Agomelatine inhibits platelet aggregation through melatonin receptor-dependent and independent mechanisms.

AIMS: Melatonin is known to inhibit platelet aggregation induced by arachidonic acid (AA). In the present study we investigated whether agomelatine (Ago), an antidepressant with agonist activity at melatonin receptor 1 (MT1) and MT2 could reduce platelets aggregation and adhesion. MAIN METHODS: Human platelets from healthy donors were used to test the in vitro effects of Ago in the presence of different platelet activators. We performed aggregation and adhesion assays, thromboxane B2 (TxB2), cAMP and cGMP measurements, intra-platelet calcium registration and flow cytometry assays. KEY FINDINGS: Our data revealed that different concentrations of Ago reduced AA- and collagen-induced human platelet aggregation in vitro. Ago also reduced AA-induced increase in thromboxane B2 (TxB2) production, intracellular calcium levels and P-selectin expression at plasma membrane. The effects of Ago in AA-activated platelets were likely dependent on MT1 as they were blocked by luzindole (a MT1/MT2 antagonist) and mimicked by the MT1 agonist UCM871 in a luzindole-sensitive manner. The MT2 agonist UCM924 was also able to inhibit platelet aggregation, but this response was not affected by luzindole. On the other hand, although UCM871 and UCM924 reduced collagen-induced platelet aggregation and adhesion, inhibition of collagen-induced platelet aggregation by Ago was not mediated by melatonin receptors because it was not affected by luzindole. SIGNIFICANCE: The present data show that Ago suppresses human platelet aggregation and suggest that this antidepressant may have the potential to prevent atherothrombotic ischemic events by reducing thrombus formation and vessel occlusion.

Agomelatine decreases cocaine-induced locomotor sensitisation and dopamine release in rats.

BACKGROUND: Agomelatine is a melatoninergic antidepressant approved to treat the major depressive disorder. Agomelatine exerts its behavioural, pharmacological, and physiological effects through the activation of MT1 and MT2 melatonin receptors and the blockade of 5-HT2B and 5-HT2C serotonin receptors. Some studies have reported that the activation of the MT1 and MT2 melatonin receptors decreased cocaine-induced locomotor activity and cocaine self-administration. These findings from another study showed that agomelatine decreased alcohol consumption. This study aimed to evaluate the effects of agomelatine administration on cocaine-induced behavioural (cocaine-induced locomotor activity and cocaine-induced locomotor sensitisation) and neurochemical (dopamine levels) effects. METHODS: Male Wistar rats (250-280 g) received cocaine (10 mg/kg) during the induction and expression of locomotor sensitisation. Agomelatine (10 mg/kg) was administered 30 minutes before cocaine. After each treatment, locomotor activity was recorded for 30 minutes. Dopamine levels were determined in the ventral striatum, the prefrontal cortex (PFC), and the ventral tegmental area (VTA) by high-performance liquid chromatographic (HPLC) in animals treated with agomelatine and cocaine. Luzindole (30 mg/kg) was administered to block the agomelatine effect. RESULTS: In this study, we found that agomelatine decreased cocaine-induced locomotor activity and the induction and expression of locomotor sensitisation. In addition, agomelatine decreased cocaine-induced dopamine levels. Luzindole blocked the agomelatine-induced decrease in the expression of locomotor sensitisation in rats. CONCLUSION: Our results suggest (1) that agomelatine showed efficacy in decreasing cocaine psychostimulant effects and (2) that agomelatine can be a useful therapeutic agent to reduce cocaine abuse.

The effects of agomelatine in cisplatin-induced toxicity on the kidney and liver tissues: In vivo study

Abstract Nephrotoxicity and hepatotoxicity are frequently seen adverse effects during cisplatin chemotherapy. In this study, we investigated the effects of agomelatine on cisplatin-induced toxicity in the kidney and liver. Animals were administered with a single dose of cisplatin (7 mg/kg, i.p.) and treated with agomelatine (20 and 40 mg/kg, p.o) for seven days. Renal and hepatic functions were evaluated by measuring concentrations of creatinine, BUN, AST and ALT in the serum. Oxidative stress and protein peroxidation were assessed by measuring SOD, CAT, GSH and AOPP levels in both tissues. Serum PON-1 levels were also evaluated. Histopathological analysis was performed to determined structural changes in the kidney and liver. Agomelatine (20 mg/kg) treatment approximately halved cisplatin-related increase in serum creatinine, BUN, AST and ALT levels. Agomelatine (20 mg/kg) significantly prevented the cisplatin-induced excessive decrease in SOD, CAT, GSH in both tissues and serum PON-1 levels. Agomelatine (20 and 40 mg/kg) protected the structural integrity of the kidney against cisplatin-insult. Although agomelatine (40 mg/kg) protected the kidney and showed parallel results with 20 mg/kg biochemically, it failed to show the same liver tissue effects in both analyses. Although agomelatine protected against cisplatin-induced toxicity in the kidney and liver, care should be taken with higher doses for possible hepatotoxicity.

