Stress and pain: modality-specific opioid mediation of stress-induced analgesia

"He was not interested in pain": The experience of pain in child sexual abuse as conveyed by adult survivors

Although extensive efforts have been dedicated to uncovering the close link between trauma and chronic pain, very few research efforts have investigated the lived experience of pain during and following trauma. This study delves into the complex and multifaceted experiences of physical pain among adults who experienced child sexual abuse (CSA), examining 29 detailed testimonies provided to the Israeli Independent Public Inquiry into CSA. Using qualitative thematic analysis, the research identifies and elaborates on three pivotal themes: pain as a distress signal, the internalization of pain, and the intermingling of physical and mental pain. Thus, the study findings capture the immediate physical pain experienced during abusive incidents, which serves as an involuntary alert to the self and, at times, to the broader environment about the trauma being experienced. The findings also explore how this acute response transforms into a chronic state, becoming an embedded part of survivors' daily lives, influencing personal and relational dynamics, often without visible scars but with profound internal implications. Lastly, the findings reveal the blurred lines between the participant's physical and psychological pain, illustrating how they express psychological distress through physical pain symptoms and how this affects their coping mechanisms. The study underscores the necessity of recognizing pain as a complex, enduring component of the CSA survivor's experience, highlighting the need for integrated therapeutic approaches that address the intertwined nature of posttraumatic mental symptoms and physical pain. This study advocates for a more nuanced understanding and acknowledgment of pain in CSA survivors, urging further research and adapted clinical practices to better support their recovery and well-being.

Pain Sensitivity and Depressive Triad Mediate the Relationship Between Trauma and Stress, and Symptoms of Premenstrual Disorders

The aim of this study was to test if negative cognitive triad and subjective pain sensitivity mediate the relationship between known risk factors (trauma and stress) and the symptoms of premenstrual disorders (premenstrual syndrome [PMS] and premenstrual dysphoric disorder [PMDD]) measured both retrospectively and prospectively. The study was divided into two stages: a cross-sectional (N = 228) and a prospective diagnosis (N = 90) parts. Correlation and mediation analyses were performed. Both variables mediated the association of trauma and stress with retrospectively measured premenstrual symptoms (mediation between trauma and premenstrual symptoms through depressive triad was full). In the sample of prospectively diagnosed individuals, again, both negative cognitive triad and pain sensitivity mediated the relationship between trauma and PMS/PMDD symptoms partially, and there was full mediation between baseline stress level and premenstrual symptomatology. However, for the mean stress level during the prospective diagnosis phase, only pain sensitivity was a significant, partial mediator. The results suggest that depressive cognitive triad and subjective pain sensitivity may play an important role in the development and maintenance of premenstrual disorders. These findings can contribute to the improvement of PMDD and PMS treatment, emphasising the importance of pain management and addressing core beliefs in psychotherapy of premenstrual disorders.

The association between maternal stress and human milk concentrations of cortisol and prolactin

Psychosocial stress affects the relationship between prolactin (PRL) and cortisol (CORT). The dynamics of PRL and CORT changes under stress in human milk (HM) are largely unknown. We investigated how maternal stress related to recent life changes affects milk CORT and PRL concentrations. The study involved 116 mothers exclusively breastfeeding 5-month-old infants. Maternal psychological stress was evaluated using the Recent Life Changes Questionnaire (RLCQ). Stress response was determined by administering the cold pressor test and measuring CORT in saliva taken during and in milk collected after the test. Hormones concentrations were assayed using the ELISA method. The hierarchical regression models were run to test the association between maternal RLCQ, salivary CORT, and PRL, and CORT in milk. Maternal RLCQ correlated positively with the CORT in saliva, however, no direct association was found between RLCQ and PRL. After controlling for covariates, a positive association was found between salivary and milk CORT. A negative relationship was observed between salivary CORT and milk PRL. The results of the present study indicate that maternal psychological stress may affect the relationship between CORT and PRL in HM. In response to psychological stress, both hormones transported via milk can program infant development in the early postnatal period.

The Role of Mindfulness Therapy in the Treatment of Chronic Pain

PURPOSE OF REVIEW

Mindfulness therapy is a widely used treatment for many diseases and has been shown to improve pain-related functions. There is growing support for the use of psychotherapy in the treatment of chronic pain. While studies have shown a positive effect of mindfulness therapy, it is important to consider psychosocial factors as there are still a small number of studies that question its effectiveness.

RECENT FINDINGS

Based on current studies, mindfulness therapy involves cognitive factors related to chronic pain, both in terms of cognitive production and its impact on cognitive control. Psychological and neurobasic studies were reviewed to provide a deeper understanding of these components, which include thought inhibition, attention deficit, pain catastrophizing, and self-efficacy. Mindfulness therapy has the potential to normalize psychology and nerves, and increase internal and external connectivity to work networks related to stress perception, cognition, and emotion. However, further research is needed to fully understand its effects. By exploring the relationship between mindfulness therapy and chronic pain. This review provides a new avenue for future research in psychotherapy for patients with chronic pain.

