Pronociceptive and antinociceptive effects of estradiol through endogenous opioid neurotransmission in women

Women's Pain Management Across the Lifespan-A Narrative Review of Hormonal, Physiological, and Psychosocial Perspectives

Introduction: Pain perception and management differ by sex, with women frequently experiencing more acute and chronic pain and greater disability than men. Yet, anesthesiology and pain control often overlook the physiological, hormonal, and psychological factors shaping women's pain. Methods: This narrative review explores essential considerations from current literature to optimize pain management in women. We examine evidence about the impact of hormonal changes, reproductive transitions, and psychosocial factors on pain perception and responses to analgesics. By highlighting key insights and practical strategies, we aim to support the development of personalized pain management approaches tailored to women's unique needs. Results: Hormonal changes, including variations in estrogen and progesterone levels, significantly influence pain thresholds and the effectiveness of analgesics and anesthetics. The menstrual cycle, menopausal transitions, and pregnancy each alter pain responses, necessitating personalized approaches to pain management. Postmenopausal women are particularly vulnerable to chronic pain conditions, such as those associated with osteoporosis, which require adjustments in long-term treatment strategies. Furthermore, psychosocial factors like anxiety and emotional distress can intensify pain, highlighting the need for holistic, integrative care. Conclusions: The existing gaps in women's pain management across the lifespan highlight the need to revise both anesthesia and pain management protocols to better account for sex-specific biological and psychosocial factors. Addressing the unique biological and psychosocial factors that influence pain in women can enhance both the effectiveness and equity of care. By tailoring treatment strategies in women, clinicians can not only enhance pain management but also greatly improve their overall quality of life.

Depression symptoms in perimenopausal women with somatic pain: nomogram construction based on a logistic regression model

Objective

This study investigated the factors influencing depressive symptoms in women with somatic pain during the perimenopausal period in China and established and validated a nomogram prediction model.

Methods

The predictive model is based on data from the China Health and Retirement Longitudinal Study (CHARLS), which focused on individuals aged 45-59 years with somatic pain during the perimenopausal period. The study utilized participants from the CHARLS 2018 wave, 30 factors including individual characteristics, health behaviors, living environment, family economic status, and social participation, were analyzed in this study. To ensure the model's reliability, the study cohort was randomly split into a training set (80%) and a validation set (20%). The χ 2 tests and a Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis were used to identify the most effective predictors of the model. The logistic regression model was employed to investigate the factors associated with depressive symptoms in perimenopausal women with somatic pain. A nomogram was constructed to develop a prediction model, and calibration curves were used to assess the accuracy of the nomogram model. The model's performance was evaluated using the area under the curve (AUC) and decision curve analysis (DCA).

Results

In total, 2,265 perimenopausal women were included in the final analysis, of whom 1,402 (61.90%) experienced somatic pain. Multifactorial logistic regression identified marital status, pain distress, self-perceived general health, activities of daily living (ADL), sleep deprivation, life satisfaction, and air quality satisfaction, as predictive risk factors for perimenopausal women with somatic pain. The predictive model achieved an AUC of 0.7010 (95%CI = 0.677-0.725) in the training set and 0.7015 (95%CI = 0.653-0.749) in the validation set. The nomogram showed excellent predictive ability according to receiver operating characteristic (ROC) and DCA, and the model may help in the early detection of high-risk depression symptoms in perimenopausal women with somatic pain, thereby enabling the timely initiation of appropriate treatment interventions.

Conclusion

The nomogram constructed in this study can be used to identify the factors related to depression in women with perimenopausal somatic pain.

[11C]Carfentanil PET Whole-Body Imaging of μ-Opioid Receptors: A First in-Human Study

μ-opioid receptors (MORs) are G-coupled receptors widely expressed in the brain and body. MORs have a high affinity for both endogenous opioids such as β-endorphins and exogenous opioids such as fentanyl. They mediate pain and reward and have been implicated in the pathophysiology of opioid, cocaine, and other substance use disorders. Using an instrument with a long axial field of view and the MOR-selective radioligand [11C]carfentanil, we measured the whole-body distribution of MORs in 13 healthy humans. We also examined sex differences in MOR distribution at baseline and after pretreatment with the MOR antagonist naloxone. Methods: Six female and 7 male healthy subjects underwent 2 [11C]carfentanil PET imaging sessions-one at baseline and one immediately after pretreatment with the MOR antagonist naloxone (13 μg/kg). Whole-body PET imaging was performed on an instrument with a 142-cm axial bore. [11C]carfentanil brain distribution volume ratios were determined using the occipital cortex and the visual cortex within it as reference regions. For peripheral organ distribution volume ratios, the descending aorta and proximal-extremity muscle (biceps/triceps) were used as reference regions. Results: Naloxone blockade reduced MOR availability by 40%-50% in the caudate, putamen, thalamus, amygdala, and ventral tegmentum, brain regions known to express high levels of MORs. Women showed greater receptor occupancy in the thalamus, amygdala, hippocampus, and frontal and temporal lobes and a greater naloxone-induced reduction in thalamic MOR availability than men (P < 0.05). For determining brain MOR availability, there was less variance in the visual cortex than in the occipital cortex reference region. For peripheral MOR determination, the descending aorta reference region showed less variance than the extremity muscle, but both showed blocking effects of naloxone. Conclusion: [11C]carfentanil whole-body PET scans are useful for understanding MOR physiology under both baseline and blocking conditions. Extra-central nervous system reference regions may be useful for quantifying radiotracers when a region devoid of binding in the central nervous system is unavailable. The long axial field of view was useful for measuring changes in the short-lived radiotracer [11C]carfentanil, with and without naloxone blocking. Further research is needed to evaluate the behavioral and clinical relevance of sex differences in naloxone-MOR interactions.

Relationship of Reduced Pain Intensity and Improved Quality-of-Life with Menstrual Migraine with Aspirin, Acetaminophen, and Caffeine Combination

Objective: The objective of the current post hoc analysis is to evaluate whether the combination of acetaminophen, aspirin, and caffeine (AAC) is more effective than placebo in relieving the pain intensity for and improving the quality-of-life (QoL) of subjects with menstrual migraine (MM). Methods: This analysis evaluated the impact of AAC (n = 85) versus placebo (n = 100) in relieving the pain intensity for and improving the QoL of subjects with MM during baseline and at 0.5, 1, 2, 3, 4, and 6 h post treatment. Subjects reported their pain intensity using a 4-point scale and QoL using a 5-point scale. A lower score indicates reduced pain intensity and improved QoL. Results: A statistically significant difference between the AAC and placebo groups (p ≤ 0.001) was observed in pain relief after 1 h (40% vs. 14%), 2 h (56.5% vs. 24%), 3 h (63.5% vs. 31%), 4 h (65.9% vs. 34%), and 6 h (64.7% vs. 31%) post treatment. Similarly, a significantly higher proportion of subjects reported improved QoL at 1 h (48.2% vs. 28.0%; p ≤ 0.005), 2 h (61.2% vs. 40.0%; p ≤ 0.005), 3 h (68.2% vs. 44.0%; p ≤ 0.001), 4 h (67.9% vs. 39.0%; p ≤ 0.001), and 6 h (64.3% vs. 37.0%; p ≤ 0.001) post treatment. The mean pain intensity and QoL scores reduced, while the relative pain intensity and QoL (difference between the AAC and placebo groups) increased with time and was sustained for 6 h. Conclusions: The rapid onset and sustained effect of AAC make it a potential option for managing headaches and other symptoms, and to improve the QoL of subjects with MM.

Further evidence that peritraumatic 17β-estradiol levels influence chronic posttraumatic pain outcomes in women, data from both humans and animals

ABSTRACT

Chronic posttraumatic pain (CPTP) is common after traumatic stress exposure (TSE) and disproportionately burdens women. We previously showed across 3 independent longitudinal cohort studies that, in women, increased peritraumatic 17β-estradiol (E2) levels were associated with substantially lower CPTP over 1 year. Here, we assessed this relationship in a fourth longitudinal cohort and also assessed the relationship between E2 and CPTP at additional time points post-TSE. Furthermore, we used a well-validated animal model of TSE to determine whether exogenous E2 administration protects against mechanical hypersensitivity. Using nested samples and data from the Advancing Understanding of RecOvery afteR traumA study (n = 543 samples, 389 participants), an emergency department-based prospective study of TSE survivors, we assessed the relationship between circulating E2 levels and CPTP in women and men using multivariate repeated-measures mixed modeling. Male and ovariectomized female Sprague Dawley rats were exposed to TSE and administered E2 either immediately after or 3 days post-TSE. Consistent with previous results, we observed an inverse relationship between peritraumatic E2 and longitudinal CPTP in women only (β = -0.137, P = 0.033). In animals, E2 protected against mechanical hypersensitivity in female ovariectomized rats only if administered immediately post-TSE. In conclusion, peritraumatic E2 levels, but not those at post-TSE time points, predict CPTP in women TSE survivors. Administration of E2 immediately post TSE protects against mechanical hypersensitivity in female rats. Together with previous findings, these data indicate that increased peritraumatic E2 levels in women have protective effects against CPTP development and suggest that immediate post-TSE E2 administration in women could be a promising therapeutic strategy for reducing risk of CPTP.

