Anti-inflammatory effects of Metformin improve the neuropathic pain and locomotor activity in spinal cord injured rats: introduction of an alternative therapy

A Modern Approach to the Treatment of Traumatic Brain Injury

Background: Traumatic brain injury manifests itself in various forms, ranging from mild impairment of consciousness to severe coma and death. Traumatic brain injury remains one of the leading causes of morbidity and mortality. Currently, there is no therapy to reverse the effects associated with traumatic brain injury. New neuroprotective treatments for severe traumatic brain injury have not achieved significant clinical success. Methods: A literature review was performed to summarize the recent interdisciplinary findings on management of traumatic brain injury from both clinical and experimental perspective. Results: In the present review, we discuss the concepts of traditional and new approaches to treatment of traumatic brain injury. The recent development of different drug delivery approaches to the central nervous system is also discussed. Conclusions: The management of traumatic brain injury could be aimed either at the pathological mechanisms initiating the secondary brain injury or alleviating the symptoms accompanying the injury. In many cases, however, the treatment should be complex and include a variety of medical interventions and combination therapy.

Impaired Carbohydrate Metabolism among Women with Chronic Low Back Pain and the Role of Dietary Carbohydrates: A Randomized Controlled Cross-Over Experiment

Background: Impaired glucose regulation is suggested to be related to chronic low back pain (CLBP), although it is not clear how they interact with each other. Thus, the primary aim of this study was to investigate differences in postprandial glycemic responses (PPGRs) (the first sign of impaired glucose metabolism) to high- (sucrose) and low-glycemic index (GI) (isomaltulose) beverages in normoglycemic women with CLBP and healthy controls (HCs) and explore whether any group that showed greater PPGRs to high-GI beverage intake would benefit when the high-GI beverage was replaced with a low-GI beverage. Secondly, this study aimed to explore the association between PPGR and pain in patients with CLBP. Methods: This study was registered at clinicaltrials.org (NCT04459104) before the start of the study. In this study, 53 CLBP patients and 53 HCs were recruited. After 11-12 h of fasting, each participant randomly received isomaltulose or sucrose. Blood glucose levels were measured during the fasting state and 15, 30, 45, 60, 90, and 120 min after the beverage intake, and each participant underwent experimental pain measures. Results: Compared to the HCs, the CLBP group showed significantly higher PPGRs to sucrose (p < 0.021). Additionally, the CLBP group showed a significantly higher decrease in PPGR (p = 0.045) when comparing PPGR to sucrose with PPGR to isomaltulose. Correlation analysis revealed a positive association between self-reported pain sensitivity and PPGR to sucrose, while there was no association found between any experimental pain measures and glycemic responses. Conclusions: Overall, these findings suggest that normoglycemic CLBP patients might have a higher risk of developing impaired glucose tolerance than the HCs and might benefit more when high-GI foods are replaced with low-GI ones.

Protective Effects of Glatiramer Acetate Against Paclitaxel-Induced Peripheral Neuropathy in Rats: A Role for Inflammatory Cytokines and Oxidative Stress

Chemotherapy-induced peripheral neuropathy (CIPN) is a major challenge for cancer patients who undergo chemotherapy with paclitaxel. Therefore, finding effective therapies for CIPN is crucial. Glatiramer acetate is used to treat multiple sclerosis that exerts neuroprotective properties in various studies. We hypothesized that glatiramer acetate could also improve the paclitaxel-induced peripheral neuropathy. We used a rat model of paclitaxel (2 mg/kg/every other day for 7 doses)-induced peripheral neuropathy. Rats were treated with either different doses of glatiramer acetate (1, 2, 4 mg/kg/day) or its vehicle for 14 days in separate groups. The mechanical and thermal sensitivity of the rats by using the Von Frey test and the Hot Plate test, respectively, were assessed during the study. The levels of oxidative stress (malondialdehyde and superoxide dismutase), inflammatory markers (TNF-α, IL-10, NF-kB), and nerve damage (H&E and S100B staining) in the sciatic nerves of the rats were also measured at the end of study. Glatiramer acetate (2 and 4 mg/kg) exerted beneficial effects on thermal and mechanical allodynia tests. It also modulated the inflammatory response by reducing TNF-α and NF-κB levels, enhancing IL-10 production, and improving the oxidative stress status by lowering malondialdehyde and increasing superoxide dismutase activity in the sciatic nerve of the rats. Furthermore, glatiramer acetate enhanced nerve conduction velocity in all treatment groups. Histological analysis revealed that glatiramer acetate (2 and 4 mg/kg) prevented paclitaxel-induced damage to the nerve structure. These results suggest that glatiramer acetate can alleviate the peripheral neuropathy induced by paclitaxel.

Anti-Neuroinflammatory Effects of Adaptogens: A Mini-Review

Introduction: Adaptogens are a group of plants that exhibit complex, nonspecific effects on the human body, increasing its ability to adapt, develop resilience, and survive in stress conditions. They are found in many traditional medicinal systems and play a key role in restoring the body's strength and stamina. Research in recent years has attempted to elucidate the mechanisms behind their pharmacological effects, but it appears that these effects are difficult to define precisely and involve multiple molecular pathways. Neuroinflammation: In recent years, chronic inflammation has been recognized as one of the common features of many central nervous system disorders (dementia and other neurodegenerative diseases, depression, anxiety, ischemic stroke, and infections). Because of the specific nature of the brain, this process is called neuroinflammation, and its suppression can result in an improvement of patients' condition and may promote their recovery. Adaptogens as anti-inflammatory agents: As has been discovered, adaptogens display anti-inflammatory effects, which suggests that their application may be broader than previously thought. They regulate gene expression of anti- and proinflammatory cytokines (prostaglandins, leukotriens) and can modulate signaling pathways (e.g., NF-κB). Aim: This mini-review aims to present the anti-neuroinflammatory potential of the most important plants classified as adaptogens: Schisandra chinensis, Eleutherococcus senticosus, Rhodiola rosea and Withania somnifera.

Metformin inhibits paclitaxel-induced mechanical allodynia by activating opioidergic pathways and reducing cytokines production in the dorsal root ganglia and thalamus

It has been shown that AMP-activated protein kinase (AMPK) is involved in the nociceptive processing. This observation has prompted us to investigate the effects of the AMPK activator metformin on the paclitaxel-induced mechanical allodynia, a well-established model of neuropathic pain. Mechanical allodynia was induced by four intraperitoneal (i.p) injections of paclitaxel (2 mg/kg.day) in mice. Metformin was administered per os (p.o.). Naltrexoneandglibenclamide were used to investigate mechanisms mediating metformin activity. Concentrations of cytokines in the dorsal root ganglia (DRG) and thalamus were determined. After a single p.o. administration, the two highest doses of metformin (500 and 1000 mg/kg) attenuated the mechanical allodynia. This response was attenuated by all doses of metformin (250, 500 and 1000 mg/kg) when two administrations, 2 h apart, were carried out. Naltrexone (5 and 10 mg/kg, i.p.), but not glibenclamide (20 and 40 mg/kg, p.o.), attenuated metformin activity. Concentrations of tumor necrosis factor (TNF)-α, interleukin (IL)-1β and CXCL-1 in the DRG were increased after administration of paclitaxel. Metformin (1000 mg/kg) reduced concentrations of TNF-α, IL-1β and CXCL-1 in the DRG. Concentration of IL-6, but not TNF-α, in the thalamus was increased after administration of paclitaxel. Metformin (1000 mg/kg) reduced concentration of IL-6 in the thalamus. In summary, metformin exhibits activity in the model of neuropathic pain induced by paclitaxel. This activity may be mediated by activation of opioidergic pathways and reduced production of TNF-α, IL-1β and CXCL-1 in the DRG and IL-6 in the thalamus.

The Pharmacological Treatment of Neuropathic Pain in Children

The International Association for the Study of Pain (IASP) defines neuropathic pain as pain caused by a lesion or disease of the somatosensory nervous system. It is characterized as a clinical condition in which diagnostic studies reveal an underlying cause of an abnormality in the peripheral or central nervous system. Many common causes of neuropathic pain in adults are rare in children. The purpose of this focused narrative review is, to 1) provide an overview of neuropathic pain in children, 2) highlight unique considerations related to the diagnosis and mechanisms of neuropathic pain in children, and 3) perform a comprehensive analysis of the pharmacological treatments available. We emphasize that data for routine use of pharmacological agents in children with neuropathic pain are largely inferred from adult literature with little research performed on pediatric populations, yet have clear evidence of harms to pediatric patients. Based on these findings, we propose risk mitigation strategies such as utilizing topical treatments whenever possible, assessing pain phenotyping to guide drug class choice, and considering pharmaceuticals in the broader context of the multidisciplinary treatment of pediatric pain. Furthermore, we highlight important directions for future research on pediatric neuropathic pain treatment.

Traumatic Human Spinal Cord Injury: Are Single Treatments Enough to Solve the Problem?

