[Effect of dietary water-soluble vitamins on the poor prognosis of low-grade cervical intraepithelial neoplasia-a prospective cohort study]

Objective: To explore the effect of dietary water-soluble vitamins on the poor prognosis of low-grade cervical intraepithelial neoplasia (CINⅠ). Methods: A total of 564 participants with CINⅠ were selected from a community-based married women cohort established in 2014. The general baseline information was collected, and HPV genotyping was detected. A food frequency questionnaire was used to investigate dietary water-soluble vitamins' consumption and determine their exposure levels. The follow-up program was carried out for 12 months, and the regression, persistence, and progression of CINⅠ was determined according to histopathological results at 12-month. Results: The low-levels of dietary water-soluble vitamins could promote CINⅠ's persistence and progression, showing the increasing tendency of CINⅠ poor prognosis with the decrease of water-soluble vitamin levels. Especially folate, VB1, VB2, VB6, niacin, biotin, and VC (RR values were 15.22, 1.86, 1.92, 2.11, 2.98, 2.14, 2.19, respectively) played an important role. Considering the status of high-risk human papillomavirus (HR-HPV) infection, our results showed that the low levels of folate, niacin, biotin could promote the poor prognosis of CINⅠ. Conclusions: The low-level of dietary water-soluble vitamins could facilitate the poor prognosis of CINⅠ. In addition, folate, niacin, biotin were more effective on HR-HPV positive women.

[The optimal model of diagnosis to low-grade cervical intraepithelial neoplasia by combined detecting vaginal micro-environmental factors, based on the high-risk HPV infection]

Objective: To investigate the diagnostic value of different vaginal micro-environmental factors in low-grade cervical intraepithelial neoplasia (CIN Ⅰ) and determine the optimal model in high-risk human papillomavirus (HR-HPV) infection. Methods: A total of 926 women, including 623 with normal cervical (NC) condition and 303 CINⅠ patients, had undergone pathological examinations, and were enrolled in the study. All the women were from a community previously established cohort. Vaginal cleanliness, pH, H₂O₂, β-glucuronidase, coagulase, sialidase, and leukocyte esterase (LE) were detected by the combined detection method aerobic vaginitis/bacterial vaginosis in vaginal secretions. HPV genotyping was performed by using the flow-through hybridization technology. The data were analyzed by SAS 9.2 and SPSS 23.0. Results: The vaginal cleanliness, pH, sialidase, and LE were determined as the representative vaginal micro-environment factors by principal component analysis. Based on logistic regression theory to analyze the ROC curve, the results showed that the highest sensitivity was with pH value (76.2%), and the highest specificity was with sialidase (90.9%). The area under ROC curve were higher in combination detection modes of sialidase+LE (0.714), pH+sialidase+LE (0.719), vaginal cleanness+sialidase+LE (0.713) and pH+vaginal cleanness+sialidase+LE (0.709). According to HR-HPV infection status, the TOPSIS method was used to analyze the combined detection optimal model. Specifically, we found that the best diagnostic model was pH+sialidase +LE (C_i=0.585) in the HR-HPV positive group and vaginal cleanness+sialidase+LE (C_i=0.641) in the negative group. Conclusions: The combined detection of vaginal microenvironment factors could be used for auxiliary diagnosis for CINⅠ. It would be more effective when detecting pH, sialidase, and LE in HR-HPV positive women while vaginal cleanness, sialidase, and LE in HR-HPV negative women at the same time.

