Mindfulness intervention improves cognitive function in older adults by enhancing the level of miRNA-29c in neuron-derived extracellular vesicles.

Although mindfulness-based stress reduction (MBSR) improves cognitive function, the mechanism is not clear. In this study, people aged 65 years and older were recruited from elderly communities in Chitose City, Japan, and assigned to a non-MBSR group or a MBSR group. Before and after the intervention, the Japanese version of the Montreal Cognitive Assessment (MoCA-J) was administered, and blood samples were collected. Then, neuron-derived extracellular vesicles (NDEVs) were isolated from blood samples, and microRNAs, as well as the target mRNAs, were evaluated in NDEVs. A linear mixed model analysis showed significant effects of the MBSR x time interaction on the MoCA-J scores, the expression of miRNA(miR)-29c, DNA methyltransferase 3 alpha (DNMT3A), and DNMT3B in NDEVs. These results indicate that MBSR can improve cognitive function by increasing the expression of miR-29c and decreasing the expression of DNMT3A, as well as DNMT3B, in neurons. It was also found that intracerebroventricular injection of miR-29c mimic into 5xFAD mice prevented cognitive decline, as well as neuronal loss in the subiculum area, by down-regulating Dnmt3a  and Dnmt3b  in the hippocampus. The present study suggests that MBSR can prevent neuronal loss and cognitive impairment by increasing the neuronal expression of miR-29c.

Potential effects of mesenchymal stem cell derived extracellular vesicles and exosomal miRNAs in neurological disorders.

Mesenchymal stem cells are multipotent cells that possess anti-inflammatory, anti-apoptotic and immunomodulatory properties. The effects of existing drugs for neurodegenerative disorders such as Alzheimer's disease are limited, thus mesenchymal stem cell therapy has been anticipated as a means of ameliorating neuronal dysfunction. Since mesenchymal stem cells are known to scarcely differentiate into neuronal cells in damaged brain after transplantation, paracrine factors secreted from mesenchymal stem cells have been suggested to exert therapeutic effects. Extracellular vesicles and exosomes are small vesicles released from mesenchymal stem cells that contain various molecules, including proteins, mRNAs and microRNAs. In recent years, administration of exosomes/extracellular vesicles in models of neurological disorders has been shown to improve neuronal dysfunctions, via exosomal transfer into damaged cells. In addition, various microRNAs derived from mesenchymal stem cells that regulate various genes and reduce neuropathological changes in various neurological disorders have been identified. This review summarizes the effects of exosomes/extracellular vesicles and exosomal microRNAs derived from mesenchymal stem cells on models of stroke, subarachnoid and intracerebral hemorrhage, traumatic brain injury, and cognitive impairments, including Alzheimer's disease.

Bone marrow-derived mesenchymal stem cells improve cognitive impairment in an Alzheimer's disease model by increasing the expression of microRNA-146a in hippocampus.

Alzheimer's disease (AD) is characterized by the accumulation of amyloid-ß and tau. We previously reported that administration of bone marrow mesenchymal stem cells (BM-MSCs) ameliorates diabetes-induced cognitive impairment by transferring exosomes derived from these cells into astrocytes. Here, we show that intracerebroventricularly injected BM-MSCs improve cognitive impairment in AD model mice by ameliorating astrocytic inflammation as well as synaptogenesis. Although AD model mice showed an increase in NF-κB in the hippocampus, BM-MSC-treated AD model mice did not show this increase but showed an increase in levels of microRNA (miR)-146a in the hippocampus. Intracerebroventricularly injected BM-MSCs were attached to the choroid plexus in the lateral ventricle, and thus, BM-MSCs may secrete exosomes into the cerebrospinal fluid. In vitro experiments showed that exosomal miR-146a secreted from BM-MSCs was taken up into astrocytes, and an increased level of miR-146a and a decreased level of NF-κB were observed in astrocytes. Astrocytes are key cells for the formation of synapses, and thus, restoration of astrocytic function may have led to synaptogenesis and correction of cognitive impairment. The present study indicates that exosomal transfer of miR-146a is involved in the correction of cognitive impairment in AD model mice.

