Accepted

The underlying mechanisms of opioid-induced hyperalgesia (OIH) remain unclear. Herein, we found that the protein expression of metabotropic glutamate receptor 1 (mGluR1) was significantly increased in the right but not in the left laterocapsular division of central nucleus of the amygdala (CeLC) in OIH rats. In CeLC neurons, the frequency and the amplitude of mini-excitatory postsynaptic currents (mEPSCs) were significantly increased in fentanyl group which were decreased by acute application of a mGluR1 antagonist, A841720. Finally, the behavioral hypersensitivity could be reversed by A841720 microinjection into the right CeLC. These results show that the right CeLC mGluR1 is an important factor associated with OIH that enhances synaptic transmission and could be a potential drug target to alleviate fentanyl-induced hyperalgesia.

The glymphatic system is a recently discovered glial-dependent macroscopic interstitial waste clearance system that promotes the efficient elimination of soluble proteins and metabolites from the central nervous system. Its anatomic foundation is the astrocytes and aquaporin-4 (AQP4) water channels on the endfeet of astrocytes. The aim of this study is to evaluate the plasticity of the spinal glymphatic system in male SD rats with painful diabetic neuropathy (PDN) induced by type 2 diabetes mellitus. PDN rats were modeled under a high-fat and high-glucose diet with a low dose of streptozotocin. MRI was applied to observe the infiltration and clearance of contrast to indicate the functional variability of the glymphatic system at the spinal cord level. The paw withdrawal threshold was used to represent mechanical allodynia. The numerical change of glial fibrillary acidic protein (GFAP) positive astrocytes was assessed and the polarity reversal of AQP4 protein was measured by immunofluorescence. As a result, deceased contrast infiltration and clearance, enhanced mechanical allodynia, increased number of GFAP positive astrocytes, and reversed polarity of AQP4 protein were found in the PDN rats. The above molecular level changes may contribute to the impairment of the spinal glymphatic system in PDN rats. This study revealed the molecular and functional variations of the spinal glymphatic system in PDN rats and for the first time indicated that there might be a correlation between the impaired spinal glymphatic system and PDN rats.

This report illustrates the case of a female patient suffering from severe ocular discomfort, tinnitus and ageusia, 7 months after a SARS-CoV-2 infection. The medical history implicated a diagnosis of LONG-COVID with ocular pain as the most debilitating symptom. In-vivo confocal microscopy revealed corneal microneuromas with hyperreflectivity and irregular enlargement of nerve endings in both eyes, which led to the diagnosis of neuropathic corneal pain. The aim of this report is to increase awareness that COVID-19 induced neuropathic pain can also occur in the cornea representing the human body's most richly innervated tissue.

Fibromyalgia is a chronic medical condition of unclear etiopathology that diminished patients' quality of life; chronic pain is the main symptom, yet patients with fibromyalgia struggle also with depression, anxiety, and insomnia. For many years, pharmaceutical management of pain was the mainstay of treatment. In the latest decade, conventional low-impact aerobic exercise and complementary and alternative medical (CAM) exercise have become important when structuring a personalized therapeutic plan, since side effects are practically inexistent. Heterogenous studies with different methodological approaches have failed to display a clear clinical effect. We conducted a systematic review with meta-analysis of clinical trials putting emphasis on standardized measurable outcomes (Fibromyalgia Impact Questionnaire, FIQ) in our effort to draw a safe conclusion on CAM exercise's effect. After analyzing 14 studies, including 886 patients, meta analysis showed CAM exercise had a beneficial effect on patients' FIQ score reports: standardized mean difference (SMD) 1.330 (95% CI 0.733-1.928). Among them, dance and Tai chi, had a more profound effect: SMD 1.969 (95% CI 0.575-3.364) and SMD 1.852 (95% CI 0.119-3.584), respectively. However, the risk of bias was overall medium to high and statistical heterogeneity was very high. Our meta-regression analysis failed to identify any variable that could account for high heterogeneity. Even though more experimental studies should be done on this subject, CAM exercise seems beneficial for patients with Fibromyalgia.

Chronic low back pain it is one of the most common health problems worldwide. Usually is accompanied by a complex set of symptoms and generates significant direct and indirect socioeconomic and health costs. From a therapeutic point of view, there are a wide variety of methods to address the treatment of this pathology, however, these therapies have not been shown definitive efficacy. To investigate the effect of a mixed treatment with exercise and electrical stimulation versus exercise and kinesio taping in patients with non-specific chronic low back pain. A total of 58 patients participated in this single-blinded randomised clinical trial. Participants were assigned to the exercises- kinesio taping group, or exercises- analgesic current group, both received 12 treatment sessions. Disability, fear of movement, anxiety, depression, sleeps quality, pain, lower limb mechanosensitivity and pressure-pain thresholds were recorded at baseline and after 4 weeks of treatment. The 2 × 2 mixed analysis of covariance test showed statistically significant differences between groups for pain (P = 0.046). Pair-wise comparisons with baseline demonstrated significant differences for both groups in pain (P ≤ 0.001), disability (P ≤ 0.001), pressure-pain thresholds (P ≤ 0.044), lower limb mechanosensitivity, (P ≤ 0.047), anxiety (P ≤ 0.001), depression (P ≤ 0.001) and sleep quality (P ≤ 0.010). Patients with chronic low back pain who received a combined treatment of exercises and kinesio taping or analgesic current showed an improvement in pain, disability, anxiety, depression and sleep pattern. Moreover, exercises combined with electrotherapy produces greater improvements over these variables.Trial registration: NCT02812459.