The hypothalamic-pituitary-adrenal axis in the pathogenesis of rheumatic diseases

Disruptive compensatory mechanisms in fibromyalgia syndrome and their association with pharmacological agents

Fibromyalgia syndrome (FMS) is a chronic disorder characterized commonly by widespread musculoskeletal pain and fatigue, predominantly affecting women, with its complexity often leading to underdiagnosis and complicating treatment effectiveness. Transcranial magnetic stimulation (TMS) metrics are potential markers to optimize FMS treatments; however, evidence is limited. Our study aimed to explore the relationship between cortical excitability and inhibition, assessed through TMS markers, and clinical characteristics in patients with FMS. This presented cross-sectional study employed baseline data from a clinical trial with 108 FMS patients, mostly female (88.8%), and mean age of 47.3 years old (SD = 12.06). Our analysis showed that decreased short-intracortical inhibition (SICI) was associated with gabapentinoids use, nicotine history, and increased fatigue levels, suggesting its connection with compensatory mechanisms for non-painful FMS features. Increased motor intracortical facilitation (ICF) was linked with greater pain severity and shorter FMS duration, implying its relationship with a reorganization of sensorimotor pathways due to chronic pain. Additionally, higher resting motor threshold (rMT) was associated with less effective pain modulation (lower conditioned pain modulation [CPM]), indicating a disruption of pain compensatory mechanism. Given the role of SICI in indexing homeostatic brain mechanisms and its association with fatigue, a hallmark characteristic of FMS-induced behavioral changes, these results suggest that FMS likely has a deleterious effect on brain inhibitory function, thus providing a potential novel insight for FMS mechanisms. In addition, it seems that this compensatory mechanism's disruption is enhanced by pharmacological agents such as gabapentioids and nicotine.

Effectiveness of transcutaneous electrical nerve stimulation improves pain intensity, disability and quality of life in patients with fibromyalgia syndrome: a systematic review with meta-analysis

PURPOSE

The transcutaneous electrical nerve stimulation (TENS) is one of the most frequently electrophysical agents employed in reducing the impact of FMS. This meta-analysis intended to determine the effectiveness of TENS on pain, disability, and quality of life (QoL) in patients with FMS.

METHODS

According to PRISMA, we performed a meta-analysis (CRD42023456439), searching in PubMed Medline, PEDro, CINAHL Complete, Web of Science, and Scopus, since inception up to October 2023. This review focused on controlled clinical trials evaluating the effect of TENS on pain, disability, and QoL in patients with FMS. The pooled effect was estimated using Cohen's standardized mean difference (SMD) and its 95% confidence interval (95%CI).

RESULTS

Twelve studies, providing data from 944 patients, were included (PEDro score of 5.6 points). Meta-analyses showed that TENS interventions are effective in improving pain (SMD = -0.61; 95%CI -1 to -0.16); disability (SMD = -0.27; 95%CI -0.41 to -0.12); and physical dimension of QoL (SMD = 0.26; 95%CI 0.08 to 0.44). Additionally, when TENS is used as a unique therapy, it represents the best therapeutic option for improving pain, disability, and QoL.

CONCLUSIONS

This meta-analysis, including the largest number of studies, showed that TENS intervention is an effective therapy to reduce pain and disability and increase QoL in FMS patients.

Changes in Widespread Pain After Surgical Weight Loss in Racialized Adults: A Secondary Analysis From a 2-Year Longitudinal Study

Widespread pain (WP) is associated with reduced function and disability. Importantly, three-fourths of the approximately 42% of U.S. adults with obesity have WP. Moreover, rates of adult obesity are higher, and WP outcomes are worse in racialized non-Hispanic Black and Hispanic/Latino/a/X groups, potentially exacerbating existing pain disparities. Bariatric surgery significantly reduces weight and improves pain. However, recurrent or unresolved pain after bariatric surgery can hinder weight loss or facilitate weight regain. The current study conducted a secondary analysis of a longitudinal study of predictors and mechanisms of weight loss after bariatric surgery to examine the point prevalence of WP and pain trajectories 24 months post surgery. Our secondary aim was to examine the association between weight loss and pain characteristics. Our exploratory aim was to longitudinally examine racial differences in pain trajectories after bariatric surgery. Our results showed that point prevalence decreased after bariatric surgery. Additionally, significant improvements in pain trajectories occurred within the first 3 months post surgery with a pattern of pain reemergence beginning at 12 months post surgery. Hispanic/Latino/a/X participants reported a higher number of painful anatomical sites before bariatric surgery, and the rate of change in this domain for this group was faster compared with the racialized non-Hispanic Black participants. These findings suggest that pain improvements are most evident during the early stages of surgical weight loss in racialized populations of adults with WP. Thus, clinicians should routinely monitor patients' weight changes after bariatric surgery as they are likely to correspond to changes in their pain experiences. PERSPECTIVE: This article presents the prevalence and pain trajectories of racialized adults with WP after surgical weight loss. Clinicians should evaluate changes in the magnitude and spatial distribution of pain after significant weight change in these populations so that pain interventions can be prescribed with greater precision.

Motor Cortex Inhibition and Facilitation Correlates with Fibromyalgia Compensatory Mechanisms and Pain: A Cross-Sectional Study

The role of transcranial magnetic stimulation (TMS) measures as biomarkers of fibromyalgia syndrome (FMS) phenotypes is still unclear. We aimed to determine the clinical correlates of TMS measures in FMS patients. We conducted a cross-sectional analysis that included 58 patients. We performed standardized TMS assessments, including resting motor threshold (MT), motor-evoked potential (MEP), short intracortical inhibition (SICI), and intracortical facilitation (ICF). Sociodemographic, clinical questionnaires, and quantitative sensory testing were collected from all of the patients. Univariate and multivariate linear regression models were built to explore TMS-associated factors. We found that SICI did not significantly correlate with pain levels but was associated with sleepiness, comorbidities, disease duration, and anxiety. On the other hand, ICF showed a positive correlation with pain levels and a negative correlation with body mass index (BMI). BMI was a negative effect modifier of the ICF and pain association. The clinical correlates of MT and MEP were scarce. Our results suggest that SICI and ICF metrics are potential phenotyping biomarkers in FMS related to disease compensation and levels of pain perception, respectively. The clinical translation of TMS paired-pulse protocols represents an opportunity for a mechanistic understanding of FMS and the future development of precision treatments.

“Ferrocrinology”—Iron Is an Important Factor Involved in Gluco- and Lipocrinology

“Ferrocrinology” is the term used to describe the study of iron effects on the functioning of adipose tissue, which together with muscle tissue makes the largest endocrine organ in the human body. By impairing exercise capacity, reducing AMP-activated kinase activity, and enhancing insulin resistance, iron deficiency can lead to the development of obesity and type 2 diabetes mellitus. Due to impaired browning of white adipose tissue and reduced mitochondrial iron content in adipocytes, iron deficiency (ID) can cause dysfunction of brown adipose tissue. By reducing ketogenesis, aconitase activity, and total mitochondrial capacity, ID impairs muscle performance. Another important aspect is the effect of ID on the impairment of thermogenesis due to reduced binding of thyroid hormones to their nuclear receptors, with subsequently impaired utilization of norepinephrine in tissues, and impaired synthesis and distribution of cortisol, which all make the body’s reactivity to stress in ID more pronounced. Iron deficiency can lead to the development of the most common endocrinopathy, autoimmune thyroid disease. In this paper, we have discussed the role of iron in the cross-talk between glucocrinology, lipocrinology and myocrinology, with thyroid hormones acting as an active bystander.

