol and cortisol in human urine and plasma by liquid chromatography with ultraviolet absorbance detection for phenotyping the CYP3A activity

This study describes an high-performance liquid chromatographic (HPLC)-UV method for the simultaneous determination of 6beta-hydroxycortisol (6beta-OHF) and cortisol (F) in human urine and plasma. The within-day relative standard deviation of the three concentrations for both analytes was less than 6.2%. Accuracy determined at three concentrations ranged between 95 and 107%. The extraction recoveries were 64.1+/-4.3 and 88.1+/-2.4% at three concentrations for 6beta-OHF and F in urine, respectively. The extraction recoveries were 88.7+/-1.4% at three concentrations for F in plasma. This is the first HPLC method that can simultaneously determine 6beta-OHF and F in human urine and plasma and is suitable for routine assessment of the CYP3A activity expressed as 6beta-hydroxylation clearance.

Pituitary-adrenal dynamics after ACTH-secreting pituitary tumor resection in patients receiving no steroids post-operatively

It has recently been suggested that the classical routine of glucocorticoid administration before and after transsphenoidal surgery (TSS) in Cushing's disease (CD) patients may not be necessary, since it is likely that peritumoral normal corticotrophs are not completely suppressed during this period. We compared the dynamics of ACTH and cortisol from a group of CD patients (cured and not cured), receiving no steroids post-operatively, with a control group of acromegalic patients who presented normal hypothalamic-pituitary-adrenal (HPA) axis. Blood samples for ACTH and cortisol determination were obtained immediately before, at the end of surgery and at 4, 8, 12, 16, 24, 48 and 72 h after surgery, in 8 cured CD patients (Group I), 9 not cured CD patients (Group II) and in 7 subjects with acromegaly (Group III) who presented normal HPA axis (control group). The mean ACTH level in Group I was significantly lower than in Group III from 4 to 12 h and lower than in Group II from 8 to 12 h post-operatively. The mean cortisol level in Group I was lower than in Groups II and III from 8 to 72 h after surgery. No difference in mean cortisol level was observed among Groups II and III during the evaluated period. The lowest cortisol value in Group II was 193 nmol/l (at 24 h after surgery) and in Group I patients, after 20 h post-operatively, the highest cortisol level was 165 nmol/l. Although all cured CD patients (Group I) presented serum cortisol level lower than 55 nmol/l until 72 h after surgery, none had significant complications related to adrenal insufficiency. Ours findings are in agreement with recent observations that there is probably no need for glucocorticoid administration until clinical and/or laboratorial data are suggestive of adrenal insufficiency. However, we have also shown that a subphysiological HPA axis response could be observed in cured CD patients after TSS, and a definitive conclusion about glucocorticoid management during and after this procedure could not be made on the ground of the few cases studied in the literature.

A fluorimetric assay for cortisol

A simple, rapid and sensitive fluorimetric assay for the quantitative determination of cortisol is reported. The assay is based on the formation of a fluorescent dye when cortisol is incubated with a mixture of sulfuric acid and acetic acid. The fluorescence spectrum recorded for the resulting dye shows a maximum extinction at 475 nm and a maximum emission at 525 nm. The solvent 2-methyl-4-pentanone was used for extraction and was found to act as a fluorescence amplifier. A limit of detection of 2.7 muM was achieved, making it possible to forego solvent evaporation. The assay suffers minor interference from 11-deoxycortisol which exhibits low fluorescence at lambda (ex): 460 nm; lambda (em): 505 nm. Typical standard deviations were below 4%. We validated the assay using a biotransformation with recombinant Schizosaccharomyces pombe which regioselectively hydroxylates 11-deoxycortisol to cortisol. The method described herein is suitable for preliminary screening of microorganisms capable of steroid hydroxylation.