Genetics and Gender in Acute Pain and Perioperative Opioid Analgesia

Biological sex as a variable in pain perception has been rigorously studied. However, there is little correlation between clinical and experimental studies with regard to this. There has been a surge of interest and research in the correlation of genes and single-nucleotide polymorphisms in relation to pain perception, and opioid pharmacokinetics. However, there have not yet been studies or reports of generalized application of this testing to improve acute postoperative pain outcomes.

Microglia-dependent peripheral neuropathic pain in adulthood following adolescent exposure to morphine in male rats

Persistent effects of adolescent morphine exposure on neurobiological processes and behaviors in adulthood have been partially identified. Hypersensitivity following adolescent exposure to morphine is a complex and multifaceted phenomenon whose underlying mechanisms remain largely unknown. This study aimed to investigate the involvement of microglia in neuropathic pain sensitivity following adolescent morphine exposure, focused on hippocampal genes expression and plasticity. To achieve this, adolescent male Wistar rats received morphine, along with minocycline, to inhibit microglial activity. The allodynia and hyperalgesia of adult rats were evaluated using von-Frey filaments and the Hargreaves plantar test in both baseline and neuropathic pain conditions. Hippocampal genes expression was analyzed following the behavioral tests. The plasticity of the Schaffer-CA1 hippocampal synapses was also assessed using field potential recording following neuropathy. Results showed that adolescent morphine exposure exacerbated the allodynia and hyperalgesia in both baseline and neuropathic pain states in adult rats, which was significantly reduced by the co-administration of minocycline during adolescence. Neuropathy in adult rats was found to increase hippocampal expression of inflammatory mediators, but adolescent morphine prevented this effect. Additionally, we observed a reduction in the baseline synaptic transmission and long-term potentiation (LTP) at the Schaffer-CA1 hippocampal synapses after neuropathy in adult rats following adolescent exposure to morphine. The reduction of synaptic activity was not altered by the co-administration of minocycline with morphine during adolescence. It is concluded that microglia play an important role in mediating hypersensitivity induced by adolescent morphine exposure, although hippocampal microglia may not be directly involved in this process.

[ 11 C]Carfentanil PET Whole-Body Imaging of Mu-Opioid Receptors: A First In-Human Study

Introduction

Mu-opioid receptors (MORs) are G-coupled protein receptors with a high affinity for both endogenous and exogenous opioids. MORs are widely expressed in the central nervous system (CNS), peripheral organs, and the immune system. They mediate pain and reward and have been implicated in the pathophysiology of opioid, cocaine, and other substance use disorders. Using the long axial field-of-view (LAFOV) PennPET Explorer instrument and the MOR selective radioligand [ 11 C]carfentanil ([ 11 C]CFN), we measured the whole-body distribution of MORs in 13 healthy humans. We also examined sex differences in MOR distribution at baseline and after pretreatment with the MOR antagonist naloxone.

Methods

Six female and seven male healthy subjects underwent two [ 11 C]CFN PET imaging sessions-one at baseline and one immediately following pre-treatment with the MOR antagonist naloxone (13 mcg/kg). Whole-body PET imaging was performed on the PennPET Explorer, a 142-cm axial bore instrument. [ 11 C]CFN brain distribution volume ratios (DVRs) were determined using the occipital cortex and the visual cortex within it as reference regions. For peripheral organ DVRs, the descending aorta and proximal extremity muscle (biceps/triceps) were used as reference regions.

Results

Naloxone blockade reduced MOR availability by 40-50% in the caudate, putamen, thalamus, amygdala, and ventral tegmentum, brain regions known to express high levels of MORs. Women showed greater receptor occupancy in the thalamus, amygdala, hippocampus and frontal and temporal lobes and a greater naloxone-induced reduction in thalamic MOR availability than men (p's <0.05). For determining brain MOR availability, there was less variance in the visual cortex than the occipital cortex reference region. For peripheral MOR determination, the descending aorta reference region showed less variance than the extremity muscle, but both showed blocking effects of naloxone.

Conclusions

[ 11 C]CFN whole- body PET scans are useful for understanding MOR physiology under both baseline and blocking conditions. Extra-CNS reference regions may be useful for quantifying radiotracers when a region devoid of binding in the CNS is unavailable. The LAFOV PET instrument was useful for measuring changes in the short-lived radiotracer [ 11 C]CFN, with and without naloxone blocking. Further research is needed to evaluate the behavioral and clinical relevance of sex differences in naloxone-MOR interactions.

Pain during menopause

Menopause is a biological process marking the end of a woman's reproductive years, typically occurring between the ages of 45 and 55. While often associated with hot flashes, mood swings, and hormonal changes, pain is a frequently overlooked and under-addressed aspect of the menopausal experience. This review article explores the multifaceted nature of pain during menopause, and sheds light on its various manifestations and the factors contributing to its prevalence and severity. Pain during menopause may include musculoskeletal discomfort, headaches or migraines, and vulvovaginal pain. The etiology of these is intricate, involving hormonal fluctuations, psychosocial factors, and genetic predispositions. Fluctuations in estrogen and progesterone levels play a pivotal role in musculoskeletal pain and joint stiffness, and increase susceptibility to conditions such as osteoarthritis. Furthermore, mood disorders, stress, and sleep disturbances may exacerbate the perception of pain. Gender norms, as well as changes in reproductive capacity and societal views on aging, may adversely the impact the self-esteem of individuals undergoing menopause. These symptoms can significantly impact a woman's quality of life, underscoring the need for early identification and appropriate management strategies. This review article highlights the factors contributing to pain during menopause, evaluates the effects of hormones on menopausal pain, and investigates management strategies for pain during menopause, including both pharmacological and non-pharmacological approaches. It also emphasizes the need for further research to better understand the interplay of factors contributing to pain during menopause, in order to allow for more tailored and effective interventions. In understanding and addressing this often-neglected aspect of menopause, healthcare providers can enhance the overall wellbeing and quality of life for women transitioning through this natural life stage.

Tonic Cold Pain Temporal Summation and Translesional Cold Pressor Test-Induced Pronociception in Spinal Cord Injury: Association with Spontaneous and Below-Level Neuropathic Pain

Background/Objectives: Although increased nociceptive excitability and deficient endogenous pain modulation are considered key features of pronociception and central sensitization, their contribution to neuropathic pain (NP) characteristics in SCI is unclear. The aim of this study was to characterize tonic cold perception and endogenous pain modulation in individuals with and without SCI-NP, considering the stage and severity of SCI and, secondarily, NP phenotype. Methods: Temporal summation of pain (TSP) and neuropathic features were assessed using the numerical rating scale (NRS) and Douleur Neuropathique 4 screening questionnaire (DN4) during the tonic cold pressor test (CPT, 12 °C 60 s) applied to the dominant hand and foot. CPT-induced pronociception was assessed as change in algometer pressure pain thresholds (PPTs) measured at the V2, C6, and L4 dermatomes. Results: A total of 72 individuals were recruited (age-sex-matched noninjured, n = 24; SCI-NP, n = 24; SCI-noNP, n = 24 [AIS A: n = 12, AIS B-D: n = 12; subacute SCI: n = 12, chronic SCI: n = 12]). TSP in response to the foot CPT was higher in subacute compared to chronic incomplete SCI-NP, while TSP to the hand CPT was significantly higher in chronic compared to the subacute complete SCI-NP group. Evoked pain intensity during the hand CPT correlated with duration of below-level SCI-NP. The hand CPT induced widespread pronociception (lower PPT), which correlated with 7-day non-evoked (spontaneous) pain intensity in individuals with incomplete SCI-NP. Individuals with below-level NP, but not at-level NP, showed higher TSP during the foot CPT and greater hand CPT-induced L4 dermatome pronociception. Conclusions: Collectively, measurements of above and below-level temporal summation of pain and translesional-induced pronociception in the SCI-NP group highlight the role of these mechanisms in widespread central sensitization, spontaneous pain intensity, and spinothalamic tract hyperexcitability, especially in individuals diagnosed with below-level NP.

