Funktionsst�rung der hypothalamisch-hyphophys�r-adrenalen Achse bei Patienten mit akuten, chronischen und intervallartigen Schmerzsyndromen

Can Endocrine Dysfunction Be Reliably Tested in Aged Horses That Are Experiencing Pain?

Simple Summary

Pituitary pars intermedia dysfunction (PPID) is an endocrine (secreting internally) disease of aged horses and ponies. An enlargement (hyperplasia) of the pars intermedia of the pituitary gland leads to an increased secretion of hormones, including adrenocorticotropic hormone (ACTH). The main tests for a diagnosis of PPID are the measurement of basal ACTH and the thyrotropin-releasing hormone (TRH) stimulation test, where TRH stimulates the secretion of ACTH. Since pain can also lead to elevated concentrations of ACTH, it is unclear whether horses with pain can be tested for PPID correctly. The aim of the present study was to find out whether pain caused a marked increase of ACTH can lead to a false positive result in the diagnosis of PPID. Therefore, we examined fifteen horses treated for different pain conditions, which also served as their own controls as soon as they were pain-free again. The ACTH and cortisol were measured before and after the TRH stimulation test. There was no significant difference in the ACTH concentration in horses with pain and the controls, between different pain intensities or between disease groups. Thus, measuring the basal ACTH concentration and performing the TRH stimulation test for the diagnosis of PPID seem to be possible in horses with a treated low to moderate pain condition.

Abstract

The aim of the present study was to evaluate (i) the effects of different intensities and types of treated pain on the basal concentrations of adrenocorticotropic hormone (ACTH) and cortisol, and (ii) the thyrotropin-releasing hormone (TRH) stimulation test, to determine whether treated pain caused a marked increase of ACTH, which would lead to a false positive result in the diagnosis of pituitary pars intermedia dysfunction (PPID). Methods: Fifteen horses with treated low to moderate pain intensities were part of the study. They served as their own controls as soon as they were pain-free again. The horses were divided into three disease groups, depending on their underlying disease (disease group 1 = colic, disease group 2 = laminitis, disease group 3 = orthopedic problems). A composite pain scale was used to evaluate the intensity of the pain. This pain scale contained a general part and specific criteria for every disease. Subsequently, ACTH and cortisol were measured before and after the intravenous application of 1 mg of TRH. Results: There was no significant difference in the basal or stimulated ACTH concentration in horses with pain and controls, between different pain intensities or between disease groups. Descriptive statistics, however, revealed that pain might decrease the effect of TRH on the secretion of ACTH. There was an increase of ACTH 30 min after TRH application (p = 0.007) in the treated pain group, but this difference could not be statistically confirmed. Measuring the basal ACTH concentration and performing the TRH stimulation test for the diagnosis of PPID seem to be possible in horses with low to moderate pain.

Exploring the relationship between chronic pain and cortisol levels in subjects with osteoarthritis: results from a systematic review of the literature

OBJECTIVE

Several reports in the literature have identified an association between cortisol levels and the presence of chronic pain in conditions such as rheumatoid arthritis, low back pain or whiplash. In contrast, few have examined the association of cortisol and pain in people with osteoarthritis (OA). The purpose of this systematic review was to verify the association between cortisol and pain in the OA population.

DESIGN

The databases MEDLINE, CINAHL, EMBASE were searched systematically for human studies written in English up to December 2018. Two researchers screened titles and abstracts against predefined inclusion criteria; a third resolved discrepancies. Articles were included if they measured the cortisol levels in adults with pain in the OA population. Methodological quality was assessed using Methodological Index for non-randomized Studies (MINORS) score.

RESULTS

Seven studies reporting on 415 patients were included in this review. The MINORS scale yielded mean scores of 8.6 of 16 and 17.5 of 24, for the cohort and case-control studies respectively. In general, the studies were of poor quality. A discrepancy of noteworthy associations between cortisol level comparison and pain was found.

CONCLUSIONS

This study shows that there is a discrepancy in the relationship between cortisol and pain dependent on how and when cortisol is measured. Evidence from three low-quality studies suggest increased cortisol levels in patients with pain but the conclusions have a high risk of bias. It was not possible to make a quantitative analysis comparing the relationship between cortisol and pain in the OA population.

Transitioning from acute to chronic pain: a simulation study of trajectories of low back pain

Background

Identifying how pain transitions from acute to chronic is critical in designing effective prevention and management techniques for patients’ well-being, physically, psychosocially, and financially. There is an increasingly pressing need for a quantitative and predictive method to evaluate how low back pain trajectories are classified and, subsequently, how we can more effectively intervene during these progression stages.

