Objective:To evaluate the effect of metformin preconditioning on adenosine monophosphate-activated protein kinase(AMPK)/PTEN-induced putative protein kinase(PINK1) signaling pathway during ischemia-reperfusion (I/R) injury in diabetic rats.Methods:Thirty-six clean-grade healthy male Sprague-Dawley rats, aged 6 weeks, weighing 120-160 g, were divided into 3 groups ( n=12 each) by the random number table method: diabetic sham operation group (DS group), diabetic myocardial I/R group (DI/R group) and diabetic myocardial I/R+ metformin preconditioning group(DI/R+ Met group). After 4 weeks of feeding a high-fat and high-glucose diet, the model of type 2 diabetes mellitus was induced by a single intraperitoneal injection of 1% streptozotocin 40 mg/kg. The myocardial I/R injury was induced by blocking the anterior descending branch of the left coronary artery for 30 min followed by 120-min reperfusion in anesthetized animals. In DI/R+ Met group, metformin 200 mg/kg was given by intragastric gavage once a day within 1 week before myocardial ischemia. Blood samples from the femoral vein were collected at 120 min of reperfusion for determination of the serum creatine kinase isoenzymes (CK-MB) and cardiac troponin I (cTnI) concentrations by enzyme-linked immunosorbent assay. Then the rats were sacrificed and myocardial tissues were obtained for examination of the pathological changes(by HE staining) and for determination of the percentage of myocardial infarct size (by the double staining of Ewan blue and TTC) and expression of myocardial autophagy-related protein Beclin-1, PTEN-induced putative kinase 1 (PINK1), phosphorylated 5′-adenosine monophosphate-activating protein kinase (p-AMPK), and ratio of microtubule-associated protein 1 light chain 3Ⅱ/Ⅰ (LC3Ⅱ/Ⅰ) (by Western blot). Results:Compared with DS group, the percentage of myocardial infarct size and serum CK-MB and cTnI concentrations were significantly increased, the expression of Beclin-1, p-AMPK and PINK1 in myocardial tissues was up-regulated, the ratio of LC3II/I was increased( P<0.05), and the pathological changes were aggravated in DI/R group and DI/R+ Met group. Compared with DI/R group, the percentage of myocardial infarct size and serum CK-MB and cTnI concentrations were significantly decreased, the expression of Beclin-1, p-AMPK and PINK1 in myocardial tissues was up-regulated, the ratio of LC3Ⅱ/Ⅰ was increased ( P<0.05), and the pathological changes were significantly reduced in DI/R+ Met group. Conclusions:The mechanism by which metformin preconditioning reduces myocardial I/R injury is related to activation of AMPK/PINK1 signaling pathway and up-regulation of mitochondrial autophagy in diabetic rats.

Objective:To evaluate the effect of resveratrol on ferropotosis in cardiomyocytes of mice with diabetic cardiomyopathy.Methods:Thirty healthy adult male C57BL/6 mice, aged 8 weeks, weighing 22-26 g, were divided into 3 groups ( n=10 each) using a random number table method: control group (group C), diabetic cardiomyopathy group (group DCM) and resveratrol group (group RSV). Freshly prepared streptozotocin (STZ) 40 mg·kg -1·d -1 was intraperitoneally injected for 5 consecutive days to develop the model of type 1 diabetes mellitus. After the model was successfully developed, resveratrol 25 mg·kg -1·d -1 was intragastrically given for 12 consecutive weeks in group RSV, while the equal volume of dimethyl sulfoxide was given instead in group C and group DCM. Echocardiography was performed to examine the cardiac structure and function at the end of the 12th week. Then mice were sacrificed, and myocardial tissue specimens were harvested for microscopic examination of the pathological changes of myocardial tissues (by Hematologist-Eosin staining) and mitochondrial morphology of myocardial cells (with a transmission electron microscope) and for determination of the contents of iron, malondialdehyde (MDA) and glutathione (GSH) (by colorimetry) and expression of glutathione peroxidase 4 (GPX4) (by Western blot). Results:Compared with group C, the left ventricular end-diastolic diameter and left ventricular end-systolic diameter were significantly increased, the left ventricular ejection fraction and left ventricular fractional shortening were decreased, the contents of iron and MDA were increased, the content of GSH was decreased, and the expression of GPX4 was down-regulated in group DCM ( P<0.05). Compared with group DCM, the left ventricular end-diastolic diameter and left ventricular end-systolic diameter were significantly decreased, the left ventricular fractional shortening and ejection fraction were increased, the contents of iron and MDA were decreased, the content of GSH was increased, the expression of GPX4 was up-regulated ( P<0.05), and the pathological changes of myocardial tissues and changes in mitochondrial morphology of myocardial cells were significantly attenuated in group RSV. Conclusions:The mechanism by which resveratrol attenuates myocardial injury and further improves cardiac dysfunction is related to inhibition of ferroptosis in cardiomyocytes of mice with diabetic cardiomyopathy.