Traumatic spinal cord injury (SCI) results in partial or complete motor deficits, such as paraplegia, tetraplegia, and sphincter control, as well as sensory disturbances and autonomic dysregulation such as arterial hypotension, lack of sweating, and alterations in skin lability. All this has a strong psychological impact on the affected person and his/her family, as well as costs to healthcare institutions with an economic burden in the short, medium, and long terms. Despite at least forty years of experimental animal studies and several clinical trials with different therapeutic strategies, effective therapy is not universally accepted. Most of the published works on acute and chronic injury use a single treatment, such as medication, trophic factor, transplant of a cell type, and so on, to block some secondary injury mechanisms or promote some mechanisms of structural/functional restoration. However, despite significant results in experimental models, the outcome is a moderate improvement in muscle strength, sensation, or eventually in sphincter control, which has been considered non-significant in human clinical trials. Here we present a brief compilation of successful individual treatments that have been applied to secondary mechanisms of action. These studies show limited neuroprotective or neurorestorative approaches in animal models and clinical trials. Thus, the few benefits achieved so far represent a rationale to further explore other strategies that seek better structural and functional restoration of the injured spinal cord.

The role of astrocytes response triggered by hyperglycaemia during spinal cord injury

Objective: This manuscript aimed to provide a comprehensive overview of the physiological, molecular, and cellular mechanisms triggered by reactive astrocytes (RA) in the context of spinal cord injury (SCI), with a particular focus on cases involving hyperglycaemia.Methods: The compilation of articles related to astrocyte responses in neuropathological conditions, with a specific emphasis on those related to SCI and hyperglycaemia, was conducted by searching through databases including Science Direct, Web of Science, and PubMed.Results and Conclusions: This article explores the dual role of astrocytes in both neurophysiological and neurodegenerative conditions within the central nervous system (CNS). In the aftermath of SCI and hyperglycaemia, astrocytes undergo a transformation into RA, adopting a distinct phenotype. While there are currently no approved therapies for SCI, various therapeutic strategies have been proposed to alleviate the detrimental effects of RAs following SCI and hyperglycemia. These strategies show promising potential in the treatment of SCI and its likely comorbidities.

The Influence of Sildenafil-Metformin Combination on Hyperalgesia and Biochemical Markers in Diabetic Neuropathy in Mice

Background and objectives: Worldwide, approximately 500 million people suffer from diabetes and at least 50% of these people develop neuropathy. Currently, therapeutic strategies for reducing diabetic neuropathy (DN)-associated pain are limited and have several side effects. The purpose of the study was to evaluate the antihyperalgesic action of different sildenafil (phosphodiesterase-5 inhibitor) and metformin (antihyperglycemic agent) combinations in alloxan-induced DN. Methods: The study included 100 diabetic mice and 20 non-diabetic mice that were subjected to hot and cold stimulus tests. Furthermore, we determined the influence of this combination on TNF-α, IL-6 and nitrites levels in brain and liver tissues. Results: In both the hot-plate and tail withdrawal test, all sildenafil-metformin combinations administered in our study showed a significant increase in pain reaction latencies when compared to the diabetic control group. Furthermore, all combinations decreased blood glucose levels due to the hypoglycemic effect of metformin. Additionally, changes in nitrite levels and pro-inflammatory cytokines (TNF-α and IL-6) were observed after 14 days of treatment with different sildenafil-metformin combinations. Conclusions: The combination of these two substances increased the pain reaction latency of diabetic animals in a dose-dependent manner. Moreover, all sildenafil-metformin combinations significantly reduced the concentration of nitrites in the brain and liver, which are final products formed under the action of iNOS.

Metabolic alterations upon SARS-CoV-2 infection and potential therapeutic targets against coronavirus infection

The coronavirus disease 2019 (COVID-19) caused by coronavirus SARS-CoV-2 infection has become a global pandemic due to the high viral transmissibility and pathogenesis, bringing enormous burden to our society. Most patients infected by SARS-CoV-2 are asymptomatic or have mild symptoms. Although only a small proportion of patients progressed to severe COVID-19 with symptoms including acute respiratory distress syndrome (ARDS), disseminated coagulopathy, and cardiovascular disorders, severe COVID-19 is accompanied by high mortality rates with near 7 million deaths. Nowadays, effective therapeutic patterns for severe COVID-19 are still lacking. It has been extensively reported that host metabolism plays essential roles in various physiological processes during virus infection. Many viruses manipulate host metabolism to avoid immunity, facilitate their own replication, or to initiate pathological response. Targeting the interaction between SARS-CoV-2 and host metabolism holds promise for developing therapeutic strategies. In this review, we summarize and discuss recent studies dedicated to uncovering the role of host metabolism during the life cycle of SARS-CoV-2 in aspects of entry, replication, assembly, and pathogenesis with an emphasis on glucose metabolism and lipid metabolism. Microbiota and long COVID-19 are also discussed. Ultimately, we recapitulate metabolism-modulating drugs repurposed for COVID-19 including statins, ASM inhibitors, NSAIDs, Montelukast, omega-3 fatty acids, 2-DG, and metformin.

Metformin promotes Schwann cell remyelination, preserves neural tissue and improves functional recovery after spinal cord injury

Patients with a spinal cord injury (SCI) usually suffer lifelong disability as a result. Considering this, SCI treatment and pathology study are urgently needed. Metformin, a widely used hypoglycemic drug, has been indicated for its important role in central nervous system diseases. This study aimed to investigate the potential effect of metformin on remyelination after SCI. In the present study, we established a cervical contusion SCI model and metformin treatment was applied after SCI. Biomechanical parameters and behavioral assessment were used to evaluate the severity of injury and the improvement of functional recovery after SCI, respectively. The immunofluorescence and western blot were performed at the terminal time point. Our results showed that treating with metformin after SCI improved functional recovery by reducing the white matter loss and promoting Schwann cell remyelination, and the Nrg1/ErbB signaling pathway may be involved in promoting remyelination mediated by oligodendrocytes and Schwann cells. In addition, the area of spared tissues was significantly increased in the metformin group. However, metformin had no significant effects on the glial scar and inflammation after SCI. In summary, these findings indicated that the role of metformin in Schwann cell remyelination after SCI was probably related to the regulation of the Nrg1/ErbB pathway. It is, therefore, possible to suggest that metformin may be a potential therapy for SCI.

The Effect of Metformin on Chemotherapy-Induced Toxicities in Non-diabetic Breast Cancer Patients: A Randomised Controlled Study

BACKGROUND AND OBJECTIVE

Breast cancer patients treated with adriamycin-cyclophosphamide plus paclitaxel (AC-T) are often challenged with serious adverse effects for which no effective therapies are available. Here, we investigated whether metformin, an antidiabetic drug with additional pleiotropic effects could favourably offset AC-T induced toxicities.

PATIENTS AND METHODS

Seventy non-diabetic breast cancer patients were randomised to receive either AC-T (adriamycin 60 mg/m² + cyclophosphamide 600 mg/m² × 4 cycles Q21 days, followed by weekly paclitaxel 80 mg/m² × 12 cycles) alone or AC-T plus metformin (1700 mg/day). Patients were assessed regularly after each cycle to record the incidence and severity of adverse events based on the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE), version 5.0. Moreover, baseline echocardiography and ultrasonography were done and repeated after the end of neoadjuvant therapy.

RESULTS

Addition of metformin to AC-T resulted in significantly less incidence and severity of peripheral neuropathy, oral mucositis, and fatigue (p < 0.05) compared to control arm. Moreover, the left ventricular ejection fraction (LVEF%) in the control arm dropped from a mean of 66.69 ± 4.57 to 62.2 ± 5.22% (p = 0.0004) versus a preserved cardiac function in the metformin arm (64.87 ± 4.84 to 65.94 ± 3.44%, p = 0.2667). Furthermore, fatty liver incidence was significantly lower in metformin compared with control arm (8.33% vs 51.85%, p = 0.001). By contrast, haematological disturbances caused by AC-T were preserved after concurrent metformin administration (p > 0.05).

CONCLUSION

Metformin offers a therapeutic opportunity for controlling toxicities caused by neoadjuvant chemotherapy in non-diabetic breast cancer patients.

TRIAL REGISTRATION

This randomised controlled trial was registered on November 20, 2019 in ClinicalTrials.gov under registration number: NCT04170465.

Local Inflammatory Mediators Involved in Neuropathic Pain

Polyneuropathy (PNP) is a term to describe diseases of the peripheral nervous system, 50% of which present with neuropathic pain. In some types of PNP, pain is restricted to the skin distally in the leg, suggesting a local regulatory process leading to pain. In this study, we proposed a pro-inflammatory pathway mediated by NF-κB that might be involved in the development of pain in patients with painful PNP. To test this hypothesis, we have collected nerve and skin samples from patients with different etiologies and levels of pain. We performed RT-qPCR to analyze the gene expression of the proposed inflammatory pathway components in sural nerve and in distal and proximal skin samples. In sural nerve, we showed a correlation of TLR4 and TNFα to neuropathic pain, and an upregulation of TNFα in patients with severe pain. Patients with an inflammatory PNP also presented a lower expression of TRPV1 and SIRT1. In distal skin, we found a reduced expression of TLR4 and miR-146-5p, in comparison to proximal skin. Our findings thus support our hypothesis of local inflammatory processes involved in pain in PNP, and further show disturbed anti-inflammatory pathways involving TRPV1 and SIRT1 in inflammatory PNP.