Stress, mindfulness, and systemic lupus erythematosus: An overview and directions for future research

Although the pathogenesis of autoimmunity is not fully understood, it is thought to involve genetic, hormonal, immunologic, and environmental factors. Stress has been evaluated as a potential trigger for autoimmunity and disease flares in patients with systemic lupus erythematosus (SLE). The physiologic changes that occur with stress involve numerous catecholamines, hormones, and cytokines that communicate intricately with the immune system. There is some evidence that these systems may be dysregulated in patients with autoimmune disease. Mindfulness-based techniques are practices aimed at mitigating stress response and have been shown to improve quality of life in general population. This review will discuss pathophysiology of chronic stress as it relates to SLE, evidence behind mindfulness-based practices in these patients, and directions for future research.

Racial and weight discrimination associations with pain intensity and pain interference in an ethnically diverse sample of adults with obesity: a baseline analysis of the clustered randomized-controlled clinical trial the goals for eating and moving (GEM) study

BACKGROUND

Everyday experiences with racial (RD) and weight discrimination (WD) are risk factors for chronic pain in ethnically diverse adults with obesity. However, the individual or combined effects of RD and WD on pain in adults with obesity is not well understood. There are gender differences and sexual dimorphisms in nociception and pain, but the effect of gender on relationships between RD, WD, and pain outcomes in ethnically diverse adults with obesity is unclear. Thus, the purposes of this study were to: 1) examine whether RD and WD are associated with pain intensity and interference, and 2) explore gender as a moderator of the associations between RD, WD, and pain.

METHODS

This is a baseline data analysis from a randomized, controlled clinical trial of a lifestyle weight-management intervention. Eligible participants were English or Spanish-speaking (ages 18-69 years) and had either a body mass index of ≥30 kg/m2 or ≥ 25 kg/m2 with weight-related comorbidity. RD and WD were measured using questions derived from the Experiences of Discrimination questionnaire (EOD). Pain interference and intensity were measured using the PROMIS 29 adult profile V2.1. Linear regression models were performed to determine the associations between WD, RD, gender, and pain outcomes.

RESULTS

Participants (n = 483) reported mild pain interference (T-score: 52.65 ± 10.29) and moderate pain intensity (4.23 ± 3.15). RD was more strongly associated with pain interference in women (b = .47, SE = .08, p < 001), compared to men (b = .14, SE = .07, p = .06). Also, there were no significant interaction effects between RD and gender on pain intensity, or between WD and gender on pain interference or pain intensity.

CONCLUSIONS

Pain is highly prevalent in adults with obesity, and is impacted by the frequencies of experiences with RD and WD. Further, discrimination against adults with obesity and chronic pain could exacerbate existing racial disparities in pain and weight management. Asking ethnically diverse adults with obesity about their pain and their experiences of RD and WD could help clinicians make culturally informed assessment and intervention decisions that address barriers to pain relief and weight loss.

TRIAL REGISTRATION

NCT03006328.

Juvenile primary Fibromyalgia Syndrome: epidemiology, etiology, pathogenesis, clinical manifestations and diagnosis

Juvenile primary fibromyalgia syndrome (JPFS) is a chronic, musculoskeletal pain syndrome affecting children and adolescents, most commonly adolescent girls. The syndrome has a multifactorial etiology, with altered central pain processing playing an important role. The hallmark symptom is severe, widespread musculoskeletal pain. Other symptoms include sleep and mood disturbances, headaches, stiffness, and subjective joint swelling. Physical examination can reveal multiple tender points. The diagnosis is clinical, with defined criteria. Early diagnosis and intervention are important. In this part of the review, we discuss the epidemiology, etiology, pathogenesis, clinical manifestations and diagnosis of JPFS. Part two will focus on treatment and prognosis.

Interaction of pain and chronic inflammation

Rheumatic diseases are characterized by chronic inflammation of synovial joints and are often associated with persistent pain and increased pain sensitivity. The inflammatory process is a complex cascade of events involving several mediators, which can lead to a chronic condition of pain. Inflammation can stimulate angiogenesis, and angiogenesis can facilitate inflammation. Inflammatory pain arises from tissue damage via the sensitization of pain receptors (nociceptors). The main peripheral mechanism underlying nociceptive pain is a change in the activity of the nociceptors located in the affected anatomical structures (joints, tendons, and ligaments), which renders them more sensitive to normally painful stimuli (hyperalgesia) or normally non-painful stimuli (allodynia). Neuroimmune interaction has been considered to play an essential role in rheumatic disease. Neurogenic inflammation, which influences normal central nervous system signaling, leads to insufficient signaling/bioavailability of various cytokines. These central mechanisms play an important role in the increased pain sensitivity following inflammation and are responsible for the development of secondary hyperalgesia in regions beyond the injured tissue. Reduction of pain in rheumatic disease requires familiarity with various pain mechanisms.

Inflammation and Skeletal Muscle Wasting During Cachexia

Cachexia is the involuntary loss of muscle and adipose tissue that strongly affects mortality and treatment efficacy in patients with cancer or chronic inflammatory disease. Currently, no specific treatments or interventions are available for patients developing this disorder. Given the well-documented involvement of pro-inflammatory cytokines in muscle and fat metabolism in physiological responses and in the pathophysiology of chronic inflammatory disease and cancer, considerable interest has revolved around their role in mediating cachexia. This has been supported by association studies that report increased levels of pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in some, but not all, cancers and in chronic inflammatory diseases such as chronic obstructive pulmonary disease (COPD) and rheumatoid arthritis (RA). In addition, preclinical studies including animal disease models have provided a substantial body of evidence implicating a causal contribution of systemic inflammation to cachexia. The presence of inflammatory cytokines can affect skeletal muscle through several direct mechanisms, relying on activation of the corresponding receptor expressed by muscle, and resulting in inhibition of muscle protein synthesis (MPS), elevation of catabolic activity through the ubiquitin-proteasomal system (UPS) and autophagy, and impairment of myogenesis. Additionally, systemic inflammatory mediators indirectly contribute to muscle wasting through dysregulation of tissue and organ systems, including GCs via the hypothalamus-pituitary-adrenal (HPA) axis, the digestive system leading to anorexia-cachexia, and alterations in liver and adipocyte behavior, which subsequently impact on muscle. Finally, myokines secreted by skeletal muscle itself in response to inflammation have been implicated as autocrine and endocrine mediators of cachexia, as well as potential modulators of this debilitating condition. While inflammation has been shown to play a pivotal role in cachexia development, further understanding how these cytokines contribute to disease progression is required to reveal biomarkers or diagnostic tools to help identify at risk patients, or enable the design of targeted therapies to prevent or delay the progression of cachexia.

