Circadian rhythm of cortisol is altered in postsurgical patients

Postoperative cognitive dysfunction: spotlight on light, circadian rhythms, and sleep

Postoperative cognitive dysfunction (POCD) is a neurological disorder characterized by the emergence of cognitive impairment after surgery. A growing body of literature suggests that the onset of POCD is closely tied to circadian rhythm disruption (CRD). Circadian rhythms are patterns of behavioral and physiological change that repeat themselves at approximately, but not exactly, every 24 h. They are entrained to the 24 h day by the daily light-dark cycle. Postoperative CRD affects cognitive function likely by disrupting sleep architecture, which in turn provokes a host of pathological processes including neuroinflammation, blood-brain barrier disturbances, and glymphatic pathway dysfunction. Therefore, to address the pathogenesis of POCD it is first necessary to correct the dysregulated circadian rhythms that often occur in surgical patients. This narrative review summarizes the evidence for CRD as a key contributor to POCD and concludes with a brief discussion of how circadian-effective hospital lighting can be employed to re-entrain stable and robust circadian rhythms in surgical patients.

Clinical Characteristics of Patients with Adrenal Insufficiency and Fever

BACKGROUND

Because persistent fever often occurs in adrenal insufficiency, it might be confused with infectious diseases. This study aimed to identify clinical characteristics and risk factors of patients with adrenal insufficiency and fever.

METHODS

All adult patients (n = 150) admitted to a tertiary care hospital in South Korea and diagnosed with adrenal insufficiency between 1 March 2018, and 30 June 2019, were recruited. Patients were excluded if they had: 1) proven structural problems in the adrenal or pituitary gland; 2) a history of chemotherapy within 6 months prior to the diagnosis of adrenal insufficiency; and 3) other medical conditions that may cause fever.

RESULTS

Among the included patients, 45 (30.0%) had fever at the time of the diagnosis of adrenal insufficiency. The mean C-reactive protein level was higher (11.25 ± 8.54 vs. 4.36 ± 7.13 mg/dL) in patients with fever than in those without fever. A higher proportion of patients with fever changed antibiotics (33.3% vs. 1.0%). On multivariate logistic regression analysis, female sex (odds ratio [OR], 0.32) lowered the risk of adrenal insufficiency with fever, while a history of surgery within 6 months (OR, 4.35), general weakness (OR, 7.21), and cough (OR, 17.29) were significantly associated with that.

CONCLUSION

The possibility of adrenal insufficiency should be considered in patients with fever of unknown origin, especially those with risk factors.

Continuous Free Cortisol Profiles-Circadian Rhythms in Healthy Men

CONTEXT

The pituitary-adrenal axis had historically been considered a representative model for circadian rhythms. A recently developed portable collection device has provided the opportunity to evaluate free cortisol profiles using the microdialysis approach in individuals free to conduct their day-to-day activities in their own surroundings.

METHODS

Two separate experiments were conducted in healthy male volunteers. The total and subcutaneous (SC) free cortisol levels were measured at 10-minute intervals for a 24-hour period in one experiment, and the SC free cortisol levels were measured at 20-minute interval for 72 consecutive hours in free-living individuals in the second experiment.

RESULTS

The characteristic circadian rhythm was evident in both serum total and SC free cortisol, with the lowest levels achieved and maintained in the hours surrounding sleep onset and the peak levels occurring in every individual around waking. In all free-living individuals, the circadian rhythm was consistent across the 72-hour period, despite a wide range of activities. All the participants also showed increased cortisol after the consumption of lunch. The lowest levels during all 24-hour periods were observed during the hours after lights off, at the onset of sleep.

CONCLUSIONS

To the best of our knowledge, the present study is the first to report up to three consecutive 24-hour measurements of SC free cortisol in healthy individuals. We believe our study is a landmark study that paves the way for ambulatory monitoring of free cortisol profiles continuously for a period of 72 hours in free-living individuals performing their day-to-day activities whether healthy or with diseases involving the hypothalamic-pituitary-adrenal axis.

Adrenal function and dysfunction in critically ill patients

Critical illnesses are characterized by increased systemic cortisol availability, which is a vital part of the stress response. Relative adrenal failure (later termed critical-illness-related corticosteroid insufficiency (CIRCI)) is a condition in which the systemic availability of cortisol is assumed to be insufficiently high to face the stress of the illness and is most typically thought to occur in the acute phase of septic shock. Researchers suggested that CIRCI could be diagnosed by a suppressed incremental cortisol response to an injection of adrenocorticotropic hormone, irrespective of the baseline plasma cortisol. This concept triggered several randomized clinical trials on the impact of large stress doses of hydrocortisone to treat CIRCI, which gave conflicting results. Recent novel insights into the response of the hypothalamic-pituitary-adrenal axis to acute and prolonged critical illnesses challenge the concept of CIRCI, as currently defined, as well as the current practice guidelines for diagnosis and treatment. In this Review, these novel insights are integrated within a novel conceptual framework that can be used to re-appreciate adrenocortical function and dysfunction in the context of critical illness. This framework opens new avenues for further research and for preventive and/or therapeutic innovations.