[Prognosis of high-risk HPV infection and its influences by vaginal micro-environmental factors]

Objective: To describe the characteristics of high-risk human papillomavirus (HR-HPV) infection and its influences by vaginal micro-environmental factors. Methods: A total of 421 women with HR-HPV infection and normal cervix diagnosed by pathology were selected from a community cohort established earlier by our research group for a 24-month follow-up. The baseline data were collected at enrollment. The vaginal micro-environmental factors were detected by using the combined detection kit of aerobic vaginitis and bacterial vaginosis. And the HPV was detected by using the flow-through hybridization technology. According to the HR-HPV infection status in baseline and 24 months of follow-up, with the prognosis characteristics of HR-HPV infection described, the impact of vaginal micro-environmental factors on the prognosis of HR-HPV infection was explored as well. Results: Among 390 HR-HPV infected women who completed 24 months of follow-up, the top five types of persistent HR-HPV infection rate appeared as HPV16 (24.1%), HPV58 (22.2%), HPV53 (21.7%), HPV52 (20.0%), and HPV39 (11.8%), respectively. The results showed that women with abnormal vaginal pH (aOR=1.74, 95%CI: 1.08-2.80), abnormal neuraminidase (aOR=2.70, 95%CI: 1.52-4.83), or abnormal leucocyte esterase (aOR=3.41, 95%CI: 2.13-5.44), the risk of HR-HPV persistent infection increased. The abnormalities of neuraminidase and leukocyte esterase could increase the risk of persistent infection of homotype and heterotypic HR-HPV. Conclusions: HPV16 was prone to persistent infection. Abnormalities of vaginal pH, neuraminidase, and leukocyte esterase might increase the risk of HR-HPV persistent infection. Both the abnormalities of neuraminidase and leukocyte esterase play an essential role in the HR-HPV persistent infection.

Moderate endurance training reduced hepatic tumourigenesis associated with lower lactate overload compared to high-intensity interval training

The anti-tumour effects of exercise are still poorly understood. In recent years, high-intensity interval exercise has been recognised as one of the best choices for better health. However, high-intensity interval exercise induces lactate production in muscles and elevates blood lactic acid levels, and the resulting acidic microenvironment may promote tumour progression. Therefore, it is important to compare the anti-tumour effects of different types of exercise.

OBJECTIVE

In this study, we aimed to compare the anti-tumour effects of moderate endurance training and high-intensity interval training on diethylnitrosamine (DEN)-induced liver tumours and to explore the underlying mechanisms.

METHODS

Three-week-old male C57BL/6 mice were injected intraperitoneally with DEN for 10 weeks to induce hepatocellular carcinoma. DEN-treated mice were grouped and subjected to moderate endurance training (MET) or high-intensity interval training (HIIT) for 18 weeks. We performed real-time PCR to evaluate the mRNA expressions of key enzymes involved in lactate metabolism pathway and western blotting to examine the protein expressions of LDHA, AMPK/P-AMPK, PCK1, and G6Pase in the paracancerous liver tissue. We performed high-performance liquid mass spectrometry (HPLC) to detect lactate in liver.

RESULTS

Our results revealed that compared with HIIT, MET decreased hepatic tumour incidence, as HIIT increased blood lactate concentration at rest. Moreover, MET reduced the transcript-level expression of LDH subunit and significantly increased the mRNA levels of COX1 and ND1 in liver. However, no significant changes were observed in liver lactate levels and the expression of LDHA among the groups. In addition, no significant differences in the mRNA levels of critical enzymes involved in the gluconeogenesis pathway in liver were observed among the groups. Additionally, no significant differences were observed in the mRNA levels of MPC2, pdha2, and pdk4 among the groups.

CONCLUSIONS

Our findings suggest that MET may be more efficient than HIIT at reducing hepatic tumourigenesis, and that it is associated with improved mitochondrial function in liver and lower lactate load in the circulation at rest.

