Electroretinographic modifications induced by agomelatine: a novel avenue to the understanding of the claimed antidepressant effect of the drug?

Retinal markers of therapeutic responses in major depressive disorder: Effects of antidepressants on retinal function

BACKGROUND

One goal of research into major depressive disorder (MDD) is to develop markers to predict and monitor the response to psychotropic treatments. The retina is endowed with a complex neurotransmission system, composed of the main neurotransmitters involved in the pathophysiology of MDD. The retina is therefore a relevant site of investigation for the identification of reliable and robust markers. However, the effects of antidepressants on the human retina are poorly studied. Here, we seek to study the potential specific effects of various antidepressants on retinal function in MDD patients.

METHODS

We assessed retinal function using flash (fERG), pattern (PERG) and multifocal (mfERG) electroretinogram in 19 MDD patients treated using antidepressants at baseline and at weeks 4, 8 and 12.

RESULTS

We observed reduced b-wave amplitude of photopic fERG 3.0 in patients treated with Selective Serotonin Reuptake Inhibitor (SSRI) in comparison with patients treated with Serotonin-Norepinephrine Reuptake Inhibitor (SNRI) or Tricyclic Antidepressant (TCAD). We also showed that SNRIs were associated both with a decrease in PERG P50 implicit time and an increase in fERG 3.0 b-wave amplitude. TCADs were associated with an increase in fERG flicker 3.0 a- and b-wave amplitude.

CONCLUSIONS

This is the first study in real-life conditions to show a specific effect of various antidepressants on retinal function evaluated by electroretinogram. Further investigations should be led to specify the effects of antidepressants on ERG in order to isolate reliable and reproducible markers for predicting and monitoring the response to antidepressants.

Complete evaluation of retinal function in Major Depressive Disorder: From central slowdown to hyperactive periphery

BACKGROUND

Developing easy-to-access biomarkers is crucial in Major Depressive Disorder. The retina has already been suggested as relevant. However, there is a need for a global and local assessment of whole retinal function using a reproducible, standardized protocol allowing for comparison across studies. Our aim is to assess whole retinal function in patients with actual unipolar Major Depressive Episode (MDE) using pattern, flash and multifocal electroretinogram (ERG) according to the International Society for Clinical Electrophysiology of Vision standardized protocols.

METHODS

We assessed retinal function in 14 males and females with MDE, diagnosed based on the Diagnostic and Statistical Manual of Mental Disorders, and in age- and sex-matched healthy controls.

RESULTS

Comparing the patients with the controls, we observed the following using multifocal ERG: a significant increase in N1 peak time in ring 3 and a decrease in P1 amplitude in ring 2; using pattern ERG: a significant increase in P50 peak time; using flash ERG: a decrease in a- and b-wave peak time and an increase in the b-wave amplitude in dark-adapted 3.0, a decrease in a- and b-wave peak time and an increase in both wave amplitudes in light-adapted 3.0, and a decrease in the b-wave peak time in light-adapted flicker.

LIMITATIONS

Sample size. Contribution of pharmacological treatments to the outcomes cannot be formally excluded.

CONCLUSIONS

Patients with MDE exhibit delayed signaling in the central retina and hyperreactivity to light in the periphery. Central retinal function may be a marker of psychomotor retardation and cognitive impairment in MDE.

Molecular Regulation of the Melatonin Biosynthesis Pathway in Unipolar and Bipolar Depression

Melatonin is a neurohormone that maintains the circadian rhythms of the body. By regulating the secretion of other hormones and neurotransmitters, it acts as a pleiotropic modulator that affects, for example, reproductive, immune, cardiovascular, sleep, and wake systems and mood. Thus, synthetic melatonin has become an essential component in the treatment of depressive disorders. Although we know the pathway of melatonin action in the brain, we lack comprehensive cross-sectional studies on the periphery of depressed patients. This study aimed to comprehensively analyze the differences between healthy control subjects (n = 84) and unipolar and bipolar depression patients (n = 94), including an analysis of the melatonin pathway at the level of the genes and serum biomarkers. An innovative approach is a pilot study based on gene expression profiling carried out on clinical and cell culture models using agomelatine and melatonin. We confirmed the melatonin biosynthesis pathway's molecular regulation dysfunctions, with a specific pattern for unipolar and bipolar depression, at the AANAT gene, its polymorphisms (rs8150 and rs3760138), and examined the serum biomarkers (serotonin, AANAT, ASMT, and melatonin). The biological pathway analysis uncovered pathways and genes that were uniquely altered after agomelatine treatment in a clinical model and melatonin treatment in a cell culture model. In both models, we confirmed the immunomodulatory effect of melatonin agents in depression.