Effects of surgery start time on postoperative cortisol, inflammatory cytokines, and postoperative hospital day in hip surgery: Randomized controlled trial

BACKGROUND

The aim of this study was to compare morning surgery (Group A), characterized by high cortisol levels, with afternoon surgery (Group B), characterized by low cortisol levels, with respect to cortisol, inflammatory cytokines (interleukin [IL]-6, IL-8), and postoperative hospital days (POHD) after hip surgery.

METHODS

The study was conducted in a single center, prospective, randomized (1:1) parallel group trial. Patients undergoing total hip replacement or hemiarthroplasty were randomly divided into two groups according to the surgery start time: 8 AM (Group A) or 1-2 PM (Group B). Cortisol and cytokine levels were measured at 7:30 AM on the day of surgery, before induction of anesthesia, and at 6, 12, 24, and 48 hours (h) after surgery. Visual analogue scale (VAS) and POHD were used to evaluate the clinical effect of surgery start time. VAS was measured at 6, 12, 24, and 48 h postoperatively, and POHD was measured at discharge.

RESULTS

In total, 44 patients completed the trial. The postoperative cortisol level was significantly different between the two groups. (24 h, P < .001; 48 h, P < .001). The percentage of patients whose level returned to the initial level was higher in Group B than in Group A (P < .001). Significant differences in IL-6 levels were observed between the two groups at 12, 24, and 48 h after surgery (P = .015; P = .005; P = .002), and in IL-8 levels at 12 and 24 h after surgery (P = .002, P < .001). There was no significant difference between the two groups in VAS and POHD. However, only three patients in Group A were inpatients for more than 3 weeks (P = .233).

CONCLUSIONS

Afternoon surgery allowed for more rapid recovery of cortisol to the baseline level than morning surgery, and IL-6 and IL-8 were lower at 1-2 days postoperatively. The results of this study suggest that afternoon surgery may be considered in patients with postoperative delayed wound healing or inflammation because of the difference in cortisol, IL-6 and 8 in according to surgery start time.

CLINICAL TRIAL REGISTRATION NUMBER

NCT03076827 (ClinicalTRrial.gov).

Adrenal Aging and Its Implications on Stress Responsiveness in Humans

Normal aging results in subtle changes both in ACTH and cortisol secretion. Most notable is the general increase in mean daily serum cortisol levels in the elderly, without a noteworthy alteration in the normal circadian rhythm pattern. Glucocorticoid excess seen in the elderly population can have serious consequences in both the structural and functional integrity of various key areas in the brain, including the hippocampus, amygdala, prefrontal cortex, with consequent impairment in normal memory, cognitive function, and sleep cycles. The chronically elevated glucocorticoid levels also impinge on the normal stress response in the elderly, leading to an impaired ability to recover from stressful stimuli. In addition to the effects on the brain, glucocorticoid excess is associated with other age-related changes, including loss of muscle mass, hypertension, osteopenia, visceral obesity, and diabetes, among others. In contrast to the increase in glucocorticoid levels, other adrenocortical hormones, particularly serum aldosterone and DHEA (the precursor to androgens and estrogens) show significant decreases in the elderly. The underlying mechanisms for their decrease remain unclear. While the adrenomedullary hormone, norephinephrine, shows an increase in plasma levels, associated with a decrease in clearance, no notable changes observed in plasma epinephrine levels in the elderly. The multiplicity and complexity of the adrenal hormone changes observed throughout the normal aging process, suggests that age-related alterations in cellular growth, differentiation, and senescence specific to the adrenal gland must also be considered.

Perioperative corticosteroid administration: a systematic review and descriptive analysis

Background

Perioperative administration of corticosteroid is common and variable. Guidelines for perioperative corticosteroid administration before non-cardiac non-transplant surgery in patients with current or previous corticosteroid use to reduce the risk of adrenal insufficiency are lacking. Perioperative use of corticosteroid may be associated with serious adverse events, namely hyperglycemia, infection, and poor wound healing.

Objective

To determine whether perioperative administration of corticosteroids, compared to placebo or no intervention, reduces the incidence of adrenal insufficiency in adult patients undergoing non-cardiac surgery who were or are exposed to corticosteroids.

Methods

We searched MEDLINE via Ovid and PubMed, EMBASE via Ovid, and the Cochrane Central Register of Controlled Trials, all from 1995 to January 2017.

Selection criteria

We included randomized controlled trials (RCTs), cohort studies, case-studies, and systematic reviews involving adults undergoing non-cardiac non-transplant surgery and reporting the incidence of postoperative adrenal insufficiency.

Data collection and analysis

Two authors independently assessed studies' quality and extracted data. A descriptive and bias assessment analysis was performed.

Results

Two RCTs (total of 37 patients), five cohort studies (total of 462 patients), and four systematic reviews were included. Neither RCT showed a significant difference in the outcome. This result was like that of the five cohort studies. The quality of the evidence was low.

Conclusion

The current use of perioperative corticosteroid supplementation to prevent adrenal insufficiency is not supported by evidence. Given the significant studies' limitations, it is not possible to conclude that perioperative administration of corticosteroids, compared to placebo, reduces the incidence of adrenal insufficiency.

Might Cardiac Catheterization Influence Diurnal Rhythm of the Steroid Stress Hormones Secretion?

