Johannes Gjerstad

• Professor
• Head of Department at Kristiania University College

Role conflicts and role ambiguity have been identified as important risk factors for exposure to workplace bullying, particularly when combined with inadequate leadership practices. Even though role ambiguity theoretically can be considered a causal precursor to role conflicts, previous research has mainly examined these role stressors as concurren...

In the present study, we proposed and tested a conceptual model of length of service in the organization as a moderator of the relationship between exposure to workplace bullying behaviors and turnover intention, as mediated through job dissatisfaction. Specifically, based on the conservation of resources theory and organizational socialization res...

Objectives Earlier findings suggest that social stress such as abusive supervision may promote pain. In the present study we examine the possible moderating role of genetic variability in the NRCAM gene in this process. Methods The data were collected through a national survey drawn from the National Central Employee Register by Statistics Norway....

This two-part study examined if the buffering effect of transformational leadership on the association between work-related ambiguity and job satisfaction is contingent upon whether a follower holds a formal leadership position him/herself. Data from two separate surveys were employed: Study 1: A sample of 845 respondents from Belgium. Study 2: A n...

Environmental stressors such as repeated social defeat may initiate powerful activation of sub-conscious parts of the brain. Here, we examine the consequences of such stress (induced by resident-intruder paradigm) on the pituitary gland. In male stressed vs. control rats, by RNA- and bisulfite DNA sequencing, we found regulation of genes involved i...

Objectives Several studies show that severe social stressors, e.g., in the form of exposure to workplace bullying in humans, is associated with negative mental health effects such as depression and anxiety among those targeted. However, the understanding of the underlying biological mechanisms that may explain the relationship between exposure to b...

Objectives Previous findings suggest that abusive supervision, i.e., subordinates’ perceptions of their supervisor’s behaviours as hostile (excluding physical aggression), may increase the risk of health complaints. In addition, recent data suggest that the FKBP5 genotype rs9470080 important in the regulation of cortisol release, influences the sam...

Workplace bullying is, by definition, a gradually escalating process, theorized to occur from psychosocial stressors when there is a lack of management intervention in escalating conflicts, and a lack of fair and robust conflict management procedures in the organization. Based on national probability survey data gathered in 2015–2016 from the offic...

Objective Workplace bullying has been established as a significant correlate of sleep problems. However, little is known regarding the causal direction between bullying and sleep. The aim of this study was to examine temporal relationships between bullying and symptoms of insomnia. Methods Reciprocal and prospective associations between exposure t...

Objective: Previous findings suggest that exposure to social stress in the form of abusive supervision may increase the risk of anxiety disorders. In the present study, we examined the link between abusive supervision, the CRHR1 genotype and anxiety. Methods: The data was collected through a national survey drawn from the National Central Employee...

Previous findings suggest that exposure to social stress in the form of abusive supervision may increase the risk of musculoskeletal disorders. In the present study, we examined the link between abusive supervision, the CRHR1 genotype and spinal pain. The data were collected through a national survey drawn from the National Central Employee Registe...

Objective: Leadership styles can influence subordinates' health. We investigated how the gene encoding the Catechol-O-Methyltransferase (COMT) enzyme (i.e. COMT rs4680 Val158Met) influenced effects of abusive supervision and transformational leadership on subordinates' headache and neck pain. Methods: Multiple group structural equation modeling...

Objective In the present study we examined the potential association between age, gender, the genetic variant FKBP5 rs9470080 and subjective health complaints. Methods The data were collected through a three-wave nationally representative survey of 1060 Norwegian employees drawn from the Norwegian Central Employee Register by Statistics Norway. Th...

Background: Previous studies suggest that persistent exposure to social stress in mammals may be associated with multiple physiological effects. Here, we examine the effects of social stress in rats, i.e. repeated social defeat, on behavior, hypothalamic-pituitary-adrenal (HPA)-axis and immune system. Methods: A resident-intruder paradigm, where...

