Agomelatine reduces brain, kidney and liver oxidative stress but increases plasma cytokine production in the rats with chronic mild stress-induced depression

The protective role of melatonin and agomelatine against oxidative stress following laparoscopic ovariectomy in dogs

BACKGROUND

The present study was carried out to compare biomarkers of oxidative stress and antioxidant activity of agomelatine and melatonin in bitches undergoing laparoscopic ovariectomy. Twenty-four healthy female dogs were randomly divided into four groups: Control (C), laparoscopic ovariectomy (LO), agomelatine + laparoscopic ovariectomy (ALO), and melatonin + laparoscopic ovariectomy (MLO) consisting of 6 animals each. Melatonin and agomelatine were administered to the MLO group (0.3 mg/kg/day, p.o) and the ALO group (0.3 mg/kg/day, p.o) consequently one day before LO to 7 days post-intervention. Blood sampling was performed on days - 1, 0 (immediately after surgery), 3, and 8 of the study. Total oxidant status (TOS), total antioxidant capacity (TAC), and malondialdehyde (MDA) in sera and superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in hemolyzed red blood cells (RBCs) were measured.

RESULTS

Among all indices analyzed over time, only the MDA index in the ALO group showed a significant difference, being significantly lower on day 3 post-surgery compared to days - 1 and 0 (p = 0.023). Significant differences were observed between groups in terms of TOS, TAC, GPx, and SOD levels. The LO group exhibited a significant increase in the TOS index on day 3 compared to all other groups (p = 0.008). The TAC index experienced the most significant increase in the MLO group on day 0 compared to other groups (p = 0.005), and this trend continued significantly until day 3, only in comparison to the LO and C groups (p = 0.024). Agomelatine significantly increased SOD levels in the ALO group on postoperative day 3 compared to groups C and LO (p = 0.009). GPx levels were significantly elevated in ALO and MLO groups on day 8 compared to groups C and LO (p = 0.003).

CONCLUSION

The results of this study demonstrate that melatonin, by increasing total antioxidant capacity, and agomelatine, through enzymatic antioxidant pathways, contributed to the reduction of free radical levels in dogs. The present study revealed that administering agomelatine (0.3 mg/kg/day, p.o) could decrease MDA levels significantly after laparoscopic ovariectomy up to day 3.

Agomelatine Alleviates Depressive-like Behaviors by Suppressing Hippocampal Oxidative Stress in the Chronic Social Defeat Stress Model

Major depressive disorder (MDD) is a common psychiatric disorder characterized by significant mood disturbances and cognitive impairments. Chronic stress, particularly social defeat stress, plays a crucial role in the etiology of depression, with oxidative stress being a pivotal factor in its pathophysiology. Consequently, identifying effective strategies to mitigate oxidative stress and prevent the progression of depression is of paramount importance. Agomelatine, an atypical antidepressant with melatonergic and serotonergic properties, has shown promise in treating MDD due to its unique mechanisms of action. In this study, we aimed to investigate whether agomelatine could ameliorate behavioral deficits in a chronic social defeat stress (CSDS) mouse model. CSDS mice were administered agomelatine (50 mg/kg, intraperitoneally) and exhibited significant reductions in both anxiety-like and depressive-like behaviors in behavioral tests. Further analysis revealed that agomelatine treatment effectively reduced oxidative damage in the hippocampus of CSDS mice. Additionally, agomelatine attenuated mitochondrial dysfunction and restored synaptic plasticity, as evidenced by an increased density of excitatory synapses and enhanced neuronal activity. These findings suggest that agomelatine may exert therapeutic effects by reducing oxidative stress, preserving mitochondrial function, and enhancing synaptic plasticity, providing new insights into its potential as a treatment for chronic social defeat stress-induced depression.

