【Abstract】ObjectiveTo investigate the protective effect of melatonin on renal injury induced by bile duct ligation in rats. MethodsSixtyfour rats were randomly divided into four experimental groups (n=16 rats per group): the control group (CN), sham operative group (SO), bile duct ligation group (BDL) and bile duct ligation melatonin treatment group (BDL+Mel). Obstructive jaundice was induced by common bile duct ligation. Plasma level of nitric oxide (NO), total bilirubin (TB), direct bilirubin (DB), alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea nitrogen (BUN) and creatinine (Cr) were measured 4 d and 8 d after operation. NO and inducible nitric oxide synthase (iNOS) in renal tissue were detected at the same time point, too. Histopathological changes of kidneys were examined by HE staining. ResultsIn BDL group, the plasma levels of NO, TB, DB, ALT, AST, BUN and Cr were higher than those of SO group (P＜0.01）, and the level of NO and activities of iNOS in renal tissue were significantly increased (P＜0.01）. However, in BDL+Mel group, the plasma levels of NO, ALT, AST, BUN and Cr were lower than those of the BDL group (P＜0.01）, and the level of NO and activities of iNOS in renal tissue were significantly suppressed (P＜0.01）; histopathological changes of kidneys were improved.ConclusionAugmentation of iNOS activities and increasing of NO production in local tissue contributed to renal injury induced by bile duct ligation, and the mode of melatonin’s protective actions, at least in part, relates to interference with no pathways.
Objective To observe the effects of melatonin on lung injury and NDRG2 ( N-myc downstream-regulated gene 2) expression after intestinal ischemia-reperfusion ( I/R) .Methods 40 healthy SD rats were randomly assigned to a sham group, an I/R group, a high-dose melatonin group ( 10 mg/kg) , and a low-dose melatonin group ( l mg/kg) . The model of lung injury was established by superior mesenteric artery clamping/unclamping. 30 minutes before clamping, melatonin was administered intraperitoneally to the rats in two melatonin groups, and normal saline in same volume was administered to the rats in the I/R group and the shamgroup. Then superior mesenteric arteries of the rats in the I/R group and two melatonin groups were clamped for 60 minutes. 45 minutes after unclamping, right lung tissues were sampled for pathological examination and wet/dry ( W/D) ratio measurement. The rats in the sham group underwent sham operation without clamping. The expression of NDRG2 protein in the lung tissue was detected by immunohistochemistry and Western-blot. Results Compared with the sham group, hemorrhage and inflammation of lung tissues were observed. The W/D was obviously increased and the NDRG2 expression was significantly decreased in the I/R group. Compared with the I/R group, mild hemorrhage and inflammation changes of lung tissues were observed and the W/D was decreased while the NDRG2 protein expression was increased significantly in two melatonin groups. There was no significant difference between two melatonin groups. Conclusion Melatonin may relieve lung injury after intestinal ischemia-reperfusion through up-regulating NDRG2 expression.
Objective Melatonin (MLT) can increase the expression of cartilage-derived growth factor and stimulate the synthesis of cartilage matrix. To investigate the prevention and treatment effects of MLT on damaged cartilage through observing the expressions of bone morphogenetic protein 2 (BMP-2) and interleukin 1β (IL-1β) in articular cartilage of the rats with osteoarthritis (OA). Methods Forty SPF 4-week-old male SD rats (weighing 120-150 g) were randomly divided into 4 groups (n=10): normal control group (group A), OA group (group B), OA/pinealectomy group (group C), and OA/ pinealectomy/MLT group (group D). The rats of group A served as a control without treatment. The rats of groups B, C, andD underwent left knee joint injection of 0.2 mL 4% papain solution 1 time every other day for 2 weeks for establ ishing OAmodel. Two weeks after papain injection, the rats of groups C and D were exposed to continuous l ight for 24 hours (intensity of illumination: 500 lx) for creating pinealectomy models. And at the next day after pinealectomy model establ ishing, the rats of group D were treated with intra-articular injections of 0.2 mL 20 mg/mL MLT solution 4 times a week for 4 weeks. At 1 week after last MLT injection, the venous blood samples were taken in groups A, B, and C to test the level of serum MLT by ELISA, respectively, and then the specimens of left cartilage of femoral condyle were harvested for macroscopic, histological, and immunohistochemical examinations in 4 groups. Results The OA and pinealectomy models of rats were successfully establ ished, and all rats survived. There were significant differences in the serum MLT level among groups A, B, and C, and among different time points at the same group (P lt; 0.05). In group A, articular cartilage surface was smooth and elastic, and chondrocytes arranged regularly. In groups B and C, articular cartilage surface was rough, cartilage defects and subchondral bone exposure were observed in some areas, and chondrocytes arranged irregularly. In group D, cartilage surface was more smooth than that in groups B and C, and the degrees of cartilage defect and subchondral bone exposure decreased with regular arrangment of chondrocytes. There were significant differences in Mankin scores and integral absorbance values among 4 groups (P lt; 0.05). Conclusion Exposure to continuous l ight can accelerate degeneration process of articular cartilage of OA rats. Injections of 0.2 mL MLT solution (20 mg/mL) by intra-articular for 4 weeks can inhibit the progress of cartilage defects. Upregulationof anabol ic factor of BMP-2 as well as down-regulation of catabol ic factors of IL-1β is associated with cartilage repairin the pathological features of OA.