[Efficacy of Slightly Acidic Electrolyzed Water against Contamination of Water Line of Dental Units].

OBJECTIVES: The purpose of this study was to evaluate the efficacy of slightly acidic electrolyzed water (SAEW) against the contamination of the water line of dental units and the effects of SAEW on the water line. MATERIALS AND METHODS: The experimental material was a prototype dental unit equipped with a SAEW generator. SAEW is directly supplied to each device or part of this unit system. Experimental SAEW samples were collected from a high-speed handpiece (HS-1), an ultrasonic scaler, and a cup filler of the prototype dental unit. Control samples were taken before and after the prescribed flushing from another high-speed handpiece (HS-2) that is directly supplied with tap water in the same dental unit. The samples were analyzed for free chlorine and heterotrophic bacteria for 7 years to assess the efficacy and effects of SAEW. The substances eluted in SAEW were examined to investigate the effect of SAEW on the water line. A questionnaire survey was conducted on patients on whom dental uints supplied with SAEW were used. RESULTS: SAEW always showed a higher free chlorine concentration than tap water during the observation period of 7 years. In HS-2 supplied with tap water, the free chlorine concentration increased significantly owing to the prescribed flushing. SAEW always showed a significantly smaller number of heterotrophic bacteria than tap water. No abnormal levels values of water line components eluted into SAEW were observed. There were few negative comments from patients on whom dental units supplied with SAEW were used. CONCLUSIONS: SAEW continuously used for 7 years was effective for contamination control in the water line of dental units.

Exercise enhances skeletal muscle regeneration by promoting senescence in fibro-adipogenic progenitors.

Idiopathic inflammatory myopathies cause progressive muscle weakness and degeneration. Since high-dose glucocorticoids might not lead to full recovery of muscle function, physical exercise is also an important intervention, but some exercises exacerbate chronic inflammation and muscle fibrosis. It is unknown how physical exercise can have both beneficial and detrimental effects in chronic myopathy. Here we show that senescence of fibro-adipogenic progenitors (FAPs) in response to exercise-induced muscle damage is needed to establish a state of regenerative inflammation that induces muscle regeneration. In chronic inflammatory myopathy model mice, exercise does not promote FAP senescence or resistance against tumor necrosis factor-mediated apoptosis. Pro-senescent intervention combining exercise and pharmacological AMPK activation reverses FAP apoptosis resistance and improves muscle function and regeneration. Our results demonstrate that the absence of FAP senescence after exercise leads to muscle degeneration with FAP accumulation. FAP-targeted pro-senescent interventions with exercise and pharmacological AMPK activation may constitute a therapeutic strategy for chronic inflammatory myopathy.

An enriched environment prevents cognitive impairment in an Alzheimer's disease model by enhancing the secretion of exosomal microRNA-146a from the choroid plexus.

Alzheimer's disease (AD) is characterized by the extensive deposition of amyloid-ß plaques and neurofibrillary tangles. We previously found that preserved function of astrocytes is associated with cognitively normal subjects with AD pathology. Here we show that an enriched environment (EE) can prevent cognitive impairment in AD model mice by ameliorating astrocytic inflammation and increasing synaptic density in the subiculum area of the hippocampus. In AD model mice treated with an EE, increased levels of microRNA (miR)-146a and down-regulation of NF-κB were observed in the hippocampus. In addition, increased levels of interferon (IFN)-γ were seen in serum from mice exposed to an EE. In vitro, enhanced miR-146a expression was observed in exosomes derived from the choroid plexus (CP) after IFN-γ treatment. In further in vitro experiments, we transfected miR-146a into Aß/lipopolysaccharide-induced inflammatory astrocytes and showed that miR-146a ameliorated astrocytic inflammation by down-regulating tumor necrosis factor receptor-associated factor 6 and NF-κB. The present study indicates that following an EE, exosomal miR-146a derived from the CP cells is a key factor in ameliorating astrocytic inflammation, leading to synaptogenesis and correction of cognitive impairment.

p16INK4A-expressing mesenchymal stromal cells restore the senescence-clearance-regeneration sequence that is impaired in chronic muscle inflammation.

