Chronic pain in Chile: first prevalence report of noncancer chronic pain, fibromyalgia, and neuropathic pain and its associated factors

Allosteric modulation and direct activation of glycine receptors by a tricyclic sulfonamide

Ionotropic glycine receptors (GlyRs) are chloride-permeable ligand-gated ion channels expressed in the nervous system. Alterations to glycinergic inhibition and the generation of dysfunctional GlyRs have been linked to chronic pain, a widely prevalent disease. Positive allosteric modulators (PAMs) targeting GlyRs exerted analgesic effects, motivating research on glycinergic PAMs as potential pain therapies. Rationally designed tricyclic sulfonamides are novel glycinergic PAMs with analgesic activity. However, detailed electrophysiological studies on these PAMs are still limited, and the GlyR binding site structural data has not been yet validated by mutational studies. Here, we combined electrophysiology and bioinformatics to systematically study the AM-1488 actions, a prototypical tricyclic sulfonamide, on recombinant GlyRs. We determined that AM-1488 is a potent, non-selective PAM of mammalian GlyR subtypes. In addition, the compound displayed agonistic activity, with partial preference for α1GlyRs. Single channel assays revealed that the compound increased the channel open probability without changing conductance. Mutational analyses on the tricyclic sulfonamide site confirm the molecular determinants contributing to functional activity. Our findings further define the mechanistic framework underlying the GlyR modulation by this PAM class, suggesting that further structure-driven exploration within the tricyclic sulfonamide site may originate novel glycinergic modulators for future development.

Implementation of a Virtual Reality Intervention in Outpatient Physiotherapy for Chronic Pain: Protocol for a Pilot Implementation Study

BACKGROUND

Chronic pain is a global health issue that causes physical, psychological, and social disabilities for patients, as well as high costs for societies. Virtual reality (VR) is a new treatment that provides an opportunity to narrow the gap between clinical practice and recommended care in the use of patient education and behavioral interventions in the outpatient physiotherapy setting. However, there is currently no implementation strategy to integrate VR treatments into this setting.

OBJECTIVE

This protocol outlines a pilot implementation study that aims to (1) identify barriers and facilitators for implementing a VR intervention in outpatient physiotherapy care for people with chronic pain and (2) develop and pilot test an implementation strategy in 5 practices in Germany.

METHODS

The study consists of 4 phases. The first phase involves adapting the treatment protocol of the VR intervention to the local context of outpatient physiotherapy practices in Germany. The second phase includes the collection of barriers and facilitators through semistructured interviews from physiotherapists and the development of a theory-driven implementation strategy based on the Theoretical Domains framework and the Behavior Change Wheel. This strategy will be applied in the third phase, which will also include a 6-month span of using VR interventions in practices, along with a process evaluation. The fourth phase consists of semistructured interviews to evaluate the developed implementation strategy.

RESULTS

The recruitment process and phase 1, including the adaptation of the treatment protocol, have already been completed. We recruited 5 physiotherapy practices in Lower Saxony, Germany, where the VR intervention will be implemented. The collection of barriers and facilitators through semistructured interviews is scheduled to begin in February 2024.

CONCLUSIONS

This pilot implementation study aims to develop a theory-driven implementation strategy for integrating a VR intervention into outpatient physiotherapy care for people with chronic pain. The identified barriers and facilitators, along with the implementation strategy, will serve as a starting point for future randomized controlled implementation studies in different settings to refine the implementation process and integrate VR interventions into the outpatient care of people with chronic pain.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00030862; https://tinyurl.com/3zf7uujx.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/58089.

Chronic Musculoskeletal Pain and Central Sensitization-Related Symptoms in Chilean Victims of Political Violence During the 1973 to 1990 Dictatorship

People who suffer political violence (PV) are at risk of developing mental illness, chronic noncommunicable diseases, chronic pain, and decreased life expectancy. However, these indicators have been studied primarily in war veterans and refugees. The objective of this study was to estimate the prevalence of chronic musculoskeletal pain (CMP) and central sensitization-related symptoms (CSRS) in Chilean victims of PV during the 1973 to 1990 dictatorship. A cross-sectional observational multicenter study was conducted. Three hundred twenty-five people from six centers of a Ministry of Health of Chile program participated. The presence of CMP was determined by a history of pain ≥3 months, and CSRS was determined using the central sensitization inventory. About 69.23% of the sample had CMP (76.85% of females and 56.56% of males). About 60% of people with CMP showed a high level of CSRS severity (66.67% females and 44.93% males). Females presented significantly higher proportions of CMP (p < .001), and there was an association between CSRS severity and being female (p = .004). Chilean victims of PV during the 1973 to 1990 dictatorship presented a high prevalence of CMP and high-level CSRS severity. Both conditions affected females more than males. Future studies are needed to further delve into these variables' behavior and their influence on the quality of life in this population.

Regulation of Pain Perception by Microbiota in Parkinson Disease

Pain perception involves current stimulation in peripheral nociceptive nerves and the subsequent stimulation of postsynaptic excitatory neurons in the spinal cord. Importantly, in chronic pain, the neural activity of both peripheral nociceptors and postsynaptic neurons in the central nervous system is influenced by several inflammatory mediators produced by the immune system. Growing evidence has indicated that the commensal microbiota plays an active role in regulating pain perception by either acting directly on nociceptors or indirectly through the modulation of the inflammatory activity on immune cells. This symbiotic relationship is mediated by soluble bacterial mediators or intrinsic structural components of bacteria that act on eukaryotic cells, including neurons, microglia, astrocytes, macrophages, T cells, enterochromaffin cells, and enteric glial cells. The molecular mechanisms involve bacterial molecules that act directly on neurons, affecting their excitability, or indirectly on non-neuronal cells, inducing changes in the production of proinflammatory or anti-inflammatory mediators. Importantly, Parkinson disease, a neurodegenerative and inflammatory disorder that affects mainly the dopaminergic neurons implicated in the control of voluntary movements, involves not only a motor decline but also nonmotor symptomatology, including chronic pain. Of note, several recent studies have shown that Parkinson disease involves a dysbiosis in the composition of the gut microbiota. In this review, we first summarize, integrate, and classify the molecular mechanisms implicated in the microbiota-mediated regulation of chronic pain. Second, we analyze the changes on the commensal microbiota associated to Parkinson disease and propose how these changes affect the development of chronic pain in this pathology. SIGNIFICANCE STATEMENT: The microbiota regulates chronic pain through the action of bacterial signals into two main locations: the peripheral nociceptors and the postsynaptic excitatory neurons in the spinal cord. The dysbiosis associated to Parkinson disease reveals increased representation of commensals that potentially exacerbate chronic pain and reduced levels of bacteria with beneficial effects on pain. This review encourages further research to better understand the signals involved in bacteria-bacteria and bacteria-host communication to get the clues for the development of probiotics with therapeutic potential.