Articles: neuralgia.
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Dissecting the organization of circuit pathways involved in pain affect is pivotal for understanding behavior associated with noxious sensory inputs. The central nucleus of the amygdala (CeA) comprises distinct populations of inhibitory GABAergic neurons expressing a wide range of molecular markers. CeA circuits are associated with aversive learning and nociceptive responses. ⋯ We find that monosynaptic PBn input is preferentially organized to molecularly specific neurons in distinct subdivisions of the CeA. The spared nerve injury model of neuropathic pain differentially altered PBn monosynaptic excitatory input to CeA neurons based on molecular identity and topographical location within the CeA. These results provide insight into the functional organization of affective pain pathways and how they are altered by chronic pain.
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The monosodium iodoacetate knee osteoarthritis model has been widely used for the evaluation of osteoarthritis pain, but the pathogenesis of associated chronic pain is not fully understood. The T-type calcium channel 3.2 (CaV3.2) is abundantly expressed in the primary sensory neurons, in which it regulates neuronal excitability at both the somata and peripheral terminals and facilitates spontaneous neurotransmitter release at the spinal terminals. In this study, we investigated the involvement of primary sensory neuron-CaV3.2 activation in monosodium iodoacetate osteoarthritis pain. ⋯ Perineural application of TTA-P2 into the ipsilateral sciatic nerve alleviated mechanical hypersensitivity and weight-bearing asymmetry in monosodium iodoacetate osteoarthritis rats. Overall, our findings demonstrate an elevated CaV3.2 expression and enhanced function of primary sensory neuron-T channels in the monosodium iodoacetate osteoarthritis pain. Further study is needed to delineate the importance of dysfunctional primary sensory neuron-CaV3.2 in osteoarthritis pain.
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Recently, ultrasound- (US-) guided selective nerve root block (SNRB) has been reported to have similar effects compared to fluoroscopy- (FL-) guided cervical epidural steroid injection (CESI). There is no published study comparing the therapeutic efficacy and safety of interlaminar- (IL-) CESI and transforaminal- (TF-) CESI with US-guided SNRB. Our retrospective study aimed to compare the mid-term effects and advantages of the US-guided SNRB, FL-guided IL-CESI, and TF-CESI for radicular pain in the lower cervical spine through assessment of pain relief and functional improvement. ⋯ Our results suggest that, compared with FL-guided IL and TF-CESI, US-guided SNRB has a low intravascular injection rate; it is unlikely that serious complications will occur. Also, US-guided SNRB requires a shorter administration duration while providing similar pain relief and functional improvements. Therefore, for the treatment of patients with lower cervical radicular pain, US-guided SNRB should be considered as a prior epidural steroid injection.
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This study set out to investigate the effect of massage on the Toll-like receptor 4 (TLR4) signalling pathway in the dorsal root ganglia of rats that had undergone spinal nerve ligation (SNL), with the hypothesis that massage could be used as an analgesic. Forty female SD rats were randomly divided into 5 groups: the control group, sham-operated group, model group, sham massage group, and massage group. There were 8 rats in each group. ⋯ The PWTL and PWMT of SNL rats were decreased, while these parameters were elevated after massage. SNL rats showed higher levels of TLR4, IRAK1, TRAF6, IL-6, and TNF-α, and massage effectively lowered the expression levels of these molecules. Inhibiting activation of the TLR4 signalling pathway, which can reduce the release of inflammatory factors, may be one mechanism by which massage treats neuropathic pain.
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Neuropathic pain is a chronic disease state resulting from injury to the nervous system. This type of pain often responds poorly to standard treatments and occasionally may get worse instead of better over time. Patients who experience neuropathic pain report sensitivity to cold and mechanical stimuli. ⋯ Finally, we used RNAscope to probe for TRPA1 and TRPM8 messenger RNA expression in dorsal root ganglia of both species. We found increased TRPA1 messenger RNA, but decreased TRPM8 punctae in naked mole-rats when compared with mice. Our findings likely reflect species differences due to evolutionary environmental responses that are not easily explained by differences in receptor expression between the species.