Recent progress on wearable point-of-care devices for ocular systems

The eye is a complex sensory organ that contains abundant information for specific diseases and pathological responses. It has emerged as a facile biological interface for wearable healthcare platforms because of its excellent accessibility. Recent advances in electronic devices have led to the extensive research of point-of-care (POC) systems for diagnosing and monitoring diseases by detecting the biomarkers within the eye. Among these systems, contact lenses, which make direct contact with the ocular surfaces, have been utilized as one of the promising candidates for non-invasive POC testing of various diseases. The continuous and long-term measurement from the sensor allows the patients to manage their symptoms in an effective and convenient way. Herein, we review the progress of contact lens sensors in terms of the materials, methodologies, device designs, and target biomarkers. The anatomical structure and biological mechanisms of the eye are also discussed to provide a comprehensive understanding of the principles of contact lens sensors. Intraocular pressure and glucose, which are the representative biomarkers found in the eyes, can be measured with the biosensors integrated with contact lenses for the diagnosis of glaucoma and diabetes. Furthermore, contact lens sensors for various general pathologies as well as other ocular diseases are also considered, thereby providing the prospects for further developments of smart contact lenses as a future POC system.

New insights on the role of the retina in diagnostic and therapeutic strategies in major depressive disorder

Major depressive disorder (MDD) affects people worldwide. MDD treatments include antidepressants, which involve a delayed onset of action, long-term treatment, side effects and, frequently, only partial efficacy. The lack of access to the living brain, and the complex and still poorly elucidated pathophysiology of MDD, hinders treatment development. There is not only a need for new treatment strategies, but also for new approaches to investigating the pathophysiology of MDD. Light therapy is a well-established treatment acting through the retina. Since the retina is part of the central nervous system, it has been suggested as a useful area for investigating mental illness. In this article, we will first set out the evidence that MDD affects the retina's structure and function. We will then review studies evaluating the efficacy of light therapy in unipolar non-seasonal MDD. Finally, we discuss the disruption of melatoninergic pathways in MDD, its assessment through the retina and the treatment of this disruption with light therapy.

Experimental evidence for the involvement of F0/F1 ATPase and subsequent P2Y12 receptor activation in prothymosin alpha-induced protection of retinal ischemic damage

The inhibition of retinal ischemia-induced damage by post-ischemic prothymosin alpha (ProTα) was not affected in toll-like receptor 4 knockout (TLR4^-/-) mice but blocked by the pretreatment with antibody against F₀/F₁ ATPase α- or β-subunit, novel candidate for ProTα-receptor. In addition to the previous observation of ProTα-induced ATP release from cells, the present study showed a ProTα-induced enhancement of ATP hydrolysis activity of recombinant ATP5A1/5B complex. As the protection of retinal function by post-ischemic ProTα was abolished by anti-P2Y₁₂ antibody, the activation of F₀/F₁ ATPase and subsequent P2Y₁₂ receptor system may play roles in beneficial actions by post-ischemic ProTα.

Electroretinography in psychiatry: A systematic literature review

This review aims to consolidate the available information on use of electroretinography as a diagnostic tool in psychiatry. The electroretinogram (ERG) has been found to have diagnostic utility in cocaine withdrawal (reduced light-adapted b-wave response), major depressive disorder (reduced contrast gain in pattern ERG), and schizophrenia (reduced a- and b-wave amplitudes). This review examines these findings as well as the applicability of ERG to substance use disorder, Alzheimer's disease, autism spectrum disorder, panic disorder, eating disorders, attention deficit hyperactivity disorder, and medication use. While there have been promising results, current research suffers from a lack of specificity. Further research that quantifies anomalies in ERG present in psychiatric illness is needed.

Effect of agomelatine treatment on C-reactive protein levels in patients with major depressive disorder: an exploratory study in "real-world," everyday clinical practice

OBJECTIVE

Agomelatine is a newer antidepressant but, to date, no studies have been carried out investigating its effects on C-reactive protein (CRP) levels in major depressive disorder (MDD) before and after treatment. The present study aimed (i) to investigate the effects of agomelatine treatment on CRP levels in a sample of patients with MDD and (ii) to investigate if CRP variations were correlated with clinical improvement in such patients.