Methods

In order to better understand pain mechanisms, we investigated, using computational modeling, how best to describe pain trajectories by developing a platform by which we studied the transition of acute chronic pain.

Results

The present study uses a computational neuroscience-based method to conduct such trajectory research, motivated by the use of hypothalamic–pituitary–adrenal (HPA) axis activity-history over a time-period as a way to mimic pain trajectories. A numerical simulation study is presented as a “proof of concept” for this modeling approach.

Conclusions

This model and its simulation results have highlighted the feasibility and the potential of developing such a broader model for patient evaluations.

The Effects of Exercise on Pain and Reproductive Performance in Female Pregnant Mice With Neuropathic Pain

Pain can have negative, physiological and psychological impacts on pregnancy. Pregnant women are fearful of using pain medication because of teratogenic effects. In this study, we evaluated whether exercise could lower pain sensitivity in pregnant mice with neuropathic pain and reduce the negative effects of maternal pain on newborns. We randomly assigned 32 female mice to one of four groups (eight mice/group): Sham surgery with standard environment (SE) or enriched environment (EE) or spare nerve injury (SNI) with SE or EE. Mice in EE groups had access to an exercise wheel. Mothers were evaluated for mechanical sensitivity with Von Frey filaments and for exercise performance with computerized running wheels. Mice were impregnated 2 weeks after the initiation of EE. Pups were weighed and measured for length at birth and evaluated for negative geotaxis, righting, forelimb grasping, rooting, and crawling at 3 days postpartum and for crawling at 6 days postpartum. Following euthanasia, mothers' frontal cortexes were analyzed for selected neuropeptides. After exercise exposure, only SNI-SE females remained neuropathic. Exercise levels were similar between EE groups. Some brain neuropeptides (endorphins, enkephalins, and oxytocin) from SNI females showed significant differences with exercise. Number of pups was significantly smaller in the SNI-SE group. Significantly more pups died at birth in the SNI-SE group, but pup behavior tests (except righting) were similar across groups. Exercise can reduce neuropathic pain in pregnant mice. Neuropathic pain does not impact motor neurodevelopment of mice pups but does appear to affect litter size and neonatal mortality.

Cytotoxic activity and subset populations of peripheral blood natural killer cells in patients with chronic pain

Background

Chronic pain reportedly exerts complex effects on immune function. Natural killer (NK) cells are lymphocytes that play a critical role in cellular and innate immunity. This study examined changes in the subset populations and cytotoxic activity of peripheral blood NK cells in patients with chronic pain.

Methods

Thirty patients with chronic moderate-to-severe pain (group P) and age-matched pain-free subjects (group NoP) were enrolled. Peripheral whole blood was analyzed for the percentage and expression of NK cell surface markers (CD56 and CD16) by flow cytometry. Cytotoxic activity was assayed by evaluating CD69 expression on CD3⁻/CD56⁺NK cells.

Results

The percentage of NK cells among total lymphocytes was not significantly different between groups P and NoP (16.3 ± 9.3 vs. 20.2 ± 10.5%). Likewise, the percentages of two major NK cell subsets, CD56^bright and CD56^dim, were also not significantly different between the two groups. However, the percentage of CD56^bright/CD16⁺ subset, was slightly but significantly increased in group P (1.0 ± 0.9%; P < 0.01) compared with group NoP (0.5 ± 0.6%). The cytotoxicity of NK cells was not different between the two groups, showing similar CD69 expression (P vs. NoP = 29.2 ± 15.2 vs. 32.0 ± 15.0%). These findings were not influenced by pain intensity, opioid use, or disease causing pain in group P.

Conclusions

NK cell cytotoxic activity and major subset populations, with the exception of an increased percentage of the CD56^bright/CD16⁺ subset, are not significantly altered in patients with chronic severe pain.

Exploring the relationship between disease-related pain and cortisol levels in women with osteoarthritis

OBJECTIVES

To determine if (1) Osteoarthritis (OA)-related pain is associated with the diurnal cortisol pattern and cortisol levels; (2) the diurnal pattern of cortisol varies with severity of OA pain and (3) the association between OA pain and cortisol is mediated by daily experience variables (DEV).

DESIGN

In a community-based study of changes in regional and widespread pain among women with OA, participants (n = 31) completed daily diaries and collected three saliva samples daily for 7 days. Severity of OA-related pain was assessed by the validated Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) pain subscale. Multilevel regression analyses estimated associations between OA pain and diurnal cortisol levels and slopes, controlling for body mass index (BMI), medication use, time and day. Mediation analyses examined DEV as potential mediators of the association between OA pain and cortisol.