Objective To investigate inhibited effects of melatonin (MLT) on proliferative activity of retinoblastoma cell line HXORB44 and its related mechanism. Methods HXO-RB44 cells were treated by MLT of different concentration (10-10, 10-9, 10-8, 10-7 mmol/L. Cell counting and tetrazolium dyereduction assay (MTT) were used to determine the effect of MLT on the survival and proliferation of HXO-RB44 cells. Apoptotic nuclei were further analyzed by HoechstPI fluorescence staining. Flow cytometry was used to measure the fluorescent intensity of ROS, cell cycle distribution and apoptosis. Results 10 -6 mmol/L (or exceed) of MLT could inhibit the proliferation of HXO-RB44cells in vitro while 10-7 mmol/L (or below) of MLT couldn't. With the increase of MLT concentration from 10-10 mmol/L to 10-7 mmol/L, HXO-RB44 cells gradually increased the expression of ROS. Hoechst staining showed that 4, 8, 12 and 24 hours after the incubation with MLT, the nuclear pyknosis and nuclear fragmentation increased in HXORB44 cells. The extent of apoptosis was proportional to the concentrations of MLT. Flow cytometry revealed that with the increasing of MLT concentration, G0/G1 and G2/M phase cells increased, S phase cells decreased. The apoptotic rate was also increased. Conclusion 10 -6 M of MLT could inhibit the proliferation of HXO-RB44 cells. This effect may relate to the increased ROS expression, cell cycle arrest at G0/G1 phase and apoptosis of HXO-RB44 cells.
Objective To evaluate the efficacy and safety of melatonin as an adjuvant therapy for the tumor patients receiving chemotherapy or radiotherapy. Methods Such databases as MEDLINE (1980 to Jan. 2010), The Cochrane Library (Issue 4, 2009), WanFang Data (1980 to Jan. 2010), CBM (1980 to Jan. 2010), CNKI (1980 to Jan. 2010), ELSEVIER ScienceDirect (SDOS, 1980 to Jan. 2010), Nature (1980 to Jan. 2010) and ongoing clinical trials (www.clinicaltrials.gov and www.controlled-trials.com) were searched to collect randomized controlled trials (RCTs). The data were extracted and the quality of the included RCTs was assessed by two reviewers. Then meta-analyses were performed by using Stata 10.1 software. Results Eight RCTs were included. The results of meta-analyses showed that melatonin significantly improved the remission rate for tumor patients (RR=1.98, 95% CI 1.52 to 2.58) and the one-year survival rate (RR=1.90, 95%CI 1.28 to 2.83), and significantly reduced the toxic effects of bone marrow suppression caused by chemotherapy or radiotherapy (RR=0.12, 95%CI 0.06 to 0.27). No reports of adverse events were associated with melatonin. Conclusion The existing evidence reveals that the melatonin, as an adjuvant therapy drug for tumor, plays a certain role in improving disease remission rate, reducing the toxicity of chemotherapy and radiotherapy, and prolonging the life. It requires more high-quality RCTs for further verification because of the limitation of the included studies.
