AIM： To investigate the role of endogenous pain modulatory mechanisms in the central sensitization implicated by the visceral hypersensitivity demonstrated in patients with irritable bowel syndrome （IBS）. Dysfuncti...AIM： To investigate the role of endogenous pain modulatory mechanisms in the central sensitization implicated by the visceral hypersensitivity demonstrated in patients with irritable bowel syndrome （IBS）. Dysfunction of modulatory mechanisms would be expected to also result in changes of somatic sensory function. METHODS： Endogenous pain modulatory mechanisms were assessed using heterotopic stimulation and somatic and visceral sensory testing in IBS. Pain intensities （visual analogue scale, VAS 0-100） during suprathreshold rectal distension with a barostat, cold pressor stimulation of the foot and during both stimuli simultaneously （heterotopic stimulation） were recorded in 40 female patients with IBS and 20 female healthy controls. RESULTS： Rectal hypersensitivity （defined by 95% Cl of controls） was seen in 21 （53%）, somatic hypersensitivity in 22 （55%） and both rectal and somatic hypersensitivity in 14 of these IBS patients. Heterotopic stimulation decreased rectal pain intensity by 6 （-11 to -1） in controls, but increased rectal pain by 2 （-3 to ＋6） in all IBS patients （P 〈 0.05） and by 8 （-2 to ＋19） in IBS patients with somatic and visceral hypersensitivity （P 〈 0.02）. CONCLUSION： A majority of IBS patients had abnormal endogenous pain modulation and somatic hypersensitivity as evidence of central sensitization.展开更多
Compelling evidence indicates sex and gender differences in epidemiology, symptomatology, pathophysiology, and treatment outcome in irritable bowel syndrome (IBS). Based on the female predominance as well as the corre...Compelling evidence indicates sex and gender differences in epidemiology, symptomatology, pathophysiology, and treatment outcome in irritable bowel syndrome (IBS). Based on the female predominance as well as the correlation between IBS symptoms and hormonal status, several models have been proposed to examine the role of sex hormones in gastrointestinal (GI) function including differences in GI symptoms expression in distinct phases of the menstrual cycle, in pre- and post-menopausal women, during pregnancy, hormonal treatment or after oophorectomy. Sex hormones may influence peripheral and central regulatory mechanisms of the brain-gut axis involved in the pathophysiology of IBS contributing to the alterations in visceral sensitivity, motility, intestinal barrier function, and immune activation of intestinal mucosa. Sex differences in stress response of the hypothalamic-pituitary-adrenal axis and autonomic nervous system, neuroimmune interactions triggered by stress, as well as estrogen interactions with serotonin and corticotropin-releasing factor signaling systems are being increasingly recognized. A concept of “microgenderome” related to the potential role of sex hormone modulation of the gut microbiota is also emerging. Significant differences between IBS female and male patients regarding symptomatology and comorbidity with other chronic pain syndromes and psychiatric disorders, together with differences in efficacy of serotonergic medications in IBS patients confirm the necessity for more sex-tailored therapeutic approach in this disorder.展开更多
Nociceptive signals conveyed to the dorsal horn of the spinal cord by primary nociceptors are subject to extensive modulation by local neurons and by supraspinal descending pathways to the spinal cord before being rel...Nociceptive signals conveyed to the dorsal horn of the spinal cord by primary nociceptors are subject to extensive modulation by local neurons and by supraspinal descending pathways to the spinal cord before being relayed to higher brain centers. Descending modulatory pathways to the spinal cord comprise,among others, noradrenergic, serotonergic, γ-aminobutyric acid(GABA)ergic, and dopaminergic fibers.The contributions of noradrenaline, serotonin, and GABA to pain modulation have been extensively investigated. In contrast, the contributions of dopamine to pain modulation remain poorly understood.The focus of this review is to summarize the current knowledge of the contributions of dopamine to pain modulation. Hypothalamic A11 dopaminergic neurons project to all levels of the spinal cord and provide the main source of spinal dopamine. Dopamine receptors are expressed in primary nociceptors as well as in spinal neurons located in different laminae in the dorsal horn of the spinal cord, suggesting that dopamine can modulate pain signals by acting at both presynaptic and postsynaptic targets. Here, I will review the literature on the effects of dopamine and dopamine receptor agonists/antagonists on the excitability of primary nociceptors, the effects of dopamine on the synaptic transmission between primary nociceptors and dorsal horn neurons, and the effects of dopamine on pain in rodents. Published data support both anti-nociceptive effects of dopamine mediated by D2-like receptors and pro-nociceptive effects mediated by D1-like receptors.展开更多