Platelet monoamine oxidase B (MAO-B) activity and its relationship to DL-fenfluramine-induced prolactin response in healthy men

Several techniques are used to assess central serotonergic neurotransmission in man, e.g. challenge tests (hormonal and physiological responses to serotonin active drugs), platelet MAO-B activity as well as brain imaging techniques. Little is known about how these tests relate to each other. The aim of the present study was therefore to investigate if platelet MAO-B activity could be related to hormonal and temperature responses to the serotonin active drug DL-fenfluramine in healthy men. Twelve male subjects without any history of psychiatric disorders or drug abuse/dependencies were recruited. Prior to the challenge with 60 mg DL-fenfluramine, which was given orally, blood for determination of platelet MAO-B activity was drawn. Blood samples for determination of serum prolactin and serum cortisol were drawn at baseline and thereafter every hour for the following six hours. In addition, body temperature was measured at the same time-points. Delta-values were calculated as the difference between the baseline values and the highest (prolactin and cortisol) or lowest value (temperature) thereafter. There was a strong positive correlation (r = 0.75, p < 0.02) between platelet MAO-B activity and Delta-prolactin. No correlations were found to Delta-cortisol, Delta-temperature or any of the baseline values. The results support the notion that the peripheral marker platelet MAO-B activity is related to the function of the central serotonergic neurotransmitter system as assessed by the prolactin response to 60 mg DL-fenfluramin.

Stress responses at birth: determinants of cord arterial cortisol and links with cortisol response in infancy

To investigate (A) the determinants of infant stress response at delivery and (B) test the hypothesis that stress at birth, as reflected by cord arterial cortisol, influences cortisol response to vaccination at two months. Prospective observational study. Tertiary referral maternity hospital. One hundred and seventy-two primiparous women with uncomplicated singleton pregnancies. Women were recruited antenatally. At birth, cord arterial blood and obstetric data were collected. Saliva was collected from infants immediately before and after vaccination at two months. Cortisol was analysed from cord blood and saliva by radio-immunoassay. Stress response at birth, as demonstrated by cord arterial cortisol; association with saliva cortisol response to vaccination at two months. Cord arterial cortisol varied with mode of delivery, combined spinal/epidural use and pH. Salivary cortisol response at two months correlated with cord arterial cortisol (r= 0.24, P < 0.05). Infants with the highest and lowest cord arterial cortisol had markedly different cortisol responses at two months (P= 0.017). These groups had different modes of delivery with caesarean rates of <8% in the high cortisol response group and 83% in the low cortisol response group (P < 0.0001). Babies born vaginally mount greater cortisol responses at birth than those delivered by caesarean section. Stress at delivery may influence the infant HPA axis response for up to two months.

Method Development for Cortisol and Cortisone by Micellar Liquid Chromatography Using Sodium Dodecyl Sulphate: Application to Urine Samples of Rugby Players

The chromatographic behavior of cortisol and cortisone using a micellar medium of sodium dodecyl sulphate (SDS) as surfactant, a Hypersil C18 (150- x 3.2-mm i.d., 5 microm) column, a flow rate of 0.5 mL/min, and UV absorbance detection at 245 nm is described. The effect of several organic modifiers and the surfactant concentration on the separation is studied. A mobile phase of 18 mM SDS and 8.3% tetrahydrofuran allows for the separation of cortisol and cortisone up to baseline. These results are also achieved by applying a bivariant optimization method. The proposed method is sensitive, reproducible, and selective. In addition, it is less expensive than conventional high-performance liquid chromatography methods for cortisol and cortisone. The method is applied to the determination of cortisol and cortisone in urine samples of rugby players before and after stress for doping control purposes.

