Pain
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Paradoxical associations have been observed for leisure-time physical activity (LTPA) and occupational physical activity (OPA) and several health-related outcomes. Typically, higher LTPA is associated with health benefits and high OPA with health hazards. Using data from the Tromsø Study (2015-2016), we assessed how questionnaire-based LTPA and OPA (n = 21,083) and accelerometer-measured physical activity (PA) (n = 6778) relate to pain outcomes. ⋯ Higher levels of accelerometer-measured PA were associated with less pain. To summarize, we found inverse associations for LTPA and OPA. Benefits from LTPA seem to depend on low levels of OPA.
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This study set out to investigate in a population-based longitudinal cohort, whether chronification of back pain (BP) is related to structural gray matter changes in corticolimbic brain structures. Gray matter volume (GMV) was measured in participants with chronic BP (CBP, n = 168) and controls without chronic pain (n = 323) at 2 time points with an interval of 7 years (baseline t1, follow-up t2). Over this time period, participants with CBP showed an increase of GMV in the left ventral striatum, whereas controls showed a decrease. ⋯ Those with emerging CBP had less GMV in the right entorhinal area, right amygdala, and left medial frontal cortex. Additional variables differing between those who had BP at t1 and later developed CBP or not were pain intensity, body mass index, and depression score. In sum, these findings are in accordance with the notion that limbic brain properties are both predisposing risk factors and drivers of brain reorganization during the development of CBP.
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Menstrual pain is associated with deficits in central pain processing, yet neuroimaging studies to date have all been limited by focusing on group comparisons of adult women with vs without menstrual pain. This study aimed to investigate the role of the triple network model (TNM) of brain networks in adolescent girls with varied menstrual pain severity ratings. One hundred participants (ages 13-19 years) completed a 6-min resting state functional magnetic resonance imaging (fMRI) scan and rated menstrual pain severity, menstrual pain interference, and cumulative menstrual pain exposure. ⋯ In addition, menstrual pain interference was positively associated with connectivity within the left CEN, whereas connectivity both within the right CEN and between the right CEN and cortical areas outside the network (including the insula) were negatively associated with menstrual pain interference. Cumulative menstrual pain exposure shared a strong negative association with connectivity between the default mode network and other widespread regions associated with large-scale brain networks. These findings support a key role for the involvement of TNM brain networks in menstrual pain characteristics and suggest that alterations in pain processing exist in adolescents with varying levels of menstrual pain.
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Translational models of the sensitized pain system are needed to progress the understanding of involved mechanisms. In this study, long-term potentiation was used to develop a mechanism-based large-animal pain model. Event-related potentials to electrical stimulation of the ulnar nerve were recorded by intracranial recordings in pigs, 3 weeks before, immediately before and after, and 3 weeks after peripheral high-frequency stimulation (HFS) applied to the ulnar nerve in the right forelimb (7 pigs) or in control animals (5 pigs). ⋯ The relative increase in N1 30 minutes after HFS and the degree of mechanical hyperalgesia 2 weeks post-HFS was correlated ( P < 0.033). These results show for the first time that the pig HFS model resembles the human HFS model closely where the profile of sensitization is comparable. Interestingly, the degree of sensitization was associated with the cortical signs of hyperexcitability at HFS induction.
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As the incidence and survival rates of patients with cancer continues to grow, an increasing number of people are living with comorbidities, which often manifests as cancer-induced bone pain (CIBP). The majority of patients with CIBP report poor pain control from currently available analgesics. A conotoxin, Contulakin-G (CGX), has been demonstrated to be an antinociceptive agent in postsurgical and neuropathic pain states via a neurotensin receptor 2 (NTSR2)-mediated pathway. ⋯ Moreover, at antinociceptive doses, CGX had no impact on motor behavior in rodents with CIBP. Finally, RNAScope and immunoblotting analysis revealed expression of NTSR2 in both dorsal and ventral horns, while Cav2.3 was minimally expressed in the ventral horn, possibly explaining the sensory selectivity of CGX. Together, these findings support advancing CGX as a potential therapeutic for cancer pain.