Glucocorticoids (GCs) are steroid hormones produced by the adrenal cortex in reaction to stress stimuli. GCs production is not stable over a 24-hour period; the plasma concentration peaks in the morning (approximately upon awakening) and then the plasma levels decrease, reaching the nadir in the evening. In our experiments, the levels of cortisol, cortisone, DHEA and DHEAS were tested in young female pigs (n=23) during heart catheterization at two different day times (in the morning and in the afternoon). The non-parametric Mann-Whitney test for statistical analysis was used. We found only minimal statistical differences in studied markers between the morning and afternoon group (p>0.05). The absence of circadian variation in GCs levels could originate either at an early age of our experimental pigs, or in stressful conditions on the experiment day, or most likely the day before (e.g. social isolation, fasting, transport, and catheterization), respectively. We can conclude there is no difference in the stress load between morning and afternoon experiments, and therefore we can assume the stress load is not a limiting factor for the timing when catheterization should be preferably performed.

Circadian aspects of post-operative morbidity and mortality

It has been well established that there exists a circadian concentration of cardiovascular, cerebrovascular and cardiopulmonary events. The aim was to describe aspects of circadian variation in relation to cardiovascular, cerebrovascular and thromboembolic diseases and to describe the literature concerning post-operative circadian disturbances. We also present the literature concerning circadian variation in post-operative morbidity and mortality. PubMed and the Cochrane database were searched for papers using a combination of 'circadian,''surgery,''post-operative,''mortality' and 'morbidity.' Eleven relevant studies were found, and seven of these were excluded due to the use of time of surgery and not time of morbidity or mortality as the main variable. The results from the four articles showed a circadian distribution of morbidity and mortality that mimics the one seen without surgery. There is a peak incidence of myocardial ischemia, fatal thromboembolism and sudden unexpected death in the morning hours. A circadian variation exists in post-operative morbidity and mortality. The observed circadian variation in post-operative morbidity and mortality may warrant a chronopharmacological approach to patients in the perioperative period. The underlying pathophysiological mechanisms should be the focus for future studies.

Perioperative glucocorticosteroid supplementation is not supported by evidence

Ever since the first descriptions of adrenal insufficiency following exogenous supplementation physicians dread to abolish perioperative glucocorticosteroid supplementation. Now, 55 years after the first publications we can challenge those first reports. However, these cases have resulted in the supplementation of supraphysiological doses of glucocorticosteroids to patients that use exogenous corticosteroids: the so-called perioperative glucocorticosteroid supplementation or "(gluco)corticosteroid stress scheme". It is very questionable whether a dose that exceeds the normal daily production of 5.7 mg cortisol per square meter of body surface area is necessary to prevent perioperative hypotension. Retrospective, prospective and randomised studies, though all methodologically flawed, are discussed and show that continuation of the "basal" amount of glucocorticosteroids is sufficient to counterbalance surgical stress. The current and rather defensive strategy of perioperative supraphysiological glucocorticosteroid supplementation is not embedded in medical evidence. Additionally, high doses of glucocorticosteroids have disadvantages that should not be ignored.

Unravelling the pathophysiology of delirium: a focus on the role of aberrant stress responses

Delirium is a common and serious acute neuropsychiatric syndrome with core features of inattention and cognitive impairment, and associated features including changes in arousal, altered sleep-wake cycle, and other changes in mental status. The main risk factors are old age, cognitive impairment, and other comorbidities. Though delirium has consistent core clinical features, it has a very wide range of precipitating factors, including acute illness, surgery, trauma, and drugs. The molecular mechanisms by which these precipitating factors lead to delirium are largely obscure. In this article, we attempt to narrow down some specific causal pathways. We propose a basic classification for the etiological factors: (a) direct brain insults and (b) aberrant stress responses. Direct brain insults are largely indiscriminate and include general and regional energy deprivation (e.g., hypoxia, hypoglycaemia, stroke), metabolic abnormalities (e.g., hyponatraemia, hypercalcaemia), and the effects of drugs. Aberrant stress responses are conceptually and mechanistically distinct in that they constitute adverse effects of stress-response pathways, which, in health, are adaptive. Ageing and central nervous system disease, two major predisposing factors for delirium, are associated with alterations in the magnitude or duration of stress and sickness behavior responses and increased vulnerability to the effects of these responses. We discuss in detail two stress response systems that are likely to be involved in the pathophysiology of delirium: inflammation and the sickness behavior response, and activity of the limbic-hypothalamic-pituitary-adrenal axis. We conclude by discussing the implications for future research and the development of new therapies for delirium.

Adrenal insufficiency in prolonged critical illness

INTRODUCTION

Adrenal insufficiency is common in critically ill patients and affects their prognosis, but little is known about how adrenal function changes during prolonged critical illness. This study was conducted to investigate dynamic changes in cortisol levels in patients with critical illness who do not improve after treatment.

METHODS

This observational cohort study was performed in the intensive care units of a university hospital. We studied acutely ill patients with initial cortisol level above 34 microg/dl, but who did not improve after treatment and in whom follow-up cortisol levels were determined during critical illness. All clinical information and outcomes were recorded.