Lipopolysaccharide Challenge Reveals Hypothalamic-Pituitary-Adrenal Axis Dysfunction in Murine Systemic Lupus Erythematosus

Crosstalk between the brain and innate immune system may be dysregulated in systemic lupus erythematosus (SLE), a chronic autoimmune disease that presents with dysautonomia and aberrant inflammation. The hypothalamic-pituitary-adrenal (HPA) axis is an endogenous neuro-endocrine-immune pathway that can regulate inflammation following activation of vagal afferents. We hypothesized that chronic inflammatory processes in SLE are in part due to HPA axis dysfunction, at the level of either the afferent vagal-paraventricular nuclei (PVN) interface, the anterior pituitary, and/or at the adrenal glands. To study this, we challenged female control and SLE mice with lipopolysaccharide (LPS) and measured c-Fos expression as an index of neuronal activation, plasma adrenocorticotrophic hormone (ACTH) as an index of anterior pituitary function, and plasma corticosterone as an index of adrenal function. We found that c-Fos expression in the PVN, and plasma ACTH and corticosterone were comparable between unchallenged SLE and control mice. PVN c-Fos was increased similarly in control and SLE mice three hours after LPS challenge; however, there were no changes in plasma ACTH amongst any experimental groups post inflammatory challenge. Plasma corticosterone was markedly increased in LPS-challenged SLE mice compared to their vehicle-treated counterparts, but not in controls. Paradoxically, following LPS challenge, brain and spleen TNF-α were elevated in LPS-challenged SLE mice despite heightened plasma corticosterone. This suggests that, despite normal c-Fos expression in the PVN and activation of the HPA axis following LPS challenge, this cumulative response may not adequately defend SLE mice against inflammatory stimuli, leading to abnormally heightened innate immune responses and peripheral inflammation.

The Role of Systemic Inflammation in Cancer-Associated Muscle Wasting and Rationale for Exercise as a Therapeutic Intervention

Progressive skeletal muscle wasting in cancer cachexia involves a process of dysregulated protein synthesis and breakdown.  This catabolism may be the result of mal-nutrition, and an upregulation of both pro-inflammatory cytokines and the ubiquitin proteasome pathway (UPP), which can subsequently increase myostatin and activin A release.  The skeletal muscle wasting associated with cancer cachexia is clinically significant, it can contribute to treatment toxicity or the premature discontinuation of treatments resulting in increases in morbidity and mortality.  Thus, there is a need for further investigation into the pathophysiology of muscle wasting in cancer cachexia to develop effective prophylactic and therapeutic interventions.  Several studies have identified a central role for chronic-systemic inflammation in initiating and perpetuating muscle wasting in patients with cancer.  Interestingly, while exercise has shown efficacy in improving muscle quality, only recently have investigators begun to assess the impact that exercise has on chronic-systemic inflammation.  To put this new information into context with established paradigms, here we review several biological pathways (e.g. dysfunctional inflammatory response, hypothalamus pituitary adrenal axis, and increased myostatin/activin A activity) that may be responsible for the muscle wasting in patients with cancer.  Additionally, we discuss the potential impact that exercise has on these pathways in the treatment of cancer cachexia.  Exercise is an attractive intervention for muscle wasting in this population, partially because it disrupts chronic-systemic inflammation mediated catabolism.  Most importantly, exercise is a potent stimulator of muscle synthesis, and therefore this therapy may reverse muscle damage caused by cancer cachexia. 

Serum levels of leptin and adiponectin and clinical parameters in women with fibromyalgia and overweight/obesity

OBJECTIVES

The objectives of this study were to evaluate the serum levels of adipokines in women with fibromyalgia with and without overweight/obesity, and to correlate the adipokines levels with clinical parameters associated with fibromyalgia and adipose tissue mass (body fat).

SUBJECTS AND METHODS

The study included 100 women divided into four groups: (a) fibromyalgia and overweight/obesity; (b) fibromyalgia and normal weight; (c) controls and overweight/obesity; and (d) controls and normal weight. Patients and controls were evaluated for clinical, anthropometric, and fibromyalgia-related parameters. Assessments included serum levels of leptin, adiponectin, monocyte chemoattractant protein-1 (MCP-1), and C-reactive protein (CRP). Levels of adipokines were further adjusted for fat mass.

RESULTS

Fibromyalgia patients with overweight/obesity or normal weight had no differences in clinical parameters. Unadjusted leptin levels were lower in fibromyalgia patients than controls, a finding that was more remarkable in fibromyalgia patients with overweight/obesity. Leptin levels had no correlation with clinical parameters of fibromyalgia or inflammation markers (MCP-1 and CRP), and adiponectin levels showed no difference between groups.

CONCLUSIONS

No correlation was observed between adjusted leptin levels and clinical parameters of fibromyalgia. Patients with fibromyalgia and overweight/obesity presented lower levels of leptin than controls with overweight/obesity.

Chronic pain assessment from bench to bedside: lessons along the translation continuum

The first step to providing effective healthcare is accurate assessment and diagnosis. The importance of accurate assessment is particularly important for chronic pain, given its subjective and multidimensional nature. The purpose of the current review is to discuss the dilemma of chronic pain assessment within a translational framework. First, assessment issues specific to chronic pain will be introduced along the entire continuum of translational activities. Important barriers along the continuum include inconsistent measurement of pain, possibly inaccurate preclinical models, and other practical limitations such as time, cost, and training. Second, the review will highlight promising areas worth further consideration in research and practice to bridge some of the gaps that currently impede effective chronic pain assessment and care. Specifically, consideration will be given to observational, biological, and technology-driven measures of chronic pain.

Circulating microRNA Profiles as Liquid Biopsies for the Characterization and Diagnosis of Fibromyalgia Syndrome

This work was aimed at investigating the circulating microRNA (miRNA) profiles in serum and saliva of patients affected by fibromyalgia syndrome (FM), correlating their expression values with clinical and clinimetric parameters and to suggest a mathematical model for the diagnosis of FM. A number of 14 FM patients and sex- and age-matched controls were enrolled in our study. The expression of a panel of 179 miRNAs was evaluated by qPCR. Statistical analyses were performed in order to obtain a mathematical linear model, which could be employed as a supporting tool in the diagnosis of FM. Bioinformatics analysis on miRNA targets were performed to obtain the relevant biological processes related to FM syndrome and to characterize in details the disease. Six miRNAs were found downregulated in FM patients compared to controls. Five of these miRNAs have been included in a linear predictive model that reached a very high sensitivity (100 %) and a high specificity (83.3 %). Moreover, miR-320b displayed a significant negative correlation (r = -0.608 and p = 0.036) with ZSDS score. Finally, several biological processes related to brain function/development and muscular functions were found potentially implicated in FM syndrome. Our study suggests that the study of circulating miRNA profiles coupled to statistical and bioinformatics analyses is a useful tool to better characterize the FM syndrome and to propose a preliminary model for its diagnosis.