RESULTS

The mean age was 57 years and average BMI 31 kg/m². Mean WOMAC pain subscale score was 8.8. Women with higher WOMAC pain scores had higher cortisol throughout the day. The estimated association of WOMAC with cortisol [β 0.083(0.02, 0.15) P = 0.009] represents a ∼9% increase in cortisol for every unit increase in WOMAC pain score. Women with WOMAC pain scores ≥9 had higher cortisol levels than those with scores <9. Examination of DEV revealed no significant mediated associations between these relationships at the daily level.

CONCLUSION

In women with OA, disease-related pain is positively associated with cortisol production, particularly with greater pain severity. Future studies should explore biologic mediating variables between OA pain and cortisol.

Achieving Remission in Gulf War Illness: A Simulation-Based Approach to Treatment Design

Gulf War Illness (GWI) is a chronic multi-symptom disorder affecting up to one-third of the 700,000 returning veterans of the 1991 Persian Gulf War and for which there is no known cure. GWI symptoms span several of the body’s principal regulatory systems and include debilitating fatigue, severe musculoskeletal pain, cognitive and neurological problems. Using computational models, our group reported previously that GWI might be perpetuated at least in part by natural homeostatic regulation of the neuroendocrine-immune network. In this work, we attempt to harness these regulatory dynamics to identify treatment courses that might produce lasting remission. Towards this we apply a combinatorial optimization scheme to the Monte Carlo simulation of a discrete ternary logic model that represents combined hypothalamic-pituitary-adrenal (HPA), gonadal (HPG), and immune system regulation in males. In this work we found that no single intervention target allowed a robust return to normal homeostatic control. All combined interventions leading to a predicted remission involved an initial inhibition of Th1 inflammatory cytokines (Th1Cyt) followed by a subsequent inhibition of glucocorticoid receptor function (GR). These first two intervention events alone ended in stable and lasting return to the normal regulatory control in 40% of the simulated cases. Applying a second cycle of this combined treatment improved this predicted remission rate to 2 out of 3 simulated subjects (63%). These results suggest that in a complex illness such as GWI, a multi-tiered intervention strategy that formally accounts for regulatory dynamics may be required to reset neuroendocrine-immune homeostasis and support extended remission.

Hormone testing and treatment enters pain care

A number of factors have recently coalesced to bring hormone testing and treatment to the field of pain care. Uncontrolled, severe pain as well as opioid drugs have a profound impact on the endocrine system. Because pain is a potent stressor, it initially causes pituitary, adrenal, and gonadal hormones to elevate in the serum. If severe pain goes uncontrolled for too long, however, hormone levels deplete in the serum. The finding of abnormal (too high or low) serum hormone levels serve as biomarker of endocrinopathies, which helps inform the clinician that enhanced analgesia as well as hormone replacement may be necessary. Adequate, physiologic levels of some specific hormones are necessary for optimal analgesia, neuroprotection, and neurogenesis. Although not a substitute for opioids, some hormone replacements may minimize their use. We know that the central nervous system produces a group of hormones called neurohormones whose natural function is neuroprotection and neurogenesis. Their clinical use in centralized pain states is new, and early reports indicate that they may have considerable benefit for treatment.

The physiologic effects of pain on the endocrine system

Severe pain has profound physiologic effects on the endocrine system. Serum hormone abnormalities may result and these serve as biomarkers for the presence of severe pain and the need to replace hormones to achieve pain control. Initially severe pain causes a hyperarousal of the hypothalamic-pituitary-adrenal system which results in elevated serum hormone levels such as adrenocorticotropin, cortisol, and pregnenolone. If the severe pain does not abate, however, the system cannot maintain its normal hormone production and serum levels of some hormones may drop below normal range. Some hormones are so critical to pain control that a deficiency may enhance pain and retard healing.