Citrate-coated silver nanoparticles loaded with agomelatine provide neuronal therapy in acute cerebral ischemia/reperfusion of rats by inhibiting the oxidative stress, endoplasmic reticulum stress, and P2X7 receptor-mediated inflammasome

Cerebral ischemia and reperfusion are related to various situations like injuries after various traumas, oxidative stress, increased calcium ion, capillary hypoperfusion, microvascular hyperpermeability, leukocyte infiltration, and blood-brain barrier disruption. An antidepressant Agomelatine which is a melatonin receptor (MT1/MT2) agonist and serotonin receptor (5-HT2C) antagonist has been reported by studies to have antioxidant and anti-inflammatory effects. In our study, we aimed to detect the effects of citrate-coated silver nanoparticle-loaded agomelatine application on neurodegeneration, endoplasmic reticulum stress, autophagic and apoptotic cell death, inflammation, and P2X7R expression in the cerebral ischemia-reperfusion model to facilitate the passage of blood-brain barrier. Forty two Sprague-Dawley rats in total were divided into six equal groups (n:7) and applications were performed. Acute cerebral injury in the ischemia-reperfusion model was created 2 h after internal carotid artery ligation in rats and then at the 2nd hour of reperfusion citrate-coated silver nanoparticles loaded with Agomelatine were applied. Twenty four hours later, neurologic analysis on animals in experimental groups was performed, animals were decapitated and GSH, GPx, SOD, CAT, MDA, IL-1β, and TNF-α parameters were examined after taking blood and the cerebral tissue samples. As a result, it was determined that ischemia-reperfusion caused endoplasmic reticulum stress in the cerebral tissues and thus caused cellular injury.

Screening the components in multi-biological samples and the comparative pharmacokinetic study in healthy and depression model rats of Suan-Zao-Ren decoction combined with a network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Suanzaoren Decoction (SZRD) is a classic traditional Chinese prescription, which has been commonly used for treating insomnia, depression and other nerve system diseases for a long time.

AIM OF THIS STUDY

The present study aimed to explore the metabolic profiles in multi-biological samples and pharmacokinetic mechanism between healthy and depression model rats combined with a network pharmacology approach after administration of SZRD.

MATERIALS AND METHODS

In our study, an ultra-high performance liquid chromatography (UPLC)-Q-Exactive Orbitrap Mass Spectrometry method was firstly used to study the prototype components and metabolites of SZRD in plasma, brain, urine, and feces between healthy and depressed rats. The possible metabolic pathways were also speculated. Then a network pharmacological study was conducted on the components in the plasma of model rats. According to the above components screened by network pharmacology and the other reported representative active components, the comparative pharmacokinetic study was established for the simultaneous determination of mangiferin, spinosin, ferulic acid, liquiritin, formononetin. magnoflorine and isoliquiritin between healthy and depression model rats. Finally, molecular docking was used to validate the binding affinity between key potential targets and active components in pharmacokinetics.

RESULTS

A total of 115 components were identified in healthy rats, and 101 components were identified in model rats. The prototype components and metabolites in plasma, brain, urine, and feces were also distinguished. The main metabolic pathways included phase I and phase II metabolic reactions, such as dehydrogenation, oxidation, hydroxylation, gluconaldehyde conjugation, glutathione conjugation and so on. These results provided a basis for the further study of antidepressive pharmacokinetic and pharmacological action in SZRD. Then, according to the degree value of network pharmacological study, it was predicted that 10 components and 10 core targets, which involved in the critical pathways such as neuroactive ligand-receptor interaction, cyclic adenosine monophosphate (cAMP) signaling pathway, serotonergic synapse, phosphatidylinositol-3 kinase (PI3K)-Akt signaling pathway, etc. Finally, the established pharmacokinetic method was successfully applied to compare the pharmacokinetic behavior of these 7 active components in plasma of healthy and depressed rats after oral administration of SZRD. It showed that except magnoflorine, the pharmacokinetic parameters of each component were different between healthy and depressed rats. Molecular docking analysis also indicated that the active compounds in pharmacokinetics could bind tightly to the key targets of network pharmacological study.

CONCLUSION

This study may provide important information for studying the action mechanism of SZRD in treating depression.