Objective:To evaluate the effect of activating adenosine A2B receptors on autophagy during myocardial ischemia-reperfusion (I/R) and the role of phosphatidylinositol 3-kinase/serine/threonine protein kinase (PI3K/Akt) signaling pathway in rats.Methods:Forty-eight clean-grade healthy male Sprague-Dawley rats, weighing 220-280 g, were divided into 4 groups ( n=12 each) using a random number table method: sham operation group (group Sham), myocardial I/R group (group I/R), adenosine A2B receptor agonist BAY 60-6583 group (group BAY) and BAY 60-6583+ PI3K inhibitor LY 294002 group (group BAY+ LY). Myocardial I/R was induced by occlusion of the anterior descending branch of the left coronary artery for 30 min followed by 120-min reperfusion.BAY 60-6583 1 mg/kg was intraperitoneally injected at 5 min before reperfusion in group BAY.BAY 60-6583 1 mg/kg was intraperitoneally injected at 5 min before reperfusion and LY 294002 10 mg/kg was intraperitoneally injected at 10 min before reperfusion in group BAY+ LY.Blood samples were obtained at the end of reperfusion for determination of concentrations of lactate dehydrogenase (LDH) and creatine kinase-MB (CK-MB) in serum (by enzyme-linked immunosorbent assay). The animals were sacrificed, and myocardial tissues were obtained for measurement of the percentage of myocardial infarct size (by Evan Blue and TTC double-staining) and for determination of the expression of microtubule-associated protein 1 light chain 3 (LC3Ⅰ), LC3Ⅱ, Beclin-1 and phosphorylated Akt (p-Akt) (by Western blot). The ratio of LC3Ⅱ/LC3Ⅰ was calculated. Results:Compared with group Sham, the serum LDH and CK-MB concentrations and percentage of myocardial infarct size were significantly increased, the expression of p-Akt was down-regulated, the expression of Beclin-1 and LC3Ⅱ was up-regulated, and the ratio of LC3Ⅱ/LC3Ⅰ was increased in group I/R ( P<0.05). Compared with group I/R, the concentrations of serum LDH, CK-MB and percentage of myocardial infarct size were significantly decreased, the expression of p-Akt was up-regulated, the expression of Beclin-1 and LC3Ⅱ was down-regulated, and the ratio of LC3Ⅱ/LC3Ⅰ was decreased in the group BAY ( P<0.05), and no significant change was found in the parameters mentioned above in group BAY+ LY ( P>0.05). Compared with group BAY, the concentrations of serum LDH, CK-MB and percentage of myocardial infarct size were significantly increased, the expression of p-Akt was down-regulated, the expression of Beclin-1 and LC3Ⅱ was up-regulated and the ratio of LC3Ⅱ/LC3Ⅰ was increased in group BAY+ LY ( P<0.05). Conclusion:Activating adenosine A2B receptors can decrease autophagy of myocardial cells during myocardial I/R injury, and the mechanism may be related to activating PI3K/Akt signaling pathway in rats.