[Effects of hnRNP E1 on expression of early genes E2, E6 of HPV16 and biological function in cervical cancer cells]

Objective: To explore the effects of hnRNP E1 on the expression of early genes E2, E6 of HPV16 and the biological function in cervical cancer SiHa cell lines. Methods: The cell experiments in vitro were carried out in cervical cancer cell lines SiHa. The expression levels of E2, E6 mRNA and protein of HPV16 were detected by Real-time PCR and Western blot, respectively, before and after up-regulating hnRNP E1. Meanwhile, the cell proliferation, cycle and apoptosis were evaluated by CCK-8 and flow cytometry. Data analyses were performed using SPSS 22.0 and Graphpad Prism 7.0 software. Results: Compared with the blank and the blank plasmid group, the cells activity and proliferation decreased at 24, 48 and 72 h after up-regulating hnRNP E1 (P<0.05), while the percentage of cells in G0/G1 phase increased and the percentage in S and G2/M phase and proliferation index decreased (P<0.05). Moreover, the late apoptotic rate and the total apoptotic rate increased (P<0.05). The expression levels of E6 mRNA and protein of HPV16 in hnRNP E1 up-regulated group were significantly lower than that in both blank group and blank plasmid group, the differences were significant (P<0.05), showing the tendency of cells proliferation index decrease and total apoptotic rate increase with decreased HPV16 E6 expression. There were no significant differences in the expression of E2 mRNA of HPV16 among the three groups (P=0.427), and no E2 protein of HPV16 was detected. Conclusions: hnRNP E1 could inhibit the transcription and translation of E6 oncogene of HPV16 and further inhibit the proliferation and promote apoptosis of cervical cancer cells, suggesting that hnRNP E1 might be a potential target marker to prevent cervical lesions. But no association between hnRNP E1 and HPV16 E2 was found in SiHa cells.

Betulin attenuates pneumolysin-induced cell injury and DNA damage

AIMS

Pneumolysin, a pore-forming toxin, is an important virulence factor of Streptococcus pneumoniae with multiple biological activity, such as cell lysis and DNA damage. Thus, targeting this toxin is alternative strategy for the treatment of S. pneumoniae infection.

METHODS AND RESULTS

Haemolysin assay was performed to identify the potential PLY inhibitor. The mechanism by which betulin, a natural compound from birch bark, against PLY was determined via MICs determination, western blot analysis and oligomerization analysis. Cytotoxicity and Immunofluorescence assays were further used to evaluate the protection of betulin against PLY-induced cell injury and DNA damage. Here, betulin, a natural compound from birch bark, was indentified as an effective inhibitor of PLY. Importantly, at the concentrations required for such inhibition, betulin has no influence on S. pneumoniae viability or PLY production. The interaction of betulin with PLY restrict the olgomerizaiton of this toxin and, thus, directly neutralizing the activity of PLY. Additionally, betulin treatment alleviate PLY induced cells injury and DNA damage in the co-culture system of PLY and A549 cells.

CONCLUSIONS

Betulin could be used as a promising leading compound against S. pneumoniae virulence by directly targeting PLY without antibacterial activity.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results presented in this work provided a novel strategy and candidate for S. pneumoniae infection.

Understanding the Role of Exercise in Nonalcoholic Fatty Liver Disease: ERS-Linked Molecular Pathways

Nonalcoholic fatty liver disease (NAFLD) is globally prevalent and characterized by abnormal lipid accumulation in the liver, frequently accompanied by insulin resistance (IR), enhanced hepatic inflammation, and apoptosis. Recent studies showed that endoplasmic reticulum stress (ERS) at the subcellular level underlies these featured pathologies in the development of NAFLD. As an effective treatment, exercise significantly reduces hepatic lipid accumulation and thus alleviates NAFLD. Confusingly, these benefits of exercise are associated with increased or decreased ERS in the liver. Further, the interaction between diet, medication, exercise types, and intensity in ERS regulation is more confusing, though most studies have confirmed the benefits of exercise. In this review, we focus on understanding the role of exercise-modulated ERS in NAFLD and ERS-linked molecular pathways. Moderate ERS is an essential signaling for hepatic lipid homeostasis. Higher ERS may lead to increased inflammation and apoptosis in the liver, while lower ERS may lead to the accumulation of misfolded proteins. Therefore, exercise acts like an igniter or extinguisher to keep ERS at an appropriate level by turning it up or down, which depends on diet, medications, exercise intensity, etc. Exercise not only enhances hepatic tolerance to ERS but also prevents the malignant development of steatosis due to excessive ERS.