Women in Dental Clinical and Translational Research

This article presents a summary of the third American Association for Dental, Oral, and Craniofacial Research Meeting within a Meeting, which was held during the 2024 annual meeting in New Orleans, Louisiana. Speakers were challenged to reflect on how women are differentially affected by health and societal issues by factors that go beyond biology. The goal was to promote current research on women's issues that are relevant to dental, oral, and craniofacial scientists.

Musculoskeletal pain among Chinese women during the menopausal transition: findings from a longitudinal cohort study

ABSTRACT

The profiles of muscle and joint pain throughout the menopausal transition and the factors associated with these symptoms have not been determined. A total of 609 participants from a longitudinal cohort study conducted in an urban Chinese community were enrolled in this study. We assessed the prevalence of musculoskeletal symptoms at different menopausal stages and explored the factors associated with these symptoms. The prevalence and severity of muscle and joint pain increase as menopausal stages progress, and late menopausal transition may be a crucial timepoint that triggers the onset of musculoskeletal pain. The results of the multivariate analysis revealed that poor health status (OR = 2.245, 95% CI = 1.714-2.94, P < 0.001), body mass index (BMI) (OR = 1.046, 95% CI = 1.01-1.084, P = 0.011), the presence of anxiety (OR = 1.601, 95% CI = 1.211-2.117, P < 0.001), and depression (OR = 1.368, 95% CI = 1.143-1.639, P < 0.001) were independently associated with muscle and joint pain. In addition, the severity of musculoskeletal pain was related to poor health status (OR = 2.738, 95% CI = 1.91-3.924, P < 0.001) and depression (OR = 1.371, 95% CI = 1.095-1.718, P = 0.006). Musculoskeletal symptoms are frequent somatic symptoms experienced by Chinese middle-aged women. Women with poor health status, high BMI, anxiety, and depression were at heightened risk of experiencing musculoskeletal pain. The severity of pain increased over time.

The influence of sex on neuroimmune communication, pain, and physiology

With the National Institutes of Health's mandate to consider sex as a biological variable (SABV), there has been a significant increase of studies utilizing both sexes. Historically, we have known that biological sex and hormones influence immunological processes and now studies focusing on interactions between the immune, endocrine, and nervous systems are revealing sex differences that influence pain behavior and various molecular and biochemical processes. Neuroendocrine-immune interactions represent a key integrative discipline that will reveal critical processes in each field as it pertains to novel mechanisms in sex differences and necessary therapeutics. Here we appraise preclinical and clinical literature to discuss these interactions and key pathways that drive cell- and sex-specific differences in immunity, pain, and physiology.

Identifying microRNAs Possibly Implicated in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Fibromyalgia: A Review

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and fibromyalgia (FM) are chronic syndromes of unknown etiology, accompanied by numerous symptoms affecting neurological and physical conditions. Despite frequent revisions of the diagnostic criteria, clinical practice guidelines are often outdated, leading to underdiagnosis and ineffective treatment. Our aim was to identify microRNA (miRNA) biomarkers implicated in pathological mechanisms underlying these diseases. A comprehensive literature review using publicly accessible databases was conducted. Interesting miRNAs were extracted from relevant publications on ME/CFS and/or FM, and were then linked to pathophysiological processes possibly manifesting these chronic diseases. Dysregulated miRNAs in ME/CFS and FM may serve as promising biomarkers for these diseases. Key identified miRNAs, such as miR-29c, miR-99b, miR-128, miR-374b, and miR-766, were frequently mentioned for their roles in immune response, mitochondrial dysfunction, oxidative stress, and central sensitization, while miR-23a, miR-103, miR-152, and miR-320 were implicated in multiple crucial pathological processes for FM and/or ME/CFS. In summary, both ME/CFS and FM seem to share many dysregulated biological or molecular processes, which may contribute to their commonly shared symptoms. This miRNA-based approach offers new angles for discovering molecular markers urgently needed for early diagnosis or therapeutics to tackle the pathology of these medically unexplained chronic diseases.

Type I Kounis syndrome in a young woman without chest pain: a case report

BACKGROUND

Kounis syndrome is defined as the concurrence of acute coronary syndromes in the setting of allergic or anaphylactic reactions. It primarily affects men aged 40-70 years and is often associated with chest pain. This syndrome is often unrecognized and undiagnosed in clinical practice due to a low level of awareness. Herein, we present a case of type I Kounis syndrome in a young woman without chest pain.

CASE PRESENTATION

A 28-year-old Japanese woman with a history of atopic dermatitis received a glycyrrhizin, glutathione, and neurotropin preparation (a preparation of inflamed skin extract from rabbits inoculated with vaccinia virus) at a dermatology clinic to treat pruritus caused by atopic dermatitis. Immediately after the administration, the patient developed abdominal pain and generalized body wheals. The patient was diagnosed with anaphylaxis and was transported to our hospital. She had no chest pain on arrival at our hospital; however, a 12-lead electrocardiogram showed ST elevation in leads I, aVL, V2, and V3, and an echocardiogram showed decreased wall motion in the anterior and lateral walls of the left ventricle. Sublingual nitroglycerin administration improved ST-segment elevation and left ventricular wall motion abnormalities. The patient underwent emergency coronary angiography, which revealed no significant stenosis, and was diagnosed with type I Kounis syndrome.

CONCLUSION

Kounis syndrome without chest pain is rare in young women. Since it can be fatal in cases with severe allergic symptoms such as anaphylaxis, the possibility of concurrent acute coronary syndrome should be considered when treating systemic allergic reactions, regardless of age, sex, or the presence or absence of chest symptoms.

Interactions Between Endocannabinoid and Endogenous Opioid Systems Prospectively Influence Postoperative Opioid Use in Pregnant Patients Undergoing Cesarean Delivery

Both endocannabinoid (EC) and endogenous opioid systems are involved in nociceptive processing and may work together synergistically based on preclinical models. This study evaluated the interactive effects of preoperative beta-endorphin (BE) concentrations (a key analgesic endogenous opioid) in cerebrospinal fluid (CSF) and ECs (CSF and plasma 2-arachidonoylglycerol and plasma anandamide) on postoperative opioid use and pain intensity in a prospective cohort of n = 112 pregnant patients undergoing scheduled cesarean delivery. Maternal blood and CSF samples were collected preoperatively for BE and EC assays. Patients completed measures of outpatient opioid use (number of tablets used and days of use) and average pain intensity at 2 weeks postoperatively. Results of general linear model analyses controlling for maternal age, body mass index at time of delivery, and race revealed significant multiplicative interactions between EC and BE concentrations on number of opioid tablets used (based on pill count), days of opioid use, and total milligram morphine equivalents used in the 2-week follow-up period. Elevated preoperative plasma and CSF 2-arachidonoylglycerol predicted reduced outpatient opioid analgesic use, particularly for patients low in CSF BE. Similar analyses for pain intensity at 2-week follow-up indicated a significant interaction (P < .02) characterized by higher preoperative BE concentrations being associated with lower subsequent pain only for individuals with low preoperative plasma anandamide concentrations. Further exploration of interactions between EC and endogenous opioid inhibitory systems as they influence responses to opioid analgesics in other clinical pain populations may help guide the development of precision pain management approaches. PERSPECTIVE: In the postoperative setting of patients undergoing cesarean delivery, elevated ECs were linked to reduced outpatient opioid analgesic use in individuals who had low endogenous opioid concentrations in CSF. Further exploration of interactions between these 2 inhibitory systems as they impact responses to pain management interventions appears warranted.

Menopausal Hormone Therapy and Osteoarthritis Risk: Retrospective Population-Based Study in South Korea

OBJECTIVES

This study aimed to investigate the risk of osteoarthritis associated with menopausal hormone therapy (MHT).

METHODS

This population-based retrospective cohort study used a database of Korean health insurance claims (2007-2020). Females aged ≥ 40 who initiated menopause-related healthcare visits between 2011 and 2014 were identified. The MHT group comprised females aged ≥ 40 who initiated MHT for ≥ 6 months during this period. The non-MHT group comprised females aged ≥ 40 who attended menopause-related healthcare visits but did not receive MHT. To account for potential confounding factors, the two groups were matched at a 1:1 ratio using propensity score matching.

RESULTS

A cohort of 453,040 postmenopausal females aged ≥ 40 years was identified, with 26,354 assigned to either the MHT or non-MHT group after propensity matching. The median age was 49 years, and the median follow-up was 8.2 years. The Cox proportional hazards model demonstrated an elevated risk of osteoarthritis with MHT (hazard ratio [HR], 1.154; 95% confidence interval [CI], 1.117-1.193) for knee (HR, 1.148; 95% CI, 1.102-1.195) and other arthritis (HR, 1.205; 95% CI, 1.151-1.261), although not statistically significant for hip arthritis. Tibolone (HR, 1.211; 95% CI, 1.161-1.263), estrogen-progestogen therapy (EPT) (HR, 1.092; 95% CI, 1.048-1.137), and estrogen therapy (ET) (HR, 1.235; 95% CI, 1.148-1.329) were associated with a higher risk of osteoarthritis compared to non-MHT users.

