Pain
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The number of people immigrating from one country to another is increasing worldwide. Research has shown that immigration background is associated with chronic pain (CP) and pain disability in adults. However, research in this issue in children and adolescents has yielded inconsistent results. ⋯ Furthermore, the association between immigration background and CP was higher in children (OR = 6.92, p <.001) and younger adolescents (OR = 1.66, p <.05) than in older adolescents. Children and adolescents with an immigration background are at higher risk for having CP -especially younger children- and HICP. More resources should be allocated in the prevention of CP and HICP in children and adolescents with an immigration background.
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The effect of emotion regulation on the emotional modulation of pain and nociceptive flexion reflex.
Positive emotions inhibit pain, whereas negative emotions facilitate pain. Thus, many psychosocial interventions capitalize on this emotion-pain relationship to improve patients' abilities to regulate emotion (ie, reduce negative emotion, increase positive emotion), influence nociception, and manage pain. This study extended the existing literature to examine whether emotion regulation procedures could influence emotional modulation of the nociceptive flexion reflex (NFR), a marker of spinal nociception. ⋯ Instructions to enhance emotion increased subjective responding to emotional pictures but did not alter physiological responding to pictures or emotional modulation of pain/NFR in predictable ways. Results imply that downregulation/suppression of negative emotions may work best to reduce pain facilitation. Furthermore, this study contributes to the existing literature that shows that pain and pain signaling is tightly coupled with emotional states and that emotion regulation can impact pain perception.
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Comparative Study
Healthy women show more experimentally induced central sensitization compared with men.
Women more often experience chronic pain conditions than men. Central sensitization (CS) is one key mechanism in chronic pain that can differ between the sexes. It is unknown whether CS processes are already more pronounced in healthy women than in men. ⋯ The objective CS proxy differences indicate that dorsal horn CS processes are more pronounced in healthy women. The even larger sex differences in subjective CS proxies potentially reflect greater supraspinal influence in women. This study shows that sex differences are present in experimentally induced CS in healthy subjects, which might contribute to women's vulnerability for chronic pain.
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Abnormal encoding of somatosensory modalities (ie, mechanical, cold, and heat) are a critical part of pathological pain states. Detailed phenotyping of patients' responses to these modalities have raised hopes that analgesic treatments could one day be tailored to a patient's phenotype. Such precise treatment would require a profound understanding of the underlying mechanisms of specific pain phenotypes at molecular, cellular, and circuitry levels. ⋯ We then tested what range of stimuli produce dynamic stimulus-response relationships for different outcome measures in naive mice. We finally used this assay to show that nerve injury produces modality-specific sex differences in pain behavior. Our improved assay opens new avenues to study the basis of modality-specific abnormalities in pain behavior.
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Neuropathic corneal pain (NCP) is a new and ill-defined disease characterized by pain, discomfort, aching, burning sensation, irritation, dryness, and grittiness. However, the mechanism underlying NCP remain unclear. Here, we reported a novel rat model of primary NCP induced by long ciliary nerve (LCN) ligation. ⋯ At a molecular level, upregulated mRNA levels of ion channels Piezo2, TRPM8, and TRPV1, as well as inflammatory factors TNF-α, IL-1β, and IL-6, were also detected in the TG after LCN ligation. Meanwhile, consecutive oral gabapentin attenuated LCN ligation-induced corneal hyperalgesia and increased levels of ion channels and inflammation factors in TG. This study provides a reliable primary NCP model induced by LCN ligation in rats using a simple, minimally invasive surgery technique, which may help shed light on the underlying cellular and molecular bases of NCP and aid in developing a new treatment for the disease.