THU0544 MULTIMODAL PHOTOACOUSTIC/ULTRASONIC IMAGING SYSTEM: A NEW IMAGING METHOD FOR EVALUATING RA

Background:

Photoacoustic imaging (PAI), a new imaging technique which can be integrating with ultrasound (US) imaging, has shown potential in visualizing small joints. We have developed a multimodal photoacoustic/ultrasound (PA/US) imaging system, equipped with a handheld probe, which can provide dual-wavelength PA/US imaging to identify the micro-vessels of the inflamed articular regions and measure the oxygenation level of human inflamed synovium.

Objectives:

To validate the potential value for RA of the imaging system.

Methods:

A total of 32 RA patients received PA/US examination on seven small joints (MCP2, MCP3, PIP2, PIP3, MTP2, MTP5, and wrist of the clinically dominant side). The 0-3 score was used to semi-quantify the PA and PD signals of the inflammatory articular lesions, and the sums of PA and PD scores (PA-sum and PD-sum) were utilized. The relative oxygen saturation (SO2) values of the inflamed regions were measured by calculating the ratio of PA signals at the wavelength of 750nm and 830nm. All the patients were classified to 3 PA+SO2 patterns (Pattern 1: no or minimal PA signals; Pattern 2: evident PA signals and hyperoxia; Pattern 3: evident PA signals and hypoxia). The correlations between imaging scores and laboratory data, as well as clinical scoring systems were assessed.

Results:

A total of 32 patients of RA were recruited aged from 25-71 years-old were examined. PD-sum had moderate correlation with the clinical scores (r=0.529, 0.546, 0.490, 0.493 for DAS28ESR, DAS28CRP, SDAI, CDAI), moderate correlations with TJC (r=0.575) and SJC (r=0.491), fair correlation with VAS (r=0.239), poor correlation with PGA (r=0.153), and moderate correlation with EGA (r=0.457). The PA-sum had substantial correlations with the clinical scores (r= 0.699, 0.746, 0.723, 0.736 for DAS28ESR, DAS28CRP, SDAI, CDAI), substantial correlations with TJC (r=0.787) and SJC (r=0.694), moderate correlations with VAS (r=0.544) and PGA (r=0.529), and substantial correlation with EGA (r=0.708).

Ten patients were classified as Pattern 1, 12 as Pattern 2, 9 as Pattern 3. The PA+ SO2 patterns presented substantial correlations with the clinical scores (DAS28ESR r=0.690, DAS28CRP r=0.782, SDAI r=0.805, CDAI r=0.799, SJC r=647, TJC r=0.676, respectively), substantial correlation with VAS (r=0.714), and moderate correlation with PGA (r=0.476) and EGA (r=0.502). Significant differences between those who were classified as hypoxia and hyperoxia with evident PA signals, were detected in VAS (p=0.020) and PGA (p=0.026).

Conclusion:

The PA-sum scores and the PA+SO2 patterns can be utilized as objective imaging parameters reflecting the disease activity of RA. PAI may serve as a supplement to conventional US examinations for RA patients.

References:

[1]Backhaus, M., et al., Evaluation of a novel 7-joint ultrasound score in daily rheumatologic practice: a pilot project. Arthritis Rheum, 2009. 61(9): p. 1194-201.

[2]Colebatch, A.N., et al., EULAR recommendations for the use of imaging of the joints in the clinical management of rheumatoid arthritis. Ann Rheum Dis, 2013. 72(6): p. 804-14.