Objective To investigate the protective effect of melatonin on rat liver injury induced by bile duct ligation. Methods Sixty-four rats were randomly divided into four groups：control group （CN group， n=16）， shamoperation group （SO group， n=16）， bile duct ligation group （BDL group， n=16）， and bile duct ligation with melatonin injection （BDL＋MT group， n=16）. The model of obstructive jaundice was done by ligation of the common bile duct. Melatonin was injected daily （0.5 mg/kg） via peritoneal cavity from 1 d before the operation to 7 d following oper-ation. On day 4 and 8 after the ligation， the plasma levels of total bilirubin （TBIL）， alanine aminotransferase （ALT）， aspartate aminotransferase （AST）， gamma glutamyl transferase （GGT）， and alkaline phosphatase （AKP） were measured by routine methods. Malonaldehyde （MDA）， superoxide dismutase （SOD）， glutathione （GSH）， catalase （CAT）， and glutathione peroxidase （GSH-Px） in the liver tissue were determined by spectrophtometry， too. Hepatocytes apoptosis was analyzed by terminal deoxynucleotidyl transferase-mediated deoxynuridine triphosphate nick-end labeling （TUNEL） assay. Results Compared with the CN group and SO group， the levels of TBIL， ALT， AST， GGT， and AKP in the plasma， the content of MDA in the liver tissue， and the apoptosis index （AI） in the hepatocyte markedly increased （P＜0.05， P＜0.01）， the content of GSH and the activities of SOD， CAT， and GSH-Px in the liver tissue markedly decreased（P＜0.01） in the BDL group. Compared with the BDL group， the levels of TBIL， ALT， AST， GGT， and AKP in the plasma， the content of MDA in the liver tissue， and the AI in the hepatocyte markedly decreased （P＜0.01）， the content of GSH and the activities of SOD， CAT， and GSH-Px in the liver tissue markedly increased （P＜0.01） in the BDL＋MT group. In the BDL group， the level of MDA in the liver tissue and the levels of TBIL， ALT， AST， GGT， and AKP were positively correlated （P＜0.01）， the content of GSH and the activities of SOD， CAT， and GSH-Px in the liver tissue and TBIL， ALT， AST， GGT， and AKP were negatively correlated （P＜0.01）. The level of MDA in the liver tissue and AI in the hepatocyte was positively correlated （P＜0.01）. The content of GSH and the activities of SOD， CAT， and GSH-Px in the liver tissue and AI were negatively correlated （P＜0.01）. Conclusions The participation of free radical of oxygen in the pathogenesis and severity of cholestasis produced by the acute obstruction of the extra-hepatic biliary duct is likely. The result of the present study indicates that melatonin exerts a protective effect on cholestatic liver injury in rats with BDL. The mechanism of melatonin’s protection on hepatocyte may be through its antioxidant action and by inhibiting hepatocyte apoptosis.
Objective To evaluate the efficacy of anti-oxidative treatment in cats with pancreaticobiliary maljunction. Methods Thirteen healthy cats as control group were made a model that resembling the common channel of pancreaticobiliary maljunction as in humans，and were divided randomly into two groups：7 cats in untreated group were not treated，6 cats in anti-oxidative group were treated with melatonin，vitamin C， and vitamin E. Six months later， the gallbladders of these animals were removed and histopathological changes were evaluated by pathological and electron microscopic examination. The level of MDA，amylase concentration in the gallbladder bile，and percentage of proliferating cell nuclear antigen （PNCA） positive cells were also test. Results All cats had survived for 6 months after operation. The wall of gallbladder and the bile became thicker in untreated group than that in normal control group， and there were no significant differences between untreated group and anti-oxidative group. The gallbladder epithelium became villous in appearance in untreated group，although the epithelium of that in normal control group was flat with few folds. The epithelial cells of gallbladder arranged tightly in normal control group， while a significant change such as endoplasmic reticulum expanding， intercellular space broadening， and cellular nucleus deforming were observed in untreated group. The things in anti-oxidative group were better than untreated group. The amylase concentration in the gallbladder bile was （203.02±65.04）U in normal control group，（9 368.09±2 204.42） U in untreated group， and（8 746.25±2 077.95） U in anti-oxidative group， respectively. The amylase concentration in untreated group and anti-oxidative group were higher than that in normal control group （P=0.003），and there was no significant difference between the untreated group and anti-oxidative group （P=0.642）. The percentage of PNCA positive cells was （7.29±2.70）% in normal control group，（54.71±10.90）% in untreated group, and （48.17±13.06）% in anti-oxidative group， respectively （F=48.11，P=0.001），and the percentage of PNCA positive cells in untreated group was higher than that in anti-oxidative group （P=0.001）. The level of MDA was （1.095±0.653） nmol/mg prot in normal control group，（2.745±1.533） nmol/mg prot in untreated group, and （1.302±0.771） nmol/mg prot in anti-oxidative group， respectively （F=5.17，P=0.017）, and the level of MDA in untreated group was higher than that in anti-oxidative group （P=0.017）. Conclusion The anti-oxidative treatment is effective to pancreaticobiliary maljunction.