Dysfunctional stress responses in chronic pain

Many dysfunctional and chronic pain conditions overlap. This review describes the different modes of chronic deregulation of the adaptive response to stress which may be a common factor for these conditions. Several types of dysfunction can be identified within the hypothalamo-pituitary-adrenal axis: basal hypercortisolism, hyper-reactivity, basal hypocortisolism and hypo-reactivity. Neuroactive steroid synthesis is another component of the adaptive response to stress. Dehydroepiandrosterone (DHEA) and its sulfated form DHEA-S, and progesterone and its derivatives are synthetized in cutaneous, nervous, and adipose cells. They are neuroactive factors that act locally. They may have a role in the localization of the symptoms and their levels can vary both in the central nervous system and in the periphery. Persistent changes in neuroactive steroid levels or precursors can induce localized neurodegeneration. The autonomic nervous system is another component of the stress response. Its dysfunction in chronic stress responses can be expressed by decreased basal parasympathethic activity, increased basal sympathetic activity or sympathetic hyporeactivity to a stressful stimulus. The immune and genetic systems also participate. The helper-T cells Th1 secrete pro-inflammatory cytokines such as IL-1-β, IL-2, IL-6, IL-8, IL-12, IFN-γ, and TNF-α, whereas Th2 secrete anti-inflammatory cytokines: IL-4, IL-10, IGF-10, IL-13. Chronic deregulation of the Th1/Th2 balance can occur in favor of anti- or pro-inflammatory direction, locally or systemically. Individual vulnerability to stress can be due to environmental factors but can also be genetically influenced. Genetic polymorphisms and epigenetics are the main keys to understanding the influence of genetics on the response of individuals to constraints.

Neurobiology of fibromyalgia and chronic widespread pain

Fibromyalgia is the current term for chronic widespread musculoskeletal pain for which no alternative cause can be identified. The underlying mechanisms, in both human and animal studies, for the continued pain in individuals with fibromyalgia will be explored in this review. There is a substantial amount of support for alterations of central nervous system nociceptive processing in people with fibromyalgia, and that psychological factors such as stress can enhance the pain experience. Emerging evidence has begun exploring other potential mechanisms including a peripheral nervous system component to the generation of pain and the role of systemic inflammation. We will explore the data and neurobiology related to the role of the CNS in nociceptive processing, followed by a short review of studies examining potential peripheral nervous system changes and cytokine involvement. We will not only explore the data from human subjects with fibromyalgia but will relate this to findings from animal models of fibromyalgia. We conclude that fibromyalgia and related disorders are heterogenous conditions with a complicated pathobiology with patients falling along a continuum with one end a purely peripherally driven painful condition and the other end of the continuum is when pain is purely centrally driven.

How to diagnose fibromyalgia

This review discusses the basic pathophysiological mechanisms that are necessary to understand the principles of diagnosis and management of fibromyalgia, and outlines a practical diagnostic approach to patients presenting with chronic widespread pain.

Glucocorticoid receptor function in health and disease

Glucocorticoid hormones are essential for life in vertebrates. They act through the glucocorticoid receptor (GR), which is expressed in virtually all cells of the human body. Yet the actions of glucocorticoids (GCs) are specific to particular cell types. Broadly GCs regulate carbohydrate metabolism, inflammation, stress and cell fate. Synthetic GCs are widely used in medicine and are by far the most frequent cause of Cushing's syndrome in routine practice. The advent of novel drugs targeting the GR offers new opportunities to treat patients with immune, or malignant disease, and may also offer new opportunities to manage patients with adrenal insufficiency also. This review covers the latest understanding of how GCs work, how their actions are affected by disease, and where the new drugs may take us.

Fibromyalgia and related conditions

Fibromyalgia is the currently preferred term for widespread musculoskeletal pain, typically accompanied by other symptoms such as fatigue, memory problems, and sleep and mood disturbances, for which no alternative cause can be identified. Earlier there was some doubt about whether there was an "organic basis" for these related conditions, but today there is irrefutable evidence from brain imaging and other techniques that this condition has strong biological underpinnings, even though psychological, social, and behavioral factors clearly play prominent roles in some patients. The pathophysiological hallmark is a sensitized or hyperactive central nervous system that leads to an increased volume control or gain on pain and sensory processing. This condition can occur in isolation, but more often it co-occurs with other conditions now being shown to have a similar underlying pathophysiology (eg, irritable bowel syndrome, interstitial cystitis, and tension headache) or as a comorbidity in individuals with diseases characterized by ongoing peripheral damage or inflammation (eg, autoimmune disorders and osteoarthritis). In the latter instance, the term centralized pain connotes the fact that in addition to the pain that might be caused by peripheral factors, there is superimposed pain augmentation occurring in the central nervous system. It is important to recognize this phenomenon (regardless of what term is used to describe it) because individuals with centralized pain do not respond nearly as well to treatments that work well for peripheral pain (surgery and opioids) and preferentially respond to centrally acting analgesics and nonpharmacological therapies.

Cardiovascular responses to an acute psychological stressor are associated with the cortisol awakening response in individuals with chronic neck pain

INTRODUCTION

Dysregulation of the hypothalamic-pituitary-adrenal axis (HPA-axis) is common in individuals who experience chronic psychological stress, as well as individuals with chronic pain. Changes in cortisol availability in the presence of a chronic stressor such as pain may influence the sympathetic-adrenal-medullary (SAM) system, which contributes to cardiovascular responses to stress and also exhibits altered responsiveness in the presence of pain. The purpose of this study was to investigate the relationship between HPA activity during the cortisol awakening response and cardiovascular reactivity during exposure to an acute psychological stressor in individuals with chronic neck pain.

METHODS

Area under the curve (AUC) of the salivary cortisol awakening response was assessed in 41 individuals with chronic neck pain aged 19-80 years (22 men, 23 women). Slopes representing the change in mean arterial pressure and heart rate during a baseline quiet sitting condition, a low stress condition with mental concentration, and a high stress condition combining mental concentration with social evaluative threat were calculated for each individual as an index of cardiovascular responsiveness to the acute stressor. Cardiovascular responses were regressed on cortisol awakening AUC and pain duration, adjusting for age and sex.

RESULTS

Greater mean arterial pressure (β = -0.33, p = 0.02) and heart rate responses (β = -0.41, p = 0.007) to the acute psychological stressor were associated with lower cortisol awakening responses after adjusting for age and sex. Individuals with a shorter duration of chronic pain also demonstrated a larger increase in mean arterial pressure during the laboratory stressor (β = -0.39, p = 0.01), but there was no relationship between pain duration and changes in heart rate (p = 0.25).

CONCLUSIONS

Individuals with a shorter duration of chronic neck pain who demonstrate heightened cardiovascular responsiveness to an acute psychological stressor also exhibit lower cortisol awakening response. These results are consistent with time-dependent adaptations across the two major stress systems in the presence of chronic pain.