Agomelatine reduces circulating triacylglycerides and hepatic steatosis in fructose-treated rats.

Agomelatine (AGO) is an antidepressant drug with agonistic activity at melatonin receptor 1 (MT1) and MT2 and with neutral antagonistic activity at serotonin receptor 5-HT2C. Although experimental studies show that melatonin reduces hypertriglyceridemia and hepatic steatosis induced by excessive fructose intake, no studies have tested if AGO exerts similar actions. To address this issue we have treated male Wistar rats with fructose (15% in the drinking water) and/or AGO (40 mg/kg/day) for two weeks. AGO reduced body weight gain, feeding efficiency and hepatic lipid levels without affecting caloric intake in fructose-treated rats. AGO has also decreased very low-density lipoprotein (VLDL) production and circulating TAG levels after an oral load with olive oil. Accordingly, treatment with AGO reduced the hepatic expression of fatty acid synthase (Fasn), a limiting step for hepatic de novo lipogenesis (DNLG). The expression of apolipoprotein B (Apob) and microsomal triglyceride transfer protein (Mttp) in the ileum, two crucial proteins for intestinal lipoprotein production, were also downregulated by treatment with AGO. Altogether, the present data show that AGO mimics the metabolic benefits of melatonin when used in fructose-treated rats. This study also suggests that it is relevant to evaluate the potential of AGO to treat metabolic disorders in future clinical trials.

Anxiolytic properties of compounds that counteract oxidative stress, neuroinflammation, and glutamatergic dysfunction: a review

Objective: Anxiety disorders are highly prevalent and the efficacy of the available anxiolytic drugs is less than desired. Adverse effects also compromise patient quality of life and adherence to treatment. Accumulating evidence shows that the pathophysiology of anxiety and related disorders is multifactorial, involving oxidative stress, neuroinflammation, and glutamatergic dysfunction. The aim of this review was to evaluate data from animal studies and clinical trials showing the anxiolytic effects of agents whose mechanisms of action target these multiple domains. Methods: The PubMed database was searched for multitarget agents that had been evaluated in animal models of anxiety, as well as randomized double-blind placebo-controlled clinical trials of anxiety and/or anxiety related disorders. Results: The main multitarget agents that have shown consistent anxiolytic effects in various animal models of anxiety, as well in clinical trials, are agomelatine, N-acetylcysteine (NAC), and omega-3 fatty acids. Data from clinical trials are preliminary at best, but reveal good safety profiles and tolerance to adverse effects. Conclusion: Agomelatine, NAC and omega-3 fatty acids show beneficial effects in clinical conditions where mainstream treatments are ineffective. These three multitarget agents are considered promising candidates for innovative, effective, and better-tolerated anxiolytics.

Agomelatine's effect on circadian locomotor rhythm alteration and depressive-like behavior in 6-OHDA lesioned rats.

Parkinson's disease (PD) patients often suffer from circadian locomotor rhythms impairment and depression, important non-motor symptoms. It is known that toxin-based animal models of PD can reproduce these features. In a 6-hydroxydopamine (6-OHDA) intranigral model, we first investigated the possible disturbances on circadian rhythms of locomotor activity. The rats were divided into 6-OHDA and Sham groups. After a partial dopaminergic lesion, the 6-OHDA group showed slight alterations in different circadian locomotor rhythms parameters. In a second experiment, we hypothesized agomelatine, an melatoninergic antidepressant with potential to resynchronize disturbed rhythms, could prevent neuronal damage and rhythm alterations in the same 6-OHDA model. The animals were divided into four groups: 6-OHDA+vehicle, 6-OHDA+ago, Sham+vehicle and 6-OHDA+ago. However, the treated animals (agomelatine 50 mg/kg for 22 days) showed an impaired rhythm robustness, and agomelatine did not induce significant changes in the other circadian parameters nor neuroprotection. Finally, in a third experiment, we examined the effects of agomelatine in the 6-OHDA model regarding depressive-like behavior, evaluated by sucrose preference test. The animals were also divided into four groups: 6-OHDA+vehicle, 6-OHDA+ago, Sham+vehicle and 6-OHDA+ago. The toxin infused animals showed a decrease in sucrose preference in comparison with the vehicle infused animals, however, agomelatine did not prevent this decrease. Our findings indicate that agomelatine worsened circadian locomotor rhythm and was not able to reverse the depressive-like behavior of rats in the 6-OHDA PD model.