RESULTS

Fifty-seven patients were included. Ten patients had follow-up cortisol levels above 34 microg/dl, 32 patients had levels between 34 and 15 microg/dl, and 15 patients had levels under 15 microg/dl. Outcomes did not differ significantly among the three groups with different follow-up cortisol levels. In Cox regression analysis, those patients who survived to hospital discharge with second cortisol levels under 15 microg/dl had a longer hospital length of stay (odds ratio = 14.8, 95% confidence interval = 2.4 to 90.0; P = 0.004).

CONCLUSION

The majority of acutely ill patients who remained in a critical condition had decreased serum cortisol levels. Depressed cortisol levels at follow up may lead to worse clinical outcomes. We propose that repeated adrenal function testing be conducted in patients with prolonged critical illness.

Adrenal response in patients with septic shock of abdominal origin: relationship to survival

OBJECTIVE

To evaluate the prognostic value of adrenocortical response to corticotropin in septic shock patients operated on exclusively for an intra-abdominal source of infection.

DESIGN AND SETTING

Prospective, observational, single-center study in a surgical intensive care unit of a university hospital

PATIENTS

118 consecutive septic shock patients undergoing laparotomy or drainage for intra-abdominal infection.

MEASUREMENTS AND RESULTS

Baseline cortisol (t (0)) and cortisol response to corticotropin test (Delta) were measured during the first 24 h following onset of shock. The relationship between adrenal function test results and survival was analyzed as well as the effect of etomidate anesthesia. Cortisol plasma level at t (0) was higher in nonsurvivors than in survivors (33 +/- 23 vs. 25 +/- 14 microg/dl), but the response to corticotropin test did not differ between these two subgroups. ROC analysis showed threshold values for t (0) (32 microg/dl) and Delta (8 microg/dl) that best discriminated survivors from nonsurvivors in our population. We observed no difference in survival at the end of hospital stay using log rank test when patients were separated according to t (0), Delta, or both. In addition, adrenal function tests and survival did not differ in patients who received etomidate anesthesia (n = 69) during the surgical treatment of their abdominal sepsis.

CONCLUSIONS

In this cohort of patients with abdominal septic shock baseline cortisol level and the response to corticotropin test did not discriminate survivors from nonsurvivors. No deleterious impact of etomidate anesthesia on adrenal function tests and survival was observed in these patients.

Disturbances in Melatonin, Cortisol and Core Body Temperature Rhythms after Major Surgery

BACKGROUND

It has been suggested that circadian rhythm disturbances are present after major surgery and that this may play a role in the development of postoperative sleep disturbances, fatigue, cognitive dysfunction and cardiovascular morbidity. The objective of this study was to examine the profile of melatonin, cortisol and core body temperature rhythms before and after major surgery.

METHODS

Blood samples (melatonin and cortisol) and core body temperature readings were collected every hour in the 24-h period prior to surgery and the 48 h after surgery from 11 patients undergoing major abdominal surgery. All patients had private rooms. Light exposure was controlled and monitored. Phase markers [50% dim light melatonin onset (DLMO 50%) and offset (DLMOff 50%), cortisol and core body temperature acrophase] for the three circadian rhythm profiles were calculated before and after surgery. The correlation between the melatonin rhythm and time of surgery, duration of surgery and opioid use was examined.

RESULTS

A median delay in the onset of melatonin was seen on the first postoperative day [median DLMO 50% 22:46 hours (range: 21:15-01:08 hours) on the preoperative day compared with 23:54 hours (range: 19:09-02:46 hours) on the first postoperative day; P </= 0.05] . A significant positive correlation existed between the duration of surgery and the time of melatonin onset (r = 0.67, P </= 0.05) . There was a significantly reduced basal secretion of melatonin immediately after surgery, with a subsequent significant increase in maximum melatonin values on the second postoperative night. A median delay of up to 4 h was seen in the timing of the peak of the temperature rhythm on the second postoperative day. Both cortisol secretion and core body temperature were increased after surgery and did not return to preoperative values in the 48 h of the postoperative study period. No significant correlation between opioid dose and the basal or maximum melatonin levels or the time of melatonin onset was found.

CONCLUSION

We found disturbances in three circadian markers after major surgery. The clinical consequences of postoperative circadian disturbances should be investigated further in the future.

Traumatic brain injury regulates adrenocorticosteroid receptor mRNA levels in rat hippocampus

Glucocorticoid activation of two types of adrenocorticosteroid receptors (ACRs), the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR), influences the vulnerability of hippocampal neurons to insult. To examine the potential impact of ACR activation following traumatic brain injury (TBI), the current study assesses regulation of MR and GR expression and glucocorticoid levels following controlled cortical impact (CCI). Male Sprague-Dawley rats were pretreated for 48 h with vehicle, the MR antagonist spironolactone, or the GR antagonist mifepristone (RU486). On day three, subjects were sham-operated or injured by unilateral CCI. In situ hybridization analysis determined that pretreatment with either MR antagonist spironolactone or GR antagonist RU486 increased 24-h hippocampal GR mRNA levels in sham-operated animals only, suggesting that MR and GR regulation of GR mRNA is suppressed following TBI. Injury decreased GR mRNA levels in the ipsilateral dentate gyrus of all pretreatment groups and bilaterally increased MR mRNA levels in CA3 of antagonist-pretreated animals. One day post-injury, plasma corticosterone levels were comparable in sham and injured animals pretreated with vehicle. A separate group of animals that did not receive pretreatment injections prior to sham operation or injury were included for a 24-h time course analysis of plasma ACTH and corticosterone levels. Injury increased hypothalamic-pituitary-adrenal (HPA) activation for approximately 6 h following injury. These results indicate that hippocampal ACR mRNA levels and HPA activation are altered by TBI. Regulation of MR and GR expression following TBI may influence hippocampal neuron viability by modulating glucocorticoid signaling after injury.