Muscle as a secretory organ

Skeletal muscle is the largest organ in the body. Skeletal muscles are primarily characterized by their mechanical activity required for posture, movement, and breathing, which depends on muscle fiber contractions. However, skeletal muscle is not just a component in our locomotor system. Recent evidence has identified skeletal muscle as a secretory organ. We have suggested that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert either autocrine, paracrine, or endocrine effects should be classified as "myokines." The muscle secretome consists of several hundred secreted peptides. This finding provides a conceptual basis and a whole new paradigm for understanding how muscles communicate with other organs such as adipose tissue, liver, pancreas, bones, and brain. In addition, several myokines exert their effects within the muscle itself. Many proteins produced by skeletal muscle are dependent upon contraction. Therefore, it is likely that myokines may contribute in the mediation of the health benefits of exercise.

Regulation of intestinal immune response by selective removal of the anterior, posterior, or entire pituitary gland in Trichinella spiralis infected golden hamsters

The influence of anterior pituitary hormones on the gastrointestinal tract of humans and animals has been previously reported. Hypophysectomy (HYPOX) in the rat causes atrophy of the intestinal mucosa, and reduction of gastric secretion and intestinal absorption, as well as increased susceptibility to bacterial and viral infections. However, to our knowledge, no findings have been published concerning the immune response following HYPOX during worm infection, particularly that which is caused by the nematode Trichinella spiralis. The aim of this work was to analyze the effects of total or partial HYPOX on colonization of T. spiralis in the intestinal lumen, together with duodenal and splenic cytokine expression. Our results indicate that 5 days post infection, only neurointermediate pituitary lobectomy (NIL) reduces the number of intestinally recovered T. spiralis larvae. Using semiquantitative inmunofluorescent laser confocal microscopy, we observed that the mean intensity of all tested Th1 cytokines was markedly diminished, even in the duodenum of infected controls. In contrast, a high level of expression of these cytokines was noted in the NIL infected hamsters. Likewise, a significant decrease in the fluorescence intensity of Th2 cytokines (with the exception of IL-4) was apparent in the duodenum of control and sham infected hamsters, compared to animals with NIL surgeries, which showed an increase in the expression of IL-5 and IL-13. Histology of duodenal mucosa from NIL hamsters showed an exacerbated inflammatory infiltrate located along the lamina propria, which was related to the presence of the parasite. We conclude that hormones from each pituitary lobe affect the gastrointestinal immune responses to T. spiralis through various mechanisms.

Effect of experimental stress in 2 different pain conditions affecting the facial muscles

Chronic facial muscle pain is a common feature in both fibromyalgia (FM) and myofascial (MF) pain conditions. In this controlled study, a possible difference in the mode of deregulation of the physiological response to a stressing stimulus was explored by applying an acute mental stress to FM and MF patients and to controls. The effects of the stress test were observed on pain, sympathetic variables, and both tonic and reflex electromyographic activities of masseteric and temporal muscles. The statistical analyses were performed through a generalized linear model including mixed effects. Painful reaction to the stressor was stronger (P < .001) and longer (P = .011) in FM than in MF independently of a higher pain level at baseline. The stress-induced autonomic changes only seen in FM patients did not reach significance. The electromyographic responses to the stress test were strongest for controls and weakest for FM. The stress test had no effect on reflex activity (area under the curve [AUC]) or latency, although AUC was high in FM and latencies were low in both pain groups. It is suggested that FM is characterized by a lower ability to adapt to acute stress than MF.

PERSPECTIVE

This study showed that an acute psychosocial stress triggered several changes in 2 pain conditions including an increase in pain of larger amplitude in FM than in MF pain. Similar stress-induced changes should be explored as possible mechanisms for differentiation between dysfunctional pain conditions.

Fibromyalgia syndrome: etiology, pathogenesis, diagnosis, and treatment

Fibromyalgia syndrome is mainly characterized by pain, fatigue, and sleep disruption. The etiology of fibromyalgia is still unclear: if central sensitization is considered to be the main mechanism involved, then many other factors, genetic, immunological, and hormonal, may play an important role. The diagnosis is typically clinical (there are no laboratory abnormalities) and the physician must concentrate on pain and on its features. Additional symptoms (e.g., Raynaud's phenomenon, irritable bowel disease, and heat and cold intolerance) can be associated with this condition. A careful differential diagnosis is mandatory: fibromyalgia is not a diagnosis of exclusion. Since 1990, diagnosis has been principally based on the two major diagnostic criteria defined by the ACR. Recently, new criteria have been proposed. The main goals of the treatment are to alleviate pain, increase restorative sleep, and improve physical function. A multidisciplinary approach is optimal. While most nonsteroidal anti-inflammatory drugs and opioids have limited benefit, an important role is played by antidepressants and neuromodulating antiepileptics: currently duloxetine (NNT for a 30% pain reduction 7.2), milnacipran (NNT 19), and pregabalin (NNT 8.6) are the only drugs approved by the US Food and Drug Administration for the treatment of fibromyalgia. In addition, nonpharmacological treatments should be associated with drug therapy.

Hypothalamic-pituitary-adrenal axis function in patients with complex regional pain syndrome type 1

An exaggerated inflammatory process is considered an important pathophysiological feature of complex regional pain syndrome type 1 (CRPS-1). The hypothalamic-pituitary-adrenal (HPA) axis serves as a negative feedback mechanism for inflammatory processes. The present study examined the HPA axis function in patients with CRPS-1 by a determination of cortisol concentrations in saliva. Three sets of saliva samples were sequentially collected from 24 patients with CRPS-1 during medication (on-Med), 72 h after stopping medication (off-Med) and 8h after the oral administration of 1mg dexamethasone. One set of saliva samples was collected from healthy controls. The cortisol awakening response (CAR) and diurnal cortisol decline (DCD) were used as indices for HPA axis function. Cortisol levels during the post-awakening period in patients were increased following withdrawal of medications. The CAR during the off-Med condition was disappeared after administration of dexamethasone. Among the examined CRPS-related numerical variables, the frequency of spontaneous pain attacks showed relationships with the indices of HPA axis function. After classifying the patients into two subgroups, we observed that the CAR and DCD in patient who had a relatively high frequency of spontaneous pain attacks (subgroup 5 ≤) were lower and less steep than those in patient who had a relatively low frequency of spontaneous pain attacks (subgroup 0-4) for the on- and off-Med conditions. The CAR and DCD in subgroup 5 ≤ during their off-Med condition were comparable to those in controls. These results suggest that the increase in frequency of spontaneous pain attacks is associated with a reduced CAR and flattened DCD in patients CRPS-1.

Glucocorticoid regulation of inflammation and its functional correlates: from HPA axis to glucocorticoid receptor dysfunction

Enhanced susceptibility to inflammatory and autoimmune disease can be related to impairments in HPA axis activity and associated hypocortisolism, or to glucocorticoid resistance resulting from impairments in local factors affecting glucocorticoid availability and function, including the glucocorticoid receptor (GR). The enhanced inflammation and hypercortisolism that typically characterize stress-related illnesses, such as depression, metabolic syndrome, cardiovascular disease, or osteoporosis, may also be related to increased glucocorticoid resistance. This review focuses on impaired GR function as a molecular mechanism of glucocorticoid resistance. Both genetic and environmental factors can contribute to impaired GR function. The evidence that glucocorticoid resistance can be environmentally induced has important implications for management of stress-related inflammatory illnesses and underscores the importance of prevention and management of chronic stress. The simultaneous assessment of neural, endocrine, and immune biomarkers through various noninvasive methods will also be discussed.

