Neuroscience
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A 62-year-old diabetologist diagnosed himself to have diabetes type-2, with an HbA1c of 9.5. Five months after lifestyle intervention and a multi-drug approach, HbA1c was 6.3, systolic blood pressure was below 135mmHg and BMI reduced to 27. But he suffered from severe painful diabetic neuropathy. ⋯ Are there imaging techniques helpful for the diagnosis of this diabetic complication, starting in the distal nerve endings of the foot and slowly moving ahead? 5. Can you suggest any drug, specific and effective, for relieving painful diabetic neuropathy? This review will use the experts' answers to the questions of the diabetologist, not only to give a summary of the current knowledge, but even more to highlight areas of research needed for improving the fate of patients with painful diabetic neuropathy. Based on the unknowns, which exceed the knowns in diabetic neuropathy, a quest for more public support of research is made.
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An accumulating body of evidence suggests that the hypothalamic neuropeptide oxytocin (OT) has a modulatory effect on pain processing. Particularly strong evidence comes from animal models. Here, we review recent advances in animal research on the analgesic effects of OT and discuss possible target sites of OT within descending and ascending pain pathways in the brain. ⋯ Moreover, we also address how OT might alleviate pain by influencing socio-emotional components in humans. We conclude that further investigating specific OT and OT-sensitive circuits, which modulate pain processing especially in primates, will improve our understanding of OT-analgesic effects. In human research, the increased use of neuroimaging and autonomic measures might help to bridge the gap to animal studies.
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In addition to being a key component of the autonomic nervous system, acetylcholine acts as a prominent neurotransmitter and neuromodulator upon release from key groups of cholinergic projection neurons and interneurons distributed across the central nervous system. It has been more than forty years since it was discovered that cholinergic transmission profoundly modifies the perception of pain. Directly activating cholinergic receptors or extending the action of endogenous acetylcholine via pharmacological blockade of acetylcholine esterase reduces pain in rodents as well as humans; conversely, inhibition of muscarinic cholinergic receptors induces nociceptive hypersensitivity. ⋯ Moreover, we attempt to provide an overview of how some of the salient regions in the pain network spanning the brain, such as the primary somatosensory cortex, insular cortex, anterior cingulate cortex, the medial prefrontal cortex and descending modulatory systems are influenced by cholinergic modulation. Finally, we critically discuss the clinical relevance of cholinergic signaling to pain therapy. Cholinergic mechanisms contribute to several both conventional as well as unorthodox forms of pain treatments, and reciprocal interactions between cholinergic and opioidergic modulation impact on the function and efficacy of both opioids and cholinomimetic drugs.
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Advances in pediatric cancer treatment have led to a ten year survival rate greater than 75%. Platinum-based chemotherapies (e.g. cisplatin) induce peripheral sensory neuropathy in adult and pediatric cancer patients. The period from birth through to adulthood represents a period of maturation within nociceptive systems. ⋯ The percentage of IB4+ve, CGRP+ve and NF200+ve DRG neurons was not different between groups at P45. There was an increase in TrkA+ve DRG neurons in the cisplatin group at P45, in addition to increased TrkA, NF200 and vGLUT2 immunoreactivity in the lumbar dorsal horn versus controls. These data highlight the impact pediatric cancer chemotherapy has upon the maturation of pain pathways and later life pain experience.
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Cortical reorganization has been proposed as a major factor involved in phantom pain with prior nociceptive input to the deafferented region and input from the non-deafferented cortex creating neuronal activity that is perceived as phantom pain. There is substantial evidence that these processes play a role in neuropathic pain, although causal evidence is lacking. Recently it has been suggested that a maintenance of the cortical representation of the former hand area is related to phantom pain. ⋯ Although often introduced as contradictory, we suggest that cortical reorganization, preserved limb function and peripheral factors interact to create the various painful and nonpainful aspects of the phantom limb experience. In addition, the type of task (sensory versus motor), the interaction of injury- and use-dependent plasticity, the type of data analysis, contextual factors such as the body representation and psychological variables determine the outcome and need to be considered in models of phantom limb pain. Longitudinal studies are needed to determine the formation of the phantom pain experience.