Adrenal insufficiency in critically ill emergency department patients: a Taiwan preliminary study

OBJECTIVE

Unrecognized adrenal insufficiency can have serious consequences in critically ill emergency department (ED) patients. This prospective pilot study of adrenal function in patients with severe illness was undertaken to determine the prevalence of adrenal dysfunction and any relation to prior herbal drug use.

METHODS

In a high-volume urban tertiary care ED, adult patients with sepsis or acute myocardial infarction (AMI) were eligible for the study. Over a two-month period, a convenience sample was enrolled by the authors on arrival to the ED. Inclusion criteria were systemic inflammatory response syndrome (SIRS) criteria plus evidence of at least one organ dysfunction or cardiac marker plus electrocardiogram-proven AMI. Exclusion criteria included known corticosteroid use. Serum cortisol was measured on arrival and for those patients with a level of <15 microg/dL (<414 nmol/L), an adrenocorticotropic hormone (ACTH) stimulation test was performed.

RESULTS

Of the 30 enrolled patients, 23 (77%) were suffering from severe sepsis and the other seven (23%) had an AMI. Thirteen of the 30 patients (43%; 95% CI = 25% to 65%) had serum cortisol levels of <15 microg/dL, consistent with adrenal insufficiency, nine with severe sepsis and four with an AMI. Eight (62%; 95% CI = 32% to 86%) of the 13 patients with low cortisol levels reported using herbal medications, while only two (12%; 95% CI = 1% to 36%) of the 17 with normal cortisol levels reported taking herb drugs (p = 0.01). Only two (15%; 95% CI = 2% to 45%) of the patients with low cortisol levels failed their corticotropin stimulation test, suggestive of true adrenocortical insufficiency. Both reported using herbal preparations.

CONCLUSIONS

These results indicate that adrenal dysfunction is common among a group of critically ill patients seen in this Taiwanese ED. Moreover, the use of herbal drugs was high in the patients with low serum cortisols. Further studies are required to both confirm these findings and clarify whether a number of herbal medications contain corticosteroids.

Postoperative dissociation of blood levels of cortisol and adrenocorticotropin after coronary artery bypass grafting surgery

The regulation of the hypothalamo-pituitary-adrenal (HPA) axis in the operative and perioperative period of major surgical procedures is necessary for successful adaption to surgical stress. We report evidence on an altered response of HPA axis regulation in patients who underwent coronary artery bypass grafting (CABG) surgery. Plasma levels of adrenocorticotropin (ACTH), beta-endorphin, and cortisol were determined with radio-immune assay in 50 males for elective CABG surgery. The patients received general anesthesia using a balanced technique with sufentanil, isoflurane, and midazolam. Pre- and intraoperatively, there was no significant increase in plasma cortisol, ACTH, and beta-endorphin levels. On the evening of surgery, all plasma hormone levels were increased. On the evening of the first and second postoperative day, plasma ACTH and beta-endorphin levels returned to the preoperative baseline values. During the same time interval, plasma cortisol levels were significantly elevated and remained high until the end of the study period (p < 0.001). Our results indicate an altered regulation of the HPA axis in the postoperative period of patients after CABG surgery, as they are compatible with similar results in patients after major abdominal surgery, burned patients, and critically ill patients. Therefore, it is assumed that the finding of a postoperative dissociation between ACTH and cortisol is a result of the severity of perioperative adaptive mechanisms rather than of the specific conditions related to cardiac surgery.

Glycosylated and non-glycosylated prolactin forms are increased after opioid administration as part of surgical anaesthesia

OBJECTIVE

Previous studies have shown that non-glycosylated prolactin (NG-PRL) increased more markedly than glycosylated hormone (G-PRL) after TRH or metoclopramide stimulation. The aim of the present study was to determine whether such results could be extended to opioid-induced PRL stimulation.

DESIGN

Open and prospective study. Using a newly developed IRMA specific for NG-PRL, we determined G-PRL and NG-PRL immunoreactivities after administration of 0.8-1.2 mg of the opioid drug phenoperidine as part of an anaesthesia.

PATIENTS

Ten male patients anaesthetized for surgical treatment of a prolapsed lumbar intervertebral disc.

MEASUREMENTS

Samples were obtained hourly pre and post-operatively, and every 15 minutes during operation for determination of plasma PRL, NG-PRL and G-PRL. Plasma cortisol, ACTH and GH levels were measured in an attempt to differentiate the respective roles of stress and opiate agonists in the variations of PRL levels during surgery.