CONCLUSIONS

MHT was associated with an increased risk of osteoarthritis, consistently observed across tibolone, EPT, and ET, particularly affecting joints other than the hip, with a trend toward an elevated risk of hip osteoarthritis.

Unraveling the interplay of neuroinflammatory signaling between parenchymal and meningeal cells in migraine headache

BACKGROUND

The initiation of migraine headaches and the involvement of neuroinflammatory signaling between parenchymal and meningeal cells remain unclear. Experimental evidence suggests that a cascade of inflammatory signaling originating from neurons may extend to the meninges, thereby inducing neurogenic inflammation and headache. This review explores the role of parenchymal inflammatory signaling in migraine headaches, drawing upon recent advancements. BODY: Studies in rodents have demonstrated that sterile meningeal inflammation can stimulate and sensitize meningeal nociceptors, culminating in headaches. The efficacy of relatively blood-brain barrier-impermeable anti-calcitonin gene-related peptide antibodies and triptans in treating migraine attacks, both with and without aura, supports the concept of migraine pain originating in meninges. Additionally, PET studies utilizing inflammation markers have revealed meningeal inflammatory activity in patients experiencing migraine with aura, particularly over the occipital cortex generating visual auras. The parenchymal neuroinflammatory signaling involving neurons, astrocytes, and microglia, which eventually extends to the meninges, can link non-homeostatic perturbations in the insensate brain to pain-sensitive meninges. Recent experimental research has brought deeper insight into parenchymal signaling mechanisms: Neuronal pannexin-1 channels act as stress sensors, initiating the inflammatory signaling by inflammasome formation and high-mobility group box-1 release in response to transient perturbations such as cortical spreading depolarization (CSD) or synaptic metabolic insufficiency caused by transcriptional changes induced by migraine triggers like sleep deprivation and stress. After a single CSD, astrocytes respond by upregulating the transcription of proinflammatory enzymes and mediators, while microglia are involved in restoring neuronal structural integrity; however, repeated CSDs may prompt microglia to adopt a pro-inflammatory state. Transcriptional changes from pro- to anti-inflammatory within 24 h may serve to dampen the inflammatory signaling. The extensive coverage of brain surface and perivascular areas by astrocyte endfeet suggests their role as an interface for transporting inflammatory mediators to the cerebrospinal fluid to contribute to meningeal nociception.

CONCLUSION

We propose that neuronal stress induced by CSD or synaptic activity-energy mismatch may initiate a parenchymal inflammatory signaling cascade, transmitted to the meninges, thereby triggering lasting headaches characteristic of migraine, with or without aura. This neuroinflammatory interplay between parenchymal and meningeal cells points to the potential for novel targets for migraine treatment and prophylaxis.

Pivotal role of orexin signaling in the posterior paraventricular nucleus of the thalamus during the stress-induced reinstatement of oxycodone-seeking behavior

BACKGROUND

The orexin (OX) system has received increasing interest as a potential target for treating substance use disorder. OX transmission in the posterior paraventricular nucleus of the thalamus (pPVT), an area activated by highly salient stimuli that are both reinforcing and aversive, mediates cue- and stress-induced reinstatement of reward-seeking behavior. Oral administration of suvorexant (SUV), a dual OX receptor (OXR) antagonist (DORA), selectively reduced conditioned reinstatement of oxycodone-seeking behavior and stress-induced reinstatement of alcohol-seeking behavior in dependent rats.

AIMS

This study tested whether OXR blockade in the pPVT with SUV reduces oxycodone or sweetened condensed milk (SCM) seeking elicited by conditioned cues or stress.

METHODS

Male Wistar rats were trained to self-administer oxycodone (0.15 mg/kg, i.v., 8 h/day) or SCM (0.1 ml, 2:1 dilution [v/v], 30 min/day). After extinction, we tested the ability of intra-pPVT SUV (15 µg/0.5 µl) to prevent reinstatement of oxycodone or SCM seeking elicited by conditioned cues or footshock stress.

RESULTS

The rats acquired oxycodone and SCM self-administration, and oxycodone intake correlated with signs of physical opioid withdrawal, confirming dependence. Following extinction, the presentation of conditioned cues or footshock elicited reinstatement of oxycodone- and SCM-seeking behavior. Intra-pPVT SUV blocked stress-induced reinstatement of oxycodone seeking but not conditioned reinstatement of oxycodone or SCM seeking or stress-induced reinstatement of SCM seeking.

CONCLUSIONS

The results indicate that OXR signaling in the pPVT is critical for stress-induced reinstatement of oxycodone seeking, further corroborating OXRs as treatment targets for opioid use disorder.

Deciphering nociplastic pain: clinical features, risk factors and potential mechanisms

Nociplastic pain is a mechanistic term used to describe pain that arises or is sustained by altered nociception, despite the absence of tissue damage. Although nociplastic pain has distinct pathophysiology from nociceptive and neuropathic pain, these pain mechanisms often coincide within individuals, which contributes to the intractability of chronic pain. Key symptoms of nociplastic pain include pain in multiple body regions, fatigue, sleep disturbances, cognitive dysfunction, depression and anxiety. Individuals with nociplastic pain are often diffusely tender - indicative of hyperalgesia and/or allodynia - and are often more sensitive than others to non-painful sensory stimuli such as lights, odours and noises. This Review summarizes the risk factors, clinical presentation and treatment of nociplastic pain, and describes how alterations in brain function and structure, immune processing and peripheral factors might contribute to the nociplastic pain phenotype. This article concludes with a discussion of two proposed subtypes of nociplastic pain that reflect distinct neurobiological features and treatment responsivity.

Sex Differences in Visceral Pain and Comorbidities: Clinical Outcomes, Preclinical Models, and Cellular and Molecular Mechanisms

Sexual dimorphism of visceral pain has been documented in clinics and experimental animal models. Aside from hormones, emerging evidence suggests the sex-differential intrinsic neural regulation of pain generation and maintenance. According to the International Association for the Study of Pain (IASP) and the American College of Gastroenterology (ACG), up to 25% of the population have visceral pain at any one time, and in the United States 10-15 percent of adults suffer from irritable bowel syndrome (IBS). Here we examine the preclinical and clinical evidence of sex differences in visceral pain focusing on IBS, other forms of bowel dysfunction and IBS-associated comorbidities. We summarize preclinical animal models that provide a means to investigate the underlying molecular mechanisms in the sexual dimorphism of visceral pain. Neurons and nonneuronal cells (glia and immune cells) in the peripheral and central nervous systems, and the communication of gut microbiota and neural systems all contribute to sex-dependent nociception and nociplasticity in visceral painful signal processing. Emotion is another factor in pain perception and appears to have sexual dimorphism.

Associations between the severity of menopausal symptoms and musculoskeletal pain in postmenopausal Portuguese women

OBJECTIVE

To analyze the association of the severity of the menopausal symptoms with musculoskeletal pain in Portuguese postmenopausal women.

METHODS

A cross-sectional, observational study was conducted on 167 women (63.85 ± 9.36 years). The Menopause Rating Scale was used to evaluate the menopausal symptoms severity, while the Nordic Musculoskeletal Questionnaire was employed to assess the localization of the musculoskeletal pain, and multi-located pain was determined if two or more body regions were affected. Depression (Hospital Anxiety and Depression Scale), age, body mass index (BMI) and physical activity level were considered as potential confounders.

RESULTS

A greater severity of the somato-vegetative menopausal symptoms was related to the prevention from usual activities because of pain in the neck, shoulders, elbows, wrists/hands and knees (R2 of Nagelkerke = 0.064, 0.043, 0.074, 0.045 and 0.045, respectively). Associations were also observed between greater age and pain in the knees, ankles and feet (R2 of Nagelkerke = 0.036 and 0.034, respectively), and being physically inactive with upper back pain (R2 of Nagelkerke = 0.060). Higher depressive symptoms were linked to pain in the hip/thighs and knees (R2 of Nagelkerke = 0.067 and 0.085, respectively), as well as being physically inactive was related ton in the neck (R2 of Nagelkerke = 0.053). Only a greater BMI was related to multi-located pain in the last 7 days (R2 of Nagelkerke = 0.041).

CONCLUSIONS

The findings of our study showed that, taking into account possible confounders, greater severity of the menopausal symptoms at a somatic-vegetative level was associated with more anatomical regions with musculoskeletal pain.