Figure 1.

the photo of the multimodal PA/US imaging system

Figure 2.

an example of the PA/US imaging

Disclosure of Interests:

Chenyang Zhao: None declared, Qian Wang: None declared, Xixi Tao: None declared, Chen Yu: None declared, Sirui Liu: None declared, Mengtao Li: None declared, Xinping Tian: None declared, Zhenhong Qi: None declared, Jianchu Li: None declared, Fang Yang: None declared, Lei Zhu: None declared, Xiaofeng Zeng Consultant of: MSD Pharmaceuticals, Meng Yang: None declared, Yuxin Jiang: None declared

Macrophage Depletion Improves Chronic Rejection in Rats With Allograft Heart Transplantation

BACKGROUND

Macrophages may be important in chronic rejection after organ transplantation. This study aimed to investigate the possibility of depleting macrophages for a certain amount of time to alleviate chronic rejection in a heart transplant model of Fischer to Lewis rats.

METHODS

Clodronate liposome was injected abdominally to deplete macrophages for 2 time frames. The expression levels of ectodysplasin 1, arginase 1 (Arg1), chitinase-like lectin (Ym1), interferon gamma, tumor necrosis factor α (TNF-α), smooth muscle α-actin (α-SMA), monocyte chemoattractant protein 1 (MCP-1), and interleukin 10 (IL-10) were detected.

RESULTS

1. The expression levels of α-SMA, interferon gamma, TNF-α, and MCP-1 and the transformation of peripheral T cells were lower after macrophage depletion for 2 or 4 weeks. 2. The expression levels of α-SMA, TNF-α, and MCP-1 and the transformation of peripheral T cells were even lower after 4 weeks compared with 2 weeks, except for interferon gamma. 3. A higher level of expression of Arg1 and Ym1 after macrophage depletion for 2 weeks was observed. 4. A higher level of expression of IL-10 after macrophage depletion for 2 weeks, but not 4 weeks, was also observed.

CONCLUSIONS

Macrophage clearance after heart transplantation alleviated chronic rejection probably via M2 polarization of regenerated macrophages, reduced T-lymphocyte proliferation, and changed the expression levels of interferon gamma, TNF-α, MCP-1, and IL-10.

Endurance training but not high-intensity interval training reduces liver carcinogenesis in mice with hepatocellular carcinogen diethylnitrosamine

Physical activity may reduce cancer initiation. High-intensity interval training (HIT) has been reported to be superior to moderate continuous endurance training (ET) for maximizing health outcomes in cardiovascular disease, obesity and type 2 diabetes. However, the role of HIT vs. ET in the prevention of liver cancer is poorly understood. This study aimed to determine how HIT vs. ET affects cancer initiation in mice with the hepatocellular carcinogen diethylnitrosamine (DEN). C57BL/6 mice were treated with DEN at 3-12 weeks of age and, from 8 to 26 weeks of age, treated with either of exercise modes on treadmill: HIT (85-90% VO2max with intervals) and ET (65-75% VO2max without intervals). We found that mice treated with ET had lower cancer initiation but higher fat mass compared to control DEN-injected mice. In contrast, HIT could not significantly reduce cancer initiation and tumor volumes. Metabolomic analysis in the liver indicated marked differences in cholesterol, palmitic acid, stearic acid, uracil, hydroxypyridine and maltose between HIT- and ET-treated mice, and demonstrated good and obvious separation between ET and DEN control group. Furthermore, mice treated with ET had lower expression of pro-inflammatory cytokines and pro-proliferation genes in liver compared to DEN control group. ET protocol reduced the accumulation of toxic metabolite carbamate, increased the protein level of caspase-1, and reduced JNK phosphorylation in liver. These data indicates that moderate-intensity endurance training may be superior to high-intensity interval training for reducing liver cancer initiation in mice.