Objective:To evaluate the role of endoplasmic reticulum stress in myocardial ischemia-reperfusion (I/R) injury and the relationship with autophagy in rats.Methods:Thirty-six healthy adult male Sprague-Dawley rats, weighing 250-300 g, were divided into 3 groups ( n=12 each) using a random number table method: sham operation group (Sham group), myocardial I/R group (IR group), and endoplasmic reticulum stress inhibitor 4-PBA group (PBA group). Myocardial I/R was produced by occlusion of left anterior descending branch of coronary artery for 30 min followed by reperfusion for 120 min.Sham group only underwent thoracotomy without block of left anterior descending branch of coronary artery.Endoplasmic reticulum stress inhibitor 4-PBA 500 mg·kg -1·d -1 was given intragastrically for 3 consecutive days before the I/R model was developed in PBA group, while the equal volume of normal saline was given instead in Sham and IR groups.The blood samples from the iliac vein were collected at 120 min of reperfusion for determination of the plasma creatine kinase isoenzymes (CK-MB) and cardiac troponin I (cTnI) concentrations (by enzyme-linked immunosorbent assay). The rats were then sacrificed, and myocardial tissues were removed for detection of myocardial glucose-regulated protein 78 (GRP78) and microtubule-associated protein 1 light chain 3 Ⅱ (LC3 Ⅱ) and autophagy-related protein 5 (ATG5) expression (by Western blot). Result:Compared with Sham group, the concentrations of CK-MB and cTnI in plasma were significantly increased in IR and PBA groups, the expression of GRP78, ATG5 and LC3Ⅱ was up-regulated, and the pathological damage was aggravated in IR group ( P<0.05). Compared with IR group, the concentrations of CK-MB and cTnI in plasma were significantly decreased, the expression of GRP78, ATG5 and LC3Ⅱ was down-regulated ( P<0.05), and the pathological changes were significantly attenuated in PBA group. Conclusion:Endoplasmic reticulum stress is involved in the process of myocardial I/R injury, and the mechanism may be related to promotion of autophagy in rats.

Objective:To construct and identify the lentiviral vector of adenosine RNAi-adenosine A2a receptor (A2aR) in rats.Methods:Three pairs of short hairpin RNA(shRNA)-A2aR sequences (shRNA-A2aR 1, shRNA-A2aR 2, shRNA-A2aR 3) were designed, and three pairs of double-stranded shRNA oligos were respectively inserted into the shRNA virus vector to gain three kinds of shRNA lentiviral recombinant plasmid.The recombinant plasmid, packaging vector, and shuttle vector were co-transfected into 293T cells to obtain virus liquid.The experiment was performed in two parts.Part Ⅰ The rat primary cardiomyocytes were divided into 3 groups ( n= 6 each) by a random number table method: vehicle group (V group), shRNA-A2aR 1 group and shRNA-A2aR 3 group.Each group was transfected with virus solution of MOI 10 for 48 h. The expression of A2aR was detected by Western blot to select the most efficient lentivirus vector.Part Ⅱ The cardiomyocytes were randomly divided into 6 groups ( n=36 each): vehicle group (V group), MOI5 group, MOI10 group, MOI15 group and MOI20 group.Each group was transfected with the corresponding MOI virus liquid (the most effective lentivirus vector). At 24, 48, and 72 h of transfection, the cell viability and cell death were observed with a fluorescent microscope, and the A2aR expression was detected by Western blot to determine the interference efficiency. Results:Part Ⅰ Two types of shRNA-A2aR lentiviral vectors (shRNA-A2aR 1, 3) were successfully constructed, among which shRNA-A2aR 3 virus solution with a titer of 3.5×10 8 TU/ml had the best effect.Compared with group V and group shRNA-A2aR 1, the expression of A2aR in cardiomyocytes was significantly down-regulated ( P<0.01), and the interference efficiency of shRNA-A2aR 3 was 73% in shRNA-A2aR 3 group.Part Ⅱ shRNA-A2aR 3 was selected to screen out the transfection plan.The cell survival rate in each group was more than 85% at 24 h of transfection, the cell survival rate was more than 80% at 48 h of transfection in MOI5 and MOI10 groups; the cell survival rate in each group was less than 70% at 72 h of transfection.Under an inverted fluorescent microscope, a slightly lower fluorescence density was found in MOI5 group, the fluorescent density was higher and the cell condition was better at 48 h of transfection in MOI10 group and at 24 h of transfection in MOI20 group, and the cardiomyocyte viability was significantly decreased, and dead cells were increased at 72 h of transfection in each group.The results of Western blot showed that the interference efficiency at 48 h of transfection in MOI10 group, 48 h in MOI15 group, 24 and 48 h in MOI20 group was all > 70%. Conclusion:MOI of 10, transfection for 48 h or MOI of 20, transfection for 24 h is the optimal transfection protocol.