Effects of agomelatine on rat liver regeneration following partial hepatectomy

Primary or metastatic hepatic malignancies are common. Partial hepatectomy (PH) is the primary treatment for both benign and malignant hepatic neoplasms; it also is used for living donor liver transplantation. The regenerative potential of the liver after PH is 70-80% in humans. We investigated the protective and therapeutic effects of agomelatine (AGM) on rat liver regeneration following PH. We used 32 rats distributed equally into four groups: group 1, sham control; group 2, PH group; group 3, administered 20 mg/kg AGM orally once/day for 7 days following PH; group 4, administered 20 mg/kg AGM orally once/day 3 days before and 7 days following PH for 10 days. Liver samples were analyzed for antioxidants and free radicals. Tissue samples were processed and stained with hematoxylin and eosin to assess histopathological status and stained immunohistochemically for Ki-67. We found that PH reduced antioxidant enzymes and increased tissue reactive oxygen species, whereas AGM treatment had the opposite effect on these parameters. Our biochemical and histopathological findings were consistent. PH caused sinusoid congestion and dilation. Intensity of Ki-67 immunostaining of hepatocytes was increased in group 2, whereas these were reduced in group 4. Intensity of Ki-67 immunostaining of hepatocytes was increased in group 2, whereas it was reduced in the group 4 compared to group 1. We found that AGM was hepatoprotective following PH due to its antioxidant and free radical scavenger properties.

Shuxie-1 Decoction Alleviated CUMS -Induced Liver Injury via IL-6/JAK2/STAT3 Signaling

Introduction: Chronic stress has been shown to cause liver damage in addition to psychological depression. Besides, drug-induced liver injury is frequently caused by antidepressants. Shuxie-1 decoction (SX-1) is a formula of traditional Chinese medicine commonly used in nourishing liver blood, and relieving depression. However, the underlying molecular mechanism remains unclear. Therefore, this study was designed to explore the effects and mechanisms of SX-1 in treating chronic stress-induced depression as well as liver injury.

Methods: Chronic unpredictable mild stress (CUMS) was applied to male Wistar rats for 4 weeks, with or without administration of SX-1 at low-dose and high-dose for 6 weeks, using Fluoxetine (Flu) as a positive control. Body weight was monitored once every 2 weeks. In the sixth week, the sugar preference test and open field test were carried out to evaluate the depression status. After that, the serum and liver tissues were collected. The quality control of SX-1 decoctions and drug-containing serum was controlled by UHPLC-QE-MS. The cell viability was measured by Cell Counting Kit-8 (CCK8). Enzyme-linked immunosorbent assay (Elisa), Western Blot and immunohistochemistrical staining was obtained to detect the protein levels in the plasma and the hepatic tissues, respectively.

Results: CUMS led to decreased 1) body weight, 2) the preference for sugar water, 3) the desire to explore in open field, and increased serum levels of corticosterone. All these factors were completely reversed by SX-1 treatment. Hematoxylin-eosin staining (HE) showed that SX-1 improved the hepatocyte vacuolization in CUMS treated rats, decreased the serum levels of alanine aminotransferase (ALT) and the deposition of type I collagen (Col I) in hepatocytes as well. CUMS increased the levels of hepatic Interleukin-6 (IL-6), and provoked the activation of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3), which was abrogated by SX-1 treatment. Cobalt chloride (CoCl₂) increased the protein expression of IL-6 and p-STAT3 in AML12 cells. Besides, nuclear pyknosis was observed under electron microscope, which were recovered after rat SX serum.

Conclusion: SX-1 effectively ameliorated CUMS-induced depression-like behaviors as well as hepatic injuries, probably by the blockade of hepatic IL-6/JAK2/STAT3 signaling.

Role of IL-6/STAT3 pathway in mediating the protective effect of agomelatine against methotrexate-induced lung/intestinal tissues damage in rats

BACKGROUND

Methotrexate (MTX), an anticancer drug, has been linked to multiple organ toxicity. The drug-induced acute toxic symptoms can negatively affect the patient's commitment to the course of treatment.

MATERIALS AND METHODS

This study aimed to investigate the mitigating action of agomelatine (Ago) against MTX-induced lung and intestinal toxicity. Forty eight male Wister rats were randomized into six experimental groups: Group 1: Control; Groups 2 and 3: received Ago L&H (20/40 mg/kg, respectively by gavage); Group 4: received MTX 10 mg/kg/day, i.p. on days 7-9; Group 5: received Ago L (20 mg/kg) + MTX; Group 6: received Ago H (40 mg/kg) +MTX. The duration of the study was 10 days. Lung/intestine oxidative markers were measured. Lung/intestinal tissues IL-6, STAT3, and HO-1 levels were evaluated by ELISA. Besides, lung/intestinal tissues were examined for Histological changes, collagen fibers detection using Massonꞌs trichome stain, and immunohistochemical study using HSP70 antibody.