BACKGROUND: The therapeutic benefits of mesenchymal stromal cells (MSCs) include treatment of chronic inflammation. However, given the short-lived engraftment of these cells in vivo, their therapeutic efficacy remains mysterious. Transient induction of cellular senescence contributes to activation of immune cells, which promotes clearance of damaged cells during tissue remodelling. This may occur in tissue-resident mesenchymal progenitor cells during regeneration. Elucidation of the role of senescence in tissue-resident mesenchymal progenitor cells during regeneration would provide insight into the profile of therapeutic MSCs for treatment of chronic inflammatory disease. METHODS: We evaluated multipotent mesenchymal progenitor cells, termed fibro/adipogenic progenitors (FAPs), and immune cells in acute muscle injury (AMI) model mice and mice with myosin-induced experimental autoimmune myositis, a model of chronic inflammatory myopathy (CIM). Human bone marrow MSCs were optimised for the treatment of CIM using placental extract. FINDING: FAPs in AMI transiently expressed p16INK4A on days 1 and 2 after injury and recruited phagocytic immune cells, whereas in CIM, p16INK4A expression in FAPs was low. Cellular senescence occurs during the natural maturation of the placenta. Therefore, we used human placental extract to induce p16INK4A expression in therapeutic human bone marrow MSCs in culture. Treatment of CIM with p16INK4A-expressing MSCs promoted tissue remodelling by transiently increasing the abundance of engrafted MSCs, inducing cellular senescence in innate FAPs, and recruiting phagocytic immune cells. INTERPRETATION: MSCs may exert their effect by remodelling the chronic inflammatory environment via senescence-related regenerative processes.

Effect of Once-Weekly Dulaglutide on Glucose Levels in Japanese Patients with Type 2 Diabetes: Findings from a Phase 4, Randomized Controlled Trial.

INTRODUCTION: Dulaglutide is a recombinant glucagon-like peptide-1 immunoglobulin G4 Fc fusion protein approved for treating patients with type 2 diabetes (T2D). The aim of this study was to assess postprandial data over 4 weeks for dulaglutide (0.75 mg) versus placebo after a standardized test meal in Japanese patients with T2D. METHODS: The pharmacodynamic (PD) effects of once-weekly dulaglutide (0.75 mg) in Japanese patients with T2D on diet and exercise therapy (N = 12) were evaluated by assessing postprandial data up to week 4 in a phase 4, single-center, randomized, cross-over, single-blind, placebo-controlled study. The primary end point was the change in 4-h glucose area under the concentration versus time curve [AUC (0-4 h)] from baseline to week 4. Secondary end points included changes from baseline in other PD parameters (insulin, C-peptide, glucagon, and triglycerides) at weeks 1, 2, and 4 and the safety and tolerability of dulaglutide 0.75 mg. Continuous glucose monitoring (CGM) during the 1st week was performed as an exploratory measure in each treatment period. RESULTS: The decrease in AUC (0-4 h) from baseline to week 4 following dulaglutide administration was statistically significant compared with placebo at weeks 1, 2, and 4 (P < 0.0001). Insulin and C-peptide levels were also significantly increased (P < 0.05) with dulaglutide versus placebo at weeks 2 and 4. There were no statistically significant differences between groups in glucagon and triglyceride levels. Daily average glucose concentrations were decreased on the day after the first administration of dulaglutide and remained at similar levels for 4 days. The incidence of treatment-emergent adverse events was slightly higher with dulaglutide versus placebo. CONCLUSION: In conclusion, dulaglutide decreased postprandial glucose from week 1 in Japanese patients with T2D, indicating that dulaglutide treatment is associated with favorable PD effects soon after treatment begins. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT03315780. FUNDING: Eli Lilly Japan K.K. (Kobe, Japan).