Sex- and gender-specific differences in symptoms and health-related quality of life among patients with gastroesophageal reflux disease

Gastroesophageal Reflux Disease (GERD) is a common chronic gastrointestinal disorder affecting both men and women. Nonerosive reflux disease generally affects more women, whereas GERD complications such as Barrett's esophagus (BE) or esophageal cancer affect more men. The aim of this study was to evaluate sex- and gender-specific symptoms and health-related quality of life (HRQoL) among men and women with GERD. Patients with clinical signs of reflux and completion of 24-hour pH-Impedance testing at the University Hospital Cologne were included into the study. Evaluation of symptoms and HRQoL included the following validated questionnaires: GERD-Health-Related Quality of Life (GERD HRQL), Gastrointestinal Quality of Life Index (GIQLI), and Hospital Anxiety and Depression Scale (HADS). In all, 509 women and 355 men with GERD were included. Men had a significantly higher DeMeester score (60.2 ± 62.6 vs. 43 ± 49.3, P < 0.001) and a higher incidence of BE (18.6 vs. 11.2%, P = 0.006). Women demonstrated significantly higher levels of anxiety (30.9 vs. 14.5%, P = 0.001), more severely impacting symptoms (45.3 ± 11.3 vs. 49.9 ± 12.3, P < 0.001), as well as physical (14.2 ± 5.7 vs. 16.7 ± 5.6, P < 0.001) and social dysfunction (13.3 ± 4.8 vs. 14.8 ± 4.3, P = 0.002). Women further reported a lower HRQoL (85.3 ± 22.7 vs. 92.9 ± 20.8, P < 0.001). Men and women differ on biological, psychological, and sociocultural levels.

Menstrually associated migraine

Menstrually related migraine is a disabling condition affecting 35% to 54% females with migraine during their fertile years. The International Headache Classification distinguishes menstrually related migraine from pure menstrual migraine based on the occurrence of the attacks even outside the perimenstrual periods. Hormonal fluctuations are the main driver for the disease in subjects with genetic susceptibility and alterations of brain structures and connectivity. Menstrually related attacks are often particularly severe and disabling requiring proper management. Acute treatment mainly consists of nonsteroidal anti-inflammatory drugs (NSAIDs), recommended in patients also suffering from dysmenorrhea, and triptans. Prevention is specifically indicated in women with high monthly headache frequency or burdensome attacks during perimenstrual periods. Trials proved the efficacy of short-term prevention with triptans and NSAIDs but did not evaluate possible long-term effectiveness and tolerability. Evidence of prevention using hormonal treatments is poor, but extended-cycle treatments might be suitable for women requiring hormonal replacement for concomitant conditions. Few data are available on treatments targeting CGRP, among whom gepants are the most promising because of their utility both in migraine acute and preventive treatment. A greater recognition of disease and a deep knowledge of patients' comorbidities are essential to its proper management.

Estradiol and Mu opioid-mediated reward: The role of estrogen receptors in opioid use

Opioid use and opioid use disorder are characterized by sex and gender differences, and some of these differences may be mediated by differences in the hormonal milieu within and across individuals. This review focuses on the role of ovarian hormones, and particularly estradiol, on the endogenous mu opioid receptor system. There is an abundance of data indicating that estradiol influences the activity of endogenous mu opioid peptides, the activation of mu opioid receptors, and the internalization and desensitization of mu opioid receptors. These effects have functional consequences on behaviors mediated by endogenous mu opioid receptor activity and on sensitivity to mu opioid agonists and antagonists. Recent behavioral data suggest these consequences extend to mu opioid reward, and preclinical studies report that estradiol decreases self-administration of mu opioid receptor agonists across a range of experimental conditions. Data collected in human laboratory studies suggest that estradiol may have functionally similar effects in clinical populations, and thus estrogen receptors may be a potential target in the development of novel therapeutics. This review summarizes data from cellular assays to clinical trials to explore how estradiol influences mu opioid receptor activity, as well as potential ways in which estrogen receptors may be targeted to address the problems of opioid use.

Daily treatment with the dual orexin receptor antagonist DORA-12 during oxycodone abstinence decreases oxycodone conditioned reinstatement

Chronic opioid use disturbs circadian rhythm and sleep, encouraging opioid use and relapse. The orexin (OX) system is recruited by opioids and regulates physiological processes including sleep. Dual OX receptor antagonists (DORAs), developed for insomnia treatment, may relieve withdrawal-associated sleep disturbances. This study investigated whether DORA-12, a recently developed DORA, reduces physiological activity disturbances during oxycodone abstinence and consequently prevents oxycodone-seeking behavior. Male and female Wistar rats were trained to intravenously self-administer oxycodone (0.15 mg/kg, 21 sessions; 8 h/session) in the presence of a contextual/discriminative stimulus (SD). The rats were subsequently housed individually (22 h/day) to monitor activity, food and water intake. They received DORA-12 (0-30 mg/kg, p.o.) after undergoing daily 1-h extinction training (14 days). After extinction, the rats were tested for oxycodone-seeking behavior elicited by the SD. Hypothalamus sections were processed to assess oxycodone- or DORA-12-associated changes to the OX cell number. In males, oxycodone-associated increases in activity during the light-phase, reinstatement, and decreases in the number of OX cells observed in the vehicle-treated group were not observed with DORA-12-treatment. Oxycodone-associated increases in light-phase food and water intake were not observed by day 14 of 3 mg/kg DORA-12-treatment and dark-phase water intake was increased across treatment days. In females, OX cell number was unaffected by oxycodone or DORA-12. Three and 30 mg/kg DORA-12 increased females' day 7 dark-phase activity and decreased reinstatement. Thirty mg/kg DORA-12 reduced oxycodone-associated increases in light-phase food and water intake. The results suggest that DORA-12 improves oxycodone-induced disruptions to physiological activities and reduces relapse.

Advances of autoimmune rheumatic diseases related to malignant tumors

BACKGROUND

Malignant neoplasms are a well-recognized global public health concern, with significant impacts on human health and quality of life. The interplay between tumors and autoimmune rheumatic diseases is complex, and the resulting tumor-associated rheumatic diseases represent a rare and intricate group of conditions that occur in the context of malignant tumors. In addition, various rheumatic diseases can arise as a consequence of oncology treatment. These diseases present with intricate clinical manifestations and pathological features, often rendering them challenging to diagnose and impacting patients' quality of life. Despite this, they have yet to be fully recognized.

METHODS

This article presents a literature review of published original articles and review articles concerning paraneoplastic rheumatic syndromes and rheumatic diseases associated with cancer treatment. We conducted a comprehensive literature search in PubMed, Web of Science and Google Scholar databases, excluding duplicated and irrelevant studies. In cases of duplicated research, we selected articles with higher impact factors for the review.

RESULTS

This review focuses on the clinical features, diagnosis, and treatment of paraneoplastic rheumatic diseases, as well as the pathogenesis of these diseases. Additionally, we summarize the autoimmune rheumatic diseases associated with cancer treatment. Ultimately, the goal of this review is to enhance recognition and improve the management of autoimmune rheumatic diseases related to tumors.

Migraine in older adults

Migraine is an evolving, and sometimes lifelong disorder. The prevalence of episodic migraine peaks among individuals aged in their late 30s, implying a tendency for the disorder to remit with increasing age thereafter, whereas chronic migraine is more likely to persist into later life. Diagnosis and treatment of migraine in older adults, defined as individuals aged 60 years or older, is rendered more complex by increasing probabilities of atypical clinical features and comorbidities, with patients' comorbidities sometimes limiting their therapeutic options. However, the changing clinical presentation of migraine over an individual's lifespan is not well characterised. The neurobiological basis of remission in older adults remains unclear, although vascular, neuronal, and hormonal changes are likely to be involved. Long-term longitudinal studies of individuals with migraine would be particularly informative, with the potential not only to suggest new research directions, but also to lead to the identification of novel therapeutic agents. Although several novel migraine medications are becoming available, their effectiveness, tolerability, and safety often remain uncertain in older adults, who have commonly been excluded from the evaluation of these agents in randomised controlled trials, or who constitute only a small proportion of study populations. There is a need to recognise these limitations in the available evidence, and the specific, and often unmet, clinical needs of older adults with migraine, not least because older adults constitute an increasing proportion of populations worldwide.

Sexual Dimorphism in the Mechanism of Pain Central Sensitization

It has long been recognized that men and women have different degrees of susceptibility to chronic pain. Greater recognition of the sexual dimorphism in chronic pain has resulted in increasing numbers of both clinical and preclinical studies that have identified factors and mechanisms underlying sex differences in pain sensitization. Here, we review sexually dimorphic pain phenotypes in various research animal models and factors involved in the sex difference in pain phenotypes. We further discuss putative mechanisms for the sexual dimorphism in pain sensitization, which involves sex hormones, spinal cord microglia, and peripheral immune cells. Elucidating the sexually dimorphic mechanism of pain sensitization may provide important clinical implications and aid the development of sex-specific therapeutic strategies to treat chronic pain.