RESULTS

MDA, NOx, IL-6, and STAT3 levels were significantly higher in the MTX group's lungs and intestines, indicating lung and intestinal toxicity. There were substantial decreases in GSH, SOD tissue levels, and HSP 70 immunoexpression, as well as histological changes suggesting significant lung and intestinal injury. All of the above parameters improved significantly by using Ago.

CONCLUSION

By reducing oxidative stress, inflammatory processes, and modulating the IL-6/STAT3 pathway, Ago has potent ameliorative effects against MTX-induced lung/intestinal toxicities.

Antidepressant actions of melatonin and melatonin receptor agonist: Focus on pathophysiology and treatment

Depression has become one of the most commonly prevalent neuropsychiatric disorders, and the main characteristics of depression are sleep disorders and melatonin secretion disorders caused by circadian rhythm disorders. Abnormal endogenous melatonin alterations can contribute to the occurrence and development of depression. However, molecular mechanisms underlying this abnormality remain ambiguous. The present review summarizes the mechanisms underlying the antidepressant effects of melatonin, which is related to its functions in the regulation of the hypothalamic-pituitary-adrenal axis, inhibition of neuroinflammation, inhibition of oxidative stress, alleviation of autophagy, and upregulation of neurotrophic, promotion of neuroplasticity and upregulation of the levels of neurotransmitters, etc. Also, melatonin receptor agonists, such as agomelatine, ramelteon, piromelatine, tasimelteon, and GW117, have received considerable critical attention and are highly implicated in treating depression and comorbid disorders. This review focuses on melatonin and various melatonin receptor agonists in the pathophysiology and treatment of depression, aiming to provide further insight into the pathogenesis of depression and explore potential targets for novel agent development.

Agomelatine protects against obesity-induced renal injury by inhibiting endoplasmic reticulum stress/apoptosis pathway in rats

Obesity is recognized as a risk for the development of chronic kidney disease. Excessive fat accumulation in obesity is associated with the overproduction of reactive oxygen species with the underproduction of antioxidant mechanisms generating oxidative stress together with chronic low-grade inflammation which subsequently leads to the development of several obesity-related complications. It has been suggested that the abnormal lipid accumulation can induce endoplasmic reticulum (ER) stress and cellular apoptosis in several tissue types. Agomelatine is a relatively new antidepressant which is a synthetic agonist of melatonin. Previous study reported the antioxidant and anti-inflammatory effects of agomelatine. In this study, we investigated the therapeutic effects of agomelatine in obesity-related renal injury. Male Wistar rats were fed with normal diet or high-fat diet (HF) for 16 weeks. After that, vehicle or agomelatine or vildagliptin was orally administered to HF rats for 4 weeks. Our results indicated that HF rats demonstrated insulin resistance which was accompanied by an impairment of renal function and renal organic anion transporter 3 (Oat3) function as well as renal oxidative stress, ER stress, and apoptosis. Interestingly, agomelatine treatment not only improved the metabolic parameters, renal function and renal Oat3 function but also attenuated renal oxidative stress, ER stress and subsequent apoptosis. Therefore, agomelatine exerted renoprotective effects in obese insulin-resistant condition. These results suggested that agomelatine could be used as a drug to improve metabolic disturbance and prevent kidney dysfunction in obese condition.

Liver proteome alterations in psychologically distressed rats and a nootropic drug

BACKGROUND

Chronic psychological distress is considered today a pandemic due to the modern lifestyle and has been associated with various neurodegenerative, autoimmune, or systemic inflammation-related diseases. Stress is closely related to liver disease exacerbation through the high activity of the endocrine and autonomic nervous systems, and the connection between the development of these pathologies and the physiological effects induced by oxidative stress is not yet completely understood. The use of nootropics, as the cognitive enhancer and antioxidant piracetam, is attractive to repair the oxidative damage. A proteomic approach provides the possibility to obtain an in-depth comprehension of the affected cellular processes and the possible consequences for the body. Therefore, we considered to describe the effect of distress and piracetam on the liver proteome.

