Background/Aims: Paeoniflorin (PF) is known to have anti-inflammatory and paregoric effects, but the mechanism underlying its analgesic effect remains unclear. The aim of this study was to clarify the effect of PF on Freund’s complete adjuvant (CFA)-induced inflammatory pain and explore the underlying molecular mechanism. Methods: An inflammatory pain model was established by intraplantar injection of CFA in C57BL/6J mice. After intrathecal injection of PF daily for 8 consecutive days, thermal and mechanical withdrawal thresholds, the levels of inflammatory factors TNF-α, IL-1β and IL-6, microglial activity, and the expression of Akt-NF-κB signaling pathway in the spinal cord tissue were detected by animal ethological test, cell culture, enzyme-linked immunosorbent assay, immunofluorescence histochemistry, and western blot. Results: PF inhibited the spinal microglial activation in the CFA-induced pain model. The production of proinflammatory cytokines was decreased in the central nervous system after PF treatment both in vivo and in vitro. PF further displayed a remarkable effect on inhibiting the activation of Akt-NF-κB signaling pathway in vivo and in vitro. Conclusion: These results suggest that PF is a potential therapeutic agent for inflammatory pain and merits further investigation.

Background/Aims: Diabetes mellitus (DM) can lead to renal damage and dysfunction, and exacerbate renal ischemia/reperfusion injury (RI/RI). The aim of this study was to investigate the protective effect of GSK-3β inhibitor TDZD-8 against RI/RI through Nrf2/TrxR2 signaling pathway in a rat DM model. Methods: A DM rat model was established by a single injection of streptozocin. Diabetic rats were pretreated with TDZD-8 (1 mg/kg bw) or TDZD-8+auranofin (10 nmol/L, 5ml/kg bw), and then subjected to 45-min ischemia and 24-h reperfusion. Rats were equally randomized into four groups: a Sham-operated group, a RI/RI group, a TDZD-8 group, and a TDZD-8+auranofin group. Serum levels of BUN and Scr were measured. SOD activity, MDA content, and Nrf2, TrxR2 and caspase-3 expressions in rat kidney tissues were determined. Results: Renal function was improved, oxidative stress and cell apoptosis were reduced, and the expression of Nrf2 and TrxR2 was up-regulated in TDZD-8 treated rats as compared with those in auranofin treated rats. Conclusion: TDZD-8 may exert its protective effect against RI/RI by regulating the Nrf2/TrxR2 signaling pathway in the kidney tissue in DM.

Background/Aims: Diabetes mellitus can exacerbate renal ischemia-reperfusion (I/R) injury (RI/RI). The aim of the present study was to evaluate the protective effect of GSK-3β inhibition (TDZD-8) on I/R-induced renal injury through the Nrf2/HO-1 pathway in a streptozocin (STZ)-induced diabetic rat model. Methods: STZ-induced diabetic rats preconditioned with TDZD-8 and ZnPP were subjected to renal I/R. The extent of renal morphologic lesions. Renal function was assessed from blood urea nitrogen (BUN) and serum creatinine (Scr), as determined utlizing commercial kits. Oxidative stress and inflammatory activity in the kidney tissue was estimated from levels of malondialdehyde (MDA), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), and nitric oxide (NO), as well as the activities of superoxide dismutase (SOD) and glutathione (GSH) using qRT-PCR and ELISA. The expressions of Nrf2, HO-1, Bcl-2 and NF-κB in the renal tissue were measured by qRT-PCR and western blotting. Results: I/R-induced renal inflammation was reduced significantly by TDZD-8 pretreatment. Preconditioning with TDZD-8 suppressed NF-κB expression and enhanced Bcl-2 expression in the renal tissue. The upregulated level of malondialdehyde (MDA), and reduced activities of superoxide dismutase (SOD) and glutathione (GSH) in I/R-shocked rats were markedly restored by TDZD-8 pretreatment. Furthermore, pretreatment with TDZD-8 enhanced activation of the Nrf2/HO-1 pathway in the renal tissue of diabetic RI/RI rats. Conclusion: These findings suggest that preconditioning with TDZD-8 may protect the kidney from I/R-induced damage via the activation of the Nrf2/HO-1 pathway in STZ-induced diabetic rats. Further detailed studies are needed to further clarify the underlying mechanisms.