Low back pain and osteoarthritis pain: a perspective of estrogen

Low back pain (LBP) is the world's leading cause of disability and is increasing in prevalence more rapidly than any other pain condition. Intervertebral disc (IVD) degeneration and facet joint osteoarthritis (FJOA) are two common causes of LBP, and both occur more frequently in elderly women than in other populations. Moreover, osteoarthritis (OA) and OA pain, regardless of the joint, are experienced by up to twice as many women as men, and this difference is amplified during menopause. Changes in estrogen may be an important contributor to these pain states. Receptors for estrogen have been found within IVD tissue and nearby joints, highlighting the potential roles of estrogen within and surrounding the IVDs and joints. In addition, estrogen supplementation has been shown to be effective at ameliorating IVD degeneration and OA progression, indicating its potential use as a therapeutic agent for people with LBP and OA pain. This review comprehensively examines the relationship between estrogen and these pain conditions by summarizing recent preclinical and clinical findings. The potential molecular mechanisms by which estrogen may relieve LBP associated with IVD degeneration and FJOA and OA pain are discussed.

The effects of estradiol levels on crossmodal perception: a study on the sound induced flash illusion in healthy and menstrually related migraine individuals

OBJECTIVE

The sound-induced flash illusion (SIFI) is a valid paradigm to study multisensorial perception. In the "fission" SIFI, multiple flashes are perceived when observing a single flash paired with two or more beeps. SIFI is largely dependent on visual and acoustic cortex excitability; in migraine, dysfunctional cortical excitability affects SIFI perception. Since estrogen peak occurring during ovulation can increase neuronal excitability, the present study aims to verify whether cortical excitability shifts linked to the menstrual cycle could influence SIFI.

METHODS

In a comparative prospective study, we tested the effect of estrogens on crossmodal perception using the SIFI. We recruited 27 females in reproductive age, including 16 healthy and 11 menstrually related migraine females, testing their proneness to SIFI on day 14 (high estradiol) and day 27 (low estradiol) of menstrual cycle.

RESULTS

Women on day 14 reported less flashes than on day 27 (p = 0.02) in the fission illusion, suggesting a pro-excitatory effect of estradiol on visual cortex excitability during ovulation. Moreover, we confirmed that migraine women perceived less flashes (p = 0.001) than controls, independently from cycle phase. Non-migraineurs women significantly reported more flashes on day 27 than on day 14 (p = 0.04).

CONCLUSIONS

This study suggests that estradiol may influence the multisensory perception due to changes of visual cortex excitability, with high estradiol peak leading to increased visual cortical sensitivity during ovulation in non-migraineurs. Visual cortex hyperresponsiveness, here reflected by reduced SIFI, is not influenced by estradiol fluctuations in migraine women, as shown by reduced fission effects on day 14 and 27.

The historical progression of positron emission tomography research in neuroendocrinology

The rapid and continual development of a number of radiopharmaceuticals targeting different receptor, enzyme and small molecule systems has fostered Positron Emission Tomography (PET) imaging of endocrine system actions in vivo in the human brain for several decades. PET radioligands have been developed to measure changes that are regulated by hormone action (e.g., glucose metabolism, cerebral blood flow, dopamine receptors) and actions within endocrine organs or glands such as steroids (e.g., glucocorticoids receptors), hormones (e.g., estrogen, insulin), and enzymes (e.g., aromatase). This systematic review is targeted to the neuroendocrinology community that may be interested in learning about positron emission tomography (PET) imaging for use in their research. Covering neuroendocrine PET research over the past half century, researchers and clinicians will be able to answer the question of where future research may benefit from the strengths of PET imaging.

Ovarian vein surgical ablation versus endovascular technique for treatment of pelvic vein incompetence

OBJECTIVE

Chronic pelvic pain in women is a disorder brought on by pelvic vein incompetence (PVI). In this prospective, randomized study, the effects of percutaneous coil embolization and surgical ovarian vein ligation and division combined with retrograde sclerotherapy were compared with regard to ovarian vein occlusion, improvement of pelvic congestion symptoms, and their influence on estradiol level after intervention.

METHODS

A total of 50 patients with PVI were enrolled, with a mean age of 31.9 ± 4.7 years and a pain score of 9 (range, 0-10; from 0 [no pain] to 10 [the highest level of pain]). Both percutaneous coil embolization of ovarian veins (endovascular group) and surgical ovarian vein ablation with retrograde sclerotherapy were offered to the patients at random.

RESULTS

In the open group, the pain level decreased to 2, whereas in the endovascular group, it decreased to 1 (range, 0-10). Estradiol levels were 224 (range, 9-612) in the open group and 478 (range, 18-613) in the endovascular group before the intervention, with no significant change (P = .1120). After 1 week of intervention, estradiol levels in the open group were 89 (range, 18-243) and 124 (range, 22-298) in the endovascular group, respectively, with statistical insignificance (P = .225). After 1 month of intervention, the endovascular group's estradiol level was 101 (range, 20-196) and the open group's was 89 (range, 15-190) (P = .382). After 3 months of intervention, the open group's estradiol level was 78 (range, 12-132) and the endovascular group's was 65 (range, 18-110) (P = .045).

CONCLUSIONS

In addressing PVI, both methods seemed to have promising results. Nevertheless, endovascular management was more effective at decreasing estrogen levels and relieving discomfort. Three months should be the time at which estradiol levels are measured, because this is when they are at their lowest. In both the open and endovascular groups as well as in the pooled data, there was a significant association between estradiol level from before the intervention and improvement in pain scores (P = .005). Because it was linked to a lower pain score, the high preoperative estradiol level can be used to predict postintervention improvement.

Sex-specific differences in alcohol-induced pain sensitization

Pain sensitization is a phenomenon that occurs to protect tissues from damage and recent studies have shown how a variety of non-noxious stimuli included in our everyday lives can lead to pain sensitization. Consumption of large amounts of alcohol over a long period of time invokes alcohol use disorder (AUD), a complex pathological state that has many manifestations, including alcohol peripheral neuropathy (neuropathic pain). We asked if 'non-pathological' alcohol consumption can cause pain sensitization in the absence of other pathology? Studies have pointed to glia and other immune cells and their role in pain sensitization that results in cell and sex-specific responses. Using a low-dose and short-term ethanol exposure model, we investigated whether this exposure would sensitize mice to a subthreshold dose of an inflammatory mediator that normally does not induce pain. We observed female mice exhibited specific mechanical and higher thermal sensitivity than males. We also observed an increase in CD68⁺ macrophages in the ipsilateral dorsal root ganglia (DRG) and Iba1⁺ microglia in the ipsilateral spinal dorsal horn of animals that were exposed to ethanol and injected with subthreshold inflammatory prostaglandin E2. Our findings suggest that short-term ethanol exposure stimulates peripheral and central, immune and glial activation, respectively to induce pain sensitization. This work begins to reveal a possible mechanism behind the development of alcoholic peripheral neuropathy.

The genetic basis of endometriosis and comorbidity with other pain and inflammatory conditions

Endometriosis is a common condition associated with debilitating pelvic pain and infertility. A genome-wide association study meta-analysis, including 60,674 cases and 701,926 controls of European and East Asian descent, identified 42 genome-wide significant loci comprising 49 distinct association signals. Effect sizes were largest for stage 3/4 disease, driven by ovarian endometriosis. Identified signals explained up to 5.01% of disease variance and regulated expression or methylation of genes in endometrium and blood, many of which were associated with pain perception/maintenance (SRP14/BMF, GDAP1, MLLT10, BSN and NGF). We observed significant genetic correlations between endometriosis and 11 pain conditions, including migraine, back and multisite chronic pain (MCP), as well as inflammatory conditions, including asthma and osteoarthritis. Multitrait genetic analyses identified substantial sharing of variants associated with endometriosis and MCP/migraine. Targeted investigations of genetically regulated mechanisms shared between endometriosis and other pain conditions are needed to aid the development of new treatments and facilitate early symptomatic intervention.