RESULTS

A dramatic increase in PRL levels was observed in all patients from an average of 300 +/- 90 to 1200 +/- 330 mU/l (mean + SEM) 30 minutes after drug administration. The proportion of G-PRL immunoreactivity was not significantly different when basal (25.2%) and stimulated (27%) values were compared (P > 0.05), and when mean increments of NG-PRL and G-PRL were compared (345 and 348%, respectively). The opioid drug induced a significant decrease in cortisol levels after injection and during operation (from 585 +/- 63 to 99 +/- 51 nmol/l) with a concomitant decrease in ACTH levels. GH levels were not significantly altered during anaesthesia but were significantly greater (P < 0.05) after than before surgery (5.0 +/- 1.3 vs 0.98 +/- 0.54 mU/l, respectively).

CONCLUSIONS

We conclude from the present and from previous data that opioid induced anaesthesia is accompanied by an increase in both glycosylated and non-glycosylated PRL and that different PRL secretagogues may induce distinct responses in terms of PRL molecular forms.

Adrenocortical function: an indicator of severity of disease and survival in chronic critically ill patients

Plasma cortisol levels and modified Apache II (Apache IIm-stay) severity of disease scores were determined at weekly intervals in 159 patients who were treated for at least 7 days at the Critical Care Unit of our hospital. The mean (+/- SD) plasma cortisol level (0.60 +/- 0.28 mumol/l) was clearly elevated in these patients. The highest plasma cortisol levels were measured in patients treated with vasoactive drugs (0.76 +/- 0.39 mumol/l). Non-survivors (n = 36) had a significantly higher mean plasma cortisol level and Apache IIm-stay score than survivors (respectively 0.78 +/- 0.40 vs. 0.54 +/- 0.21 mumol/l; p less than 0.0003 and 12.6 +/- 4.8 vs. 7.3 +/- 4.1; p less than 0.0001). A significant correlation was found between the individual weekly plasma cortisol levels and the Apache IIm-stay scores (r = 0.41; p less than 0.0001), especially in the subgroup of patients, who never received glucocorticoids during their stay at the ICU (r = 0.51; p less than 0.0001). During the 14-month study period only two patients showed a clinical picture of adrenocortical insufficiency and a blunted response of cortisol to 0.25 mg synthetic ACTH(1-24). In conclusion, our data suggest that a high plasma cortisol level, like a high Apache IIm-stay score, indicates severity of disease and poor survival in critically ill patients. De novo adrenocortical insufficiency is rare and therefore routine screening of adrenocortical function is superfluous.

Behavior, episodic secretion of cortisol, and adrenocortical reactivity in bulls subjected to tethering

To study the effect of individual housing on behavior and adrenocortical activity, eight bulls were moved to a novel housing environment and subjected to 5 weeks of tethering in individual stanchions with a concrete and partially slatted floor. During the first and fourth week, resting behavior and episodic cortisol secretion were analyzed over two 24-hr periods and compared to those of eight control bulls kept free on deep straw. In addition, in the fifth week adrenocortical reactivity after ACTH(1-24) stimulation was analyzed in all subjects. Resting behavior was markedly influenced by type of housing. Although duration of lying down over 24 hr was similar in tethered and control bulls, the number of periods of lying down was significantly reduced and the frequency of investigating the lying area prior to lying down was significantly increased in tethered bulls. In the first week of study, the cortisol secretory patterns of experimental and control bulls differed. The frequency of secretory episodes was significantly reduced, and the mean amplitude of the episodes increased, though not significantly in experimental compared with control bulls. After 4 weeks of tethering, however, the secretory pattern had returned to levels similar to those of control bulls. Despite this return of the basic cortisol secretion, adrenocortical reactivity after a high dosage of ACTH(1-24) was significantly reduced in tethered bulls. The results suggest that an adaptation to tethering at the brain-pituitary level does not occur, but that the return of the basal cortisol secretion could be due to changes at the adrenocortical level.

24-hour pulsatile and circadian patterns of cortisol secretion in alcoholic men

Pulsatile and circadian patterns of cortisol secretion during acute (3 to 16 days) and chronic (29 to 39 days) abstinence were examined in alcoholic men with no clinical or laboratory evidence of hepatic dysfunction or nutritional deficiencies. Mean and integrated 24-hour serum concentrations of cortisol determined by sampling the blood every 20 minutes over a 24-hour period were increased in six out of 10 alcoholic subjects during acute abstinence when compared with normal controls. Sustained abstinence in seven subjects with follow-up studies caused significant decreases in the mean maximal cortisol peak amplitude (13 +/- 1.0 SEM acutely vs. 10.3 +/- 0.52 micrograms/dl follow-up; P = 0.01), mean 24-hour serum cortisol concentrations (10.9 micrograms/dl +/- 1.2 vs. 8.5 micrograms/dl +/- 0.26; P = 0.047), interpulse valley mean (9.3 micrograms/dl +/- 0.88 vs. 6.5 micrograms/dl +/- 0.34; P = 0.007), and valley nadir (7.9 micrograms/dl +/- 0.69 vs. 5.4 micrograms/dl +/- 0.30; P = 0.0036) concentrations. Cortisol pulse frequency was normal. Although circadian cortisol rhythmicity was maintained in alcoholics, the timing of the circadian acrophase was delayed significantly (P = 0.006) during acute abstinence (1022 [clocktime] +/- 34 min) as compared with normal controls (0743 [clocktime] +/- 34 min), and the amplitude of circadian cortisol rhythms exceeded normal in five of 10 alcoholics. Analysis of data in one alcoholic subject by a new multiparameter deconvolution method demonstrated increases in secretory burst amplitude (0.64 microgram/dl +/- 0.08 SD), mass of cortisol released per burst (9.8 micrograms/dl +/- 1.2 SD), and daily endogenous cortisol production rate (22 mg +/- 2.4 SD) during acute abstinence. These values were statistically different when compared with seven normal controls and the subjects' values during sustained abstinence (P less than 0.02). In conclusion, the results of the present study suggest increased daily production of cortisol as a possible mechanism underlying the elevated serum cortisol concentrations in chronic alcoholics during acute abstinence. This abnormality is shown to be reversible with sustained abstinence from alcohol.