An enriched environment prevents diabetes-induced cognitive impairment in rats by enhancing exosomal miR-146a secretion from endogenous bone marrow-derived mesenchymal stem cells.

Increasing evidence suggests that an enriched environment (EE) ameliorates cognitive impairment by promoting repair of brain damage. However, the mechanisms by which this occurs have not been determined. To address this issue, we investigated whether an EE enhanced the capability of endogenous bone marrow-derived mesenchymal stem/stromal cells (BM-MSCs) to prevent hippocampal damage due to diabetes by focusing on miRNA carried in BM-MSC-derived exosomes. In diabetic streptozotocin (STZ) rats housed in an EE (STZ/EE), cognitive impairment was significantly reduced, and both neuronal and astroglial damage in the hippocampus was alleviated compared with STZ rats housed in conventional cages (STZ/CC). BM-MSCs isolated from STZ/CC rats had functional and morphological abnormalities that were not detected in STZ/EE BM-MSCs. The miR-146a levels in exosomes in conditioned medium of cultured BM-MSCs and serum from STZ/CC rats were decreased compared with non-diabetic rats, and the level was restored in STZ/EE rats. Thus, the data suggest that increased levels of miR-146a in sera were derived from endogenous BM-MSCs in STZ/EE rats. To examine the possibility that increased miR-146a in serum may exert anti-inflammatory effects on astrocytes in diabetic rats, astrocytes transfected with miR-146a were stimulated with advanced glycation end products (AGEs) to mimic diabetic conditions. The expression of IRAK1, NF-κB, and tumor necrosis factor-α was significantly higher in AGE-stimulated astrocytes, and these factors were decreased in miR-146a-transfected astrocytes. These results suggested that EEs stimulate up-regulation of exosomal miR-146a secretion by endogenous BM-MSCs, which exerts anti-inflammatory effects on damaged astrocytes and prevents diabetes-induced cognitive impairment.

Umbilical cord extracts improve osteoporotic abnormalities of bone marrow-derived mesenchymal stem cells and promote their therapeutic effects on ovariectomised rats.

Bone marrow-derived mesenchymal stem cells (BM-MSCs) are the most valuable source of autologous cells for transplantation and tissue regeneration to treat osteoporosis. Although BM-MSCs are the primary cells responsible for maintaining bone metabolism and homeostasis, their regenerative ability may be attenuated in postmenopausal osteoporosis patients. Therefore, we first examined potential abnormalities of BM-MSCs in an oestrogen-deficient rat model constructed by ovariectomy (OVX-MSCs). Cell proliferation, mobilisation, and regulation of osteoclasts were downregulated in OVX-MSCs. Moreover, therapeutic effects of OVX-MSCs were decreased in OVX rats. Accordingly, we developed a new activator for BM-MSCs using human umbilical cord extracts, Wharton's jelly extract supernatant (WJS), which improved cell proliferation, mobilisation and suppressive effects on activated osteoclasts in OVX-MSCs. Bone volume, RANK and TRACP expression of osteoclasts, as well as proinflammatory cytokine expression in bone tissues, were ameliorated by OVX-MSCs activated with WJS (OVX-MSCs-WJ) in OVX rats. Fusion and bone resorption activity of osteoclasts were suppressed in macrophage-induced and primary mouse bone marrow cell-induced osteoclasts via suppression of osteoclast-specific genes, such as Nfatc1, Clcn7, Atp6i and Dc-stamp, by co-culture with OVX-MSCs-WJ in vitro. In this study, we developed a new activator, WJS, which improved the functional abnormalities and therapeutic effects of BM-MSCs on postmenopausal osteoporosis.