Objective:To evaluate the effect of valproic acid on the expression of M1/M2 microglia in the prefrontal cortex of rats with neuropathic pain (NP).Methods:Thirty-six clean-grade healthy male Sprague-Dawley rats, aged 6-7 weeks, weighing 200-230 g, were divided into 3 groups ( n=12 each) using a random number table method: sham operation group (group S), group NP, and valproic acid group (group V). The NP model was established by ligation of the L 5 spinal nerve (SNL) of anesthetized rats.Valproic acid 300 mg/kg was intraperitoneally injected immediately after SNL and every day after ligation, once a day, for 3 consecutive days in group V, while the equal volume of normal saline was given instead of valproic acid in S and NP groups.The mechanical paw withdrawal threshold (MWT) was measured before ligation and at 1, 3, 7, 14, 21 and 28 days after ligation.Sucrose preference test and forced-swim test were performed on day 28 after ligation.After the end of the behavior test, the prefrontal cortex was removed for determination of the expression of cluster of differentiation (CD) 16 and CD206 by Western blot.The ratio of CD206/CD16 was calculated. Results:Compared with group S, the MWT at each time point after ligation and rate of preference for sucrose were significantly decreased, the duration of immobility in forced-swim test was prolonged, the expression of CD16 and CD206 was up-regulated, and the ratio of CD206/CD16 was decreased in group NP ( P<0.05). Compared with group NP, the MWT at each time point after ligation and rate of preference for sucrose were significantly increased, the duration of immobility in forced-swim test was shortened, the expression of CD16 was down-regulated, the expression of CD206 was up-regulated, and the ratio of CD206/CD16 was increased in group V ( P<0.05). Conclusion:The mechanism by which valproic acid improves depression may be related to promoting the expression of M2 microglia and inhibiting the expression of M1 microglia in the prefrontal cortex of rats with NP.

Objective:To evaluate the role of histone deacetylase 6 (HDAC6) in the maintanence of neuropathic pain (NP) and the relationship with myeloid differentiation factor 88 (MyD88)/nuclear factor kappa B (NF-κB) signaling pathway in the rats.Methods:Twenty-four clean-grade healthy male Sprague-Dawley rats, aged 6-8 weeks, weighing 200-260 g, were divided into 4 groups ( n=6 each) using a random number table method: control group (group C), sham operation group (group S), NP group and NP plus HDAC6 inhibitor ACY-1215 group (group NP+ ACY). The rat model of NP was established by ligating the L 5 spinal nerve in anesthetized rats.The L 5 spinal nerve was only exposed without ligation in group S. In NP+ ACY group, ACY-1215 25 mg/kg was intraperitoneally injected daily for 21 days after the end of model establishing.The equal volume of solvent was intraperitoneally injected in S and NP groups, and group C was reared normally.The mechanical paw withdrawal threshold (MWT) was measured on 3 days before establishing the model (T 0), the day before establishing the model (T 1) and 1, 3, 7, 10, 14 and 21 days after establishing the model (T 2-7). The rats were sacrificed after measurement of MWT on day 21 after ligation, and the spinal dorsal horn tissues of L 4-6 were removed for determination of the expression of MyD88, NF-κB and phosphorylated NF-κB (p-NF-κB) (by Western blot) and expression of interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) mRNA (by real-time polymerase chain reaction). Results:Compared with C and S groups, the MWT was significantly decreased at T 2-7, and the expression of MyD88, NF-κB, p-NF-κB, TNF-α mRNA and IL-1β mRNA was up-regulated in NP and NP+ ACY groups ( P<0.05). Compared with group NP, the MWT was significantly increased at T 5-7, and the expression of MyD88, NF-κB, p-NF-κB, TNF-α mRNA and IL-1β mRNA was down-regulated in group SNL+ ACY ( P<0.05). Conclusion:HDAC6 activation is involved in the maintanence of NP, which is related to activating MyD88/NF-κB signaling pathway in the rats.