Background Previous studies suggest that persistent exposure to social stress in mammals may be associated with multiple physiological effects. Here, we examine the effects of social stress in rats, i.e. repeated social defeat, on behavior, hypothalamic-pituitary-adrenal (HPA)-axis and immune system. Methods A resident-intruder paradigm, where an i...

Objective: Earlier studies documenting the effect of candidate genes on recovery have seldom taken into consideration the impact of emotional distress. Thus, we aimed to assess the modifying effect of emotional distress on genetic variability as a predictor for pain recovery in lumbar radicular (LRP) and low back pain (LBP). Results: The study p...

Background: Previous studies suggest that regulatory microRNAs (miRs) may modulate neuro-inflammatory processes. The purpose of the present study was to examine the role of miR-17 following intervertebral disc herniation. Methods: In a cohort of 97 patients with leg pain and disc herniation verified on MRI, we investigated the association betwee...

Prolonged exposure to bullying behaviors may give rise to symptoms such as anxiety, depression and chronic pain. Earlier data suggest that these symptoms often are associated with stress-induced low-grade systemic inflammation. Here, using data from both animals and humans, we examined the moderating role of microRNAs (miRNAs, miRs) in this process...

Several lines of evidence show that systematic exposure to negative social acts at the workplace i.e., workplace bullying, results in symptoms of depression and anxiety among those targeted. However, little is known about the association between bullying, inflammatory genes and sleep problems. In the present study, we examined the indirect associat...

The aim of this study was to determine the direction of associations between perceived leadership styles of an immediate leader and state anxiety among subordinates using time-lagged data from a large and heterogeneous probability sample of Norwegian employees. It was hypothesised that high levels of transformational leadership would be associated...

Introduction Lumbar radicular pain after disk herniation is associated with local release of many inflammatory molecules from nucleus pulposus (NP) cells leaking out of the intervertebral disk. Here, we have used a rat model to investigate the role of epiregulin (EREG), a member of the epidermal growth factor (EGF) family, in this process. Methods...

Stressors in the work environment and individual dispositions among targets have been established separately as antecedents and risk factors of workplace bullying. However, few studies have examined these stressors in conjunction in order to determine personal dispositions among targets as possible moderators in the work stressor–bullying relations...

Study design: A prospective observational study with translation and psychometric analyses of a questionnaire. Objective: Cross-cultural adaptation of the Short-Form McGill Pain Questionnaire-2 into Norwegian. Summary of background data: The different versions of the McGill Pain Questionnaire (MPQ) have been important and influential tools for...

Background: Chronic Fatigue Syndrome (CFS) is one of the most important causes of disability among adolescents while limited knowledge exists on genetic determinants underlying disease pathophysiology. Methods: We analyzed deregulated immune-gene modules using Pathifier software on whole blood gene expression data (29 CFS patients, 18 controls)....

Objective To examine the impact of demographic, clinical, and genetic factors as well as herniated discs on 5-year development of disc degeneration in the lumbar spine, and to investigate associations between changes in lumbar degenerative findings and pain. Materials and methodsIn 144 patients with lumbar radicular pain or low back pain, we scored...

The placebo effect is considered the core example of mind-body interactions. However, individual differences produce large placebo response variability in both healthy volunteers and patients. The placebo response in pain, placebo analgesia, may be dependent on both the opioid system and the dopaminergic system. Previous studies suggest that geneti...

Background: There is a lack of published data on the association between alcohol consumption and health and well-being in working populations. Aims: To determine how levels of alcohol consumption are associated with psychological distress, somatic complaints, sleep, and job satisfaction in the Norwegian workforce. Methods: Survey questionnaire...

Background: Although alcohol use can have detrimental effects for employees, little is known about the prevalence, distribution, and correlates in the Norwegian workforce. Aims: To determine the overall and the work-related prevalence of weekly alcohol use, and to establish associations between psychosocial work stressors and alcohol use among Norw...