Anti-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) antibody in necrotizing myopathy: treatment outcomes, cancer risk, and role of autoantibody level

Objective: To evaluate clinical associations of anti-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) antibody (Ab) and statin exposure in necrotizing myopathy (NM) patients. Methods: NM without a known myositis-specific autoantibody (MSA) was ascertained from a large single-centre myositis database between 1985 and 2012. A comparison NM cohort included 32 anti-SRP⁺ autoantibody patients, and other control groups included 74 non-NM myositis patients and 21 non-myositis controls. Sera from all cases and controls were tested using a validated anti-HMGCR enzyme-linked immunosorbent assay. Clinical features including statin use and anti-HMGCR Ab status were compared between cases and controls. Results: Of the 256 NM muscle biopsies reviewed, only 48 subjects with available sera were identified as traditional MSA-negative NM. Anti-HMGCR positivity was significantly (p < 0.001) associated with MSA-negative NM [48% (23/48)] compared to all of the myositis and non-myositis controls [5% (6/127)]. Most anti-HMGCR Ab-positive NM patients had high titres of anti-HMGCR (83%) and a history of statin exposure (78%), along with severe muscle weakness, high creatine kinase (CK) levels (90% ≥ 5000 IU/L), a paucity of other organ manifestations, and the need for immunosuppression with prednisone and methotrexate, but generally favourable outcomes. Anti-HMGCR serum levels were associated with baseline CK levels but not muscle weakness. Conclusion: HMGCR Ab-positive NM patients are associated with statin exposure, have severe muscle weakness and high CK at presentation, lack other organ manifestations, and generally have favourable outcomes from immunosuppression. Anti-HMGCR Abs should be assessed in MSA-negative NM patients, particularly those with a history of statin exposure.

Understanding the Fertilizer Management Impacts on Water and Nitrogen Dynamics for a Corn Silage Tile-Drained System in Canada

Effective management of dairy manure is important to minimize N losses from cropping systems, maximize profitability, and enhance environmental sustainability. The objectives of this study were (i) to calibrate and validate the DeNitrification-DeComposition (DNDC) model using measurements of silage corn ( L.) biomass, N uptake, soil temperature, tile drain flow, NO leaching, NO emissions, and soil mineral N in eastern Canada, and (ii) to investigate the long-term impacts of manure management under climate variability. The treatments investigated included a zero-fertilizer control, inorganic fertilizer, and dairy manure amendments (raw and digested). The DNDC model overall demonstrated statistically "good" performance when simulating silage corn yield and N uptake based on normalized RMSE (nRMSE) < 10%, index of agreement () > 0.9, and Nash-Sutcliffe efficiency (NSE) > 0.5. In addition, DNDC, with its inclusion of a tile drainage mechanism, demonstrated "good" predictions for cumulative drainage (nRMSE < 20%, > 0.8, and NSE > 0.5). The model did, however, underestimate daily drainage flux during spring thaw for both organic and inorganic amendments. This was attributed to an underestimation of soil temperature and soil water under frequent soil freezing and thawing during the 2013-2014 overwinter period. Long-term simulations under climate variability indicated that spring applied manure resulted in less NO leaching and NO emissions than fall application when manure rates were managed based on crop N requirements. Overall, this study helped highlight the challenges in discerning the short-term climate interactions on fertilizer-induced N losses compared with the long-term dynamics under climate variability.

MicroRNA-30b inhibits non-small cell lung cancer cell growth by targeting the epidermal growth factor receptor

Lung cancer, especially non-small cell lung cancer (NSCLC), is the leading cause of cancer-related mortality in the world. Both microRNAs and epidermal growth factor receptor (EGFR) are important factors in NSCLC. In our study, the expression of miR-30b in 47 tumor tissues and paired normal tissues of NSCLC were detected by RT-PCR, and we found that miR-30b was down-regulated in NSCLC tumor tissues and was associated with TNM stage, differentiation, and lymph node metastases. Then we investigated the ability of miR-30b to regulate EGFR in several NSCLC cell lines, and found that miR-30b inhibited proliferation, migration and invasion, induced apoptosis and enhanced sensitivity of the NSCLC cells to EGFR tyrosine kinase inhibitors (EGFR-TKIs) by targeting EGFR and repressing EGFR signaling pathways. Overall, these results indicate that miR-30b may be a potential therapeutic target in NSCLC patients.