The biological significance of evolution in autoimmune phenomena

It is an inherent part of living to be in constant modification, which are due to answers resulting from environmental changes. The different systems make adaptations based on natural selection. With respect to the immune system of mammals, these changes have a lot to do with the interactions that occur continuously with other living species, especially microorganisms. The immune system is primarily designed to defend from germs and this response triggers inflammatory reactions which must be regulated in order not to generate damage to healthy tissue. The regulatory processes were added over time to prevent such damage. Through evolution the species have stored “an immunological experience,” which provides information that is important for developing effective responses in the future. The human species, which is at a high level of evolutionary immunological accumulation, have multiple immune defense strategies which, in turn, are highly regulated. Imbalances in these can result in autoimmunity.

“There is nothing permanent except change.”

(Heraclitus)

Functional disturbance of the stress-adaptation system in patients with scleroderma

There have been several reports indicating the association between recent stress experiences and the onset or the exacerbation of rheumatic diseases, although few such reports exist in patients with scleroderma (SSc). The present study was performed to elucidate whether there were any functional disturbances in the neuro-endocrine-immune system as a homeostatic system upon stress in SSc patients. Various serum levels of stress-related hormones and cytokines were examined before and after a mental calculation stress test, and a basal questionnaire study of sense of coherence (SOC, which is related to the ability to cope with stress), recent stress experiences, and quality of life (QOL) was performed in 17 SSc patients and in 38 healthy volunteers. Physical QOL state was impaired in patients, but there were no differences in recent stress experiences and SOC scores between patients and controls. Basal serum cortisol levels were similar in patients and controls, but increased levels of proinflammatory cytokine and noradrenalin were seen in SSc patients. Characteristically, contrary to the control group, whose cortisol levels increased significantly following the mental calculation stress test, no significant increase was observed in the patients when post-test cortisol levels were compared to pre-test levels, suggesting a defect in the normal cortisol response upon stress in SSc patients. The present results suggest that there may be impaired function of the neuro-endocrine-immune system upon stress in SSc patients.

Chronic pelvic pain and endometriosis: translational evidence of the relationship and implications

BACKGROUND

Many clinicians and patients believe that endometriosis-associated pain is due to the lesions. Yet causality remains an enigma, because pain symptoms attributed to endometriosis occur in women without endometriosis and because pain symptoms and severity correlate poorly with lesion characteristics. Most research and reviews focus on the lesions, not the pain. This review starts with the recognition that the experience of pain is determined by the central nervous system (CNS) and focuses on the pain symptoms.

METHODS

Comprehensive searches of Pubmed, Medline and Embase were conducted for current basic and clinical research on chronic pelvic pain and endometriosis. The information was mutually interpreted by a basic scientist and a clinical researcher, both in the field of endometriosis. The goal was to develop new ways to conceptualize how endometriosis contributes to pain symptoms in the context of current treatments and the reproductive tract.

RESULTS

Endometriotic lesions can develop their own nerve supply, thereby creating a direct and two-way interaction between lesions and the CNS. This engagement provides a mechanism by which the dynamic and hormonally responsive nervous system is brought directly into play to produce a variety of individual differences in pain that can, in some women, become independent of the disease itself.

CONCLUSIONS

Major advances in improving understanding and alleviating pain in endometriosis will likely occur if the focus changes from lesions to pain. In turn, how endometriosis affects the CNS would be best examined in the context of mechanisms underlying other chronic pain conditions.

The α7 nicotinic acetylcholine receptor and the acute stress response: maternal genotype determines offspring phenotype

α7 Nicotinic acetylcholine receptors (α7nAchRs) modulate immune activation by suppressing production of pro-inflammatory cytokines in peripheral immune cells. α7nAchRs also modulate inhibitory output in the hippocampus, which provides input to key circuits of the HPA axis. Therefore, the α7 nicotinic acetylcholine receptor gene (CHRNA7) may be associated with cortisol stress response. Polymorphisms in the CHRNA7 promoter decrease its expression and may dampen the cholinergic response, leading to an increase in inflammation. Increased inflammation may change the intrauterine environment, altering neuroendocrine development in the offspring. Maternal CHRNA7 genotype could affect an offspring's HPA regulation via reprogramming in utero. Patients with allergic disorders have a differential cortisol response to stress. This study utilized samples collected from a cohort of 198 adolescents in a previous study of atopic disorders, who demonstrated a disturbance in HPA response associated with atopy. Salivary cortisol samples collected from the adolescents after a series of laboratory procedures and DNA samples collected from the adolescents and their parents were used for further analysis. DNA samples were genotyped for allelic variation in the CHRNA7 promoter. Genetic association analyses with the cortisol levels were performed in the adolescents. Maternal genotype influences were investigated for the CHRNA7 gene. We also included maternal and child atopy diagnosis as covariates in determining cortisol levels and tested for association of CHRNA7 to atopy. Polymorphisms in the CHRNA7 promoter were associated with lower cortisol levels after a small laboratory stress. Our findings also show that although the child's CHRNA7 genotype affects stress response, the maternal genotype has a stronger influence on cortisol release after stress in male offspring. These effects were independent of atopy status.

The role of corticosteroids and stress in chronic pain conditions

The relationship between corticosteroids (endogenous and exogenous) and stress is well known, as is the use of steroids as concomitant treatment in pain management during acute inflammation. In the past, steroids have not been considered the first line of treatment in pain management. In this review, we examine new scientific and clinical evidence that demonstrates the direct role that steroids play in the generation and clinical management of chronic pain. We will discuss the new findings demonstrating the fact that steroids and related mediators produce paradoxical effects on pain such as analgesia, hyperalgesia, and even placebo analgesia. In addition, we will examine the physiologic effect of stress, high allostatic load, and idiopathic disease states such as chronic fatigue syndrome, fibromyalgia, irritable bowel syndrome, and burnout. The recently observed positive relationship between glutaminergic activity in the insula and clinical pain will be examined in the context of understanding the central role of steroids in chronic pain. The complex role of the hypothalamic-pituitary-adrenal axis in pain will be discussed as well as other heterogeneous forms of chronic pain that involve many components of the central nervous system. Components of the hypothalamic-pituitary-adrenal axis have paradoxical effects on certain types of pain that are dependent on dose and on site (whether peripheral or central) and mode of application. Recent studies on glia have shown that they prolong a state of neuronal hypersensitization in the dorsal root ganglia by releasing growth factors and other substances that act on the immune system. We will discuss the implication of these new findings directly linking pain to steroids, stress, and key higher brain regions in the context of future therapeutic targets.

Evaluation of the hypothalamic–pituitary–adrenal axis in untreated patients with polymyalgia rheumatica and healthy controls

OBJECTIVE

To explore the hypothalamic-pituitary-adrenal (HPA) axis in polymyalgia rheumatica (PMR).