Metformin, a biological and synthetic overview

Metformin is the most widely known anti-hyperglycemic, officially acquired by the USA government in 1995 and in 2001 it became the most prescribed treatment for type II diabetes. But how did it become the must-use drug for this disease in such a short period of time? it all started with traditional medicine, by using a plant known as "goat's rue" for the reduction of blood glucose levels. Its use arose in 1918 and evolved to the metformin synthesis in laboratories a couple of years later, using very rudimentary methods which involved melting and strong heating. Thus, a first synthetic route that allowed the preparation of the initial metformin derivates was established. Some of these resulted toxics, and others outperformed the metformin, reducing the blood glucose levels in such efficient way. Nevertheless, the risk and documented cases of lactic acidosis increased with metformin derivatives like buformin and phenformin. Recently, metformin has been widely studied, and it has been associated and tested in the treatment of type II diabetes, cancer, polycystic ovarian syndrome, cell differentiation to oligodendrocytes, reduction of oxidative stress in cells, weight reduction, as anti-inflammatory and even in the recent COVID-19 disease. Herein we briefly review and analyze the history, synthesis, and biological applications of metformin and its derivates.

Nano-Hydroxyapatite Composite Scaffolds Loaded with Bioactive Factors and Drugs for Bone Tissue Engineering

Nano-hydroxyapatite (n-HAp) is similar to human bone mineral in structure and biochemistry and is, therefore, widely used as bone biomaterial and a drug carrier. Further, n-HAp composite scaffolds have a great potential role in bone regeneration. Loading bioactive factors and drugs onto n-HAp composites has emerged as a promising strategy for bone defect repair in bone tissue engineering. With local delivery of bioactive agents and drugs, biological materials may be provided with the biological activity they lack to improve bone regeneration. This review summarizes classification of n-HAp composites, application of n-HAp composite scaffolds loaded with bioactive factors and drugs in bone tissue engineering and the drug loading methods of n-HAp composite scaffolds, and the research direction of n-HAp composite scaffolds in the future is prospected.

The leptomeninges as a critical organ for normal CNS development and function: First patient and public involved systematic review of arachnoiditis (chronic meningitis)

BACKGROUND & IMPORTANCE

This patient and public-involved systematic review originally focused on arachnoiditis, a supposedly rare "iatrogenic chronic meningitis" causing permanent neurologic damage and intractable pain. We sought to prove disease existence, causation, symptoms, and inform future directions. After 63 terms for the same pathology were found, the study was renamed Diseases of the Leptomeninges (DLMs). We present results that nullify traditional clinical thinking about DLMs, answer study questions, and create a unified path forward.

METHODS

The prospective PRISMA protocol is published at Arcsology.org. We used four platforms, 10 sources, extraction software, and critical review with ≥2 researchers at each phase. All human sources to 12/6/2020 were eligible for qualitative synthesis utilizing R. Weekly updates since cutoff strengthen conclusions.

RESULTS

Included were 887/14286 sources containing 12721 DLMs patients. Pathology involves the subarachnoid space (SAS) and pia. DLMs occurred in all countries as a contributor to the top 10 causes of disability-adjusted life years lost, with communicable diseases (CDs) predominating. In the USA, the ratio of CDs to iatrogenic causes is 2.4:1, contradicting arachnoiditis literature. Spinal fusion surgery comprised 54.7% of the iatrogenic category, with rhBMP-2 resulting in 2.4x more DLMs than no use (p<0.0001). Spinal injections and neuraxial anesthesia procedures cause 1.1%, and 0.2% permanent DLMs, respectively. Syringomyelia, hydrocephalus, and arachnoid cysts are complications caused by blocked CSF flow. CNS neuron death occurs due to insufficient arterial supply from compromised vasculature and nerves traversing the SAS. Contrast MRI is currently the diagnostic test of choice. Lack of radiologist recognition is problematic.

DISCUSSION & CONCLUSION

DLMs are common. The LM clinically functions as an organ with critical CNS-sustaining roles involving the SAS-pia structure, enclosed cells, lymphatics, and biologic pathways. Cases involve all specialties. Causes are numerous, symptoms predictable, and outcomes dependent on time to treatment and extent of residual SAS damage. An international disease classification and possible treatment trials are proposed.

The effect of metformin on ameliorating neurological function deficits and tissue damage in rats following spinal cord injury: A systematic review and network meta-analysis

Spinal cord injury (SCI) is a devastating condition with few treatment options. Metformin, a classical antidiabetic and antioxidant, has extended its application to experimental SCI treatment. Here, we performed a systematic review to evaluate the neurobiological roles of metformin for treating SCI in rats, and to assess the potential for clinical translation. PubMed, Embase, China National Knowledge Infrastructure, WanFang data, SinoMed, and Vip Journal Integration Platform databases were searched from their inception dates to October 2021. Two reviewers independently selected controlled studies evaluating the neurobiological roles of metformin in rats following SCI, extracted data, and assessed the quality of methodology and evidence. Pairwise meta-analyses, subgroup analyses and network analysis were performed to assess the roles of metformin in neurological function and tissue damage in SCI rats. Twelve articles were included in this systematic review. Most of them were of moderate-to-high methodological quality, while the quality of evidence from those studies was not high. Generally, Basso, Beattie, and Bresnahan scores were increased in rats treated with metformin compared with controls, and the weighted mean differences (WMDs) between metformin and control groups exhibited a gradual upward trend from the 3rd (nine studies, n = 164, WMD = 0.42, 95% CI = −0.01 to 0.85, P = 0.06) to the 28th day after treatment (nine studies, n = 136, WMD = 3.48, 95% CI = 2.04 to 4.92, P < 0.00001). Metformin intervention was associated with improved inclined plane scores, tissue preservation ratio and number of anterior horn motor neurons. Subgroup analyses indicated an association between neuroprotection and metformin dose. Network meta-analysis showed that 50 mg/kg metformin exhibited greater protection than 10 and 100 mg/kg metformin. The action mechanisms behind metformin were associated with activating adenosine monophosphate-activated protein kinase signaling, regulating mitochondrial function and relieving endoplasmic reticulum stress. Collectively, this review indicates that metformin has a protective effect on SCI with satisfactory safety and we demonstrate a rational mechanism of action; therefore, metformin is a promising candidate for future clinical trials. However, given the limitations of animal experimental methodological and evidence quality, the findings of this pre-clinical review should be interpreted with caution.

Metformin prevents morphine-induced apoptosis in rats with diabetic neuropathy: a possible mechanism for attenuating morphine tolerance

Morphine is a drug of choice for the treatment of severe and chronic pain, but tolerance to the antinociceptive effect limits its use. The development of tolerance to morphine has recently been associated with neuronal apoptosis. In this study, our aim was to investigate the effects of metformin on morphine-induced neuronal apoptosis and antinociceptive tolerance in diabetic rats. Three days of cumulative dosing were administered to establish morphine tolerance in rats. The antinociceptive effects of metformin (50 mg/kg) and test dose of morphine (5 mg/kg) were considered at 30-min intervals by thermal antinociceptive tests. To induce diabetic neuropathy, streptozotocin (STZ, 65 mg/kg) was injected intraperitoneally. ELISA kits were used to measure caspase-3, bax, and bcl-2 levels from dorsal root ganglion (DRG) tissue. Semi-quantitative scoring system was used to evaluate apoptotic cells with the the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) method. The findings suggest that co-administration of metformin with morphine to diabetic rats showed a significant increase in antinociceptive effect compared to morphine alone. The antinociceptive tests indicated that metformin significantly attenuated morphine antinociceptive tolerance in diabetic rats. In addition, metformin decreased the levels of apoptotic proteins caspase 3 and Bax in DRG neurons, while significantly increased the levels of antiapoptotic Bcl-2. Semi-quantitative scoring showed that metformin provided a significant reduction in apoptotic cell counts in diabetic rats. These data revealed that metformin demonstrated antiapoptotic activity in diabetic rat DRG neurons and attenuated morphine tolerance. The antiapoptotic activity of metformin probably plays a significant role in reducing morphine tolerance.

Curcumin and metformin synergistically modulate peripheral and central immune mechanisms of pain

Metformin is a well-tolerated antidiabetic drug and has recently been repurposed for numerous diseases, including pain. However, a higher dose of metformin is required for effective analgesia, which can potentiate its dose-dependent gastrointestinal side effects. Curcumin is a natural polyphenol and has beneficial therapeutic effects on pain. Curcumin has been used as an analgesic adjuvant with several analgesic drugs, allowing synergistic antinociceptive effects. Nevertheless, whether curcumin can exert synergistic analgesia with metformin is still unknown. In the present study, the nature of curcumin-metformin anti-inflammatory interaction was evaluated in in vitro using lipopolysaccharide-induced RAW 264.7 macrophage and BV-2 microglia cells. In both macrophage and microglia, curcumin effectively potentiates the anti-inflammatory effects of metformin, indicating potential synergistic effects in both peripheral and central pathways of pain. The nature of the interaction between curcumin and metformin was further recapitulated using a mouse model of formalin-induced pain. Coadministration of curcumin and metformin at a 1:1 fixed ratio of their ED₅₀ doses significantly reduced the dose required to produce a 50% effect compared to the theoretically required dose in phase II of the formalin test with a combination index value of 0.24. Besides, the synergistic interaction does not appear to involve severe CNS side effects indicated by no motor alterations, no alterations in short-term and long-term locomotive behaviors, and the general well-being of mice. Our findings suggest that curcumin exerts synergistic anti-inflammation with metformin with no potential CNS adverse effects.