Background/Aims: Chelerythrine (CHE), a benzophenanthridine alkaloid, is a potent, selective, and cell-permeable protein kinase C (PKC) inhibitor. The purpose of the present study was to evaluate the effect of CHE on myocardial recovery after renal ischemia/reperfusion (I/R)-induced myocardial injury (RI/RMI) in a streptozocin (STZ)-induced diabetic rat model. Methods: Diabetes mellitus (DM) rats preconditioned with CHE and D, L-propargylglycine (PAG) were subjected to renal I/R. The extent of cardiac morphologic lesions and the biochemical markers of cardiorenal function and oxidative stress were detected utilizing hematoxylin-eosin staining, commercial kits, and enzyme-linked immunoassay, respectively. The expressions of cystathionine-γ-lyase (CSE), PKC-α, PKC-β₂, and nuclear factor-kappa B (NF-κB) in the rat myocardial tissue were measured utilizing western blotting. Results: Renal I/R treatment resulted in myocardial injury. CHE-preconditioning promoted the recovery from myocardial damage by ameliorating the biochemical parameters of myocardial injury, reducing oxidative stress, increasing the H₂S level, up-regulating the expression of CSE, and down-regulating the expressions of PKC-α, PKC-β₂, and NF-κB. Conclusion: These findings suggest that CHE-pretreatment may exert a protective effect on the myocardium against RI/RMI by activating endogenous CSE/H₂S via PKC/NF-κB pathway in STZ-induced diabetic rats. Further studies are needed defining underlying mechanisms.

Background/Aims: Myocardial ischemia/reperfusion (I/R) injury (MI/RI) is a critical cause of death in patients with heart disease. However, the pharmaco-therapeutical outcome for MI/RI remains unsatisfactory. Innovative approaches for enhancing drug sensitivity and recovering myocardial function in MI/RI treatment are urgently needed. The purpose of this study was to evaluate the protective effects of exenatide-loaded poly(L-lysine)-poly(ethylene glycol)-poly(L-lysine) (PLL-PEG-PLL) nanoparticles (NPs) against MI/RI. Methods: The size of PLL-PEG-PLL NPs and the loading and release rates of exenatide were determined. The in vitro NP cytotoxicity was evaluated using newborn rat cardiomyocytes. Rats pretreated with free exenatide or exenatide/PLL-PEG-PLL polyplexes were subjected to 0.5-h ischemia and 2-h reperfusion in the left anterior descending coronary artery. The histopathologic lesions were assessed using hematoxylin-eosin staining. The general physiological indices, including blood pressure (BP), heart rate (HR), the left ventricular ejection fraction (LVEF) and end-diastolic pressure (LEVDP), and the left ventricular pressure maximal rate of rising (dp/dt_max), were monitored using a non-invasive blood pressure analyzer and color Doppler echocardiography. The antioxidative activity in the myocardial tissue was measured. The myocardial enzymatic activity was further estimated by determining the serum levels of creatine kinase (CK), lactate dehydrogenase (LDH), cardiac troponin T (cTnT), and glucagon-like peptide-1 (GLP-1), as well as the expression of GLP-1R in the myocardial tissue. Results: Exenatide preconditioning attenuated the oxidative stress injury and promoted the myocardial function in I/R-induced myocardial injury, while the application of block copolymer PLL-PEG-PLL as a potential exenatide nanocarrier with sustained release significantly enhanced the bioavailability of exenatide. Conclusion: The block copolymer PLL-PEG-PLL may function as a potent exenatide nanocarrier for augmenting pharmacotherapy against MI/RI with unprecedented clinical benefits. Further study is needed to better clarify the underlying mechanisms.

Background/Aims: Renal ischemia/reperfusion (I/R) injury (RI/RI) is a common complication of diabetes, and it may be involved in altering intracellular calcium concentrations at its onset, which can result in inflammation, abnormal lipid metabolism, the production of reactive oxygen species (ROS), and nitroso-redox imbalance. The calcium-sensing receptor (CaSR) is a G-protein coupled receptor, however, the functional involvement of CaSR in diabetic RI/ RI remains unclear. The present study was intended to investigate the role of CaSR on RI/RI in diabetes mellitus (DM). Methods: The bilateral renal arteries and veins of streptozotocin (STZ)-induced diabetic rats were subjected to 45-min ischemia followed by 2-h reperfusion with or without R-568 (agonist of CaSR) and NPS-2143 (antagonist of CaSR) at the beginning of I/R procedure. DM without renal I/R rats served as control group. The expressions of CaSR, calmodulin (CaM), and p47phox in the renal tissue were analyzed by qRT-PCR and Western blot. The renal pathomorphology, renal function, oxidative stress, inflammatory response, and calcium disorder were evaluated by detection of a series of indices by hematoxylin-eosin (HE) staining, transmission electron microscope (TEM), commercial kits, enzyme-linked immunosorbent assay (ELISA), and spectrophotofluorometry, respectively. Results: Results showed that the expressions of CaSR, CaM, and p47phox in I/R group were significantly up-regulated as compared with those in DM group, which were accompanied by renal tissue injury, increased calcium, oxidative stress, inflammation, and nitroso-redox imbalance. Conclusion: These results suggest that activation of CaSR is involved in the induction of damage of renal tubular epithelial cell during diabetic RI/RI, resulting in lipid peroxidation, inflammatory response, nitroso-redox imbalance, and apoptosis.