Objective To evaluate the effect of activating adenosine A2A receptors on myocardial is-chemia-reperfusion ( I∕R) injury in diabetic rats and the relationship with autophagy. Methods Clean-grade healthy male Sprague-Dawley rats, aged 6 weeks, weighing 200-250 g, were studied. The diabetic rat model was established by intraperitoneal injection of 1％ streptozotocin 60 mg∕kg. Forty diabetic rats were divided into 4 groups ( n=10 each ) using a random number table method: sham operation group ( group Sham) , I∕R group ( group I∕R) , I∕R plus adenosine A2A receptor agonist CGS21680 group ( group CGS) , and I∕R plus CGS21680 plus adenosine A2A receptor antagonist ZM241385 group ( group CGS+ZM) . Myocardial I∕R was produced by occlusion of the left anterior descending branch of the coronary artery for 30 min followed by 120-min reperfusion. Adenosine A2A receptor agonist CGS2168010μg∕100g was in-travenously injected at 10 min before reperfusion in group CGS. CGS2168010 ug∕100g and ZM2413850. 2 mg∕kg were intravenously injected sequentially at 10 min before reperfusion in group CGS+ZM. Blood sam-ples were obtained at the end of reperfusion for determination of concentrations of creatine kinase-MB ( CK-MB), lactate dehydrogenase (LDH) and cardiac troponin I (cTnI) in serum (by enzyme-linked immu-nosorbent assay). The animals were sacrificed, and myocardial tissues were obtained for measurement of the percentage of myocardial infarct volume ( by TTC staining) and for determination of the expression of mi-crotubule-associated protein 1 light chain 3 Ⅰ ( LC3Ⅰ) , LC3 Ⅱ, p62 and Beclin-1 ( by Western blot) . LC3 Ⅱ∕LC3 Ⅰ ratio was calculated. Results Compared with group Sham, the serum CK-MB, LDH and cTnI concentrations and percentage of myocardial infarct volume were significantly increased, the expression of p62 and Beclin-1 was up-regulated, and the LC3Ⅱ∕LC3Ⅰratio was increased in group I∕R ( P<0. 05) . Compared with group I∕R, the concentrations of serum CK-MB, LDH and cTnI and percentage of myocardial infarct volume were significantly decreased, the expression of p62 and Beclin-1 was down-regulated, and the ratio of LC3Ⅱ∕LC3Ⅰwas increased in group CGS ( P<0. 05) , and no significant change was found in the pa-rameters mentioned above in group CGS+ZM (P>0. 05). Compared with group CGS, the concentrations of serum CK-MB, LDH and cTnI and percentage of myocardial infarct volume were significantly increased, the expression of p62 and Beclin-1 was down-regulated, and the ratio of LC3Ⅱ∕LC3Ⅰwas decreased in group CGS+ZM ( P<0. 05) . Conclusion Activating adenosine A2A receptors can mitigate myocardial I∕R injury, and the mechanism may be related to enhancing autophagy in diabetic rats.