The role of AMPK-dependent pathways in cellular and molecular mechanisms of metformin: a new perspective for treatment and prevention of diseases

Metformin can suppress gluconeogenesis and reduce blood sugar by activating adenosine monophosphate-activated protein kinase (AMPK) and inducing small heterodimer partner (SHP) expression in the liver cells. The main mechanism of metformin’s action is related to its activation of the AMPK enzyme and regulation of the energy balance. AMPK is a heterothermic serine/threonine kinase made of a catalytic alpha subunit and two subunits of beta and a gamma regulator. This enzyme can measure the intracellular ratio of AMP/ATP. If this ratio is high, the amino acid threonine 172 available in its alpha chain would be activated by the phosphorylated liver kinase B1 (LKB1), leading to AMPK activation. Several studies have indicated that apart from its significant role in the reduction of blood glucose level, metformin activates the AMPK enzyme that in turn has various efficient impacts on the regulation of various processes, including controlling inflammatory conditions, altering the differentiation pathway of immune and non-immune cell pathways, and the amelioration of various cancers, liver diseases, inflammatory bowel disease (IBD), kidney diseases, neurological disorders, etc. Metformin’s activation of AMPK enables it to control inflammatory conditions, improve oxidative status, regulate the differentiation pathways of various cells, change the pathological process in various diseases, and finally have positive therapeutic effects on them. Due to the activation of AMPK and its role in regulating several subcellular signalling pathways, metformin can be effective in altering the cells’ proliferation and differentiation pathways and eventually in the prevention and treatment of certain diseases.

Using scaffolds as drug delivery systems to treat bone tumor

Surgery is the principal strategy to treat osteosarcoma and other types of bone tumors, but it causes bone defects that cannot be healed spontaneously. After surgery, patients still need to receive radiotherapy and/or chemotherapy to prevent tumor recurrence and metastasis, which leads to systemic side effects. Bone scaffolds exhibit the potentials to load cargos (drugs or growth factors) and act as drug delivery systems (DDSs) in the osteosarcoma postoperative treatment. This review introduces current types of bone scaffolds and highlights representative works using scaffolds as DDSs to treat osteosarcomas. Challenges and perspectives in the scaffold-based DDSs are also discussed. This review may provide references to develop effective and safe strategies for osteosarcoma postoperative treatment.

The Antidiabetic Drug Metformin Regulates Voltage-Gated Sodium Channel NaV1.7 via the Ubiquitin-Ligase NEDD4-2

The antidiabetic drug metformin has been shown to reduce pain hypersensitivity in preclinical models of chronic pain and in neuropathic pain in humans. Multiple intracellular pathways have been described as metformin targets. Among them, metformin is an activator of the adenosine 5′-monophosphate protein kinase that can in turn modulate the activity of the E3 ubiquitin ligase NEDD4-2 and thus post-translational expression of voltage-gated sodium channels (Na_Vs). In this study, we found that the bulk of the effect of metformin on Na1.7 is dependent on NEDD4-2. In HEK cells, the expression of Na_V1.7 at the membrane fraction, obtained by a biotinylation approach, is only reduced by metformin when cotransfected with NEDD4-2. Similarly, in voltage-clamp recordings, metformin significantly reduced Na_V1.7 current density when cotransfected with NEDD4-2. In mouse dorsal root ganglion (DRG) neurons, without changing the biophysical properties of Na_V1.7, metformin significantly decreased Na_V1.7 current densities, but not in Nedd4L knock-out mice (SNS-Nedd4L^−/−). In addition, metformin induced a significant reduction in NEDD4-2 phosphorylation at the serine-328 residue in DRG neurons, an inhibitory phosphorylation site of NEDD4-2. In current-clamp recordings, metformin reduced the number of action potentials elicited by DRG neurons from Nedd4L^fl/fl, with a partial decrease also present in SNS-Nedd4L^−/− mice, suggesting that metformin can also change neuronal excitability in an NEDD4-2-independent manner. We suggest that NEDD4-2 is a critical player for the effect of metformin on the excitability of nociceptive neurons; this action may contribute to the relief of neuropathic pain.

Effect of Metformin on Locomotor Function Recovery in Rat Spinal Cord Injury Model: A Meta-analysis

Background

Disorder of locomotor function is universal in patients with spinal cord injury (SCI) and has a severe impairment on their quality of life. Metformin, the first-line antidiabetic drug, has been used to improve locomotor function in SCI rats through antioxidative mechanisms recently.

Methods

A search strategy was conducted from databases, including PubMed, Web of Science, MEDLINE, and Scopus database until April 2021. The methodological quality of the animal experimental studies was assessed according to the Systematic Review Centre for Laboratory animal Experimentation's Risk of Bias tool. The weighted mean difference was calculated with the random-effects model.

Results

Seven eligible studies on SCI and metformin were reviewed. The meta-analysis indicated that SCI rats receiving metformin therapy showed a significant locomotor function recovery. Limitations and no obvious publication bias were presented in the studies.

Conclusion

Metformin can promote the recovery of the locomotor function of SCI rats. However, the use of this meta-analysis was influenced due to the not high quality of studies. Consequently, more high-quality studies are necessary for preclinical studies of SCI in the future.

Metformin Treatment Attenuates Brain Inflammation and Rescues PACAP/VIP Neuropeptide Alterations in Mice Fed a High-Fat Diet

High-fat diet (HFD)-induced comorbid cognitive and behavioural impairments are thought to be the result of persistent low-grade neuroinflammation. Metformin, a first-line medication for the treatment of type-2 diabetes, seems to ameliorate these comorbidities, but the underlying mechanism(s) are not clear. Pituitary adenylate cyclase-activating peptide (PACAP) and vasoactive intestinal peptide (VIP) are neuroprotective peptides endowed with anti-inflammatory properties. Alterations to the PACAP/VIP system could be pivotal during the development of HFD-induced neuroinflammation. To unveil the pathogenic mechanisms underlying HFD-induced neuroinflammation and assess metformin’s therapeutic activities, (1) we determined if HFD-induced proinflammatory activity was present in vulnerable brain regions associated with the development of comorbid behaviors, (2) investigated if the PACAP/VIP system is altered by HFD, and (3) assessed if metformin rescues such diet-induced neurochemical alterations. C57BL/6J male mice were divided into two groups to receive either standard chow (SC) or HFD for 16 weeks. A further HFD group received metformin (HFD + M) (300 mg/kg BW daily for 5 weeks) via oral gavage. Body weight, fasting glucose, and insulin levels were measured. After 16 weeks, the proinflammatory profile, glial activation markers, and changes within the PI3K/AKT intracellular pathway and the PACAP/VIP system were evaluated by real-time qPCR and/or Western blot in the hypothalamus, hippocampus, prefrontal cortex, and amygdala. Our data showed that HFD causes widespread low-grade neuroinflammation and gliosis, with regional-specific differences across brain regions. HFD also diminished phospho-AKT^(Ser473) expression and caused significant disruptions to the PACAP/VIP system. Treatment with metformin attenuated these neuroinflammatory signatures and reversed PI3K/AKT and PACAP/VIP alterations caused by HFD. Altogether, our findings demonstrate that metformin treatment rescues HFD-induced neuroinflammation in vulnerable brain regions, most likely by a mechanism involving the reinstatement of PACAP/VIP system homeostasis. Data also suggests that the PI3K/AKT pathway, at least in part, mediates some of metformin’s beneficial effects.

Metformin effect in models of inflammation is associated with activation of ATP-dependent potassium channels and inhibition of tumor necrosis factor-α production

Metformin is an oral hypoglycemic drug widely used in the management of type 2 diabetes mellitus. We have recently demonstrated that metformin exhibits activity in models of nociceptive and neuropathic pain. However, little is known about its effects in experimental models of inflammation and inflammatory pain. Thus, the present study aimed to evaluate the activity of metformin in experimental models of inflammation and inflammatory pain in mice, as well as the underlying mechanisms. Previous (1 h) per os (p.o.) administration of metformin (250, 500 or 1000 mg/kg) inhibited the mechanical allodynia and paw edema induced by intraplantar (i.pl.) injection of carrageenan (600 μg) and also the pleurisy induced by this stimulus (200 μg, intrapleural). In the model of mechanical allodynia and paw edema induced by carrageenan, metformin also exhibited activity when administered after (1 h) the inflammatory stimulus. Metformin (1000 mg/kg) reduced the production of tumor necrosis factor-α induced by i.pl. injection of carrageenan. Metformin antiallodynic effect was not affected by previous administration of naltrexone (5 or 10 mg/kg, intraperitoneal) or cyproheptadine (5 or 10 mg/kg, p.o). However, this effect was abolished by previous administration of glibenclamide (20 or 40 mg/kg, p.o). In conclusion, the results demonstrate the activity of metformin in models of inflammation and inflammatory pain. In addition, the results indicate that the activity of metformin may be mediated by activation of ATP-sensitive potassium channels and reduction of production of inflammatory mediators. Altogether, these results stimulate the conduction of studies aiming to evaluate whether metformin may be repositioned in the treatment of patients with painful and inflammatory disorders.