Activated forms of astrocytes with higher GLT-1 expression are associated with cognitive normal subjects with Alzheimer pathology in human brain.

Although the cognitive impairment in Alzheimer's disease (AD) is believed to be caused by amyloid-ß (Aß) plaques and neurofibrillary tangles (NFTs), several postmortem studies have reported cognitive normal subjects with AD brain pathology. As the mechanism underlying these discrepancies has not been clarified, we focused the neuroprotective role of astrocytes. After examining 47 donated brains, we classified brains into 3 groups, no AD pathology with no dementia (N-N), AD pathology with no dementia (AD-N), and AD pathology with dementia (AD-D), which represented 41%, 21%, and 38% of brains, respectively. No differences were found in the accumulation of Aß plaques or NFTs in the entorhinal cortex (EC) between AD-N and AD-D. Number of neurons and synaptic density were increased in AD-N compared to those in AD-D. The astrocytes in AD-N possessed longer or thicker processes, while those in AD-D possessed shorter or thinner processes in layer I/II of the EC. Astrocytes in all layers of the EC in AD-N showed enhanced GLT-1 expression in comparison to those in AD-D. Therefore these activated forms of astrocytes with increased GLT-1 expression may exert beneficial roles in preserving cognitive function, even in the presence of Aß and NFTs.

Dose-dependent acute liver injury with hypersensitivity features in humans due to a novel microsomal prostaglandin E synthase 1 inhibitor.

AIMS: LY3031207, a novel microsomal prostaglandin E synthase 1 inhibitor, was evaluated in a multiple ascending dose study after nonclinical toxicology studies and a single ascending dose study demonstrated an acceptable toxicity, safety and tolerability profile. METHODS: Healthy subjects were randomized to receive LY3031207 (25, 75 and 275 mg), placebo or celecoxib (400 mg) once daily for 28 days. The safety, tolerability and pharmacokinetic and pharmacodynamic profiles of LY3031207 were evaluated. RESULTS: The study was terminated when two subjects experienced drug-induced liver injury (DILI) after they had received 225 mg LY3031207 for 19 days. Liver biopsy from these subjects revealed acute liver injury with eosinophilic infiltration. Four additional DILI cases were identified after LY3031207 dosing had been stopped. All six DILI cases shared unique presentations of hepatocellular injury with hypersensitivity features and demonstrated a steep dose-dependent trend. Prompt discontinuation of the study drug and supportive medical care resulted in full recovery. Metabolites from metabolic activation of the imidazole ring were observed in plasma and urine samples from all subjects randomized to LY3031207 dosing. CONCLUSIONS: This study emphasized the importance of careful safety monitoring and serious adverse events management in phase I trials. Metabolic activation of the imidazole ring may be involved in the development of hepatotoxicity of LY3031207.

Umbilical cord extracts improve diabetic abnormalities in bone marrow-derived mesenchymal stem cells and increase their therapeutic effects on diabetic nephropathy.

Bone marrow-derived mesenchymal stem cells (BM-MSC) has been applied as the most valuable source of autologous cell transplantation for various diseases including diabetic complications. However, hyperglycemia may cause abnormalities in intrinsic BM-MSC which might lose sufficient therapeutic effects in diabetic patients. We demonstrated the functional abnormalities in BM-MSC derived from both type 1 and type 2 diabetes models in vitro, which resulted in loss of therapeutic effects in vivo in diabetic nephropathy (DN). Then, we developed a novel method to improve abnormalities in BM-MSC using human umbilical cord extracts, namely Wharton's jelly extract supernatant (WJs). WJs is a cocktail of growth factors, extracellular matrixes and exosomes, which ameliorates proliferative capacity, motility, mitochondrial degeneration, endoplasmic reticular functions and exosome secretions in both type 1 and type 2 diabetes-derived BM-MSC (DM-MSC). Exosomes contained in WJs were a key factor for this activation, which exerted similar effects to complete WJs. DM-MSC activated by WJs ameliorated renal injury in both type 1 and type 2 DN. In this study, we developed a novel activating method using WJs to significantly increase the therapeutic effect of BM-MSC, which may allow effective autologous cell transplantation.