Actualité des investigations biologiques pour le diagnostic du syndrome de Cushing

The demonstration of cortisol overproduction and the determination of its cause are still challenging in spite of the progress in imaging studies performances and in techniques for cortisol overproduction demonstration. The latter is established with the 24-hour urinary free cortisol determination, the best screening test when the threshold is settled at 180 μg/24 h. But, since cortisol overproduction is sometimes periodic in true Cushing's disease, two to three determinations might be necessary for the diagnosis. If 24-hour urine collection cannot be adequately obtained, measurement of salivary cortisol is a good alternative. Overnight dexamethasone test is a good screening test for the exclusion of Cushing's syndrome. Though, false negative and false positive results are frequent. Then, in many cases, the standard dexamethasone test is useful. When cortisol overproduction is established, ACTH determination and high dose dexamethasone test usually lead to the etiological diagnosis.

Local anaesthetics attenuates spinal nociception and HPA-axis activation during experimental laparotomy in pigs

The effect of local anaesthetics on spinal nociception and activation of the hypothalamic–pituitary–adrenal axis (HPA-axis) was examined in a porcine model of abdominal surgery. A standardised laparotomy without visceral involvement was performed on 24 pigs. One group received a unilateral infiltration of mixed lidocaine and bupivacaine in skin, muscle and peritoneum of the surgical area prior to surgery ( n = 12), while local anaesthetics were replaced by isotonic saline in a second group ( n = 12). A sham group was subjected to anaesthesia ( n = 8), but did not undergo surgery. Two hours after surgery, half of the pigs from each group were perfused with formalin and the spinal cord was taken out for stereological quantification of the total number of Fos-like-immunoreactive (Fos-LI) neurones in the dorsal horn. Surgery with saline gave rise to a significant increase in the number of Fos-LI neurones ipsilaterally (107,001 ± 16,548; p < 0.001) as well as contralaterally (12,766 ± 3,842; p < 0.01) compared to the sham group. In animals undergoing surgery with LA, the number of Fos-LI neurones ipsilaterally was not significantly different from the sham group ( p = 0.78), and was reduced significantly both ipsilaterally (6960 ± 1662; p < 0.001) and contralaterally (3974 ± 1131; p < 0.05) compared to the saline group. In the other half of each group, blood samples, for determination of ACTH, cortisol, C-reactive protein and interleukin-6 concentrations, were drawn prior to and at predetermined time-points during and after surgery. Surgery with saline gave rise to dramatic increases in plasma ACTH and cortisol ( p < 0.01 and p < 0.001, respectively) within 15 min of incision. In contrast, no changes from the initial concentrations of ACTH and cortisol were observed in pigs receiving local anaesthetics. No changes in plasma concentrations of C-reactive protein or interleukin-6 were observed in either of the groups. These results indicate that spinal nociception and HPA-axis activation caused by laparotomy in pigs can be attenuated by use of infiltration and incisional local anaesthetics prior to surgery. The present model provides a valuable tool in the evaluation of analgesic treatment during surgery, offering objective measures of both nociception and stress.

Disrupted coordinate regulation of farnesoid X receptor target genes in a patient with cerebrotendinous xanthomatosis

Cerebrotendinous xanthomatosis (CTX), sterol 27-hydroxylase (CYP27A1) deficiency, is associated with markedly reduced chenodeoxycholic acid (CDCA), the most powerful activating ligand for farnesoid X receptor (FXR). We investigated the effects of reduced CDCA on FXR target genes in humans. Liver specimens from an untreated CTX patient and 10 control subjects were studied. In the patient, hepatic CDCA concentration was markedly reduced but the bile alcohol level exceeded CDCA levels in control subjects (73.5 vs. 37.8 +/- 6.2 nmol/g liver). Cholesterol 7alpha-hydroxylase (CYP7A1) and Na+/taurocholate-cotransporting polypeptide (NTCP) were upregulated 84- and 8-fold, respectively. However, small heterodimer partner (SHP) and bile salt export pump were normally expressed. Marked CYP7A1 induction with normal SHP expression was not explained by the regulation of liver X receptor alpha (LXRalpha) or pregnane X receptor. However, another nuclear receptor, hepatocyte nuclear factor 4alpha (HNF4alpha), was induced 2.9-fold in CTX, which was associated with enhanced mRNA levels of HNF4alpha target genes, CYP7A1, 7alpha-hydroxy-4-cholesten-3-one 12alpha-hydroxylase, CYP27A1, and NTCP. In conclusion, the coordinate regulation of FXR target genes was lost in CTX. The mechanism of the disruption may be explained by a normally stimulated FXR pathway attributable to markedly increased bile alcohols with activation of HNF4alpha caused by reduced bile acids in CTX liver.