Objective To observe the effect of melatonin (MT) on retinal apoptosis in rats with ischemia-reperfusion injury (RIRI). Methods A total of 54 male healthy Sprague-Dawley adult rats were randomly divided into the normal control (CON) group (6 rats), RIRI group (24 rats) and MT group (24 rats). The rats of RIRI and MT group were induced using suture-occluded methods to establish RIRI model. The rats of MT group were injected with MT in the left carotid artery 30 minutes after RIRI, and RIRI group was injected with the same amount of saline. On 6, 24 hours and 3, 7 days after RIRI, the morphological changes of retina were evaluated by hematoxylin and eosin (HE) staining; the effects of MT on retinal cell apoptosis and Nrf2, HO-1 proteins were examined by immunohistochemistry staining. The correlation between active Caspase-3 and Nrf2 protein, active Caspase-3 and HO-1 protein in MT group were analyzed by linear regression analysis. Results HE staining results showed that the morphology of retinal cells was regular and retinal cells were well arranged in the CON and MT group. In the RIRI group, both the thickness of inner retinal layer and the number of retinal ganglion cells (RGC) were decreased. On 6, 24 hours and 3, 7 days after RIRI, the thickness of inner retinal layer (F=16.710, 62.303, 68.389, 57.132; P＜0.01) and RGC number (F=24.250, 11.624, 14.155, 32.442; P＜0.05) in MT group were more than those in RIRI group. Immunohistochemistry staining results showed that less active Caspase-3+ cells were observed in MT group as compared with those in RIRI group at each time points (F=49.118, 134.173, 76.225, 18.385; P＜0.01). There were more Nrf2+ (F=11.041, 31.480, 59.246, 6.740; P＜0.05) and HO-1+ cells (F=128.993, 21.606, 51.349, 8.244; P＜0.05) in MT group as compared with those in RIRI group at each time points. Linear regression analysis results showed that the difference of active Caspase-3+ cells were all linearly correlated with the Nrf2+ cells and HO-1+cells in the MT group (r2=0.810, 0.730; P＜0.01). Conclusion MT could reduce retinal cell apoptosis in RIRI rats, and its mechanism may be associated with increased Nrf2 and HO-1 expression, reduced active Caspase-3 expression.
Intravitreal injection of anti-VEGF drugs has gradually become the first-line treatment for diabetic retinopathy (DR). However, diabetic macular edema (DME) caused by DR blood-retinal barrier damage is less sensitive to anti-VEGF drugs.Therefore, it is necessary to find supplementary drugs or alternative drugs that can effectively protect the structure of the blood vessel wall. Melatonin is a hormone mainly secreted by the pineal gland, which can play a number of functions in the human body such as regulating biological rhythms, scavenging free radicals, and anti-inflammatory. In recent years, studies have shown that melatonin can improve neuronal degeneration and protect blood vessel structure through multiple mechanisms in retinopathy. In terms of its protective effect on the retinal capillary structure, melatonin can improve the damage of early DR endothelial cells and pericytes through anti-oxidative stress, anti-inflammatory, and inhibiting cell apoptosis so as to protect the integrity of the blood-retinal barrier structure. It suggests that melatonin may provide new ideas for the prevention and treatment of DR, especially with DME.
Objective To evaluate the effect of exogenous melatonin and its analogues on the prevention of delirium in critically ill patients by meta-analysis. Methods Randomized controlled trials of exogenous melatonin and its analogues in the prevention of delirium in critically ill patients were searched by computer from the Cochrane Library, PubMed, Web of Science, Embase, China National Knowledge Infrastructure, Chongqing VIP, Wanfang, and SinoMed databases. The trial group was treated with melatonin or its analogues, while the control group was treated with placebo. The retrieval period was from the establishment of database to January 14th, 2021. Two researchers independently evaluated the literature quality, and meta-analysis was performed using RevMan 5.4 software. Results A total of 11 randomized controlled trials containing 1177 patients were enrolled, including 588 patients in the trial group and 589 patients in the control group. The results showed that exogenous melatonin and its analogues could reduce the occurrence of delirium in critically ill patients [odds ratio (OR)=0.45, 95% confidence interval (CI) (0.22, 0.91), P=0.03] and shorten the time of mechanical ventilation [standard mean difference (SMD)=−0.49, 95%CI (−0.94, −0.03), P=0.04], while might not affect the mortality rate [OR=0.73, 95%CI (0.46, 1.17), P=0.19] or length of intensive care unit stay [SMD=−0.05, 95%CI (−0.26, 0.15), P=0.61]. Conclusions The current evidence shows that exogenous melatonin and its analogues have some effect on reducing the occurrence of delirium and shortening the duration of mechanical ventilation in critically ill patients, and have no significant effect on reducing the mortality or length of intensive care unit stay. The above conclusions need to be confirmed by more high-quality studies.