Cognition and pain share common neural substrates and interact reciprocally: chronic pain compromises cognitive performance, whereas cognitive processes modulate pain perception. In the present study, we established a...Cognition and pain share common neural substrates and interact reciprocally: chronic pain compromises cognitive performance, whereas cognitive processes modulate pain perception. In the present study, we established a non-drug-dependent rat model of context-based analgesia,where two different contexts(dark and bright) were matched with a high(52°C) or low(48°C) temperature in the hot-plate test during training. Before and after training,we set the temperature to the high level in both contexts.Rats showed longer paw licking latencies in trials with the context originally matched to a low temperature than those to a high temperature, indicating successful establishment of a context-based analgesic effect in rats. This effect was blocked by intraperitoneal injection of naloxone(an opioid receptor antagonist) before the probe. The context-based analgesic effect also disappeared after optogenetic activation or inhibition of the bilateral infralimbic or prelimbic sub-region of the prefrontal cortex. In brief, we established a context-based, non-drug dependent, placebo-like analgesia model in the rat. This model provides a new and useful tool for investigating the cognitive modulation of pain.展开更多
Protein kinase D （PKD） is an evolutionarily-conserved family of protein kinases. It has structural, regulatory, and enzymatic properties quite different from the PKC family. Many stimuli induce PKD signaling, includ...Protein kinase D （PKD） is an evolutionarily-conserved family of protein kinases. It has structural, regulatory, and enzymatic properties quite different from the PKC family. Many stimuli induce PKD signaling, including G-protein-coupled receptor agonists and growth factors. PKD1 is the most studied member of the family. It functions during cell proliferation, differentiation, secretion, cardiac hypertrophy, immune regulation, angiogenesis, and cancer. Previously, we found that PKD1 is also critically involved in pain modulation. Since then, a series of studies performed in our lab and by other groups have shown that PKDs also participate in other processes in the nervous system including neuronal polarity establishment, neuroprotection, and learning. Here, we discuss the connections between PKD structure, enzyme function, and localization, and summarize the recent findings on the roles of PKD-mediated signaling in the nervous system.展开更多
Pain is an unpleasant sensory and emotional experience associated with,or resembling that associated with,actual or potential tissue damage.The processing of pain involves complicated modulation at the levels of the p...Pain is an unpleasant sensory and emotional experience associated with,or resembling that associated with,actual or potential tissue damage.The processing of pain involves complicated modulation at the levels of the periphery,spinal cord,and brain.The pathogenesis of chronic pain is still not fully understood,which makes the clinical treatment challenging.Optogenetics,which combines optical and genetic technologies,can precisely intervene in the activity of specific groups of neurons and elements of the related circuits.Taking advantage of optogenetics,researchers have achieved a body of new findings that shed light on the cellular and circuit mechanisms of pain transmission,pain modulation,and chronic pain both in the periphery and the central nervous system.In this review,we summarize recent findings in pain research using optogenetic approaches and discuss their significance in understanding the pathogenesis of chronic pain.展开更多
Phantom limb pain(PLP)is a complex medical condition that is often difficult to treat,and thus can become detrimental to patients’quality of life.No standardized clinical treatments exist and there is no conclusive u...Phantom limb pain(PLP)is a complex medical condition that is often difficult to treat,and thus can become detrimental to patients’quality of life.No standardized clinical treatments exist and there is no conclusive understanding of the underlying mechanisms causing it.Noninvasive brain stimulation(NIBS)has been used to find correlations between changes in brain activity and various brain conditions,including neurological disease,mental illnesses,and brain disorders.Studies have also shown that NIBS can be effective in alleviating pain.Here,we examined the literature on a particular type of NIBS,known as transcranial direct current stimulation(tDCS),and its application to the treatment of PLP.We first discuss the current hypotheses on the working mech-anism of tDCS and then we examine published evidence of its efficacy to treat PLP.We conclude this article by discussing how tDCS alone,and in combination with brain imaging techniques such as electroencephalography(EEG)and magnetic resonance imagining,could be applied to further investigate the mechanisms underlying PLP.展开更多