Objective: To evaluate the effect of irisin preconditioning on global cerebral ischemia-reperfusion (I/R) injury in rats. Methods: Thirty-six healthy male Sprague-Dawley rats, aged 8-10 weeks, weighing 250-300 g, were divided into 3 groups (n=12 each) using a random number table method: sham operation group (group S), global cerebral I/R group (group I/R) and irisin preconditioning group (group I). Global cerebral I/R was induced by occlusion of bilateral common carotid arteries combined with hypotension (MAP maintained at 35-45 mmHg) in anesthetized rats.At 30 min before ischemia, irisin 10 μg/kg (diluted to 10 μg/ml in normal saline) was intravenously injected in group I, and the equal volume of normal saline was intravenously injected in S and I/R groups.Morris water maze test was performed at day 3 of reperfusion to assess the cognitive function.Rats were sacrificed after the end of morris water maze test, and brains were removed for determination of histopathologic changes in hippocampal CA1 region (using HE staining), neuronal apoptosis in hippocampal CA1 region (Tunel staining), glial fibrillary acidic protein (GFAP) expression (by Western blot), myeloperoxidase (MPO) activity in the hippocampal tissues (by colorimetric assay), and contents of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) in hippocampal tissues (by enzyme-linked immunosorbent assay). The cell necrosis rate and apoptotic rate were calculated. Results: Compared with group S, the escape latency was significantly prolonged on 1-5 days in group I/R and on 1-3 days in group I, the time of staying at 1st quadrant was significantly shortened, the cell necrosis rate and apoptotic rate were increased, the expression of GFAP was up-regulated, and the activity of MPO and contents of TNF-α and IL-1β were increased in I/R and I groups (P<0.05 or 0.01). Compared with group I/R, the escape latency was significantly shortened on 1-5 days, the time of staying at 1st quadrant was prolonged, the cell necrosis rate and apoptotic rate were decreased, the expression of GFAP was down-regulated, and the MPO activity and contents of TNF-α and IL-1β were decreased in group I (P<0.05 or 0.01). Conclusion Irisin preconditioning can reduce the global cerebral I/R injury in rats, and the mechanism may be related to inhibiting activation of astrocytes in hippocampus and reducing inflammatory responses.

Objective To evaluate the relationship between the pathomechanism of neuropathic pain (NP)-inducced depression and autophagy in the cortex of the frontal lobe in rats.Methods Forty healthy male Sprague-Dawley rats in which IT catheters were successfully placed,aged 8-10 weeks,weighing 200-220 g,were divided into 4 groups (n =10 each) using a random number table method:sham operation group (group S),group NP,NP plus dimethyl sulfoxide group (group ND) and NP plus autophagy inducer rapamycin group (group NR).The neuropathic pain model was established by ligation of the left fifth spinal nerve of anesthetized rats in NP,ND and NR groups.Rapamycin 0.1 μgwas intrathecally injected via the intrathecal catheter immediately after ligation of the spinal nerve and every day after ligation once a day for 21 consecutive days in group NR.The equal volume of dimethyl sulfoxide was intrathecally injected instead of rapamycin in group ND.The mechanical paw withdrawal threshold (MWT) was measured before ligation and at 1,3,7,10,14 and 21 days after ligation.The forced swimming test was performed at 3 days before ligation and 14 and 21 days after ligation.The rats were sacrificed after the last measurement of the behaviour testing,and the prefrontal cortex was removed for determination of the expression of microtubule-associated protein light chain 3 Ⅰ (LC3 Ⅰ) and LC3 Ⅱ,Beclin-1 and p62 (by Western blot).The ratio of LC3 Ⅱ/LC3 Ⅰ was calculated.Results Compared with group S,the MWT was significantly decreased after ligation,the time of immobility was prolonged,the expression of LC3 Ⅰ was down-regulated,the expression of LC3 Ⅱ,Beclin-1 and p62 was up-regulated,and the LC3 Ⅱ/LC3 Ⅰ ratio was increased in NP and ND groups (P＜0.05).Compared with group NP,the MWT was significantly increased after ligation,the time of immobility was shortened,the expression of LC3 [and p62 was down-regulated,the expression of LC3 Ⅱ and Beclin-1 was up-regulated,and the LC3 Ⅱ/LC3 Ⅰ ratio was increased in group NR (P＜0.05).Conclusion Enhanced autophagy in the cortex of the frontal lobe is involved in the endogenous antidepressant mechanism in rats with NP.