Mol Pain
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Oxytocin (OT) is recognized as a critical neuropeptide in pain-related disorders. Chronic pain caused by the comorbidity of temporomandibular disorder (TMD) and fibromyalgia syndrome (FMS) is common, but whether OT plays an analgesic role in the comorbidity of TMD and FMS is unknown. Female rats with masseter muscle inflammation combined with 3-day forced swim (FS) stress developed somatic hypersensitivity, which modeled the comorbidity of TMD and FMS. ⋯ The expression of OT receptors and 5-HT2A receptors in the L4-L5 spinal dorsal horn significantly increased following intrathecal injection of 0.5 μg OT. Intrathecal administration of either the OT receptor antagonist atosiban or 5-HT2A receptor antagonist ritanserin blocked the analgesic effect of OT. These results suggest that OT may inhibit hindpaw hyperalgesia evoked by orofacial inflammation combined with stress through OT receptors and/or 5-HT2A receptors, thus providing a therapeutic prospect for drugs targeting the OT system and for patients with comorbidity of TMD and FMS.
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Prior studies identified iron deposition in deep brain nuclei and the periaqueductal gray matter region in chronic migraine, and less is known about the cerebral iron deposition over the whole cerebral gray matter in CM. The aim of this case-control study is to investigate the cerebral iron deposition of gray matter in CM using an advanced quantitative susceptibility mapping. ⋯ CM patients had increased iron deposition in total cerebral gray matter which could be considered as a potential diagnostic and evaluated imaging biomarker in CM.
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Nervous system manifestations caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are of great concern. Neurological symptoms and the neurological effects induced by SARS-CoV-2, such as the loss of various sensory perceptions, indicate direct viral invasion into sensory neurons. Therefore, it is very important to identify the distribution of angiotensin-converting enzyme 2 (ACE2), the receptor of SARS-CoV-2, in human nervous system. ⋯ We demonstrated that Sudan Black B (SBB) remarkably reduced the massive lipofuscin-like autofluorescence and the immunofluorescence signal would be sharpened following the exposure compensation. Additionally, we confirmed that ACE2 was expressed in IB4+, CGRP+, and NF200+ sensory subpopulations. The mapping of ACE2 distribution in hDRG would facilitate the understanding of sensory disorder induced by SARS-CoV-2.
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Trigeminal neuropathic pain has been modeled in rodents through the constriction of the infraorbital nerve (CCI-ION). Sensory alterations, including spontaneous pain, and thermal and mechanical hyperalgesia are well characterized, but there is a notable lack of evidence about the affective pain component in this model. Evaluation of the emotional component of pain in rats has been proposed as a way to optimize potential translational value of non-clinical studies. ⋯ Amphetamine caused a marked increase in 50 kHz USV emission in CCI-ION rats. In addition, TH expression was lower in constricted animals and c-Fos analysis revealed an increase in neuronal activation. Taken together, these data indicate that CCI-ION causes a reduction in the emission of environmental-induced appetitive calls concomitantly with facial mechanical hyperalgesia and that both changes may be related to a reduction in the mesolimbic dopaminergic activity.
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The anterior cingulate cortex (ACC) is located in the frontal part of the cingulate cortex, and plays important roles in pain perception and emotion. The thalamocortical pathway is the major sensory input to the ACC. Previous studies have show that several different thalamic nuclei receive projection fibers from spinothalamic tract, that in turn send efferents to the ACC by using neural tracers and optical imaging methods. ⋯ We also combined with a new high-throughput VISoR imaging technique to generate a three-dimensional whole-brain reconstruction, especially the thalamus. We found that cortical neurons in the ACC received direct projections from different sub-nuclei in the thalamus, including the anterior, ventral, medial, lateral, midline, and intralaminar thalamic nuclei. These findings provide key anatomic evidences for the connection between the thalamus and ACC.