SUBJECTS AND METHODS

This study was carried out on 13 female patients with PMR who were diagnosed according to the criteria of Chuang et al (Ann Intern Med 1982;97:672-80) and 10 healthy female subjects in the Department of Physical Medicine and Rehabilitation, Erciyes University Medical School. In the patient and control groups, basal cortisol, adrenocorticotrophic hormone (ACTH), 17alpha-hydroxyprogesterone (17-OHP), 11-deoxycortisol (11-S), dehydroepiandrosterone sulfate (DHEAS), androstenedione (A), prolactin (PRL), and thyroid stimulating hormone (TSH) levels were measured. Cortisol, 17-OHP, 11-S and A responses after the low-dose (1 microg) ACTH stimulation test and cortisol and DHEAS responses after the dexamethasone suppression test were detected. We also measured acute phase reactants including C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR).

RESULTS

Age and sex characteristics were similar in both patient and control groups. The levels of basal hormones including cortisol, ACTH, 17-OHP, 11-S, DHEAS, A, prolactin and TSH and cortisol and DHEAS levels after the low-dose dexamethasone suppression test were not significantly different between the patient and control groups. However, cortisol/CRP and ACTH/CRP ratios were significantly lower in the patient group. Cortisol and DHEAS responses after the low-dose dexamethasone suppression test were not significantly different between the patient and control groups. Cortisol response after the 1 microg ACTH stimulation test was significantly lower in the patients than in the control group, but there were no significant differences in 17-OHP, 11-S and A responses between the patients and controls. Correlation analysis showed that there was a negative correlation between peak cortisol levels after the ACTH stimulation test and disease duration, and also a positive correlation between cortisol levels after the low-dose dexamethasone suppression test and acute phase reactants including CRP and ESR.

CONCLUSION

A significant low cortisol response to ACTH stimulation was detected in the patients with PMR. In addition, a negative correlation after the 1 microg ACTH stimulation test between peak cortisol levels and disease duration was detected. These findings may indicate hypoactivation in the HPA axis.

Daily affect relations in fibromyalgia patients reveal positive affective disturbance

OBJECTIVES

To examine daily positive affective disturbance in the context of negative affect (NA) and pain among patients with fibromyalgia (FM) to determine a) if FM patients experience a deficit in daily positive affect (PA) relative to osteoarthritis (OA) patients; b) if FM patients differ from OA patients in the day-to-day relations of PA and NA; and c) if patients diagnosed with both OA and FM differ from patients with either OA-only or FM-only with respect to major outcomes.

METHODS

A total of 260 women with physician-diagnosed OA (n = 106), FM (n = 53), or OA/FM (n = 101) completed a 30-day electronic diary. Participants were assessed once daily on levels of PA, NA, and pain.

RESULTS

Multilevel models indicated that FM patients had less overall PA than OA patients and exhibited a stronger inverse PA-NA relation. Analyses further suggest that the OA/FM group may have been the most impaired of the three included in our study. This group was responsible for a lagged effect of PA on both affects, whereby high PA days resulted in low next-day PA and high next-day NA.

CONCLUSION

FM patients exhibit a PA disturbance compared with OA patients. This disturbance is reflected by an overall deficit in PA and an inability to sustain PA in the face of pain and NA. Patients with both OA and FM may represent a subgroup of FM that is at particular risk for dysregulation of PA.

Poderia a atividade física induzir analgesia em pacientes com dor crônica?

A dor crônica caracteriza-se pela persistência do sintoma além do período fisiológico de recuperação do tecido lesado. Essas dores causam incapacidade física e redução da performance cognitiva, reduzem a qualidade de vida e o bem-estar dos pacientes, cujo tratamento proposto contradiz o clássico binômio da terapia da dor aguda (repouso e fármacos). Para a dor crônica prescrevem-se exercícios físicos e sugerem-se tratamentos multidisciplinares. Embora a atividade física seja prescrita há mais de 20 anos, os mecanismos neurofisiológicos envolvidos ainda não são compreendidos. Descrevemos brevemente os mecanismos endógenos de controle da dor crônica e evidências da literatura científica que defendem o sistema opioide como mecanismo de ação na analgesia induzida pelo exercício em indivíduos sadios e atletas. Esse mecanismo também parece agir na população com dor crônica, embora haja controvérsias. Finalizamos o artigo com considerações clínicas para a prescrição do exercício para a população com dor crônica.

Muscle as an endocrine organ: focus on muscle-derived interleukin-6

Skeletal muscle has recently been identified as an endocrine organ. It has, therefore, been suggested that cytokines and other peptides that are produced, expressed, and released by muscle fibers and exert paracrine, autocrine, or endocrine effects should be classified as "myokines." Recent research demonstrates that skeletal muscles can produce and express cytokines belonging to distinctly different families. However, the first identified and most studied myokine is the gp130 receptor cytokine interleukin-6 (IL-6). IL-6 was discovered as a myokine because of the observation that it increases up to 100-fold in the circulation during physical exercise. Identification of IL-6 production by skeletal muscle during physical activity generated renewed interest in the metabolic role of IL-6 because it created a paradox. On one hand, IL-6 is markedly produced and released in the postexercise period when insulin action is enhanced but, on the other hand, IL-6 has been associated with obesity and reduced insulin action. This review focuses on the myokine IL-6, its regulation by exercise, its signaling pathways in skeletal muscle, and its role in metabolism in both health and disease.

Did ‘the Princess on the Pea— Suffer from Fibromyalgia Syndrome?

Fibromyalgia syndrome (FMS) is a chronic pain syndrome characterised by central sensitisation resulting in hypersentivity of the skin and deeper tissues as well as fatigue. Possibly the princess in Hans Christian Andersen's ‘The Princess and the Pea’ suffered from FMS since chronic sleep disturbances are typical in FMS. These sleep disturbances have been attributed to a dysfunction in the systems regulating sleep and wakefulness resulting in loss of deep sleep. In addition, many patients with FMS experience cognitive dysfunction, characterised by impaired concentration and short term memory consolidation, a complaint also commonly reported in other sleep disorders.

In recent reviews evaluating the efficacy of acupuncture in FMS it has been concluded that acupuncture has no specific effect. A prerequisite for this conclusion is that all the major symptoms in the syndrome have been assessed. However, previous studies have generally focused on the pain alleviating effect of acupuncture in FMS. We have observed that not only pain but also sleep and cognitive dysfunction may be ameliorated in response to acupuncture, suggesting that these variables should be taken into account when evaluating the effects of acupuncture in FMS. Furthermore, the results demonstrated great individual variability apart from the systematic effects related to the group, indicating that individually performed treatment strategies are required. Our suggestion is supported by experimental and clinical studies showing that acupuncture may affect in somnia and alertness, and that there may be neurophysiologic bases for these specific effects.