基金the Brain-Gut Research Group, Berne, Switzerland
文摘AIM： To investigate the role of endogenous pain modulatory mechanisms in the central sensitization implicated by the visceral hypersensitivity demonstrated in patients with irritable bowel syndrome （IBS）. Dysfunction of modulatory mechanisms would be expected to also result in changes of somatic sensory function. METHODS： Endogenous pain modulatory mechanisms were assessed using heterotopic stimulation and somatic and visceral sensory testing in IBS. Pain intensities （visual analogue scale, VAS 0-100） during suprathreshold rectal distension with a barostat, cold pressor stimulation of the foot and during both stimuli simultaneously （heterotopic stimulation） were recorded in 40 female patients with IBS and 20 female healthy controls. RESULTS： Rectal hypersensitivity （defined by 95% Cl of controls） was seen in 21 （53%）, somatic hypersensitivity in 22 （55%） and both rectal and somatic hypersensitivity in 14 of these IBS patients. Heterotopic stimulation decreased rectal pain intensity by 6 （-11 to -1） in controls, but increased rectal pain by 2 （-3 to ＋6） in all IBS patients （P 〈 0.05） and by 8 （-2 to ＋19） in IBS patients with somatic and visceral hypersensitivity （P 〈 0.02）. CONCLUSION： A majority of IBS patients had abnormal endogenous pain modulation and somatic hypersensitivity as evidence of central sensitization.
基金Supported by The Veterans Administration Research Career Scientist Award(to TachéY)National Institute of Health grants No.P50 DK-64539(to TachéY)No.K01-DK088937(to Larauche M)
文摘Compelling evidence indicates sex and gender differences in epidemiology, symptomatology, pathophysiology, and treatment outcome in irritable bowel syndrome (IBS). Based on the female predominance as well as the correlation between IBS symptoms and hormonal status, several models have been proposed to examine the role of sex hormones in gastrointestinal (GI) function including differences in GI symptoms expression in distinct phases of the menstrual cycle, in pre- and post-menopausal women, during pregnancy, hormonal treatment or after oophorectomy. Sex hormones may influence peripheral and central regulatory mechanisms of the brain-gut axis involved in the pathophysiology of IBS contributing to the alterations in visceral sensitivity, motility, intestinal barrier function, and immune activation of intestinal mucosa. Sex differences in stress response of the hypothalamic-pituitary-adrenal axis and autonomic nervous system, neuroimmune interactions triggered by stress, as well as estrogen interactions with serotonin and corticotropin-releasing factor signaling systems are being increasingly recognized. A concept of “microgenderome” related to the potential role of sex hormone modulation of the gut microbiota is also emerging. Significant differences between IBS female and male patients regarding symptomatology and comorbidity with other chronic pain syndromes and psychiatric disorders, together with differences in efficacy of serotonergic medications in IBS patients confirm the necessity for more sex-tailored therapeutic approach in this disorder.
基金supported by internal funds to MP from the Department of Anesthesiology,Stony Brook Medicine,USA
文摘Nociceptive signals conveyed to the dorsal horn of the spinal cord by primary nociceptors are subject to extensive modulation by local neurons and by supraspinal descending pathways to the spinal cord before being relayed to higher brain centers. Descending modulatory pathways to the spinal cord comprise,among others, noradrenergic, serotonergic, γ-aminobutyric acid(GABA)ergic, and dopaminergic fibers.The contributions of noradrenaline, serotonin, and GABA to pain modulation have been extensively investigated. In contrast, the contributions of dopamine to pain modulation remain poorly understood.The focus of this review is to summarize the current knowledge of the contributions of dopamine to pain modulation. Hypothalamic A11 dopaminergic neurons project to all levels of the spinal cord and provide the main source of spinal dopamine. Dopamine receptors are expressed in primary nociceptors as well as in spinal neurons located in different laminae in the dorsal horn of the spinal cord, suggesting that dopamine can modulate pain signals by acting at both presynaptic and postsynaptic targets. Here, I will review the literature on the effects of dopamine and dopamine receptor agonists/antagonists on the excitability of primary nociceptors, the effects of dopamine on the synaptic transmission between primary nociceptors and dorsal horn neurons, and the effects of dopamine on pain in rodents. Published data support both anti-nociceptive effects of dopamine mediated by D2-like receptors and pro-nociceptive effects mediated by D1-like receptors.