The Role of the Mu Opioid Receptors of the Medial Prefrontal Cortex in the Modulation of Analgesia Induced by Acute Restraint Stress in Male Mice

Mu opioid receptors (MORs) represent a vital mechanism related to the modulation of stress-induced analgesia (SIA). Previous studies have reported on the gamma-aminobutyric acid (GABA)ergic "disinhibition" mechanisms of MORs on the descending pain modulatory pathway of SIA induced in the midbrain. However, the role of the MORs expressed in the medial prefrontal cortex (mPFC), one of the main cortical areas participating in pain modulation, in SIA remains completely unknown. In this study, we investigated the contributions of MORs expressed on glutamatergic (MORGlut) and GABAergic (MORGABA) neurons of the medial prefrontal cortex (mPFC), as well as the functional role and activity of neurons projecting from the mPFC to the periaqueductal gray (PAG) region, in male mice. We achieved this through a combination of hot-plate tests, c-fos staining, and 1 h acute restraint stress exposure tests. The results showed that our acute restraint stress protocol produced mPFC MOR-dependent SIA effects. In particular, MORGABA was found to play a major role in modulating the effects of SIA, whereas MORGlut seemed to be unconnected to the process. We also found that mPFC-PAG projections were efficiently activated and played key roles in the effects of SIA, and their activation was mediated by MORGABA to a large extent. These results indicated that the activation of mPFC MORGABA due to restraint stress was able to activate mPFC-PAG projections in a potential "disinhibition" pathway that produced analgesic effects. These findings provide a potential theoretical basis for pain treatment or drug screening targeting the mPFC.

D2-like dopamine receptors blockade within the dentate gyrus shows a greater effect on stress-induced analgesia in the tail-flick test compared to D1-like dopamine receptors

INTRODUCTION

Acute stress, as a protective mechanism to respond to an aversive stimulus, can often be accompanied by suppressing pain perception via promoting consistent burst firing of dopamine neurons. Besides, sensitive and advanced research techniques led to the recognition of the mesohippocampal dopaminergic terminals, particularly in the hippocampal dentate gyrus (DG). Moreover, previous studies have shown that dopamine receptors within the hippocampal DG play a critical role in induced antinociceptive responses by forced swim stress (FSS) in the presence of inflammatory pain. Since different pain states can trigger various mechanisms and transmitter systems, the present experiments aimed to investigate whether dopaminergic receptors within the DG have the same role in the presence of acute thermal pain.

METHODS

Ninety-seven adult male albino Wistar rats underwent stereotaxic surgery, and a stainless steel guide cannula was unilaterally implanted 1 mm above the DG. Different doses of SCH23390 or sulpiride as D1- and D2-like dopamine receptor antagonists were microinjected into the DG 5-10 min before exposure to FSS, and 5 min after FSS exposure, the tail-flick test evaluated the effect of stress on the nociceptive response at the time-set intervals.

RESULTS

The results demonstrated that exposure to FSS could significantly increase the acute pain perception threshold, while intra-DG administration of SCH23390 and sulpiride reduced the antinociceptive effect of FSS in the tail-flick test.

DISCUSSION

Additionally, it seems the D2-like dopamine receptor within the DG plays a more prominent role in FSS-induced analgesia in the acute pain model.

Personalized Multimodal Lifestyle Intervention as the Best-Evidenced Treatment for Chronic Pain: State-of-the-Art Clinical Perspective

Chronic pain is the most prevalent disease worldwide, leading to substantial disability and socioeconomic burden. Therefore, it can be regarded as a public health disease and major challenge to scientists, clinicians and affected individuals. Behavioral lifestyle factors, such as, physical (in)activity, stress, poor sleep and an unhealthy diet are increasingly recognized as perpetuating factors for chronic pain. Yet, current management options for patients with chronic pain often do not address lifestyle factors in a personalized multimodal fashion. This state-of-the-art clinical perspective aims to address this gap by discussing how clinicians can simultaneously incorporate various lifestyle factors into a personalized multimodal lifestyle intervention for individuals with chronic pain. To do so the available evidence on (multimodal) lifestyle interventions targeting physical (in)activity, stress, sleep and nutritional factors, specifically, was reviewed and synthetized from a clinical point of view. First, advise is provided on how to design a personalized multimodal lifestyle approach for a specific patient. Subsequently, best-evidence recommendations on how to integrate physical (in)activity, stress, sleep and nutritional factors as treatment targets into a personalized multimodal lifestyle approach are outlined. Evidence supporting such a personalized multimodal lifestyle approach is growing, but further studies are needed.