Therapeutic Effects of Azithromycin on Spinal Cord Injury in Male Wistar Rats: A Role for Inflammatory Pathways

BACKGROUND

 Inflammatory responses, including macrophages/microglia imbalance, are associated with spinal cord injury (SCI) complications. Accumulating evidence also suggests an anti-inflammatory property of azithromycin (AZM).

MATERIAL AND METHODS

 Male Wistar rats were subjected to T9 vertebra laminectomy. SCI was induced by spinal cord compression at this level with an aneurysmal clip for 60 seconds. They were divided into three groups: the sham-operated group and two SCI treatment (normal saline as a vehicle control vs. AZM at 180 mg/kg/d intraperitoneally for 3 days postsurgery; first dose: 30 minutes after surgery) groups. Locomotor scaling and behavioral tests for neuropathic pain were evaluated and compared through a 28-day period. At the end of the study, tissue samples were taken to assess neuroinflammatory changes and neural demyelination using ELISA and histopathologic examinations, respectively. In addition, the proportion of M1/M2 macrophage polarization was assessed by using flow cytometry.

RESULTS

 Post-SCI AZM treatment (180 mg/kg/d for 3 days) significantly improved locomotion (p < 0.01) and decreased sensitivity to mechanical (p < 0.01) and thermal allodynia (p < 0.001). Moreover, there was a significant tumor necrosis factor-α (TNF-α) decline (p < 0.01) and interleukin-10 (IL-10) elevation (p < 0.01) in the spinal cord tissue of the AZM-treated group compared with the control groups 28 days post-SCI. AZM significantly improved neuroinflammation as evidenced by reduction of the M1 expression, elevation of M2 macrophages, and reduction of the M1/M2 ratio in both the dorsal root ganglion and the spinal cord tissue after SCI compared with controls (p < 0.01).

CONCLUSION

 AZM treatment can be considered a therapeutic agent for SCI, as it could reduce neuroinflammation and SCI sensory/locomotor complications.

Outpatient metformin use is associated with reduced severity of COVID-19 disease in adults with overweight or obesity

Observational studies suggest outpatient metformin use is associated with reduced mortality from coronavirus disease-2019 (COVID-19). Metformin is known to decrease interleukin-6 and tumor-necrosis factor-α, which appear to contribute to morbidity in COVID-19. We sought to understand whether outpatient metformin use was associated with reduced odds of severe COVID-19 disease in a large US healthcare data set. Retrospective cohort analysis of electronic health record (EHR) data that was pooled across multiple EHR systems from 12 hospitals and 60 primary care clinics in the Midwest between March 4, 2020 and December 4, 2020. Inclusion criteria: data for body mass index (BMI) > 25 kg/m2 and a positive SARS-CoV-2 polymerase chain reaction test; age ≥ 30 and ≤85 years. Exclusion criteria: patient opt-out of research. Metformin is the exposure of interest, and death, admission, and intensive care unit admission are the outcomes of interest. Metformin was associated with a decrease in mortality from COVID-19, OR 0.32 (0.15, 0.66; p = .002), and in the propensity-matched cohorts, OR 0.38 (0.16, 0.91; p = .030). Metformin was associated with a nonsignificant decrease in hospital admission for COVID-19 in the overall cohort, OR 0.78 (0.58-1.04, p = .087). Among the subgroup with a hemoglobin HbA1c available (n = 1193), the adjusted odds of hospitalization (including adjustment for HbA1c) for metformin users was OR 0.75 (0.53-1.06, p = .105). Outpatient metformin use was associated with lower mortality and a trend towards decreased admission for COVID-19. Given metformin's low cost, established safety, and the mounting evidence of reduced severity of COVID-19 disease, metformin should be prospectively assessed for outpatient treatment of COVID-19.

Ivermectin-functionalized multiwall carbon nanotube enhanced the locomotor activity and neuropathic pain by modulating M1/M2 macrophage and decrease oxidative stress in rat model of spinal cord injury

Since the inflammation and oxidative stress is the main pathophysiological pathway of neural damage in spinal cord injury (SCI), we tried to evaluate the role of ivermectin (IVM) combined with multi-walled carbon nanotube (MWCNT) in the treatment settings of SCI and its underlying mechanism. Wistar rats with T9 vertebra laminectomy in five groups of: sham-operated, vehicle, IVM (0.1 mg/kg), IVM-MWCNT (0.1 mg/kg), and minocycline (90 mg/kg) were used. We evaluated the locomotor scaling and other behavioral tests for neuropathic pain. Also, tissue samples were obtained to evaluate the expression of M1 and M2 macrophage marker, concentration of TNF-α, IL-1β, and IL-1, and oxidative stress level to assess neuroinflammatory changes. Both IVM and IVM-MWCNT after induction of SCI significantly enhanced the experimental tasks' outcomes, including locomotion and neuropathic tests. Also, decreasing in pro-inflammatory cytokines including TNF-α, IL-1β, and IL-1 in the spinal cord and dorsal root ganglion tissues was also notable in both IVM and IVM-MWCNT-treated groups 28 days after induction of SCI in compared to the vehicle-treated SCI group. Both IVM and IVM-MWCNT significantly decreased oxidative stress, induced by SCI, based on the results of ROS and NADPH activity. IVM-MWCNT-treated animals indicated better outcome in every previous experiment in comparison to IVM-treated animals. The effectiveness of IVM-MWCNT was similar to minocycline treatment in all experimental task (as positive control group). IVM-MWCNT might be a novel treatment in spinal cord injury, which could act through decreasing the oxidative stress and increase the polarization of M1 in comparison to M2 macrophages.

Metformin reduces neuroinflammation and improves cognitive functions after traumatic brain injury

Within the brain, traumatic brain injury (TBI) alters synaptic plasticity and increases neuroinflammation and neuronal death. Yet, there lacks effective TBI treatments providing pleiotropic beneficial effects on these diverse cellular processes necessary for functional recovery. Here, we show the diabetes drug, metformin, significantly improves cognitive functions after controlled cortical impact (CCI) injury in mice, showing improved spatial learning and nest building. Furthermore, injured animals treated with metformin exhibit increased ramification of microglia processes, indicating reduced neuroinflammation. Finally, metformin treatment in vitro increased neuronal activation of partitioning defective 1 (Par1), a family of Ser/Thr kinases playing a key role in synaptic plasticity and neuroinflammation. These results suggest metformin is a promising therapeutic agent for targeting multiple cellular processes necessary for functional TBI recovery.

Prevalence and risk factors of thrombotic events on patients with COVID-19: a systematic review and meta-analysis

BACKGROUND

Coagulation abnormalities in COVID-19 patients accompanied with poor prognosis. This study aimed to determine the prevalence and risk factors of thrombotic events on COVID-19 patients.

METHODS

We systematically reviewed all the studies about thrombotic events on COVID-19 patients in PubMed, Embase, Web of Science, MedRxiv, bioRxiv, from Dec 1, 2019 to July 5, 2020. The weighted mean difference (MD) or odds ratio (OR) or relative risk (RR) with 95 % confidence intervals (CI) for clinical data in COVID-19 patients with or without thrombotic events was calculated.

RESULTS

12 articles contained 1083 patients were included for meta-analysis. The prevalence of thrombosis was 22 % (95 % CI 0.08-0.40) in COVID-19 patients and increased to 43 % (95 % CI 0.29-0.65) after admission to the intensive care unit (ICU). Compared with non-thrombotic patients, thrombotic patients had higher levels of D-dimer (MD = 2.79 μg/ml, 95 % CI 2.27-3.31 μg/ml), lactate dehydrogenase (LDH) (MD = 112.71 U/L, 95 % CI 62.40-163.02 U/L), and white blood cells (WBC) (MD = 1.14 *109/L, 95 % CI 0.47-1.81*109/L) while decreased lymphocytes (MD= -0.20*109/L, 95 % CI -0.38 - -0.02*109/L). Age, platelet counts, and male sex tended to be risks while diabetes tended to be a protection for thrombosis for COVID-19 patients, although no statistical difference was achieved. Finally, patients with thrombosis were at a higher risk of death (OR = 2.39, 95 % CI 1.36-4.20).

CONCLUSIONS

Prevalence of thrombosis in COVID-19 patients was high, especially in ICU, though pharmacologic thromboembolism prophylaxis was applied. Therefore, higher levels of D-dimer, LDH, WBC, and decreased lymphocytes needed to be paid close attention to in patients with COVID-19.

Investigating the beneficial effect of aliskiren in attenuating neuropathic pain in diabetic Sprague-Dawley rats

Objectives

Worldwide, diabetic neuropathy (DN) is a major complication of diabetes mellitus. The direct renin inhibitor aliskiren is recognized as a treatment for cardiovascular disease in diabetic patients, but little is known about its potential benefits in cases of diabetic neuropathy. Accordingly, we investigated the effects of aliskiren (ALIS) and gliclazide (GLZ) and their combination therapy on peripheral neuropathy in streptozotocin-induced diabetic rats.