Effectiveness of agomelatine on anhedonia in depressed patients: an outpatient, open-label, real-world study.

OBJECTIVE: The aim of this real-world study was to evaluate the effect of agomelatine on anhedonia as primary endpoint in outpatients under treatment of major depressive episodes. METHODS: The study was an open-label, multicenter, 8-week phase IV trial. Two hundred fifty-seven (257) patients were recruited, and 143 patients were included in the analysis. Agomelatine was administered orally as a 25-mg tablet. The dose could be increased to 50 mg after 2 weeks of treatment. RESULTS: An improvement in the severity of anhedonia (Snaith-Hamilton Pleasure Scale total score) was observed from 8.5 points at baseline to 4.1 at week 8, statistically significant (p < 0.05) from the first week. Significant decreases in scores on the severity of depression (Quick Inventory of Depressive Symptomatology 16-item Self-Report [QIDS-SR-16]), anxiety (Generalized Anxiety Disorder 7-item scale), and in overall clinical status (CGI) were also found over 8 weeks, independently from the presence of a first or recurrence episode. Response (QIDS-SR-16 score ≥ 50% of baseline) at week 8 was observed in 65.7% of the patients, while 49.6% of the patients achieved remission (QIDS-SR-16 score ≤ 5). CONCLUSION: Agomelatine was shown to be effective on anhedonia, depression, and anxiety in subjects with major depression. The pragmatic design of the study reflects real-world clinical practice providing interesting insights into routine care management.

Profile of agomelatine and its potential in the treatment of generalized anxiety disorder.

BACKGROUND: Although many generalized anxiety disorder (GAD) patients respond to the available pharmacological treatments, nearly half of them do not present the expected results. Besides, the side effects associated to some drugs have a negative impact on treatment adherence. Therefore, the aim of this review was to report the clinical profile of agomelatine, a selective melatonergic MT1/MT2 receptor agonist with serotonin 5-HT2c receptor antagonist activities, as a potential pharmacological option in the treatment of GAD. METHODS: We performed a literature review regarding studies that evaluated the use of agomelatine in GAD treatment. RESULTS: Two short-term, double-blinded studies and one prevention-treatment trial evaluated the efficacy of agomelatine in the treatment of GAD. Agomelatine was associated with higher rates of clinical response and remission, when compared to placebo. In addition, the long-term use of agomelatine decreased the risk of relapse of anxiety symptoms, even for the severely ill patients. Besides, the tolerability was satisfactory with the absence of discontinuation symptoms, as observed in previous studies. CONCLUSION: The efficacy and tolerability profiles of agomelatine in the treatment of GAD were good. However, the scarce number of trials, the small sample sizes, and the use of patients without any comorbid conditions were some limitations that impaired the generalization of the results in the general population. Nevertheless, agomelatine is an attractive off-label option in the treatment of GAD that needs more conclusive evidences to establish its role in future guidelines.

Therapeutic potential of melatonin agonists.

Melatonin, a hormone secreted by the pineal gland, has been successfully employed to improve sleep in both normal patients and insomniacs, and for the treatment of circadian rhythm sleep disorders. Melatonergic MT1 and MT2 receptors exist in high concentrations in the suprachiasmatic nucleus of the hypothalamus and have been shown to be instrumental for the sleep-promoting and circadian rhythm-regulating effects of melatonin. A lack of consistency among reports on the therapeutic efficacy of melatonin has been attributed to differences in melatonin's bioavailability and the short half-life of the hormone. In view of the need for longer acting melatonergic agonists that improve sleep efficiency without causing drug abuse or dependency, ramelteon (Rozerem™, Takeda) was developed. Ramelteon, which acts via MT1/MT2 melatonergic agonism, has been found clinically effective for improving total sleep time and sleep efficiency in insomniacs. Agomelatine (Valdoxan™, Servier) is another MT1/MT2 melatonergic agonist that also displays antagonist activity at 5-HT2C serotonin receptors. Agomelatine has been found effective in treating depression and sleep disorders in patients with major depressive disorder. A slow-release preparation of melatonin (Circadin™, Neurim) has been shown to be effective in treating sleep disorders in the elderly population.