Objective: The association between exposure to bullying at work and subsequent pain reports is relatively well-established, but few studies have examined possible moderators of this relationship. As gender is a known risk factor for pain, with women reporting pain levels of higher intensity and longer duration, a possible gender difference in the...

Background and aims Matrix metalloproteinase 9 (MMP9) is an enzyme that may affect degradation of several extracellular matrix (ECM) components in the pelvic ligaments during pregnancy. Previous studies indicate that genetic variations in the gene encoding MMP9 may affect the enzymatic activity. One such genetic variant is a single nucleotide polym...

Background: Low back-related leg pain with nerve root involvement is conceptually regarded as a neuropathic condition. However, it is uncertain to what extent patients with this condition can be formally classified with neuropathic pain. Method: First, we used the 2016 revision of the IASP Special Interest Group on Neuropathic Pain (NeuPSIG) gra...

Objectives Long-term exposure to systematic negative acts at work, usually labeled workplace bullying, is a prevalent problem at many workplaces. The adverse effects of such exposure may range from psychological symptoms, such as depression and anxiety to somatic ailments like cardiovascular disease and musculoskeletal complaints. In this study, we...

Aims Previous studies have suggested that many inflammatory cytokines, including interleukin (IL)-1α, may be associated with lumbar radicular pain after disc herniation. In the present study, we examined how variability of the IL-1α gene affects pain intensity and the pressure pain threshold (PPT) in patients with symptomatic disc herniation. Metho...

Research into “workaholism” has substantially increased over the last decade, but little effort has been put into assessing work-related correlates. In the present study, 1,608 employees (Mage = 45.2 years, range = 21–60) participated in a nationally representative cross-sectional survey in Norway examining whether job demands, job control, role am...

In the context of workplace bullying, the ability to defend refers to whether or not a target feels able to deal with those negative behaviors that typically constitute bullying. The aim of this study was to determine whether the perceived ability to defend oneself moderates the association between exposure to bullying behaviors at work and symptom...

Lumbar radicular pain after disc herniation may be associated with release of pro-inflammatory cytokines from nucleus pulposus (NP) tissue. In the present study we examined the role of interferon-γ (IFN-γ) and cluster of differentiation 68 (CD68) in the acute phase of this process. First, in an animal model mimicking the clinical situation after di...

Higher levels of fear have been shown to partly explain individual differences in placebo analgesic responding. The COMT rs4680 Val158Met polymorphism has been associated with both increased placebo analgesia and increased fear-related behavior, in what appears to be inconsistent findings in the literature. The aim of the study was therefore to inv...

Poster presentation for 6th NeuPSIG Congress, Gothenburg, Sweden, June, 2017. https://osf.io/udjr2/

The aim of the present study was to examine if genetic factors associated with pain perception could predict the placebo analgesic response in healthy volunteers. 296 participants (182 women) were randomized to either a placebo group receiving placebo cream with information that the cream was an effective painkiller, or to a natural history group r...

Background Previous findings have demonstrated that lumbar radicular pain after disc herniation may be associated with up-regulation of inflammatory mediators. In the present study we examined the possible role of extracellular microRNAs (miRs) in this process. Methods Single unit recordings, isolation of exosome-like vesicles, electron microscopy,...

Previous data suggest that persistent back pain may be associated with genetic variability. In this study, we assessed the correlation between 8 genetic polymorphisms (VDR, COL11, MMP1, MMP9, IL-1á, IL-1RN, OPRM1, COMT) and pain recovery in patients with low back pain (LBP) and lumbar radicular pain (LRP). In total, 296 patients with LBP or LRP wer...

Background The aim of the present study was to provide an overview of the literature addressing the role of genetic factors and biomarkers predicting pain recovery in newly diagnosed lumbar radicular pain (LRP) patients. Methods The search was performed in Medline OVID, Embase, PsycInfo and Web of Science (2004 to 2015). Only prospective studies of...

Background Rodent models highlight the key role of μ-opioid receptor (MOR) signaling in palatable food consumption. In humans, however, the effects of MOR stimulation on eating and food liking remain unclear. Objectives Here, we tested sweet pleasantness experience in humans following MOR drug manipulations. We hypothesized that behaviors regulated...