Methods

In total, 112 adult Sprague-Dawley rats were used for this study. Diabetes was induced using streptozotocin (STZ), whereas the control group was treated with an equal volume of citrate buffer. The diabetic rats were divided randomly into six groups according to the proposed treatment regime: diabetic control (DC), gliclazide (GLZ), aliskiren (ALIS), ramipril (RAM), (GLZ + ALIS) and (GLZ + RAM). Behavioural responses to thermal (hot-plate) and mechanical (tail-pinch) pain were evaluated. After eight weeks of daily treatments, the animals were fasted and sacrificed. The blood samples were collected, with the serum separated and subjected to various biochemical and enzyme analyses so as to assess the effect of the treatments on diabetic peripheral neuropathy.

Results

After 8 weeks, aliskiren alone and in combination with gliclazide therapy had a significant effect (P < .001) in reducing blood glucose levels and showed increased hot-plate and tail-flick latencies compared with the diabetic control group. The threshold of mechanical hyperalgesia was also significantly elevated (P < .001).

Conclusions/Interpretations

These data suggest that either aliskerin alone or in combination with gliclazide can protect against the development and progression of diabetic neuropathy.

Metformin and Covid-19: Focused Review of Mechanisms and Current Literature Suggesting Benefit

Metformin is the first-line medication for type 2 diabetes, but it also has a long history of improved outcomes in infectious diseases, such as influenza, hepatitis C, and in-vitro assays of zika. In the current Covid-19 pandemic, which has rapidly spread throughout the world, 4 observational studies have been published showing reduced mortality among individuals with home metformin use. There are several potential overlapping mechanisms by which metformin may reduce mortality from Covid-19. Metformin's past anti-infectious benefits have been both against the infectious agent directly, as well as by improving the underlying health of the human host. It is unknown if the lower mortality suggested by observational studies in patients infected with Covid-19 who are on home metformin is due to direct activity against the virus itself, improved host substrate, or both.

Pharmacological Manipulation of Translation as a Therapeutic Target for Chronic Pain

Dysfunction in regulation of mRNA translation is an increasingly recognized characteristic of many diseases and disorders, including cancer, diabetes, autoimmunity, neurodegeneration, and chronic pain. Approximately 50 million adults in the United States experience chronic pain. This economic burden is greater than annual costs associated with heart disease, cancer, and diabetes combined. Treatment options for chronic pain are inadequately efficacious and riddled with adverse side effects. There is thus an urgent unmet need for novel approaches to treating chronic pain. Sensitization of neurons along the nociceptive pathway causes chronic pain states driving symptoms that include spontaneous pain and mechanical and thermal hypersensitivity. More than a decade of preclinical research demonstrates that translational mechanisms regulate the changes in gene expression that are required for ongoing sensitization of nociceptive sensory neurons. This review will describe how key translation regulation signaling pathways, including the integrated stress response, mammalian target of rapamycin, AMP-activated protein kinase (AMPK), and mitogen-activated protein kinase-interacting kinases, impact the translation of different subsets of mRNAs. We then place these mechanisms of translation regulation in the context of chronic pain states, evaluate currently available therapies, and examine the potential for developing novel drugs. Considering the large body of evidence now published in this area, we propose that pharmacologically manipulating specific aspects of the translational machinery may reverse key neuronal phenotypic changes causing different chronic pain conditions. Therapeutics targeting these pathways could eventually be first-line drugs used to treat chronic pain disorders. SIGNIFICANCE STATEMENT: Translational mechanisms regulating protein synthesis underlie phenotypic changes in the sensory nervous system that drive chronic pain states. This review highlights regulatory mechanisms that control translation initiation and how to exploit them in treating persistent pain conditions. We explore the role of mammalian/mechanistic target of rapamycin and mitogen-activated protein kinase-interacting kinase inhibitors and AMPK activators in alleviating pain hypersensitivity. Modulation of eukaryotic initiation factor 2α phosphorylation is also discussed as a potential therapy. Targeting specific translation regulation mechanisms may reverse changes in neuronal hyperexcitability associated with painful conditions.

Low-dose metformin treatment in the subacute phase improves the locomotor function of a mouse model of spinal cord injury

Metformin, a first-line drug for type-2 diabetes, has been shown to improve locomotor recovery after spinal cord injury. However, there are studies reporting no beneficial effect. Recently, we found that high dose of metformin (200 mg/kg, intraperitoneal) and acute phase administration (immediately after injury) led to increased mortality and limited locomotor function recovery. Consequently, we used a lower dose (100 mg/kg, i.p.) metformin in mice, and compared the effect of immediate administration after spinal cord injury (acute phase) with that of administration at 3 days post-injury (subacute phase). Our data showed that metformin treatment starting at the subacute phase significantly improved mouse locomotor function evaluated by Basso Mouse Scale (BMS) scoring. Immunohistochemical studies also revealed significant inhibitions of microglia/macrophage activation and astrogliosis at the lesion site. Furthermore, metformin treatment at the subacute phase reduced neutrophil infiltration. These changes were in parallel with the increased survival rate of spinal neurons in animals treated with metformin. These findings suggest that low-dose metformin treatment for subacute spinal cord injury can effectively improve the functional recovery possibly through anti-inflammation and neuroprotection. This study was approved by the Institute Animal Care and Use Committee at the University of Texas Medical Branch (approval No. 1008041C) in 2010.

Synthesis, Characterization and Biological Evaluation of Magnolol and Honokiol Derivatives with 1,3,5-Triazine of Metformin Cyclization

Herein, we sought to evaluate the contribution of the 1,3,5-triazine ring through the metformin cyclization unit to the biological activity of magnolol and honokiol-conjugates. One of the phenolic OH groups of magnolol or honokiol was replaced by a 1,3,5-triazine ring to further explore their synthesis and medicinal versatility. In this study, a robust procedure of three steps was adopted for the synthesis of magnolol and honokiol derivatives by alkylation of potassium carbonate with a 1,3,5-triazine ring. To our knowledge, this is the first report to connect one of the phenolic OH positions of magnolol or honokiol to a 1,3,5-triazine ring cyclized by metformin. The structural characterization of three new compounds was carried out via spectroscopic techniques, i.e., 13C NMR, 1H NMR, and HRMS. Surprisingly, these compounds showed no cytotoxicity against RAW 264.7 macrophages but significantly inhibited the proliferation of MCF-7 (human breast cancer cells), HepG2 (human hepatoma cells), A549 (human lung carcinoma cells), and BxPC-3 (human pancreatic carcinoma cells) tumor cell lines. Furthermore, the compounds also significantly inhibited the release of inflammatory cytokines, including nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in the lipopolysaccharide (LPS)-activated mouse cells (RAW 264.7). Among them, compound 2 demonstrated promising broad-spectrum antiproliferative potential with half inhibitory concentration (IC50) values ranging from 5.57 to 8.74 µM and it significantly decreased caspase-3 and Bcl-2 expression in HepG2 cells. These interesting findings show that derivatization of magnolol and honokiol with 1,3,5-triazine affects and modulates their biological properties.

Effects of inflammatory and anti-inflammatory environments on the macrophage mitochondrial function

Mitochondrial response to inflammation is crucial in the metabolic adaptation to infection. This study aimed to explore the mitochondrial response under inflammatory and anti-inflammatory environments, with a focus on the tricarboxylic acid (TCA) cycle. Expression levels of key TCA cycle enzymes and the autophagy-related protein light chain 3b (LC3b) were determined in raw 264.7 cells treated with lipopolysaccharide (LPS) and metformin (Met). Additionally, reactive oxygen species (ROS) levels and mitochondrial membrane potential were assessed using flow cytometry. Moreover, 8-week-old C57BL/6J mice were intraperitoneally injected with LPS and Met to assess the mitochondrial response in vivo. Upon LPS stimulation, the expression of key TCA enzymes, including citrate synthase, α-ketoglutarate dehydrogenase, and isocitrate dehydrogenase 2, and the mitochondrial membrane potential decreased, whereas the levels of LC3b and ROS increased. However, treatment with Met inhibited the reduction of LPS-induced enzyme levels as well as the elevation of LC3b and ROS levels. In conclusion, the mitochondrial TCA cycle is affected by the inflammatory environment, and the LPS-induced effects can be reversed by Met treatment.

Metformin: A Prospective Alternative for the Treatment of Chronic Pain

Metformin (biguanide) is a drug widely used for the treatment of type 2 diabetes. This drug has been used for 60 years as a highly effective antihyperglycemic agent. The search for the mechanism of action of metformin has produced an enormous amount of research to explain its effects on gluconeogenesis, protein metabolism, fatty acid oxidation, oxidative stress, glucose uptake, autophagy and pain, among others. It was only up the end of the 1990s and beginning of this century that some of its mechanisms were revealed. Metformin induces its beneficial effects in diabetes through the activation of a master switch kinase named AMP-activated protein kinase (AMPK). Two upstream kinases account for the physiological activation of AMPK: liver kinase B1 and calcium/calmodulin-dependent protein kinase kinase 2. Once activated, AMPK inhibits the mechanistic target of rapamycin complex 1 (mTORC1), which in turn avoids the phosphorylation of p70 ribosomal protein S6 kinase 1 and phosphatidylinositol 3-kinase/protein kinase B signaling pathways and reduces cap-dependent translation initiation. Since metformin is a disease-modifying drug in type 2 diabetes, which reduces the mTORC1 signaling to induce its effects on neuronal plasticity, it was proposed that these mechanisms could also explain the antinociceptive effect of this drug in several models of chronic pain. These studies have highlighted the efficacy of this drug in chronic pain, such as that from neuropathy, insulin resistance, diabetic neuropathy, and fibromyalgia-type pain. Mounting evidence indicates that chronic pain may induce anxiety, depression and cognitive impairment in rodents and humans. Interestingly, metformin is able to reverse some of these consequences of pathological pain in rodents. The purpose of this review was to analyze the current evidence about the effects of metformin in chronic pain and three of its comorbidities (anxiety, depression and cognitive impairment).