Changes in the fecal concentrations of cortisol and androgen metabolites in captive male jaguars (Panthera onca) in response to stress

In the present study we determined the efficacy of the measurement of fecal cortisol and androgen metabolite concentrations to monitor adrenal and testicular activity in the jaguar (Panthera onca). Three captive male jaguars were chemically restrained and electroejaculated once or twice within a period of two months. Fecal samples were collected daily for 5 days before and 5 days after the procedure and stored at -20 degrees C until extraction. Variations in the concentrations of cortisol and androgen metabolites before and after the procedure were determined by solid phase cortisol and testosterone radioimmunoassay and feces dry weight was determined by drying at 37 degrees C for 24 h under vacuum. On four occasions, fecal cortisol metabolite levels were elevated above baseline (307.8 +/- 17.5 ng/g dry feces) in the first fecal sample collected after the procedure (100 to 350% above baseline). On one occasion, we did not detect any variation. Mean (+/- SEM) fecal androgen concentration did not change after chemical restraint and electroejaculation (before: 131.1 +/- 26.7, after: 213.7 +/- 43.6 ng/g dry feces). These data show that determination of fecal cortisol and androgen metabolites can be very useful for a noninvasive assessment of animal well-being and as a complement to behavioral, physiological, and pathological studies. It can also be useful for the study of the relationship between adrenal activity and reproductive performance in the jaguar.

Role of salivary cortisol determinations in the diagnosis of Cushing syndrome

Purpose of reviewIt is now clear that subclinical Cushing syndrome is more prevalent than commonly thought, particularly in patients with poorly controlled type 2 diabetes mellitus and obesity. This review highlights the usefulness of late-night salivary cortisol to screen patients with the Cushing

The effect of social rank on the physiological response during repeated stressful handling in Zebu cattle ( Bos indicus)

Although the order of entry to a handling chute is related to social rank, it is still not clear what the consequences are for Zebu cattle of occupying different ranks when being exposed repeatedly to a stressful handling procedure. Eighteen Brahman cows were observed for 243 h to obtain information on social interactions. From that information, indices of success in displacing other individuals of the herd were calculated to reflect social status of each cow. One week after behavioral observations, the cows were forced 19 times to enter a handling chute where they were palpated and 7 ml of blood was collected from their caudal vein. To have an adrenal activity profile along the experimental period, five blood samples (Days 2, 6, 10, 15, and 19) were chosen for cortisol determination. On each sampling day, the average time in the chute, the order of entry, and a value of entrance consistency were calculated. On average, the high-ranking cows entered the chute before the medium- and low-ranking cows. Medium-ranking cows showed higher consistency when entering the race than high- and low-ranking cows. Low-ranking cows had significantly lower cortisol levels than the other two groups since the second sample (Day 6 in the race), and had higher cortisol levels the first time handled than at subsequent sampling days. It is suggested that low-ranking cows adopt a passive strategy that allows them to have a better control over the stressful event, while high-ranking cows respond with higher cortisol levels perhaps because of the need to become aroused to deal with challenges. It was concluded that the herd (a) habituated to repeat handling in a squeeze chute and (b) low-ranking cows responded with lower cortisol concentration to handling.

Steroid withdrawal after long-term medication for immunosuppressive therapy in renal transplant patients: adrenal response and clinical implications.