Clonidine, an α2-adrenergic receptor agonist, decreases circulating norepinephrine and epinephrine, attenuating sympathetic activity. Although catechol-O-methyltransferase (COMT) metabolizes catecholamines, main effectors of sympathetic function, COMT genetic variation effects on clonidine treatment are unknown. Chronic fatigue syndrome (CFS) is hy...

Earlier studies suggest that lumbar radicular pain following disc herniation may be associated with a local or systemic inflammatory process. In the present study, we investigated the serum inflammatory protein profile of such patients. All 45 patients were recruited from Oslo University Hospital, Ullevål, Norway, during the period 2007–2009. The n...

In the Proximity Extension Assay (PEA) each of the 92 human protein biomarkers were addressed by a pair of oligonucleotide-labeled antibodies. The amount of the proteins was measured by quantitative real-time PCR. The dual recognition DNA-coupled method excluded cross-reactivity in the detection process.

Introduction . Lumbar radicular pain following intervertebral disc herniation may be associated with a local inflammatory response induced by nucleus pulposus (NP) cells. Methods . In anaesthetized Lewis rats, extracellular single unit recordings of wide dynamic range (WDR) neurons in the dorsal horn and qPCR were used to explore the effect of NP a...

Earlier studies have shown that genetic variability in the SLC6A4 gene encoding the serotonin transporter (5-HTT) may be important for the re-uptake of serotonin (5-HT) in the central nervous system. In the present study we investigated how the 5-HTT genotype i.e. the short (S) versus long (L) 5-HTTLPR allele and the SNP rs25531 A > G affect the ph...

Background: Chronic Fatigue Syndrome (CFS) is a common and disabling condition in adolescence with few treatment options. A central feature of CFS is orthostatic intolerance and abnormal autonomic cardiovascular control characterized by sympathetic predominance. We hypothesized that symptoms as well as the underlying pathophysiology might improve...

Earlier studies indicate that lumbar radicular pain after disc herniation may be associated with a local inflammation induced by leakage of nucleus pulposus (NP) into the spinal canal and neuroforamen. In the present study we addressed the role of two interleukins, IL-6 and IL-8 in such long-lasting lumbar radicular pain. All 127 patients were recr...

In the present study, the influence of cytokines on 1-year recovery in lumbar radicular pain was examined. In total, 110 patients with symptomatic lumbar disc herniation were followed for 1 year. Uni- and multivariate linear regression was used to assess the influence of interleukin (IL)-6, IL-8, disc degeneration and endplate changes (Modic change...

Previous studies indicate that lumbar radicular pain following disc herniation may be associated with release of several pro-inflammatory mediators, including interleukin-1 (IL1). In the present study, we examined how genetic variability in IL1A (rs1800587 C>T), IL1B (rs1143627 T>C) and IL1RN (rs2234677 G>A) influenced the clinical outcome the firs...

Background: Cross-sectional studies demonstrate that exposure to bullying in the workplace is positively correlated with self-reported health problems. However, these studies do not provide a basis to draw conclusions on the extent to which bullying leads to increased health problems or whether health problems increase the risk of being bullied. T...

Objective: To examine whether Modic changes influence pain during a 1-year follow-up in patients with lumbar radicular pain. Materials and methods: A total of 243 patients with lumbar radicular pain due to disc herniation were recruited from two hospitals in Norway and followed up at 6 weeks, 6 months, and 12 months. On baseline lumbar magnetic...

Background Earlier observations show that development of persistent pain may be associated with the genetic variability in the gene encoding for the μ-opioid receptor 1, the OPRM1 A118G (rs1799971). The aim of this study was to investigate the association between OPRM1 genotype and subjective health complaints in patients with radicular pain and di...