Dual-functional scaffolds of poly(L-lactic acid)/nanohydroxyapatite encapsulated with metformin: Simultaneous enhancement of bone repair and bone tumor inhibition

Bone defects caused by tumors are difficult to repair clinically because of their poor morphology and residual tumor cell-induced recurrence. Scaffolds with the dual function of bone repair and bone tumor treatment are urgently needed to resolve this problem. In this study, a poly(L-lactic acid) (PLLA)/nanoscale hydroxyapatite (nHA)/metformin (MET) nanocomposite scaffold was constructed via selective laser sintering. The scaffolds were expected to combine the excellent mechanical strength and biodegradability of PLLA, the good bioactivity of nHA, and the water solubility and antitumor properties of MET. The PLLA/nHA/MET scaffolds showed improved cell adhesion, appropriate porosity, good biocompatibility and osteogenic-induced ability in vitro because metformin improves water solubility and promotes the osteogenic differentiation of cells within the scaffold. The PLLA/nHA/MET scaffold had an extended drug release time because the MET particles were wrapped in the biodegradable polymer PLLA and the wrapped MET particles were slowly released into body fluids as the PLLA was degraded. Moreover, the scaffold induced osteosarcoma (OS) cell apoptosis by upregulating apoptosis-related gene expression and showed excellent tumor inhibition characteristics in vitro. In addition, the scaffold induced osteogenic differentiation of bone marrow mesenchymal cells (BMSCs) by promoting osteogenic gene expression. The results suggest that the PLLA/nHA/MET composite scaffold has the dual function of tumor inhibition and bone repair and therefore it provides a promising new approach for the treatment of tumor-induced bone defects.

Sex differences in neuro(auto)immunity and chronic sciatic nerve pain

Chronic pain occurs with greater frequency in women, with a parallel sexually dimorphic trend reported in sufferers of many autoimmune diseases. There is a need to continue examining neuro-immune-endocrine crosstalk in the context of sexual dimorphisms in chronic pain. Several phenomena in particular need to be further explored. In patients, autoantibodies to neural antigens have been associated with sensory pathway hyper-excitability, and the role of self-antigens released by damaged nerves remains to be defined. In addition, specific immune cells release pro-nociceptive cytokines that directly influence neural firing, while T lymphocytes activated by specific antigens secrete factors that either support nerve repair or exacerbate the damage. Modulating specific immune cell populations could therefore be a means to promote nerve recovery, with sex-specific outcomes. Understanding biological sex differences that maintain, or fail to maintain, neuroimmune homeostasis may inform the selection of sex-specific treatment regimens, improving chronic pain management by rebalancing neuroimmune feedback. Given the significance of interactions between nerves and immune cells in the generation and maintenance of neuropathic pain, this review focuses on sex differences and possible links with persistent autoimmune activity using sciatica as an example.

Therapeutic effect of metformin on inflammation and apoptosis after spinal cord injury in rats through the Wnt/β-catenin signaling pathway

OBJECTIVE

To verify the effect of metformin on spinal cord injury (SCI) through Wnt/β-catenin signaling pathway.

BACKGROUND

SCI is a serious traumatic disease of the central nervous system. Wnt/β-catenin signaling pathway plays important roles in SCI. Metformin has been reported to exert neuroprotective effects in the central nervous system. Whether metformin could improve SCI through Wnt/β-catenin signaling pathway remains unclear.

METHODS

Rats were divided into sham group, SCI group, SCI + metformin group, metformin + XAV939 group (XAV939 is an effective inhibitor of the Wnt/β-catenin signaling pathway), and methylprednisolone group. BBB scores were used to detect motor function recovery at different time points (0, 1, 3, 7, 14, 21, and 28 days) in SCI rats. Western blot analysis, immunofluorescence, TUNEL, HE and Nissl staining were used to observe the morphological characteristics of spinal cord tissue and the expression of inflammation and apoptosis in spinal cord neurons.

RESULTS

Metformin(50 mg/kg) promoted motor functional recovery in rats after SCI, increased the expressions of β-catenin and brain derived neurotrophic factor (BDNF), inhibited neuron apoptosis and inflammatory response, and improved the recovery of pathological morphology at the injury site by activating the Wnt/β-catenin signaling pathway.

CONCLUSION

We found a possible mechanism that metformin could reduce inflammation and apoptosis, and promote functional recovery of SCI rats through activating Wnt/β-catenin signaling pathway.

Antibiotics with therapeutic effects on spinal cord injury: a review

Accumulating evidence indicates that a considerable number of antibiotics exert anti-inflammatory and neuroprotective effects in different central and peripheral nervous system diseases including spinal cord injury (SCI). Both clinical and preclinical studies on SCI have found therapeutic effects of antibiotics from different families on SCI. These include macrolides, minocycline, β-lactams, and dapsone, all of which have been found to improve SCI sequels and complications. These antibiotics may target similar signaling pathways such as reducing inflammatory microglial activity, promoting autophagy, inhibiting neuronal apoptosis, and modulating the SCI-related mitochondrial dysfunction. In this review paper, we will discuss the mechanisms underlying therapeutic effects of these antibiotics on SCI, which not only could supply vital information for investigators but also guide clinicians to consider administering these antibiotics as part of a multimodal therapeutic approach for management of SCI and its complications.

Spinal Cord Injury: Pathophysiology, Multimolecular Interactions, and Underlying Recovery Mechanisms

Spinal cord injury (SCI) is a destructive neurological and pathological state that causes major motor, sensory and autonomic dysfunctions. Its pathophysiology comprises acute and chronic phases and incorporates a cascade of destructive events such as ischemia, oxidative stress, inflammatory events, apoptotic pathways and locomotor dysfunctions. Many therapeutic strategies have been proposed to overcome neurodegenerative events and reduce secondary neuronal damage. Efforts have also been devoted in developing neuroprotective and neuro-regenerative therapies that promote neuronal recovery and outcome. Although varying degrees of success have been achieved, curative accomplishment is still elusive probably due to the complex healing and protective mechanisms involved. Thus, current understanding in this area must be assessed to formulate appropriate treatment modalities to improve SCI recovery. This review aims to promote the understanding of SCI pathophysiology, interrelated or interlinked multimolecular interactions and various methods of neuronal recovery i.e., neuroprotective, immunomodulatory and neuro-regenerative pathways and relevant approaches.

The Antidiabetic Metformin as an Adjunct to Antidepressants in Patients with Major Depressive Disorder: A Proof-of-Concept, Randomized, Double-Blind, Placebo-Controlled Trial

Metformin (MET) has been reported to have antidepressant effects in animal models and in diabetic patients with depression, owing to its anti-inflammatory, antioxidant, and neuroprotective activity. Accordingly, we proposed that MET would show antidepressant effects in patients with major depressive disorder (MDD) without other comorbidities. In this double-blind placebo-controlled study, 80 adult outpatients with MDD (DSM-IV criteria) and a Hamilton Depression Rating Scale (HAM-D) score >18 were randomized to receive fluoxetine 20 mg once daily plus placebo (n = 40) or fluoxetine 20 mg once daily plus MET 1000 mg once daily for 12 weeks. Patients were assessed by HAM-D score (weeks 0, 4, 8, and 12). The serum levels of TNF-α, IL-1β, IL-6, IGF-1, MDA, CRP, BDNF, and serotonin were measured before and after therapy. Mixed-effects model repeated-measures analysis of covariance was used to compare the HAM-D scores and the biological markers between the two groups. After 4, 8 and 12 weeks, patients in the MET group showed a statistically significant decline in HAM-D score relative to the placebo group (least squares mean difference [LSMD] -2.347, p = 0.000, LSMD -3.369, p = 0.000, and LSMD -3.454, p = 0.000, respectively). Response and remission rates were significantly higher in the MET group (89% and 81%, respectively) than in the placebo group (59% and 46%, respectively). Moreover, the MET group was superior in conserving the measured biological markers compared with the placebo group. Our findings suggest MET as a promising, effective, and safe short-term adjunctive approach in nondiabetic MDD patients. Trial registration ID: NCT04088448.

Sumatriptan improves the locomotor activity and neuropathic pain by modulating neuroinflammation in rat model of spinal cord injury

OBJECTIVES

To investigate the therapeutic effects of sumatriptan in a rat model of spinal cord injury (SCI) and possible anti-inflammatory and analgesic mechanisms underlying this effect.