基金supported by grants from the National Natural Science Foundation of China (91732107, 31200835, 81571067, and 81521063)the National Basic Research Development Program (973 Program) of China (2014CB548200 and 2015CB554503)
文摘Cognition and pain share common neural substrates and interact reciprocally: chronic pain compromises cognitive performance, whereas cognitive processes modulate pain perception. In the present study, we established a non-drug-dependent rat model of context-based analgesia,where two different contexts(dark and bright) were matched with a high(52°C) or low(48°C) temperature in the hot-plate test during training. Before and after training,we set the temperature to the high level in both contexts.Rats showed longer paw licking latencies in trials with the context originally matched to a low temperature than those to a high temperature, indicating successful establishment of a context-based analgesic effect in rats. This effect was blocked by intraperitoneal injection of naloxone(an opioid receptor antagonist) before the probe. The context-based analgesic effect also disappeared after optogenetic activation or inhibition of the bilateral infralimbic or prelimbic sub-region of the prefrontal cortex. In brief, we established a context-based, non-drug dependent, placebo-like analgesia model in the rat. This model provides a new and useful tool for investigating the cognitive modulation of pain.
基金supported by the National Natural Science Foundation of China (81161120497, 30925015, 30830044, 30900582, and 81221002)the National Basic Research Development Program (973 Program) of China (2014CB542204)
文摘Protein kinase D （PKD） is an evolutionarily-conserved family of protein kinases. It has structural, regulatory, and enzymatic properties quite different from the PKC family. Many stimuli induce PKD signaling, including G-protein-coupled receptor agonists and growth factors. PKD1 is the most studied member of the family. It functions during cell proliferation, differentiation, secretion, cardiac hypertrophy, immune regulation, angiogenesis, and cancer. Previously, we found that PKD1 is also critically involved in pain modulation. Since then, a series of studies performed in our lab and by other groups have shown that PKDs also participate in other processes in the nervous system including neuronal polarity establishment, neuroprotection, and learning. Here, we discuss the connections between PKD structure, enzyme function, and localization, and summarize the recent findings on the roles of PKD-mediated signaling in the nervous system.
基金supported by grants from the National Natural Science Foundation of China(82073819 and 81872843)Fundamental Research Funds for the Central Universities of China(2021QNA7005).
文摘Pain is an unpleasant sensory and emotional experience associated with,or resembling that associated with,actual or potential tissue damage.The processing of pain involves complicated modulation at the levels of the periphery,spinal cord,and brain.The pathogenesis of chronic pain is still not fully understood,which makes the clinical treatment challenging.Optogenetics,which combines optical and genetic technologies,can precisely intervene in the activity of specific groups of neurons and elements of the related circuits.Taking advantage of optogenetics,researchers have achieved a body of new findings that shed light on the cellular and circuit mechanisms of pain transmission,pain modulation,and chronic pain both in the periphery and the central nervous system.In this review,we summarize recent findings in pain research using optogenetic approaches and discuss their significance in understanding the pathogenesis of chronic pain.
文摘Phantom limb pain(PLP)is a complex medical condition that is often difficult to treat,and thus can become detrimental to patients’quality of life.No standardized clinical treatments exist and there is no conclusive understanding of the underlying mechanisms causing it.Noninvasive brain stimulation(NIBS)has been used to find correlations between changes in brain activity and various brain conditions,including neurological disease,mental illnesses,and brain disorders.Studies have also shown that NIBS can be effective in alleviating pain.Here,we examined the literature on a particular type of NIBS,known as transcranial direct current stimulation(tDCS),and its application to the treatment of PLP.We first discuss the current hypotheses on the working mech-anism of tDCS and then we examine published evidence of its efficacy to treat PLP.We conclude this article by discussing how tDCS alone,and in combination with brain imaging techniques such as electroencephalography(EEG)and magnetic resonance imagining,could be applied to further investigate the mechanisms underlying PLP.