Withdrawal of steroids should be attempted after organ transplantation because of their adverse cardiovascular and metabolic effects. However, immunological, haemodynamic and symptomatic complications may occur due to the suppression of endogenous corticoid hormone synthesis under exogenous steroid intake. We have examined the effect of chronic steroid medication on adrenocortical function, and of steroid withdrawal, in immunologically stable renal transplant patients. Sixty-three patients under long-term prednisone therapy (mean+/-SD 36+/-47 months) were assessed regarding basal fasting cortisol concentration and adrenocortical stimulation by the low-dose Synacten test both prior to and after stepwise prednisone withdrawal. Renal graft function (determined as the calculated glomerular filtration rate according to the Cockroft-Gault formula), mean arterial blood pressure and clinical status were evaluated concomitantly. Basal fasting cortisol concentration was clearly suppressed in 14% of patients under long-term steroid medication, and adrenocortical stimulation by the low-dose Synacten test was impaired in 31% after steroid withdrawal. About a third of all patients were symptomatic with fatigue (60%), arthralgias (60%), muscular weakness (20%), loss of appetite (20%), hypotension (15%) or headaches (5%). The incidence of symptoms was much higher in patients with low basal fasting cortisol concentration prior to steroid withdrawal, and after >2 years of steroid medication. Renal graft function, determined as glomerular filtration rate, decreased only slightly overall by approximately 5%, and was more pronounced in symptomatic vs asymptomatic patients (-7 vs -2 ml/min, respectively), as was the fall in mean arterial pressure (-10 vs -4.2 mmHg, respectively). Adrenal function is impaired in renal transplant patients receiving long-term steroid medication as part of their immunosuppressive regimen. This may lead to mainly symptomatic complications when steroids are withdrawn. The slight decrease in glomerular filtration rate probably can be ascribed mostly to the effect of steroids on systemic renal haemodynamics. It is recommended to consider cessation of steroid medication within 48 months of therapy, and after determination of basal cortisol to identify patients with potential complications.

The Effect of Environmental Manipulation on Behavior, Salivary Cortisol, and Growth of Piglets Weaned at 14 Days of Age

Environmental enrichment can be a useful tool to reduce belly nosing behaviors in early weaned piglets. The aim of this study was to assess the effect of environmental enrichment on behavior, salivary cortisol, and productivity of piglets weaned at 14 days of age. The study assigned 112 piglets (line Camborough 22 of PIC™) into 2 treatments, control and enriched, and observed them for 192 hr in 3 periods: 14 to 28 days of age (Phase 1), 28 to 42 days of age (Phase 2), and 42 to 54 days of age (Phase 3). The study obtained saliva samples in each phase from 56 piglets selected randomly from each group for cortisol determination. Comparisons between both treatments and phases included the following: proportion of time belly nosing, latency of approaching a person, average levels of salivary cortisol, and daily weight gain. Belly nosing was higher and latency of approaching a person lower in the control group than in the enriched one (p < .05 and p < .01). Belly nosing was lower in Phase 3 (p < .05); latency of approaching a person was higher in Phase 1 with respect to Phase 2, and this was higher with respect to Phase 3 (p < .01). There were no differences in salivary cortisol levels between treatments or phases. Weight gain was higher in the enriched group (p < .001). Environmental enrichment in piglets weaned at 14 days of age resulted in a reduced proportion of time nosing, reduced latency of response to humans, and better growth than piglets in barren environments.