METHODS

We used a murine model of psychological stress by predatory odor as a distress paradigm. Female Sprague-Dawley rats were distributed into four experimental groups (n = 6 - 7/group) and were exposed or not to the stressor for five days and treated or not with piracetam (600 mg/kg) for six days. We evaluated the liver proteome by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (1D-SDS-PAGE) followed by liquid chromatography-tandem mass spectrometry (GeLC-MS/MS). Besides, we analyzed the activity of liver antioxidant enzymes, the biochemical parameters in plasma and rat behavior.

RESULTS

Our results showed that distress altered a wide range of proteins involved in amino acids metabolism, glucose, and fatty acid mobilization and degradation on the way to produce energy, protein folding, trafficking and degradation, redox metabolism, and its implications in the development of the non-alcoholic fatty liver disease (NAFLD). Piracetam reverted the changes in metabolism caused by distress exposure, and, under physiological conditions, it increased catabolism rate directed towards energy production. These results confirm the possible relationship between chronic psychological stress and the progression of NAFLD, as well as we newly evidenced the controversial beneficial effects of piracetam. Finally, we propose new distress biomarkers in the liver as the protein DJ-1 (PARK7), glutathione peroxidase 1 (GPX), peroxiredoxin-5 (PRDX5), glutaredoxin 5 (GLRX5), and thioredoxin reductase 1 (TXNDR1), and in plasma as biochemical parameters related to kidney function such as urea and blood urea nitrogen (BUN) levels.

Agomelatine effects on fat-enriched diet induced neuroinflammation and depression-like behavior in rats

Growing evidence suggests that a high fat diet (HFD) induces oxidative stress on the central nervous system (CNS), which predisposes to mood disorders and neuroinflammation. In this study we postulated that in addition to improving mood, antidepressant therapy would reverse inflammatory changes in the brain of rats exposed to a HFD. To test our hypothesis, we measured the effect of the antidepressant agomelatine (AGO) on anxiety- and depressive-like behaviors, as well as on CNS markers of inflammation in rats rendered obese. Agomelatine is an agonist of the melatonin receptors MT1 and MT2 and an antagonist of the serotonin receptors 5HT2B and 5HT2C. A subset of rats was also treated with lipopolysaccharides (LPS) to determine how additional neuroinflammation alters behavior and affects the response to the antidepressant. Specifically, rats were subjected to a 14-week HFD, during which time behavior was evaluated twice, first at the 10th week prior to LPS and/or agomelatine, and then at the 14th week after a bi-weekly exposure to LPS (250 μg/kg) and daily treatment with agomelatine (40 mg/kg). Immediately after the second behavioral testing we measured the proinflammatory cytokines tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6) and interleukin 1 beta (IL-1β), markers of oxidative stress thiobarbituric acid reactive substances (TABRS), catalase (CAT) and glutathione peroxidase (GPx), the growth factor BDNF, as well as the apoptosis marker caspase-3. Our results show that a HFD induced an anxiety-like behavior in the open field test (OFT) at the 10th week, followed by a depressive-like behavior in the forced swim test (FST) at the 14th week. In the prefrontal and hippocampal cortices of rats exposed to a HFD we noted an overproduction of TNF-α, IL-6, IL-1β, and TABRS, together with an increase in caspase-3 activity. We also observed a decrease in BDNF, as well as reduced CAT and GPx activity in the same brain areas. Treatment with agomelatine reversed the signs of anxiety and depression, and decreased the cytokines (TNF-α, IL-6 and IL-1β), TABRS, as well as caspase-3 activity. Agomelatine also restored BDNF levels and the activity of antioxidant enzymes CAT and GPx. Our findings suggest that the anxiolytic/antidepressant effect of agomelatine in obese rats could result from a reversal of the inflammatory and oxidative stress brought about by their diet.