Adeno-Associated Virus-Mediated Knockdown of SLC16A11 Improves Glucose Tolerance and Hepatic Insulin Signaling in High Fat Diet-Fed Mice

BACKGROUND

SLC16A11, a member of the SLC16 family, is associated with lipid metabolism, causing increased intracellular triacylglycerol (TAG) levels. In the current study, our primary goal was to determine if an SLC16A11 knockdown would improve glucose tolerance and hepatic insulin signaling in high fat diet (HFD)-fed mice. Additionally, the mechanism for exercise-improved insulin sensitivity remains unclear, and there is no mechanistic insight into SLC16A11's role in insulin sensitivity under exercise stress. Therefore, we also examined the impact of endurance exercise on the abundance of SLC16A11.

METHODS

C57BL/6 J male mice were fed either regular chow (Control) or HFD for 8 weeks and then injected with adeno-associated virus (AAV). Plasma parameters, tissue lipid contents, glucose tolerance, and expression profiles of hepatic insulin signaling were detected. Also, other mice were divided randomly into sedentary and exercise groups. We assessed hepatic expression of SLC16A11 after 8 weeks of endurance exercise.

RESULTS

1) Hepatic SLC16A11 expression was greater in HFD-fed mice compared to Control mice. 2) AAV-mediated knockdown of SLC16A11 improved glucose tolerance, prevented TAG accumulation in serum and liver, and increased phosphorylation of protein kinase B (Akt) and glycogen synthesis kinase-3β (GSK3β) in HFD-fed mice. 3) Endurance exercise decreased hepatic SLC16A11 expression.

CONCLUSIONS

Inactivation of SLC16A11, which is robustly induced by HFD, improved glucose tolerance and hepatic insulin signaling, independent of body weight, but related to TAG. Additionally, SLC16A11 might mediate the health benefits of endurance exercise.

Possible role of GLP-1 in antidepressant effects of metformin and exercise in CUMS mice

BACKGROUND

Both depression itself and antidepressant medication have been reported to be significantly related to the risk of type 2 diabetes mellitus (T2DM). Glucagon-like peptide-1 (GLP-1), a treatment target for T2DM, has a neuroprotective effect. As an enhancer and sensitiser of GLP-1, metformin has been reported to be safe for the neurodevelopment. The present study aimed to determine whether and how GLP-1 mediates antidepressant effects of metformin and exercise in mice.

METHODS

Male C57BL/6 mice were exposed to chronic unpredictable mild stress (CUMS) for 8 weeks. From the 4th week, CUMS mice were subjected to oral metformin treatment and/or treadmill running. A videocomputerized tracking system was used to record behaviors of mice for a 5-min session. ELISA, western blotting and immunohistochemistry were used to examine serum protein concentrations, protein levels in whole hippocampus, protein distribution and expression in dorsal and ventral hippocampus, respectively.

RESULTS

Our results supported the validity of metformin as a useful antidepressant; moreover, treadmill running favored metformin effects on exploratory behaviors and serum corticosterone levels. CUMS reduced GLP-1 protein levels and phosphorylation levels of extracellular signal-regulated kinase 1/2 (ERK1/2), but increased protein levels of B-cell lymphoma 2-associated X-protein (BAX) in mice hippocampus. All these changes were restored by both single and combined treatment with metformin and exercise.

LIMITATIONS

We did not establish a causal relationship between GLP-1 expression and related signaling, using GLP-1 agonist and antagonist or knockout techniques.

CONCLUSIONS

Our findings have demonstrated that protein levels of pERK and BAX may be relevant to the role of GLP-1 in antidepressant effects of metformin and exercise, which may provide a novel topic for future clinical research.