Pregnancy and cesarean delivery after multimodal therapy for vulvar carcinoma: A case report.

Reports of pregnancy following treatment for vulvar carcinoma are extremely uncommon, as the main problem of subsequent pregnancy is vulvar scarring following radical surgery. We herein report the case of a patient who was diagnosed with stage I squamous cell carcinoma of the vulva at the age of 17 years and was treated with multimodal therapy, including neoadjuvant chemotherapy, wide local excision with bilateral inguinal lymph node dissection and adjuvant radiotherapy. The patient became pregnant spontaneously 9 years after her initial diagnosis and the antenatal course was good, except for mild acute pyelonephritis at 25 weeks of gestation. An elective caesarean section was performed at 38 weeks of gestation due to vulvar scarring following multimodal therapy, particularly radiotherapy. The patient remains alive and well, without signs of recurrence or metastasis 12 years after her diagnosis and treatment. Radical vulvectomy as well as multimodal therapy for vulvar carcinoma, particularly radiotherapy, may cause extensive skin scarring. The presence of vulvar scarring following multimodal therapy for vulvar carcinoma may increase the incidence of caesarean delivery.

Mesenchymal stem cell therapy ameliorates diabetic nephropathy via the paracrine effect of renal trophic factors including exosomes.

Bone marrow-derived mesenchymal stem cells (MSCs) have contributed to the improvement of diabetic nephropathy (DN); however, the actual mediator of this effect and its role has not been characterized thoroughly. We investigated the effects of MSC therapy on DN, focusing on the paracrine effect of renal trophic factors, including exosomes secreted by MSCs. MSCs and MSC-conditioned medium (MSC-CM) as renal trophic factors were administered in parallel to high-fat diet (HFD)-induced type 2 diabetic mice and streptozotocin (STZ)-induced insulin-deficient diabetic mice. Both therapies showed approximately equivalent curative effects, as each inhibited the exacerbation of albuminuria. They also suppressed the excessive infiltration of BMDCs into the kidney by regulating the expression of the adhesion molecule ICAM-1. Proinflammatory cytokine expression (e.g., TNF-α) and fibrosis in tubular interstitium were inhibited. TGF-ß1 expression was down-regulated and tight junction protein expression (e.g., ZO-1) was maintained, which sequentially suppressed the epithelial-to-mesenchymal transition of tubular epithelial cells (TECs). Exosomes purified from MSC-CM exerted an anti-apoptotic effect and protected tight junction structure in TECs. The increase of glomerular mesangium substrate was inhibited in HFD-diabetic mice. MSC therapy is a promising tool to prevent DN via the paracrine effect of renal trophic factors including exosomes due to its multifactorial action.

Pharmacokinetic Profile and Palatability of Atomoxetine Oral Solution in Healthy Japanese Male Adults.

BACKGROUND AND OBJECTIVES: There is a clinical need for a liquid formulation of atomoxetine. We assessed the safety and bioequivalence of an atomoxetine oral solution. METHODS: This was an open-label, randomized, crossover study. Healthy adult male Japanese subjects (n = 42) with a cytochrome P450 2D6 extensive (including intermediate and ultrarapid) metabolizer genotype were administered atomoxetine 50 mg as oral solution and capsules once each, with a washout period >5 days between doses. Blood samples were used to analyze pharmacokinetic parameters, particularly maximum observed drug concentration (C max) and area under the concentration vs. time curve from time zero to the last time point with a measurable concentration (AUC0-last). Bioequivalence was concluded if the 90 % confidence interval of the ratio of geometric means between formulations for both C max and AUC0-last were within the interval of 0.8-1.25. Safety assessments included determination of adverse events. Taste was evaluated via a five-item questionnaire immediately and 10 min after taking atomoxetine oral solution. RESULTS: Forty subjects completed the study. Plasma concentration-time profiles of atomoxetine oral solution and capsules were similar, and the statistical analysis of systemic exposure showed that the two formulations were bioequivalent. Adverse events were mild and similar in type and frequency between the formulations. For taste acceptability, only 7.1 % of subjects responded that the oral solution would be difficult to take every day. CONCLUSION: Atomoxetine oral solution is bioequivalent to atomoxetine capsules and potentially fulfills the need for an oral solution atomoxetine formulation that will facilitate treatment of children with attention-deficit hyperactivity disorder.