Cortisol awakening response and pain-related fear-avoidance versus endurance in patients six months after lumbar disc surgery

Recent research indicates that stress-induced, prolonged deviations in basal adrenocortical activity might contribute to ongoing/recurrent pain following lumbar disc surgery. Further, fear-avoidance and endurance responses to pain (FAR and ER) are regarded as important risk factors for pain after surgery. In patients with non-specific low back pain, FAR appear to possibly increase pain-related arousal, whereas ER may have an arousal-lowering effect, indicated by adrenocortical activity. The current study explores the relationship between basal adrenocortical activity and FAR and ER. Thirty-six patients 6 months after lumbar disc surgery participated. Basal adrenocortical activity was assessed through the cortisol awakening response (CAR), using salivary samples collected on two consecutive days. FAR and ER were estimated using questionnaires. While the ER variables pain-persistence behavior and positive mood despite pain showed negative associations with the CAR, the FAR variables fear-avoidance beliefs and avoidance of social activity were positively correlated with it. Additionally, higher CAR levels were found in patients with high versus patients with low fear-avoidance beliefs and, conversely, in patients with low versus high positive mood and pain persistence. These results indicate that FAR may increase the individuals' level of pain-related stress among patients after disc surgery, while ER may lower it.

Abolished circadian rhythm of salivary cortisol in elite artistic gymnasts

OBJECTIVE

The aim of this study was to evaluate the effects of intensive physical exercise and acute psychological stress during high level athletic competition as reflected on the levels of salivary cortisol in elite artistic gymnasts (AGs).

DESIGN

The study included 239 AGs (142 females-97 males) who participated in the European Championship of Gymnastics in 2006 and 81 adolescents (40 females-41 males), matched for age, as controls. All athletes participated voluntarily in all or parts of the study, providing samples or data for each of the variables measured. Height, weight, body fat, lean body mass (LBM), bone age and Tanner stage of puberty were assessed and data concerning the time of thelarche, adrenarche and menarche as well as, the onset and the intensity (hours per week) of training were obtained.

METHODS

Saliva samples were collected, the morning before training and in the afternoon shortly after the competition. From controls, the saliva samples were collected in the morning. Cortisol concentrations were measured using a chemiluminescence method. Acute stress was assessed using a questionnaire designed for the study.

RESULTS

No difference was found between morning and afternoon salivary cortisol levels in both male and female AGs (females: AM: 15.45±7.45nmol/l vs PM: 15.73±9.38nmol/l; males: AM: 10.21±5.52nmol/l vs PM: 9.93±13.8nmol/l, p>0.05). Female AGs presented higher levels of morning salivary cortisol than female controls (p<0.05). Both male and female AGs had higher degree of psychological stress in comparison with controls (p<0.001, p<0.013, respectively). Female AGs had higher morning and afternoon salivary cortisol levels (p<0.01, p<0.01, respectively) and higher degree of stress (p<0.003) than males.

CONCLUSIONS

In elite AGs the diurnal rhythm of salivary cortisol has been abolished, probably due to the strenuous training and competition conditions. Female AGs presented higher levels of morning salivary cortisol and psychological stress compared to both male AGs and female controls. The long term consequences of these modifications of the HPA axis remain to be elucidated.

Salivary cortisol and psychological mechanisms in patients with acute versus chronic low back pain

This study was designed to explore whether the basal adrenocortical activity is related with pain-related coping, nonverbal pain behavior, depressive mood, and fatigue in patients with acute and chronic nonspecific low back pain. 19 patients with acute low back pain (ALBP) and 24 with chronic low back pain (CLBP) participated in the study. The adrenocortical activity was assessed through the cortisol awakening response. All participants provided five saliva samples (0, 15, 30, 45, and 60min after waking) on two consecutive days off work. Pain-related coping [fear-avoidance coping (FAC) and endurance coping (EC)], nonverbal pain behavior (NPB), depressive mood, and fatigue were assessed through questionnaires. Among ALPB patients, EC was negatively associated with the cortisol release, whereas fatigue was positively associated with it. Among CLBP patients, FAC, NPB, depressive mood, and fatigue were negatively associated with the cortisol awakening response, whereas EC tended to be positively associated with it. The results indicate that pain-related coping strategies which are expected to be successful appear to lower the adrenocortical activity among ALBP patients, whereas affective distress may enhance the level of cortisol in this group. Among CLBP patients, long-term maladaptive coping strategies might contribute to hypocortisolism.

Die Cortisol-Aufwachreaktion bei Patienten mit akuten und chronischen Rückenschmerzen

BACKGROUND

Peculiarities of the hypothalamic-pituitary-adrenal axis activity in stress-related pain-disorders and potential relations with psychological risk factors of pain chronicity have been discussed controversially.

MATERIAL AND METHODS

The cortisol awakening responses of 31 low back pain patients (14 acute, 17 chronic) and 14 healthy controls were compared. In addition the interrelations between awakening response and chronic stress as well as depressive mood and - for the first time - maladaptive painprocessing and -copingstrategies were investigated.