Impact of age, systemic glucocorticoids, and progressive knee arthritis on specific mRNA levels in different areas of the rabbit cornea

PURPOSE

To determine the influence of factors such as age, osteoarthritis (OA), and glucocorticoid treatment on total RNA and mRNA regulation in the cornea and how these factors differ between prepupillary and peripheral areas of the cornea.

METHODS

Molecular analyses of corneal tissue were performed using rabbits of different age groups and skeletally mature animals that had undergone anterior cruciate ligament (ACL) transection, an established model of knee OA. Systemic glucocorticoids were administered to cohorts of the osteoarthritic and control animals to determine the influence of distal joint disease on the corneal response. Corneal tissue was analyzed for changes in mRNA levels for several relevant genes: collagen I, collagen III, collagen V, decorin core protein, cyclooxygenase-2 (COX-2), glucocorticoid receptor, and the housekeeping gene beta-actin.

RESULTS

The corneal tissue was found to have diminishing total RNA with age, which is consistent with previous studies in the literature. Interestingly, in skeletally mature animals, distal joint OA was found to affect corneal mRNA levels for several important structural and inflammatory genes (collagen I, decorin core protein, and COX-2) in a manner that progressed with OA progression. Although systemic glucocorticoid treatment did not alter mRNA levels in the normal cornea, it did counteract the changes observed early after OA induction (3 weeks) while having less of an effect in later, more established arthritis (6 weeks).

CONCLUSIONS

This study reveals that distal joint OA can affect mRNA levels for several structural and inflammatory genes of the cornea, changes that seem to be suppressed by systemic glucocorticoid treatment. These findings indicate that OA has associated systemic factors that influence corneal cell metabolism.

Acute inflammatory and neuropathic pain in Lewis and Fischer rats

Inbred, histocompatible Lewis and Fischer 344 rats (LEW and FIS) have been used to identify an inverse relationship between hypothalamic-pituitary-adrenal (HPA) axis activity and susceptibility to autoimmune and chronic inflammatory disorders, with LEW showing blunted HPA axis activity and increased susceptibility toward the development of autoimmunity and chronic inflammation, and FIS showing the opposite relationship. In the present study, LEW and FIS were used to determine the relationship between HPA axis function and acute inflammatory pain (carrageenan-induced hindpaw inflammation) and neuropathic pain (partial sciatic nerve ligation; PSNL). The results showed that carrageenan-induced thermal and mechanical allodynia and hyperalgesia were greater in FIS than in LEW. Similarly, FIS showed more carrageenan-induced hindpaw swelling and higher levels of myeloperoxidase (a measure of neutrophils) in the carrageenan-inflamed hindpaw. After PSNL, LEW showed a profound mechanical allodynia and hyperalgesia, whereas mechanical sensitivity in FIS was unaltered. However, FIS, but not LEW, developed thermal allodynia and hyperalgesia after PSNL. These results provide strong evidence for a positive relationship between HPA axis activity and acute inflammatory pain. The results also support a relationship between HPA axis activity and neuropathic pain, but the relationship is complex and may depend on the pain assay.

Role of the Growth Hormone/Insulin-like Growth Factor-1 Paracrine Axis in Rheumatic Diseases

OBJECTIVES

Hypothalamic-pituitary axis abnormalities have been associated with systemic disturbances in several rheumatic diseases. Longitudinal analysis of erythrocyte, serum, urinary and synovial fluid growth hormone (GH), insulin-like growth factor-1 (IGF-1), and somatostatin levels could provide important surrogate measures of disease activity in rheumatic diseases.

METHODS

The authors reviewed the population and longitudinal studies literature on GH, IGF-1, and somatostatin levels in rheumatic disorders using the PubMed and Medlines databases from the National Library of Medicine. In addition to the literature search, primary data were analyzed for basal somatostatin levels in patients with hand, knee, and spine osteoarthritis (OA) as well as primary and secondary hip OA.

RESULTS

A review of the literature supports the view that hypothalamic-pituitary axis dysfunction accompanies clinical symptoms in many rheumatic diseases. In studies from our laboratory, serum GH levels were elevated in patients with OA, rheumatoid arthritis (RA), fibromyalgia, and diffuse idiopathic skeletal hyperostosis but not in patients with gout, pseudogout, or systemic lupus erythematosus. In OA and RA, synovial fluid GH levels exceeded serum GH levels. However, the literature remains controversial regarding the significance of changes in IGF-1 levels in rheumatic disorders. Many studies support an inverse relationship between age and IGF-1. Elevated serum GH levels in various rheumatic diseases were not coupled to changes in serum IGF-1 in diffuse idiopathic skeletal hyperostosis, RA, and fibromyalgia. In particular, serum IGF-1 levels in OA were shown to be lower or no different compared with age-matched normal subjects. Further, in OA, impaired articular chondrocyte response to IGF-1 was attributed, in part, to low synovial fluid IGF-1 that further compromised IGF-1 chondrocyte responses as a result of increased levels of synovial fluid IGF-1 binding proteins. Of note, serum somatostatin levels and "specific" somatostatin receptor levels were often lower in RA and systemic lupus erythematosus, but basal serum somatostatin levels were generally not altered in OA.

CONCLUSIONS

The results of these analyses support the view that some rheumatic diseases such as OA and diffuse idiopathic skeletal hyperostosis, heretofore considered to be purely focal and degenerative, could be reclassified as systemic metabolic disturbances. We propose that serum GH, IGF-1, and somatostatin levels be monitored on a longitudinal basis during the course of medical therapy of rheumatic diseases to determine the extent to which changes in clinical symptoms (exemplified by reduced pain and inflammation and improved range of joint motion) are accompanied by changes in the basal concentration of these hypothalamic/pituitary-related hormones.

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

INTRODUCTION

Complex disorders of the hypothalamic-pituitary-adrenal axis constitute phenomena whose etiopathogenetic significance is the subject of controversy. The frequent coincidence with depressive symptoms further complicates interpretation.

PATIENTS AND METHODS

Daily variations in cortisol levels were measured in 20 patients with acute pain, 27 with chronic pain in the lumbar musculoskeletal system, and 44 with episodic forms of headache to determine the daily average and then correlated with differentiated algesimetric data.

RESULTS

Patients with chronic and episodic pain had significantly higher scores on the McGill Pain Questionnaire and more affective items as an expression of depressive symptoms than patients with acute pain. The three groups did not however exhibit significant differences for the depression scale and list of "psychovegetative" disorders. In comparison to an age-matched pain-free control population (n=17), the average daily levels of cortisol were significantly higher in all three groups besides singularly elevated daily levels, but no correlations between the cortisol values and overall algesimetric data could be established. Chronic pain patients with high depression scores had significantly higher cortisol levels irrespective of pain intensity.

DISCUSSION

Pain experiences cause increased plasma cortisol levels with significant elevation of the daily average. Whereas in cases of acute pain, a direct but unspecific stress reaction not connected with the pain seems to be likely, the underlying cause in cases of chronic and episodic pain appears to be a complex and enduring activation of the hypothalamic-pituitary-adrenal axis, likewise independent from pain, probably associated with concomitant depressive symptoms and disruption of the circadian rhythm of release controlled by the hypothalamus.