Bone marrow-derived mesenchymal stem cells improve diabetes-induced cognitive impairment by exosome transfer into damaged neurons and astrocytes.

The incidence of dementia is higher in diabetic patients, but no effective treatment has been developed. This study showed that rat bone marrow mesenchymal stem cells (BM-MSCs) can improve the cognitive impairments of STZ-diabetic mice by repairing damaged neurons and astrocytes. The Morris water maze test demonstrated that cognitive impairments induced by diabetes were significantly improved by intravenous injection of BM-MSCs. In the CA1 region of the hippocampus, degeneration of neurons and astrocytes, as well as synaptic loss, were prominent in diabetes, and BM-MSC treatment successfully normalized them. Since a limited number of donor BM-MSCs was observed in the brain parenchyma, we hypothesized that humoral factors, especially exosomes released from BM-MSCs, act on damaged neurons and astrocytes. To investigate the effectiveness of exosomes for treatment of diabetes-induced cognitive impairment, exosomes were purified from the culture media and injected intracerebroventricularly into diabetic mice. Recovery of cognitive impairment and histological abnormalities similar to that seen with BM-MSC injection was found following exosome treatment. Use of fluorescence-labeled exosomes demonstrated that injected exosomes were internalized into astrocytes and neurons; these subsequently reversed the dysfunction. The present results indicate that exosomes derived from BM-MSCs might be a promising therapeutic tool for diabetes-induced cognitive impairment.

Imipramine ameliorates pain-related negative emotion via induction of brain-derived neurotrophic factor.

Depression-like behavior is often complicated by chronic pain. Antidepressants including imipramine (IMI) are widely used to treat chronic pain, but the mechanisms are not fully understood. Brain-derived neurotrophic factor (BDNF) is a neuromodulator that reduces depression by regulating synaptic transmission. We aimed to characterize the antidepressant effects of IMI without analgesia based on BDNF (trkB)-mediated signaling and gene expression in chronic pain. A chronic constriction injury (CCI) model was constructed in Sprague-Dawley (SD) rats. IMI (5 mg/kg, i.p.) was administered from day 10 after CCI. The pain response was assessed using the paw withdrawal latency (PWL) and depression was judged from the immobility time in a forced swim test. Anti-BDNF antibody, K252a, or 5,7-dihydroxytryptamine (5,7-DHT) were used to examine the antidepressant effects of imipramine. Changes in pERK1/2 (immunohistochemistry), 5-HT and BDNF (ELISA), and BDNF mRNA (RT-PCR) were measured in the anterior cingulate cortex (ACC), rostral ventromedial medulla (RVM), and spinal cord. After CCI, rats showed decreased PWL and increased immobility time. A low dose of IMI reduced the immobility time without having analgesic effects. This antidepressant effect was reversed by anti-BDNF antibody, K252a, and 5,7-DHT. IMI reduced excessive activation of pERK1/2 associated with decreased pCREB and BDNF mRNA, and these changes were reversed by 5,7-DHT. These results show that IMI reduces pain-related negative emotion without influencing pain and that this effect is diminished by denervation of 5-HT neurons and by anti-BDNF treatment. IMI also normalizes derangement of ERK/CREB coupling, which leads to induction of BDNF. This suggests a possible interaction between 5-HT and BDNF.