Agomelatine confers neuroprotection against cisplatin-induced hippocampal neurotoxicity

Neurotoxicity caused by cisplatin is a major obstacle during chemotherapy. Oxidative stress and inflammation are considered the primary mechanism behind neuronal damage which affects the continuing chemotherapy regimen. Agomelatine was recently described as a neuroprotective compound against toxic insults in the nervous systems. It is an analog of the well-known antioxidant and anti-inflammatory compound melatonin and currently used for depression and sleep disturbances. In the current study, we investigated the possible neuroprotective role of agomelatine against cisplatin-induced oxidative, inflammatory, and behavioral alterations in male rats. Our results show that agomelatine prevented cisplatin-induced neurotoxicity in the HT-22 mouse hippocampal neuronal cell line. Additionally, agomelatine treatment inhibited cisplatin-induced behavioral deficits and neuronal integrity in vivo. For the evaluation of the effect of agomelatine on oxidative stress and inflammation, GSH, MDA, TNF, and IL-6 levels were analyzed in HT-22 cells and hippocampal tissues. Agomelatine significantly attenuated oxidative stress and inflammation due to the cisplatin insult in vitro and in vivo. Also, agomelatine treatment ameliorated the neuronal pathology in the hippocampus, which is strongly related to cognition and memory. Taken together, our results indicate that in males, the neuroprotective effect of agomelatine is mediated through its antioxidant and anti-inflammatory actions abrogating functional deficits.

THE ROLE OF QUALITY OF LIFE IN MELATONIN CONTENT AS A REGULATOR OF DEFENSE AND AGGRESSION FACTORS IN GASTROESOPHAGEAL REFLUX DISEASE PATIENTS WITH SLEEP APNEA SYNDROME

The aim of the study: to study the effect of the quality of life on the melatonin content, and at the same time to assess the state of the factors of aggression and protection of the esophageal mucosa in patients with GERD without comorbidities and with concomitant obstructive sleep apnea/hypopnea syndrome (OSAHS). Methods. 45 patients were taken for the study. 23 of them had GERD  concomitant COPD, 22 were with isolated GERD with a non-erosive form. Melatonin levels were determined using the enzyme immunoassay method (ELIZA). Quality of life was assessed using the SF-36 questionnaire. Antioxidant protection of the mucous membrane (protection factor) – was assessed by the activity of superoxide dismutase (SOD). SOD activity in blood serum was determined by calorimetric method. Determination of the DC level was carried out in the blood by the spectrofluorimetric method. Results. The study showed that in patients with GERD with concomitant COPD, there is a significant decrease in the indicators of antioxidant activity and melatonin, both with indicators from the control group and with indicators of patients with GERD without comorbidity. At the same time, in patients with GERD without comorbidities, an increase in the level of DC was observed in comparison with the control group and patients with GERD with concomitant pathology and acidity of gastric juice. When analyzing the indicators of QOL in patients with GERD with concomitant pathology, there is a significantly more pronounced decrease in mental health, role emotional functioning and vitality. Conclusions. It has been established that in patients with GERD in the stage of exacerbation of the disease, there is a statistically significant decrease in QOL indicators with a high degree of reliability, manifesting itself in patients without combined pathology in the spectrum of indicators of the physical component of health, and in patients with GERD with concomitant obstructive sleep syndrome – in the spectrum of the psychological component quality of life. It has been shown that with a decrease in QOL in patients with GERD, the level of melatonin decreases, the decrease in which more clearly increases in patients with concomitant obstructive sleep apnea. Simultaneously with a drop in the level of melatonin in patients with GERD without associated pathology, the aggression factor increases with a high degree of certainty - that is, a decrease in the pH of gastric juice and an increase in the content of DC, while in patients with GERD with concomitant sleep apnea syndrome, the factor decreases with a high degree of certainty. Protection of the esophageal mucosa – (that is, a decrease in SOD activity), which must be taken into account when treating this category of patients.

