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Peripheral nerve injury-induced mechanical allodynia is often accompanied by abnormalities in the higher cortical regions, yet the mechanisms underlying such maladaptive cortical plasticity remain unclear. Here, we show that in male mice, structural and functional changes in the primary somatosensory cortex (S1) caused by peripheral nerve injury require neuron-microglial signaling within the local circuit. Following peripheral nerve injury, microglia in the S1 maintain ramified morphology and normal density but up-regulate the mRNA expression of brain-derived neurotrophic factor (BDNF). Using in vivo two-photon imaging and Cx3cr1CreER;Bdnfflox mice, we show that conditional knockout of BDNF from microglia prevents nerve injury-induced synaptic remodeling and pyramidal neuron hyperactivity in the S1, as well as pain hypersensitivity in mice. Importantly, S1-targeted removal of microglial BDNF largely recapitulates the beneficial effects of systemic BDNF depletion on cortical plasticity and allodynia. Together, these findings reveal a pivotal role of cerebral microglial BDNF in somatosensory cortical plasticity and pain hypersensitivity.
Learn More >Although chronic postsurgical pain (CPSP) after breast cancer surgery is a common and prevalent postsurgical adverse event, the need for CPSP treatment has not been investigated. This study examined the proportion of patients who needed treatment for CPSP and associated predictors.
Learn More >Induction of severe inflammatory arthritis in the collagen antibody-induced arthritis (CAIA) murine model causes extensive joint damage and pain-like behavior compromising analysis. While mild models are less severe, their reduced, variable penetrance makes assessment of treatment efficacy difficult. This study aimed to compare macroscopic and microscopic changes in the paws, along with central nervous system activation between a mild and moderate CAIA model. Balb/c mice (=18) were allocated to control, mild, and moderate CAIA groups. Paw inflammation, bone volume (BV), and paw volume (PV) were assessed. Histologically, the front paws were assessed for joint inflammation, cartilage damage, and pre/osteoclast-like cells and the lumbar spinal cord and the periaqueductal gray (PAG) region of the brain for glial reactivity. A moderate CAIA dose induced (1) significantly greater local paw inflammation, inflammatory cell infiltration, and PV; (2) significantly more osteoclast-like cells on the bone surface and within the surrounding soft tissue; and (3) significantly greater glial reactivity within the PAG compared with the mild CAIA model. These findings support the use of a moderate CAIA model (higher dose of monoclonal antibodies with low-dose lipopolysaccharide) to induce more consistent histopathological features, without excessive joint destruction.
Learn More >Active duty military members have significant service-related risks for developing pain from injury. Although estimates for neuropathic pain (NP) are available for civilian populations, the incidence and prevalence for NP in military members is less clear. Understanding correlates of pain in military members is vital to improving their physical, mental, and social health. Using a comparative design, a secondary analysis was conducted on longitudinal PASTOR data from 190 pain management center patients. The objectives were to compare trends in patient-reported outcomes over time between those screening positive and negative for NP (NP+, NP-, respectively) based on PROMIS Neuropathic Pain Scale T-scores. Findings showed improvements in fatigue, sleep-related impairment, and anger over time. There was a difference between those screening NP+ and NP- for sleep-related impairment, and the cross-level interaction effect showed sleep-related impairment worsening over time. These results emphasize the need to identify NP and implement and evaluate targeted therapies.
Learn More >The calcitonin (CT) receptor family is complex, comprising two receptors (the CT receptor [CTR], and the CTR-like receptor [CLR]), three accessory proteins (RAMPs), and multiple endogenous peptides. This family contains several important drug targets, including CGRP which is targeted by migraine therapeutics. The pharmacology of this receptor family is poorly characterised in species other than rats and humans. To facilitate understanding of translational and pre-clinical data we need to know the receptor pharmacology of this family in mice.
Learn More >To evaluate the effect of corticosteroid injections in the painful temporomandibular joint (TMJ) of patients with rheumatoid arthritis (RA) in relation to systemic inflammatory activity.
Learn More >Occipital neuralgia is a painful condition that affects the posterior aspect of the head and can be difficult to distinguish from other common forms of headaches. This article reviews the anatomy, pathophysiology, clinical presentation, differential diagnosis, diagnostic testing, and management approaches for occipital neuralgia.
Learn More >Opioids remain the primary mode of analgesia intraoperatively. There are limited data on how patient, procedural, and institutional characteristics influence intraoperative opioid administration. The aim of this retrospective, longitudinal study from 2012 to 2016 was to assess how intraoperative opioid dosing varies by patient and clinical care factors and across multiple institutions over time.
Learn More >We previously demonstrated that intracerebroventricular injection of resolvin D2 (RvD2), a bioactive lipid mediator derived from docosahexaenoic acid, ameliorated depression-like behavior in lipopolysaccharide-induced and chronic mild stress-induced mouse models of depression. In the present study, we examined the antidepressant effect of RvD2 on chronic pain-induced depression-like behavior.
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