Previous studies have suggested that many inflammatory cytokines, including interleukin (IL)-1α, may be associated with lumbar radicular pain after disc herniation. In the present study, we examined how variability of the IL-1α gene affects pain intensity and the pressure pain threshold in patients with symptomatic disc herniation. A total of 121 p...

Sciatica following disc herniation may be associated with compression of spinal nerves, but also by inflammatory substances released from the nucleus pulposus (NP) leaking into the spinal canal. Here, in an animal model mimicking clinical intervertebral disc herniation, we investigate the effect of NP on neuronal activity. In anaesthetized Lewis ra...

Objectives: Previous studies indicate that genetic variants in genes encoding proteins like matrix metalloproteinase (MMP) enzymes may affect degeneration of the intervertebral disk. One such genetic variant is a single nucleotide polymorphism insertion in the promoter region of the MMP1 gene, that is, the MMP1 rs1799750 2G allele, which increases...

Neuropathic pain conditions are common after nerve injuries and are suggested to be regulated in part by genetic factors. We have previously demonstrated a strong genetic influence of the rat major histocompatibility complex on development of neuropathic pain behavior after peripheral nerve injury. In order to study if the corresponding human leuko...

The purpose of the present study was to examine how genetic variability in the promoter of the SLC6A4 gene encoding the serotonin transporter (5-HTT) may influence induction of long-term potentiation (LTP). The genotyping of the 53 healthy volunteers was performed by a combination of TaqMan assay and gel electrophoresis. Based on the transcription...

Earlier studies have shown that the single nucleotide polymorphism (SNP) A118G (rs1799971) in the opioid receptor mu 1 (OPRM1) gene may affect pain sensitivity. In the present study we investigated whether the A118G SNP could predict clinical outcome regarding progression of pain intensity and disability in patients with low back pain and sciatica...

Fatty acid amide hydrolase (FAAH) is an enzyme that metabolizes endocannabinoids and fatty acid amides possibly linked to activation of the opioid system. To examine how this enzyme affects spinal signalling, electrophysiological recordings in the dorsal horn and qPCR on dorsal horn tissue following systemic administration of the FAAH inhibitor URB...

To explore the frequency of polymorphisms in adrenergic cardiovascular control genes in adolescent with chronic fatigue syndrome (CFS) and the relation of such polymorphisms to cardiovascular variables. DNA from 53 patients with CFS, 12-18 years old, was analysed for five single nucleotide polymorphisms (SNPs) in the genes catechol-O-methyltransfer...

Although low back pain is usually temporary, some patients do not recover and need treatment. Therefore, it is important to uncover causal and contributing factors. Here we give an overview of recent research on MRI findings and genetic factors that may be important for development of long-lasting low back pain. A non-systematic search in PubMed an...

Neuronal events leading to development of long-term potentiation (LTP) in the nociceptive pathways may be a cellular mechanism underlying hyperalgesia. In the present study, we examine if induction of spinal LTP may be associated with functional changes in the supraspinal opioidergic system. The opioid receptors (ORs) play a key role in nociceptive...

Several variants of the catechol-O-methyltransferase (COMT) gene have recently been linked to pain sensitivity. In the present study, electrophysiological field potential recordings from the dorsal horn in rats were used to examine the spinal effect of reduced COMT activity. The data demonstrated that 30 mg/kg of the COMT inhibitor OR 486 reduced s...

Previous data show that spinal cord long-term potentiation (LTP) can be induced by electrical high-frequency stimulation (HFS) conditioning applied to the sciatic nerve. It has been suggested that the cellular events leading to this form of plasticity may contribute to central hyperalgesia. In the present study, extracellular recordings from single...

It has been suggested that spinal cord long-term potentiation (LTP) may contribute to hypersensitivity and hyperalgesia. We have investigated if noxious stimulus-induced spinal cord LTP might have a long lasting effect on supraspinal neuronal activity. First, we verified that spinal LTP was induced by electrical high frequency stimuli (HFS) conditi...