Lipopolysaccharide regulates myostatin and MyoD independently of an increase in plasma cortisol in channel catfish ( Ictalurus punctatus)

The effects of lipopolysaccharide (LPS) on plasma cortisol and the expression of MyoD and myostatin (MSTN) mRNAs were evaluated in channel catfish. In addition, the effect of dexamethasone (Dex) on MyoD and MSTN mRNAs was examined. For the LPS injection experiments, juvenile channel catfish were injected intraperitoneally with 1.5 mg/kg LPS or sterile PBS. Blood was collected at 1, 3, 12, and 24 h post-injection for cortisol determination, and muscle samples were collected at 3, 12, and 24 h for mRNA analysis. For the Dex injection experiment, fish were injected with 1.0 mg/kg Dex or saline and muscle samples were collected at 12 and 24 h. There was no effect of LPS on plasma cortisol at any of the time points measured. Injection with LPS increased the abundance of MyoD mRNA at 3 and 12 h, and decreased the abundance of MSTN mRNA at 24 h. There was no effect of Dex injection on the abundance of MyoD mRNA. However, Dex injection decreased the abundance of MSTN mRNA at 12 h post-injection. These results suggest that LPS regulates the expression of MyoD and MSTN independently of an increase in plasma cortisol, and that the regulation of MyoD in the channel catfish differs from mammals in response to inflammatory stimuli. These results also confirm that exogenous glucocorticoids decrease the expression of MSTN as shown in other fish species.

Process irregularity of cortisol and adrenocorticotropin secretion in men with major depressive disorder

Although evidence suggests that major depressive disorder (MDD) is associated with hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis, research on basal HPA axis hormone levels in MDD patients has been inconclusive. Definitive characterization of basal cortisol and adrenocorticotropin (ACTH) secretion may be important for understanding the pathophysiology of this disorder. In recent years, a new approach to the analysis of basal hormone secretion has been developed involving the approximate entropy (ApEn) statistic, which represents the degree of disorderliness or serial irregularity in a time series of hormone levels. ApEn has been shown to reflect the degree of coordination in integrated network systems and has provided new insights into the pathophysiology of a number of endocrine conditions. In the study reported here, 15 medication-free men with MDD and 15 healthy control men were admitted to a General Clinical Research Center and had blood sampled for cortisol and ACTH determinations every hour over a 24-h period. The cortisol and ACTH time series were characterized with a cosinor analysis and with analysis of ApEn. Depressed patients and control subjects did not differ significantly on any parameter derived from the cosinor analysis or on several other standard indices of basal hormone secretion. However, the depressed men had significantly increased cortisol ApEn and significantly decreased ACTH ApEn compared with the healthy subjects. The ApEn findings suggest a loss of regulatory control over cortisol secretion, and possibly increased cortisol feedback on the pituitary in the depressed patients. Together, these results are most consistent with a primary abnormality of the adrenal gland and suggest that further investigation of adrenal gland physiology may be informative for the pathophysiology of depression.

Validation of an EIA [enzyme immunoassay] technique for the determination of salivary cortisol in cattle

This work involves the development and validation of an enzyme immunoassay technique (EIA) for the measurement of the cortisol concentration in cattle saliva. Saliva samples present several advantages over plasma samples in animal welfare studies. Saliva collection avoids venipuncture as a stress factor. Also, saliva components do not affect EIA as plasma components do. At present, there is no validated commercial method for saliva cortisol determination in cattle. Commercially available radioimmunoassay kits for human plasma (detection range: 10-100 ng ml-1) are not sensitive enough for animals with low concentrations of salivary cortisol (&lt; 4 ng ml-1). Thus, EIA is the method of choice in cattle. Sensitivity, specificity, precision and accuracy EIA tests showed this method to be suitable and reliable. The detection limit was found to be 0.024 ng ml-1, representing an improvement on previously described techniques. Intra-assay and inter-assay variation coefficients were 1.47-7.30% and 2.40-9.78%, respectively. The recovery rates for cortisol added to saliva samples were 91.36-126.5%. Parallelism tests showed that saliva cortisol levels can be determined in cattle samples without extraction. The correlation between saliva and plasma cortisol was positive (r = 0.75) and the saliva/plasma cortisol ratio was around 10%. Therefore, saliva samples are a suitable alternative to plasma samples in bovine HPA (hypothalamic-pituitary-adrenal) axis evaluation.