Suvorexant, an FDA-approved dual orexin receptor antagonist, reduces oxycodone self-administration and conditioned reinstatement in male and female rats

Background: The Department of Health and Human Services reports that prescription pain reliever (e.g., oxycodone) misuse was initiated by 4,400 Americans each day in 2019. Amid the opioid crisis, effective strategies to prevent and treat prescription opioid use disorder (OUD) are pressing. In preclinical models, the orexin system is recruited by drugs of abuse, and blockade of orexin receptors (OX receptors) prevents drug-seeking behavior. The present study sought to determine whether repurposing suvorexant (SUV), a dual OX receptor antagonist marketed for the treatment of insomnia, can treat two features of prescription OUD: exaggerated consumption and relapse. Methods: Male and female Wistar rats were trained to self-administer oxycodone (0.15 mg/kg, i. v., 8 h/day) in the presence of a contextual/discriminative stimulus (S^D) and the ability of SUV (0-20 mg/kg, p. o.) to decrease oxycodone self-administration was tested. After self-administration testing, the rats underwent extinction training, after which we tested the ability of SUV (0 and 20 mg/kg, p. o.) to prevent reinstatement of oxycodone seeking elicited by the S^D. Results: The rats acquired oxycodone self-administration and intake was correlated with the signs of physical opioid withdrawal. Additionally, females self-administered approximately twice as much oxycodone as males. Although SUV had no overall effect on oxycodone self-administration, scrutiny of the 8-h time-course revealed that 20 mg/kg SUV decreased oxycodone self-administration during the first hour in males and females. The oxycodone S^D elicited strong reinstatement of oxycodone-seeking behavior that was significantly more robust in females. Suvorexant blocked oxycodone seeking in males and reduced it in females. Conclusions: These results support the targeting of OX receptors for the treatment for prescription OUD and repurposing SUV as pharmacotherapy for OUD.

Association between nociplastic pain and premature endocrine therapy discontinuation in breast cancer patients

PURPOSE

At least 5 years of adjuvant endocrine therapy (ET) is recommended for patients with hormone receptor-positive invasive breast cancer to reduce cancer recurrence risk. Up to half of patients prematurely discontinue ET, often due to musculoskeletal pain. Nociplastic pain is abnormal central nervous system pain processing without evidence of tissue or neuronal damage. This study aimed to evaluate the relationship between baseline nociplastic pain and ET discontinuation.

METHODS

This was a retrospective, single center, cohort study. Included patients were female, had stage 0-III invasive breast cancer, did not receive neoadjuvant therapy, and completed quality of life questionnaires prior to breast surgery, including Fibromyalgia Survey for nociplastic pain. Clinical data including duration of ET were abstracted from the medical record. Patient characteristics were analyzed with t-tests and Chi-squared tests, as appropriate. Univariate and multivariable regressions were performed with Cox proportional hazard models.

RESULTS

Six hundred eighty-one patients diagnosed between 2012 and 2019 met inclusion criteria; 480 initiated ET and were included in the analysis. Of these 480 patients, 203 (42.3%) prematurely discontinued initial ET therapy. On univariate analysis, tamoxifen use (hazard ratio [HR] 0.70, p = 0.021) and premenopausal status (HR 0.73, p = 0.04) were inversely associated with ET discontinuation, while Fibromyalgia Score was positively associated (HR 1.04, p = 0.043). On multivariable analysis, baseline Fibromyalgia Score remained associated with ET discontinuation.

CONCLUSION

Nociplastic pain present prior to surgery was associated with premature ET discontinuation. Fibromyalgia Score screening may be useful for evaluating ET discontinuation risk. Treatments targeting nociplastic pain may be more effective for treating ET-emergent pain.

Sex Differences in Pain and Its Treatment

Pain is a highly personal experience. Pain is often considered to be a purely neurologic phenomenon, but in actuality, it is a combination of both sensory and emotional experiences. This has sometimes been translated clinically toward a more mechanistic approach to the assessment and treatment of pain instead of one that does not discount pain mechanisms, but also is more inclusive of the need for humanism - considering the individual. In today's medical environment, more than ever before there is a significant amount of attention being paid to educating clinicians to better understand that several physiological, neurophysiological, and psychosocial factors can significantly impact responses to pain. The composition of these factors will be unique to that individual's life narrative, context, sex, and prior life experiences. Thus, the concept that a templated approach to pain assessment and pharmacotherapeutic treatment planning should not be expected to provide optimal patient satisfaction and treatment outcomes in the majority. The hypotheses that there may be sex-based differences in the pain experience in a variety of ways including pain sensitivity, tolerance to pain, threshold at which something becomes painful, and the effectiveness of endogenous pain modulation systems are not new and have been well represented in the literature. This chapter reviews important key findings in the scientific literature with respect to sex-based differences in pain and pain responses to experimentally induced painful stimuli, pain experienced in commonly occurring painful medical conditions, and variations in responses to pain treatments. Possible explanations to account for observed differences or similarities will also be discussed.

Cardiovascular Disease in Women: What the Radiologist Needs to Know

BACKGROUND

 Sex-specific disparities are well documented for cardiovascular disease (CVD). There are differences in physiology and pathophysiology, pain perception, spectrum of disease, risk, therapeutic aspects, prognosis, and outcome. CVD represents a broad spectrum of disorders. This review focuses on cardiovascular and cardiac pathology.

METHOD

 This review summarizes the current state of the literature on cardiovascular disease in women from a radiological viewpoint. It aims to provide a deeper understanding of these differences and thereby alerts the reader to the potential of CT and MRI for diagnosing CVD in women. Special attention is paid to disparities in the underlying physiological and pathophysiological processes, clinical presentation, and the quality of care to provide a deep understanding of the topic. Cardiovascular and cardiac pathologies with a sex-specific pattern of disease are presented and typical CT and MRI findings are arranged and illustrated with imaging findings.

RESULTS AND CONCLUSION

 Sex-specific differences are not only sex hormonal in nature but are rooted in the epigenome and encompass a multitude of physiological systems. In fact, cardiovascular disease shows sex-specific characteristics spanning from incidence to clinical presentation, course of disease, and prognosis. This is of significance regarding pretest probabilities, the power of tests, imaging strategies, and interpretation of imaging results. Key sex-specific issues encompass obstructive and non-obstructive coronary artery disease (CAD), microvascular angina, myocardial infarction with non-obstructive CAD, and coronary artery dissection. Sex-specific patterns are also noted in myocardial disease and heart failure such as pregnancy-related heart disease, Takotsubo syndrome, and anthracycline-induced cardiotoxicity.

KEY POINTS

  · Cardiovascular diseases have sex-specific characteristics.. · Imaging strategies and interpretation of imaging results should be adjusted for women.. · Imaging helps in the improvement of the sex-specific management of cardiovascular disease..

Effects of sarcopenia and sarcopenic obesity on joint pain and degenerative osteoarthritis in postmenopausal women

This study aimed to identify the prevalence of sarcopenia, obesity, and sarcopenic obesity and examine their association with radiographic knee osteoarthritis (OA) and knee pain in Korean postmenopausal women. This cross-sectional study utilized the data from Korean National Health and Nutrition Examination Surveys 2009–2011. The participants were categorized into 4 groups based on body composition: either sarcopenic (appendicular skeletal muscle < 23%) or not, either obese (body mass index ≥ 25.0 kg/m²) or not. The prevalence of radiographic knee OA and knee pain was calculated. The effect of hormone replacement therapy (HRT) was also evaluated. The prevalence of radiographic knee OA, knee pain, and both were all highest in the sarcopenic obese group and lowest in the control group (61.49% vs. 41.54%, 39.11% vs. 27.55%, 32.04% vs. 17.82%, all p < 0.001). Without sarcopenia, obese women showed significantly higher ratio of radiographic knee OA only (57.64% vs. 41.54%, p < 0.001). With sarcopenia, the coexistence of obesity presented higher ratio of radiographic knee OA, knee pain, and both compared to sarcopenia without obesity (61.49% vs. 41.82%, 39.11% vs. 27.61%, 32.04% vs. 17.60%, all p < 0.001). The use of HRT for more than 1 year was not associated with radiographic knee OA, knee pain, or both (p = 0.147, 0.689 and 0.649, respectively). Obesity with sarcopenia had greater effect on knee OA compared to obesity without sarcopenia. Moreover, HRT use for more than 1 year was not associated with the prevalence of knee OA. Therefore, more efforts should focus on reducing body fat and increasing muscle in postmenopausal women with knee OA.