The NR2B-containing N-methyl-d-aspartate (NMDA) receptors may be involved in a variety of phenomena including synaptic plasticity, memory formation and pain perception. Here we used the NMDA-2B receptor antagonist Ro 25-6981 to investigate the role of the NR2B-containing NMDA receptors in spinal nociception. Extracellular single unit recordings wer...

Previous data indicate that persistent pain states often involve sensitization within the central nervous system (CNS). Many recently described human genetic variants may affect these central processes. Genetic variability influences both synthesis and function of proteins affecting the plasticity of the CNS. Hence, individual genetic variability m...

Spinal cord long-term potentiation is often studied as a model for cellular memory of nociceptive information. In the present report, extracellular single-unit recordings and quantitative real-time reverse transcriptase polymerase chain reaction were used to examine whether the induction of spinal cord long-term potentiation involves changes in exp...

Neuronal events leading to development of long-term potentiation (LTP) in the nociceptive pathways may be a cellular mechanism underlying central hyperalgesia. Here, we examine whether induction of LTP in nociceptive dorsal horn neurons at depths of 80-500 microm from the cord surface can be affected by spinal application of the Ca(2+)/calmodulin-d...

To study the effect of inositol 1,4,5-trisphosphate (IP(3)) in isolated frog vomeronasal microvillar receptor neurones, whole-cell recordings were performed with 0.5 microM caged IP(3) dissolved in the pipette solution. IP(3) was released by photolysis of caged IP(3) initiated by a 0.8-ms ultraviolet flash from a xenon flash lamp 70 s after the sta...

Long-term potentiation (LTP) in wide dynamic range (WDR) neurons in the dorsal horn has been suggested to contribute to central sensitization and the development of chronic pain. Indirect experimental evidence indicates an involvement of substance P (SP), in this respect. The aim of the present study was to monitor the extracellular level of substa...

Previous studies have shown that long-term potentiation (LTP) in the dorsal horn may be induced by noxious stimuli. In this study it is investigated whether induction of LTP in the dorsal horn may be affected by the descending pathways. Extracellular recordings of wide dynamic range (WDR) neurones in the lumbar dorsal horn in intact urethane-anaest...

Extracellular recordings of wide dynamic range neurones in the dorsal horn driven by electrical stimulation of the sciatic nerve were performed in intact urethane-anaesthetized Sprague-Dawley rats. The electrically evoked neuronal responses were defined as A- and C-fibres responses according to latencies, and the effect of a deep nociceptive condit...

We have published several reports on long-term potentiation (LTP) in single spinal wide dynamic range (WDR) neurons (responding to both innocuous and noxious stimuli) in urethane-anaesthetised rats. The protocol presented here, with single unit recordings of dorsal horn neurons before and after a nociceptive conditioning stimulation, may be useful...

In this study extracellular recordings of nociceptive dorsal horn neurones driven by electrical stimulation of the sciatic nerve were performed in intact urethane-anaesthetized Sprague-Dawley rats. Spikes 0-40, 40-250 and 250-800 ms after stimulus were defined as A- and C-fibre responses and post-discharge, respectively, and the effect of 200 micro...

We report long-term potentiation (LTP) in single spinal wide dynamic range (WDR) neurons in urethane-anaesthetized spinalized rats with a complete neuromuscular blockade. Peripheral influences were excluded by a complete lidocaine block distal to the stimulation site on the sciatic nerve. As previously shown A-beta fibre evoked responses were not i...

In this study the modulatory effects of 5-HT1B receptor activation on wide dynamic range neurones in the spinal cord were studied. Extracellular single unit recordings of dorsal horn neurones were performed in intact urethane-anaesthetized female Sprague-Dawley rats, and the receptive field distally on one hind paw was electrically stimulated with...

Spinal 5-HT1A receptor subtypes are involved in regulation of nociception. This study was performed to investigate the effect of stimulation of these receptors on wide dynamic range neurones in the spinal cord. Extracellular single unit recordings of dorsal horn neurones were performed in intact urethane-anaesthetized female Sprague-Dawley rats. Th...