The Changes of Expression and Methylation of Genes Involved in Oxidative Stress in Course of Chronic Mild Stress and Antidepressant Therapy with Agomelatine

Preclinical studies conducted so far suggest that oxidative stress processes may be associated with the mechanism of depression development. This study shows the effects of chronic administration of agomelatine on expression and the methylation status of Sod1, Sod2, Gpx1, Gpx4, Cat, Nos1, and Nos2 in the brain stricture and blood in the chronic mild stress (CMS) animal model of depression. The animals were exposed to the CMS procedure and treatment with agomelatine (10 mg/kg/day, IP) for five weeks and then were sacrificed. TaqMan Gene Expression Assay, Western blot, and methylation-sensitive high-resolution melting techniques were used to evaluate mRNA and protein expression of the genes, and the methylation status of their promoters. Gpx1, Gpx4, and Sod2 expression in the PBMCs and Sod1 and Sod2 expression in the brain were reduced in the stressed group after agomelatine administration. CMS caused an increase in the methylation of the third Gpx4 promoter in peripheral blood mononuclear cells and Gpx1 promoter in the cerebral cortex. Additionally, stressed rats treated with agomelatine displayed a significantly lower Gpx4 level in the hypothalamus. The results confirm the hypothesis that the CMS procedure and agomelatine administration change the expression level and methylation status of the promoter region of genes involved in oxidative and nitrosative stress.

Sub-Acute Oral Toxicity of a Novel Derivative of Agomelatine in Rats in a Sex-Dependent Manner

Agomelatine (AGO) is a new type of antidepressant with demonstrated antidepressant effects and a unique modulating circadian rhythm action. However, AGO has hepatotoxicity, which limits its clinical application. In order to develop new drugs that cause less liver injury than AGO, a series of derivatives were synthesized; compound GW117 was screened from derivatives due to its high receptor affinity. This study will investigate its sub-acute oral toxicity profile in rats in a sex-dependent manner. GW117 and AGO was administrated by gavage (200, 400, or 800 mg/kg/day) for 28 days. Hematological, biochemical tests, organ weights, histopathological examinations were carried out, the results showed that AGO and GW117 had adverse effects on platelet, liver and kidney, and had sex-differences in some indicators. Hematological tests showed that AGO and GW117 reduced the platelet count in male animals but had no effect in females. AGO increased plasma alanine aminotransferase (ALT) and total bilirubin in male animals, and GW117 had no effect on these two indicators. For females, AGO moderately elevated ALT, alkaline phosphatase (ALP), and total bilirubin, while GW117 only elevated ALP slightly. Two drugs could increase liver weight and coefficient, and cause liver pathological injury, including hepatic sinusoidal dilatation, hepatocyte fatty deposition and dotted cell necrosis in two genders. AGO caused mild to moderate hepatocyte and hepatobiliary injury in both genders, while only a mild hepatobiliary injury was caused by GW117 in females. Renal function tests showed that both drugs can increase blood urea nitrogen levels in males, while AGO, but not GW117, can slightly increase blood creatinine and urea nitrogen in females. The kidney weight and coefficient could be significantly increased by two drugs in males, and by AGO medium and GW117 high and low doses in females. The kidney pathological damage was mainly characterized by tubule dilatation, a thinning of the renal cortex. Kidney damage caused by GW117 was less than that of AGO, and there was no sex-difference. In summary, GW117 can cause mild liver and kidney damage in both genders, as well as mild platelets reduction in males, while degree of damage is less severe than AGO. Therefore, as an excellent derivative, GW117 deserves further development as an antidepressant.

Melatonin receptor stimulation by agomelatine prevents Aβ-induced tau phosphorylation and oxidative damage in PC12 cells

Purpose

As a novel antidepressant drug, agomelatine has good therapeutic effect on the mood disorder and insomnia in Alzheimer's disease (AD). Recent studies have shown the neuroprotective function of agomelatine, including anti-oxidative and anti-apoptosis effect. However, it remains unclear whether agomelatine exerts neuroprotection in AD. Thus, the neuroprotective effect of agomelatine against amyloid beta _25-35 (Aβ_25-35)-induced toxicity in PC12 cells was evaluated in this study.

Methods

The concentration of malondialdehyde (MDA), LDH, and ROS was investigated to evaluate oxidative damage. The expression of P-tau, tau, PTEN, P-Akt, Akt, P-GSK3β, and GSK3β proteins was assessed by Western blotting. Our results demonstrated that Aβ_25-35 significantly increased the content of MDA, LDH, and ROS. Meanwhile, Aβ_25-35 upregulated the expression of P-tau and PTEN as well as downregulated P-Akt and P-GSK3β expression. These effects could be blocked by agomelatine pretreatment. Furthermore, luzindole, the melatonin receptor (MT) antagonist, could reverse the neuroprotective effect of agomelatine.