Water temperature during the cold pressor test: A scoping review

The cold pressor test (CPT) is a commonly used method to induce pain and stress in experimental settings. Previous research has found that the temperature of the water used in the test significantly affects outcome measures such as pain tolerance. Variations in CPT protocols, specifically regarding temperature, have been criticized. Hence, our objective is to investigate water temperature and associated methodological factors through a scoping review of the CPT in adults. Among 331 included trials, the most commonly reported temperature was 1°C (33.8°F). Reporting of the water temperature was adequate (93% of all trials), but a precise range within which the temperature was maintained was reported only in 27% of all trials. Pain measurement was the primary focus for most studies (90%), predominantly utilizing pain tolerance as the main outcome (78%). Water circulation was reported in 44% of studies, and 10% reported manually agitating the water. The most common maximum immersion time (i.e., ceiling time) was 180 s; notably, 64% of trials lacked information on participant awareness of this limit specification. The limb most immersed was the hand (76%). Overall, multiple methodological factors significantly impacting outcome measures were inconsistently implemented or reported. For future studies, we advocate for precise standardization of the water temperature used during the CPT. We suggest using 1°C (33.8°F), especially when assessing pain tolerance. A cooling apparatus allowing precise temperature control and continuous water circulation is advised. At the bare minimum, the temperature should be monitored continuously. While other decisions regarding the implementation of the CPT may differ depending on the specific aims of the respective study, it remains essential to standardize the water temperature and to provide a comprehensive report of the experimental protocol.

The Biology of Stress Intolerance in Patients with Chronic Pain—State of the Art and Future Directions

Stress has been consistently linked to negative impacts on physical and mental health. More specifically, patients with chronic pain experience stress intolerance, which is an exacerbation or occurrence of symptoms in response to any type of stress. The pathophysiological mechanisms underlying this phenomenon remain unsolved. In this state-of-the-art paper, we summarised the role of the autonomic nervous system (ANS) and hypothalamus-pituitary-adrenal (HPA) axis, the two major stress response systems in stress intolerance. We provided insights into such mechanisms based on evidence from clinical studies in both patients with chronic pain, showing dysregulated stress systems, and healthy controls supported by preclinical studies, highlighting the link between these systems and symptoms of stress intolerance. Furthermore, we explored the possible regulating role for (epi)genetic mechanisms influencing the ANS and HPA axis. The link between stress and chronic pain has become an important area of research as it has the potential to inform the development of interventions to improve the quality of life for individuals living with chronic pain. As stress has become a prevalent concern in modern society, understanding the connection between stress, HPA axis, ANS, and chronic health conditions such as chronic pain is crucial to improve public health and well-being.

Emotional numbing in PTSD is associated with lower amygdala reactivity to pain

Posttraumatic stress disorder (PTSD) is associated with altered pain perception, namely increased pain threshold and higher pain response. While pain consists of physiological and affective components, affective components are often overlooked. Similar patterns of increased threshold-high response in PTSD were shown in response to emotional stimuli, i.e., emotional numbing. As both emotional numbing and pain processing are modulated by the amygdala, we aimed to examine whether individuals diagnosed with PTSD show lower amygdala activation to pain compared with combat controls, and whether the amygdala responses to pain correlates with emotional numbing. To do so, two independent samples of veterans (original study: 44 total (20 PTSD); conceptual replication study: 40 total (20 PTSD)) underwent threat conditioning, where a conditioned stimulus (CS+; visual stimulus) was paired with an unconditioned stimulus (US; electric-shock). We contrasted the amygdala activity to the CS + US pairing with the CS+ presented alone and correlated it with emotional numbing severity. In both samples, the PTSD group showed a robust reduction in amygdala reactivity to shock compared to the Combat Controls group. Furthermore, amygdala activation was negatively correlated with emotional numbing severity. These patterns were unique to the amygdala, and did not appear in comparison to a control region, the insula, a pivotal region for the processing of pain. To conclude, amygdala response to pain is lower in individuals with PTSD, and is associated with emotional numbing symptoms. Lower amygdala reactivity to mild pain may contribute to the "all-or-none" reaction to stressful situations often observed in PTSD.

A Theoretical Endogenous Opioid Neurobiological Framework for Co-occurring Pain, Trauma, and Non-suicidal Self-injury

PURPOSE OF REVIEW

Individuals with chronic pain are significantly more likely to have experienced overwhelming trauma early and often in key developmental years. There is increasing acknowledgment that childhood trauma disrupts how individuals process and cope with both physical and emotional pain. Emerging studies acknowledge elevated rates of non-suicidal self-injury (NSSI) in chronic pain populations. This review provides a theoretical framework to understand the relationship between NSSI behavior and pain experience in persons with chronic pain and childhood trauma histories. We discuss how NSSI may act to regulate neurobiological (e.g., endogenous opioid systems) and psychological (e.g., heightened negative affect and emotion dysregulation) systems affected by childhood trauma, leading to temporary pain relief and a cycle of negative reinforcement perpetuating NSSI. As these concepts are greatly understudied in pain populations, this review focuses on key areas relevant to chronic pain that may provide a testable, conceptual framework to support hypothesis generation, future empirical investigation, and intervention efforts.

RECENT FINDINGS

See Fig. 1. See Fig. 1.

Stress-induced analgesia: an evaluation of effects on temporal summation of pain and the role of endogenous opioid mechanisms

Acute stress reduced the initial pain rating in a temporal summation protocol via nonopioid mechanisms but did not affect temporal summation slope, an indicator of central sensitization.

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