Stress and the pituitary-adrenal axis

The hypothalamo-pituitary-adrenal axis is controlled by complex regulatory mechanisms. Numerous factors such as CRF, vasopressin, oxytocin, angiotensin II and conceivably other hormones--all controlled by various substances acting on central locations--stimulate the release of the stress hormone ACTH. On the other hand, glucocorticoids inhibit the secretion of ACTH by acting at the hypothalamic and/or pituitary level. The release of ACTH is therefore the final outcome of the interactions between the hypothalamus, the adrenal gland and possibly other organs. The multimolecular nature of the factors responsible for the control of the pituitary-adrenal axis is an attractive hypothesis because of the great variety of stress stimuli. The various factors could have specific roles in various stress situations. They provide a highly sensitive mechanism regulating very finely the stress hormone in response to a whole variety of endogenous and exogenous stimuli. Depending on the type of stress, they may therefore singly or in combination affect the amount and duration of ACTH and steroid secretion. The released glucocorticoids may then produce their numerous effects on inflammatory and immunological processes, carbohydrate metabolism, shock and water balance. It has been postulated that these effects may be important in order to prevent host responses from over-reacting to stress and threatening homeostasis. However, proof of the necessity of the glucocorticoid hypersecretion in response to stress remains elusive.

The neuroendocrinology of physical injury

Physical injury of any sort--accidental injury, burns or elective surgery--provokes an immediate neuroendocrine response. Neural input arising from the cerebral cortex, damaged tissues and receptors detecting fluid loss leads to increased secretion of ACTH, growth hormone, prolactin and vasopressin from the pituitary, and to a general activation of the sympathetic nervous system, with rises in adrenaline and noradrenaline concentrations. Secondary changes include stimulation of cortisol and aldosterone and inhibition of insulin and somatomedin secretion. The glucagon concentration and plasma renin activity may also be increased, either immediately or after a delay. The duration of these responses generally depends upon the severity of the injury and differs considerably between hormones, for reasons that are not understood. The only endocrine changes consistently seen at later times after trauma are an increase in insulin secretion, which supersedes the initial suppression, and decreases in the concentrations of T3 and gonadal steroids. Some of the changes in steroid, thyroid and pancreatic hormones differ temporally or even qualitatively from those of their usual stimuli and are unexplained. The initial neuroendocrine response to injury can be construed as playing a defensive role, but the function of the later changes is not understood; it seems likely that they are adaptive in nature, but the scope for therapeutic intervention remains unclear.

[Factors interfering with the dexamethasone suppression test]

The interpretation of the dexamethasone suppression test in endocrinology and psychiatry depends on several variables. False-positive results can be caused by stress, weight loss, alcohol withdrawal, treatment with diphenylhydantoin, phenobarbital, rifampicin, carbamazepine and lithium. Therapy with spironolactone, naloxone, alpha 1-mimetic agents and estrogen can be responsible for an increase in plasma-cortisol concentration. False-negative results are seen in patients with liver disease and can also result from therapy with benzodiazepines at high dosages, indomethacin and possibly methadone and ketoconazole.

Alterations in plasma amino acid levels in children with asthma: a preliminary investigation

Concentrations of plasma amino acids and cortisol were measured in 27 children with status asthmaticus, moderate, or mild asthma and in 7 controls without lung disease. Individuals with conditions potentially altering amino acid levels were excluded. Measurements were made at 8 A.M. and 4 P.M. on the same day. Of the 24 amino acids analyzed, threonine, serine, citrulline, tyrosine, proline, alanine, cystine, isoleucine, ornithine, lysine, and arginine were decreased at 8 A.M. or 4 P.M. and plasma cortisol was elevated at 4 P.M. in patients with status asthmaticus when compared with the other groups (p less than 0.05). Normal diurnal variations of amino acids and cortisol were preserved in all groups. Sequential daily determinations in eight patients with status asthmaticus showed progressive increases in total and many individual amino acids as symptoms subsided. These studies demonstrate a decrease of certain gluconeogenic amino acids in the plasma in status asthmaticus. This diminution could reflect the need for maintenance of normal glucose concentrations in status asthmaticus. The decrease in gluconeogenic amino acid levels may play a role in the severity of asthma.