Conclusion

The results demonstrated that antidepressant agomelatine might prevent the tau protein phosphorylation and oxidative damage induced by Aβ_25-35 in PC12 cells by activating MT-PTEN/Akt/GSK3β signaling. This study provided a novel therapeutic target for AD in the future.

Agomelatine-induced modulation of brain-derived neurotrophic factor (BDNF) in the rat hippocampus

Brain-derived neurotrophic factor (BDNF) is a neurotrophin that serves as a survival factor for neurons. Agomelatine is a novel antidepressant as well as a potent agonist of melatonin (MT), MT1 and MT2 receptor types and an antagonist of the serotonin (5HT), 5-HT2C receptor. The study herein established whether treatment with agomelatine alters hippocampal BDNF protein expression under chronic unpredictable mild stress (CUMS) condition. Twenty-one day treatment with agomelatine, fluoxetine or vehicle was assessed in 52 Sprague-Dawley rats undergoing CUMS. Ten naïve control rats were also evaluated after 21 days. The behavioral effects of treatments were studied using the open field test (OFT) on day 0, 7 and 21 and sucrose preference test on day 21. Hippocampal BDNF protein expression was measured using immunohistochemistry. The effect of the interventions on hippocampal neurons was histologically examined after H&E staining. Agomelatine mitigated the reduction in rearing behavior by CUMS in the OFT on day 7 as well as sucrose preference on day 21. The mean optical density value of BDNF was significantly higher in the CUMS + agomelatine group than the CUMS and CUMS + fluoxetine groups. The CUMS + agomelatine group had a significantly higher number of BDNF positive cells compared to naïve controls and CUMS group. Histology showed that hippocampal neurons in the CUMS + agomelatine and CUMS + fluoxetine groups were intact and few of them demonstrated karyopyknosis. Agomelatine-a novel antidepressant, but not fluoxetine, increased hippocampal BDNF level and of BDNF positive neurons in rats subject to CUMS.

Agomelatine protects against neuronal damage without preventing epileptogenesis in the kainate model of temporal lobe epilepsy

Recent studies about the novel antidepressant agomelatine, which is a mixed MT₁ and MT₂ melatonin receptor agonist and 5HT_2C serotonin receptor antagonist possessing an anticonvulsant and neuroprotective action, suggest that it may have potential to contribute against epileptogenesis and epilepsy-induced memory impairment. In order to ascertain whether protection of some brain structures could suppress epileptogenesis, in the present study, we evaluated the effect of chronic post-status treatment with agomelatine on epileptogenesis, behavioral and neuronal damage induced by kainate acid (KA) status epilepticus (SE). Agomelatine/vehicle treatment (40mg/kg, i.p.) started one hour after SE and continued up to 10weeks in Wistar rats. Latency for onset of spontaneous motor seizures (SMS) and their frequency was detected by a 24-h video-recording. Locomotor activity, anxiety and hippocampus-dependent spatial memory in open field (OF), elevated plus maze (EPM), light-dark test (LDT) and radial arm maze (RAM) test, respectively, were evaluated during the last two weeks after SE. Agomelatine significantly decreased the latency for onset of SMS and increased the seizure frequency during the 2nd and the 3rd week of treatment. The MT₁ and MT₂ receptor agonist and serotonin 5HT_2C receptor antagonist exacerbated the KA-induced hyperlocomotion and impulsive behavior and it was unable to prevent spatial memory impairment of epileptic rats. However, agomelatine induced a neuroprotection in the dorsal hippocampus, specifically in the CA1, septal CA2 and partially in the CA3c region, the hilus of the dentate gyrus, piriform cortex and septo-temporal and temporal basolateral amygdala. Our findings suggest that the beneficial impact against SE-induced neuronal loss exerted by agomelatine is not crucial for the suppression of epileptogenesis and its deleterious consequences in KA model of temporal lobe epilepsy.