METHODS

Using an aneurysm mini-clip model of contusive SCI, T9-10 laminectomies were performed for 60 male rats. Animals were divided into six experimental groups (n = 10 per group) as follows: a minocycline administered positive control group, a saline-vehicle negative control group, a sham-operated group, and three experimental groups which received separate doses of sumatriptan (0.1, 0.3 and 1 mg/kg). Behavioural assessments were used to evaluate locomotor activity and neuropathic pain for 28 days. At the end of the study, spinal cord tissues were collected from sacrificed animals for histopathological analysis. Levels of calcitonin gene-related peptide (CGRP) and two pro-inflammatory cytokines (tumor necrosis factor [TNF]-α and interleukin [IL]-1β) were assessed by the enzyme-linked immunosorbent assay (ELISA).

RESULTS

Sumatriptan significantly (P < 0.001) improved the locomotor activity in SCI group. Sumatriptan was also more effective than the positive control, i.e. minocycline (0.3 mg/kg). Additionally, sumatriptan and minocycline similarly attenuated the mechanical and thermal allodynia in SCI (P < 0.001). TNF-α, IL-1β and CGRP levels in sumatriptan- and minocycline-treated groups significantly (P < 0.001) decreased compared to controls. Histopathological analysis also revealed a markedly improvement in hemorrhage followed by inflammatory cell invasion, neuronal vacuolation, and cyst formation in both sumatriptan- and minocycline-treated groups compared to control animals.

CONCLUSIONS

Sumatriptan improves functional recovery from SCI through its anti-inflammatory effects and reducing pro-inflammatory and pain mediators.

Neuroimmune System as a Driving Force for Plasticity Following CNS Injury

Following an injury to the central nervous system (CNS), spontaneous plasticity is observed throughout the neuraxis and affects multiple key circuits. Much of this spontaneous plasticity can elicit beneficial and deleterious functional outcomes, depending on the context of plasticity and circuit affected. Injury-induced activation of the neuroimmune system has been proposed to be a major factor in driving this plasticity, as neuroimmune and inflammatory factors have been shown to influence cellular, synaptic, structural, and anatomical plasticity. Here, we will review the mechanisms through which the neuroimmune system mediates plasticity after CNS injury. Understanding the role of specific neuroimmune factors in driving adaptive and maladaptive plasticity may offer valuable therapeutic insight into how to promote adaptive plasticity and/or diminish maladaptive plasticity, respectively.

The protective effect of modafinil on vincristine-induced peripheral neuropathy in rats: A possible role for TRPA1 receptors

Vincristine (VCR) induces peripheral neuropathy. We aimed to assess the efficacy of modafinil on VCR-induced neuropathy in rats. Neuropathy was induced by intraperitoneal (i.p.) injections of VCR (0.1 mg/kg). Neuropathic groups received modafinil (5, 25 and 50 mg/kg); gabapentin (20 mg/kg); and a combination of modafinil (5 and 50 mg/kg) and gabapentin (20 mg/kg,). Then, electrophysiological, behavioural, biochemical and pathological evaluations were performed. Latencies of tail-flick and von Frey filament tests, motor nerve conduction velocity (MNCV) and excitation of nerve conduction were decreased. Moreover, the transient receptor potential cation channel ankyrin 1 (TRPA1) level was increased, while TRPV1 and N-Methyl-D-aspartate (NMDA) levels remained unchanged. Tumour necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) levels were markedly elevated. Pre-treatment with modafinil prevented sensorimotor neuropathy by raising latencies, MNCV and excitation, reducing TRPA1, TNF-α and IL-1β levels. Modafinil improved behavioural, electrophysiological and pathological disturbances. The results showed that TRPA1 has a more important role than NMDA and TRPV1, in VCR-induced neuropathic pain. In addition, inflammatory mediators, TNF-α and IL-1β, were involved. Further, the combination of modafinil and gabapentin improved the neuroprotective effect of gabapentin. So, modafinil might be a neuroprotective agent in the prevention of VCR-induced neuropathy.

Inhibition of phosphodiesterase IV enzyme improves locomotor and sensory complications of spinal cord injury via altering microglial activity: Introduction of Roflumilast as an alternative therapy

Despite the great search for an effective approach to minimize secondary injury in spinal cord injury (SCI) setting, there have been limited advances. Roflumilast is a selective inhibitor of phosphodiesterase 4 with potent anti-inflammatory properties. Here, we sought to explore Roflumilast efficacy in the improvement of locomotor and sensory deficits of SCI. In an animal setting, 50 male rats were randomly assigned to five groups: an SCI group receiving Placebo, three SCI groups receiving Roflumilast at the doses of 0.25, 0.5, and 1 mg/kg prior to T9 vertebra laminectomy, and a sham-operated group. Locomotor, mechanical, and thermal activities were evaluated for 28 days. At the end of the study, spinal cord samples were taken to assess the relative ratio of microglial subtypes, including M1 and M2, histopathological changes, levels of pro-inflammatory (TNF-α and IL-1β) and anti-inflammatory (IL-10) biomarkers, and cAMP level. Repeated measure analysis revealed significant effect for time-treatment interaction on locomotion [F (24, 270) = 280.7, p < 0.001], thermal sensitivity [F (16, 180) = 4.35, p < 0.001], and mechanical sensitivity [F (16, 180) = 7.96, p < 0.001]. As expected, Roflumilast significantly increased the expression of spinal cAMP. H&E staining exhibited lesser histopathological disruptions in Roflumilast-treated rodents. We also observed a significant reduction in the M1/M2 ratio (p values < 0.001) as well as in pro-inflammatory biomarkers following the administration of Roflumilast to the injured rats. Furthermore, IL-10 level was increased in rodents receiving 1 mg/kg of the reagent. In conclusion, the increased spinal cAMP following Roflumilast therapy might attenuate neuroinflammation via altering microglial activity; therefore, it could be considered as an alternative therapeutic agent for SCI complications.

Metformin loaded phosphatidylserine nanoliposomes improve memory deficit and reduce neuroinflammation in streptozotocin-induced Alzheimer's disease model

Alzheimer's disease (AD) is closely associated with neuroinflammation development in the brain. Co-delivery of metformin (MET) with phosphatidylserine liposomes neuroprotectant may be beneficial in ameliorating AD-related symptoms like memory impairment and inflammation. Therefore, we aimed to prepare metformin containing phosphatidylserine nanoliposomes formulation (MET-PSL) and to evaluate its effect on rats subjected to AD. Alzheimer's disease model was induced by bilateral intracerebroventricular injection of streptozotocin (3 mg/kg) into rat brains using the stereotactic technique. MET-PSL, MET, and PSL alone were administered intraperitoneally to AD-induced animals and factors including learning and memory storage in addition to cytokine and tissue inflammatory changes were evaluated after a 22-day experiment period. The learning and memory parameters significantly (P < 0.05) improved in AD-rats treated with MET-PSL. Moreover, MET-PSL administration significantly (P < 0.05) decreased cytokine levels of IL1-β, TNF-α, and TGF-β in hippocampal tissues of rats with AD. Histological results indicated a considerable reduction in inflammatory and necrotic neural cells along with significantly (P < 0.05) increased neurogenesis in MET-PSL treated rats. Furthermore, our results showed that MET-PSL formulation could potentially act better than the free form of MET and PSL alone in the recovery process of rats with AD. In general, our data suggest that combination therapy of metformin loaded phosphatidylserine liposomes may enhance the therapeutic performance in AD patients of a clinical study.

Exploration of metformin as novel therapy for osteoarthritis: preventing cartilage degeneration and reducing pain behavior

BACKGROUND

Metformin could activate adenosine monophosphate-activated protein kinase (AMPK) which was postulated as a potential therapeutic target for osteoarthritis. This study aimed to examine the effects of metformin on cartilage and pain in osteoarthritis mouse model.

METHODS

Eighty 10-week-old male C57BL/6 mice were randomized to 6 groups: non-operation, sham-operation, destabilization of the medial meniscus (DMM)-operation with intragastric saline/metformin, and DMM-operation with intraarticular saline/metformin. Articular cartilage degeneration was examined by scanning electron microscopy (SEM) and graded using the scoring system recommended by Osteoarthritis Research Society International (OARSI). Mechanical withdrawal threshold and hind paw weight distribution were measured to assess the pain-related behavior. Cell Counting Kit-8 assay, quantificational real-time polymerase chain reaction, and western blot analysis were conducted to examine the anabolic and anti-catabolic effect of metformin and the role of AMPK in mediating its effects on interleukin-1β stimulated primary mice chondrocytes.

RESULTS

Compared with mice receiving intragastric and intraarticular saline, mice in both intragastric and intraarticular metformin displayed attenuated articular cartilage degeneration, indicated by less cartilage damage under SEM and significantly lower OARSI scores. A higher paw withdrawal threshold and a decreased weight-bearing asymmetry were observed in the intragastric and intraarticular metformin mice compared with their corresponding saline groups in DMM model of osteoarthritis. In vitro experiments showed that metformin not only decreased the level of matrix metalloproteinase 13, but also elevated type II collagen production through activating AMPK pathway.

CONCLUSIONS

Metformin attenuates osteoarthritis structural worsening and modulates pain, suggesting its potential for osteoarthritis prevention or treatment.