RESULTS

The groups did not differ in their cortisol awakening responses. Chronic stress, depressive mood and maladaptive cognitive painprocessing did not correlate with the awakening response. There were, however, significant interrelations between awakening responses and the behavioral paincoping-strategies.

CONCLUSIONS

Behavioral paincoping-strategies should be considered as a potentially important contributing psychological factor in the relation between the activity of the hypothalamic-pituitary-adrenal axis and stress-related pain disorders.

Absence of circadian salivary cortisol rhythm in women with anorexia nervosa

STUDY OBJECTIVE

To compare the cortisol levels and 24 hour salivary cortisol rhythm in patients with anorexia nervosa (AN) and normal controls.

DESIGN

Prospective transversal controlled study.

SETTING

Tertiary-referral University Hospital.

PARTICIPANTS

Twenty-five patients aged 15 to 35 years, 13 of them with regular ovulatory cycles, and 12 with diagnosis of AN.

INTERVENTIONS

Salivary and blood collection for cortisol 24-hour rhythm determination.

MAIN OUTCOME

Salivary cortisol was determined at 9 am, 5 pm, and 11 pm. Seric follicle-stimulating hormone, luteinizing hormone (LH), prolactin, estradiol (E2), progesterone, dehydroepiandrosterone-S (DHEA-S), and cortisol were sampled together with the 9 am salivary sample.

RESULTS

LH, E2, and DHEA-S levels were reduced in patients with AN. A correlation between salivary and serum cortisol levels was observed in the 9 am sample only in controls (r = 0.67, P = 0.01; AN: r = 0.48, P = 0.12). Cortisol rhythm was present in all control subjects, whereas it was absent in one third of AN patients. The area under the curve for the AN group with preserved rhythm was significantly higher than for the control group (Me = 6811 ng/dl/24h vs 3708 ng/dl/24 h; P = 0.034).

CONCLUSION

Patients with AN have higher salivary cortisol levels when compared to normal women and some of them do not present circadian rhythm.

Effects of chronic osteoarthritis pain on neuroendocrine function in men

CONTEXT

Chronic pain has been associated with elevated cortisol, reduced LH and testosterone (T), and/or augmented circulating or excreted catecholamines. Most endocrine studies have been conducted in patients in whom the potentially confounding effects of depression, inflammatory disease, or coexistent medication use have not been controlled.

OBJECTIVE

The objective of the study was to test the hypothesis that chronic pain activates ACTH-cortisol and suppresses LH-T.

DESIGN AND SETTING

This was a case control study conducted at a clinical research center.

PARTICIPANTS

Participants included 16 opioid-naive men with chronic osteoarthritis pain, aged 35-65 yr with body mass index 20-30 kg/m2, and 12 healthy, opioid- and pain-free men of similar ages and body mass indexes.

METHODS

We compared circulating concentrations of ACTH, cortisol, LH, and T derived from every 20-min blood sampling (2000-0800 h), and 24-h urinary excretion of cortisol, epinephrine, norepinephrine, and dopamine.

RESULTS

There were no significant differences in mean or integrated concentrations of ACTH, cortisol, LH, or T, or in the corresponding approximate entropy scores in osteoarthritis patients, compared with control subjects. The 0800-h serum LH concentrations were elevated in patients vs. controls (6.42 +/- 1.65 vs. 3.99 +/- 1.54 IU/liter, mean +/- sd, P = 0.02), whereas there were no significant group differences in total or free T, SHBG, cortisol binding globulin, dehydroepiandrosterone sulfate, or urinary cortisol and catecholamines.

CONCLUSIONS

These data suggest that neuroendocrine function is not significantly altered in otherwise healthy men with chronic musculoskeletal pain and that prior reports of such hormonal abnormalities may have resulted from the confounding effects of coexistent illness or medication use.

Reward-aversion circuitry in analgesia and pain: implications for psychiatric disorders

Sensory and emotional systems normally interact in a manner that optimizes an organism's ability to survive using conscious and unconscious processing. Pain and analgesia are interpreted by the nervous system as aversive and rewarding processes that trigger specific behavioral responses. Under normal physiological conditions these processes are adaptive. However, under chronic pain conditions, functional alterations of the central nervous system frequently result in maladaptive behaviors. In this review, we examine: (a) the interactions between sensory and emotional systems involved in processing pain and analgesia in the physiological state; (b) the role of reward/aversion circuitry in pain and analgesia; and (c) the role of alterations in reward/aversion circuitry in the development of chronic pain and co-morbid psychiatric disorders. These underlying features have implications for understanding the neurobiology of functional illnesses such as depression and anxiety and for the development and evaluation of novel therapeutic interventions.