Prolonged disruption of plasma beta-endorphin dynamics following surgery

The purpose of the present study was to examine the effects of surgery on plasma beta-endorphin dynamics. Plasma beta-endorphin levels were measured by liquid chromatography/radioimmunoassay in seven patients undergoing elective surgery. Blood samples were obtained every 4 hr for two 24-hr periods: one beginning 48 hr before surgery and the other beginning 48 hr after surgery. Computer analysis of beta-endorphin levels as a function of clock time demonstrated a true circadian rhythm preoperatively with a mean of 28.0 +/- 5.9 pg/ml. In the postoperative period mean beta-endorphin levels were significantly elevated (85.6 +/- 20.7 pg/ml, P less than 0.005). Surgical procedures caused significant phase shifting in the grouped mean circadian rhythm of plasma beta-endorphin (mean = 2.4 hr). When the data was analyzed individually, plasma circadian rhythms were found to be totally abolished in the three patients with the longest operative times (mean = 3.8 hr) and significantly displaced in time in the remaining four patients. These prolonged alterations in plasma endogenous opioid peptide levels following surgery have not been previously reported, and should be considered in the management of the postsurgical patient.

Thyroid hormone in biological rhythms

An essential role for thyroid hormone in the production of biological rhythms is proposed. In order for a system to oscillate it must have two stable states. It is possible that thyroid hormone alters the concentration of substrate and product in such a way that the system moves cyclically between these two states. Experimental evidence and clinical facts are invoked to complement the theoretical considerations.

Cortisol excretion into gastric juice. Studies in health, in digestive ulcer disease, and in surgery stress

Gastric juice cortisol concentrations in 36 healthy subjects in the basal state was 10.5 +/- 2.1 ng/ml. After stimulation with pentagastrin it was 11.5 +/- 3.2 ng/ml. There were no differences related to age or sex. Cortisol outputs were 25.9 +/- 12.1 ng/min in the basal state and 35.9 +/- 13.2 during pentagastrin stimulation. After stimulation with ACTH in 6 subjects gastric juice cortisol concentration increased 5.4 times while gastric cortisol output increased 19-fold. The plasma cortisol rose by a factor of 2.3 while the plasma free cortisol rose by a factor of 2.6. Gastric juice cortisol concentration increases correlated with concentrations of free and total plasma cortisol in plasma. When plasma levels of cortisol or dexamethasone were raised by intravenous infusions, the concentration in gastric juice depended on the free corticoid concentration in plasma. Gastric juice cortisol concentrations in 38 patients with gastric, duodenal, or combined gastric and duodenal ulcers were the same as in normal subjects. In 6 patients studied up to 6 days following abdominal surgery, both plasma and gastric cortisol concentrations were elevated but the increase in gastric juice cortisol was proportionally greater. This was not due to vagal stimulation, as shown by the failure of gastric juice cortisol concentrations to rise similarly during insulin hypoglycemia. Postsurgical increases in gastric juice cortisol may reflect the loss of protein-bound cortisol into the gastrointestinal tract as a result of injury to the gastric mucosa.

Circadian patterns and dexamethasone-induced changes in uterine activity in pregnant rhesus monkeys

Five monkeys with amniotic pressure catheters were placed in restraining chairs on days 127 to 131 of gestation (term = 167 days) for examination of circadian patterns in uterine activity. Uterine activity (total area under the contraction curve) was recorded continuously for 3- to 9-day intervals while the animals were exposed to a 16-hour:8-hour light:dark photoperiod. A ratio of hourly contraction area to mean hourly contraction area was established for each individual, and a circadian pattern was observed, with the occurrence of peak uterine activity between 2200 and 0200 hours (analysis of variance, P less than 0.01). An unrestrained animal equipped with a telemetry device and monitored for 23 days demonstrated a similar pattern. Four other catheterized, chair-restrained, pregnant monkeys were used to examine the effects of dexamethasone on uterine activity rhythms. After a 48-hour control period, dexamethasone (0.1 mg/hr) was infused via a maternal venous catheter for 48 hours. Fetal and maternal estrone and estradiol levels and total uterine activity were significantly reduced during dexamethasone infusion (P less than 0.05). In the 48 hours after dexamethasone infusion, mean uterine activity returned to preinfusion levels but the nocturnal peak remained ablated. Therefore, dexamethasone, alters the magnitude, as well as the circadian pattern, of uterine activity in association with reduced estrogen biosynthesis by the fetoplacental unit. Since the effect on uterine activity is biphasic, dexamethasone probably acts by more than one mechanism.

Neuroendocrine regulation of immune processes: change in circulating corticosterone levels induced by the primary antibody response in mice

The induction of antibody formation mediated significant changes in circulating corticosterone (CS) levels in mice. On the day of the peak plaque-forming cell (PFC) response to sheep red blood cells (SRBC) or to the trinitrophenyl (TNP) hapten, the 0800 h serum CS concentration was increased. This hormonal elevation was not observed in SRBC-immunized low responder animals which did not give a significant PFC response, thus suggesting a direct correlation between immune responsiveness and hormonal changes. A change in the circadian rhythm of CS was evident in immune animals injected with SRBC. Control animals injected with saline showed a regular circadian pattern of low CS level at 0800 h followed by a high level at 1600 h. In contrast, responding animals injected with SRBC were found to have a reversed CS pattern, i.e. the hormonal concentration was high at 0800 h and low at 1600 h, on the day of the peak PFC response. This reversal of the circadian CS pattern may have important immunoregulatory significance. The immunization-induced CS response could be significantly blocked by the administration of diazepam (DZM), an effect which implies the involvement of central hypothalamic-pituitary control of the response.