Modulation of morphine physical dependence and discriminative stimulus effects by ovarian hormones: Role of estradiol

Ovarian hormones influence the activity of endogenous opioids, and exogenous administration of estradiol reduces opioid intake and opioid seeking in animal models of opioid reward and reinforcement. The purpose of this study was to examine the effects of ovarian hormones on the discriminative stimulus effects of morphine and naloxone-precipitated opioid withdrawal. To this end, separate groups of ovariectomized female rats were trained to discriminate the stimulus effects of either 3.0 or 10 mg/kg morphine, and substitution tests were conducted with estradiol or progesterone alone and in combination with morphine. At the conclusion of discrimination testing, rats were treated chronically with estradiol, progesterone, or their combination, and challenged with naloxone to measure opioid-like withdrawal symptoms. Finally, the effects of estradiol, progesterone, and their combination were examined on naloxone-precipitated withdrawal in morphine-dependent rats. Neither estradiol nor progesterone substituted for the morphine discriminative stimulus, but estradiol significantly increased the potency of morphine in rats trained to discriminate 10 mg/kg but not 3 mg/kg morphine. When administered chronically, neither hormone nor their combination produced an opioid-like withdrawal syndrome following a naloxone challenge. Acute administration of estradiol, but not progesterone or a combination of estradiol and progesterone, significantly reduced naloxone-precipitated weight loss in morphine-dependent rats. These data indicate that estradiol influences the behavioral effects of morphine, possibly by increasing endogenous tone at mu opioid receptors.

Resistance training reduced luteinising hormone levels in postmenopausal women in a substudy of a randomised controlled clinical trial: A clue to how resistance training reduced vasomotor symptoms

Background

Vasomotor symptoms (VMS) are common around menopause. Menopausal hormone therapy is the most effective treatment for VMS. Physical exercise has been proposed as an alternative treatment since physically active women have previously been found to experience fewer VMS than inactive women. In our randomised controlled trial on resistance training to treat VMS, sympoms were reduced by 50% in the intervention group compared with the control group.

Objectives

To propose a mechanism to explain how resistance training reduced VMS and to assess if luteinizing hormone (LH) and follicle stimulating hormone (FSH) were affected in accordance with the proposed mechanism.

Trial design and methods

A substudy of a randomized controlled trial on 65 postmenopausal women with VMS and low physical activity who were randomised to 15 weeks of resistance training three times per week (n = 33) or to a control group (n = 32). To be regarded compliant to the intervention we predecided a mean of two training sessions per week. The daily number of VMS were registered before and during the 15 weeks. Blood samples were drawn for analysis of LH and FSH at baseline and after 15 weeks.

Results

LH decreased significantly in the compliant intervention group compared with the control group (-4.0±10.6 versus 2.9±9.0, p = 0.028 with Mann-Whitney U test). FSH also decreased in the compliant intervention group compared with the control group, however not enough to reach statistical significance (-3.5±16.3 versus 3.2±18.2, p = 0.063 with Mann-Whitney U test). As previously published the number of hot flushes decreased significantly more in the intervention group than in the control group but there was no association between change in LH or FSH and in number of VMS.

Conclusions

We propose that endogenous opiods such as β-endorphin or dynorphin produced during resistance training decreased VMS by stimulating KNDγ-neurons to release neurokinin B to the hypothalamic thermoregulatory centre. Through effects on KNDγ-neurons, β-endorphin could also inhibit GnRH and thereby decrease the production of LH and FSH. The significanty decreased LH in the compliant intervention group compared with the control group was in accordance with the proposed mechanism.

Reliability of conditioned pain modulation in healthy individuals and chronic pain patients: a systematic review and meta-analysis

OBJECTIVES

Conditioned pain modulation (CPM) is a psychophysical parameter that is used to reflect the efficacy of endogenous pain inhibition. CPM reliability is important for research and potential clinical applications. The aim of this systematic review and meta-analysis was to evaluate the reliability of CPM tests in healthy individuals and chronic pain patients.

METHODS

We searched three databases for peer-reviewed studies published from inception to October 2020: EMBASE, Web of Science and NCBI. Risk of bias and the quality of the included studies were assessed. A meta-analysis with a random effects model was conducted to estimate intraclass correlation coefficients (ICCs).

RESULTS

Meta-analysis was performed on 25 papers that examined healthy participants (k=21) or chronic pain patients (k=4). The highest CPM intra-session reliability was with pressure as test stimulus (TS) and ischemic pressure (IP) or cold pressor test (CPT) as conditioning stimulus (CS) in healthy individuals (ICC 0.64, 95% CI 0.45-0.77), and pressure as TS with CPT as CS in patients (ICC 0.77, 95% CI 0.70-0.82). The highest inter-session ICC was with IP as TS and IP or CPT as CS (ICC 0.51, 95% CI 0.42-0.59) in healthy subjects. The only data available in patients for inter-session reliability were with pressure as TS and CPT as CS (ICC 0.44, 95% CI 0.11-0.69). Quality ranged from very good to excellent using the QACMRR checklist. The majority of the studies (24 out of 25) scored inadequate in Kappa coefficient reporting item of the COSMIN-ROB checklist.

CONCLUSIONS

Pressure and CPT were the TS and CS most consistently associated with good to excellent intra-session reliability in healthy volunteers and chronic pain patients. The inter-session reliability was fair or less for all modalities, both in healthy volunteers and chronic pain patients.

Role of Estrogens in Menstrual Migraine

Migraine is a major neurological disorder affecting one in nine adults worldwide with a significant impact on health care and socioeconomic systems. Migraine is more prevalent in women than in men, with 17% of all women meeting the diagnostic criteria for migraine. In women, the frequency of migraine attacks shows variations over the menstrual cycle and pregnancy, and the use of combined hormonal contraception (CHC) or hormone replacement therapy (HRT) can unveil or modify migraine disease. In the general population, 18–25% of female migraineurs display a menstrual association of their headache. Here we present an overview on the evidence supporting the role of reproductive hormones, in particular estrogens, in the pathophysiology of migraine. We also analyze the efficacy and safety of prescribing exogenous estrogens as a potential treatment for menstrual-related migraine. Finally, we point to controversial issues and future research areas in the field of reproductive hormones and migraine.

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.

Introduction:

Objectives:

Methods:

Results:

Conclusions:

Genetics of menstrual migraine and their association with female hormonal factors

Perimenopause is linked to increased migraine (Mg), especially menstrual Mg (MMg), influenced by hormonal changes. Compared to nonmenstrual attacks, menstrual attacks are more disabling and less responsive to treatment. Women with perimenstrual estrogen withdrawal have been linked to Mg during menstruation, whereas Mg during perimenopause has been linked to unpredictable fluctuations in estrogen levels. It has been widely established that female sex hormones play a role in Mg, but how it occurs remains unclear. This narrative review was identified using Medline and PubMed searches between 1946 and 2021. Search terms included “headache,” “migraine,” “menstrual migraine,” “menstruation,” “menopause,” “perimenopause,” “estrogen,” and “progesterone.” This article focuses on the candidate genes and female hormones that play a role in MMg. More study is necessary to understand better the environmental components that play a critical role in disease development. Currently, there is insufficient clinical evidence to support the function of menstrual Mg. The specific research facts examined MMg unique candidate genes and female hormonal factors that support their association and found MMg etiologic processes for generating an early diagnostic marker.

Effects of placebo administration on immune mechanisms and relationships with central endogenous opioid neurotransmission

Behavioral conditioning and expectation can have profound impact on animal and human physiology. Placebo, administered under positive expectation in clinical trials, can have potent effects on disease pathology, obscuring active medications. Emerging evidence suggests placebo-responsive neurotransmitter systems (e.g., endogenous opioid) regulate immune function by manipulating inflammatory proteins including IL-18, a potent pro-inflammatory, nociceptive cytokine implicated in pathophysiology of various diseases. Validation that neuroimmune interactions involving brain μ-opioid receptor (MOR) activity and plasma IL-18 underlie placebo analgesic expectation could have widespread clinical applications. Unfortunately, current lack of mechanistic clarity obfuscates clinical translation. To elucidate neuroimmune interactions underlying placebo analgesia, we exposed 37 healthy human volunteers to a standardized pain challenge on each of 2 days within a Positron Emission Tomography (PET) neuroimaging paradigm using the MOR selective radiotracer, ¹¹C-Carfentanil (CFN). Each day volunteers received an intervention (placebo under analgesic expectation or no treatment), completed PET scanning, and rated their pain experience. MOR BP_ND parametric maps were generated from PET scans using standard methods. Results showed placebo reduced plasma IL-18 during pain (W₇₄ = -3.7, p < 0.001), the extent correlating with reduction in pain scores. Placebo reduction in IL-18 covaried with placebo-induced endogenous opioid release in the left nucleus accumbens (T₁₄₈ = 3.33; p_uncorr < 0.001) and left amygdala (T₁₄₈ = 3.30; p_uncorr < 0.001). These findings are consistent with a modulating effect of placebo (under analgesic expectation in humans) on a potent nociceptive, pro-inflammatory cytokine (IL-18) and underlying relationships with endogenous opioid activity, a neurotransmitter system critically involved in pain, stress, and mood regulation.