METHODS

30 adult outpatients (12 males, 18 females) with a Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) diagnosis of MDD were recruited in "real-world," everyday clinical practice and treated with a flexible dose of agomelatine for 12 weeks. The Hamilton Rating Scale for Depression (HAM-D) and the Snaith-Hamilton Pleasure Scale (SHAPS) were used to evaluate depressive symptoms and anhedonia, respectively. Moreover, serum CRP was measured at baseline and after 12 weeks of treatment.

RESULTS

Agomelatine was effective in the treatment of MDD, with a significant reduction in HAM-D and SHAPS scores from baseline to endpoint. CRP levels were reduced in the whole sample, with remitters showing a significant difference in CRP levels after 12 weeks of agomelatine. A multivariate stepwise linear regression analysis showed that higher CRP level variation was associated with higher baseline HAM-D scores, controlling for age, gender, smoking, BMI, and agomelatine dose.

CONCLUSIONS

Agomelatine's antidepressant properties were associated with a reduction in circulating CRP levels in MDD patients who achieved remission after 12 weeks of treatment. Moreover, more prominent CRP level variation was associated with more severe depressive symptoms at baseline.

Electroretinographic anomalies in medicated and drug free patients with major depression: Tagging the developmental roots of major psychiatric disorders

The retina is tagged as an approachable part of the brain due to its common embryonic origin and appears as a promising site of investigation for psychiatric disorders. Retinal function is assessed best with the electroretinogram (ERG), which was obtained in a large sample of patients with major depressive disorder and matched controls. ERG cone and rod luminance response functions were recorded in non-dilated eyes in 100 major depressive disorder patients (MDD) and 100 controls, (mean age of 42.8 and 40.9y. o. respectively). Amongst MDD patients, 17 were drug free (mean age 41.2y. o). In medicated patients, at the cone level, a prolonged b-wave was observed (p≤0.01). In drug free patients a prolonged b-wave was discovered only when averaging the implicit time of the 3 highest b-wave amplitudes of the photopic hill. For the medicated patients, the mixed rods/cones a-wave was reduced (p=0.01) whereas a trend (p=0.06) was observed for the pure rod b-wave (reduced) and the mixed rods/cones (reduced and prolonged; p=0.05). In drug free patients, a similar pattern could be observed in terms of effect sizes. Overall, medicated and drug free MDD patients shared some deficits suggesting that some anomalies are present above and beyond the effect of medication. Of interest, the prolonged cone and reduced rod amplitude were reported by our group in schizophrenia patients, suggesting a common neurodevelopmental root of major psychiatric disorders.

A Comparative Study of Efficacy and Safety of Agomelatine and Escitalopram in Major Depressive Disorder

BACKGROUND

Major depressive disorder (MDD) is a mental disorder characterized by episodes of depressed mood, loss of interest or pleasure, feeling of guilt or low self-esteem, loss of energy, altered sleep patterns and difficulty in concentration.

OBJECTIVE

This study was carried out to compare the efficacy and safety of Agomelatine with Escitalopram in the treatment of major depressive disorder.

DESIGN AND SETTING

This is a prospective study conducted at Outpatient Department of Psychiatry, GSL Medical College & General hospital, Rajahmundry, India.

MATERIALS AND METHODS

Patients with newly diagnosed major depressive disorder (DSM-IV-TR) with minimum score of 20 in Hamilton depression rating scale were randomly assigned Agomelatine (25-50 mg/day) or Escitalopram (10-20 mg/day) for a period of 8 weeks. The main efficacy outcome considered was the mean change of HAM-D17 score from baseline to end of therapy. Secondary outcome measures were Clinical Global Impressions-improvement (CGI) and severity (CGI-S) rating scales.

STATISTICAL ANALYSIS

Student t-test was used for comparing the groups and chi-square test was used for assessing the qualitative variables. For all statistical analysis p<0.05 was considered statistically significant.

RESULTS

The drugs under study effectively reduced depressive symptoms at all the time points. The percentage of responders at 8weeks (last post baseline value) was 65.38% with Agomelatine and 57.40% with Escitalopram. The difference between the drugs was statistically not significant in all evaluations (p>0.05). The mean CGI-S and CGI-I scores were decreased in both the groups (p<0.05) and there was no statistically significant difference between the groups at any assessment during the study period. Both the treatment groups showed favourable safety profile.

CONCLUSION

The study results supported that Agomelatine is therapeutically similar to Escitalopram in terms of antidepressant effect.

Agomelatine beyond borders: current evidences of its efficacy in disorders other than major depression

Agomelatine, a melatonergic antidepressant with a rapid onset of action, is one of the most recent drugs in the antidepressant category. Agomelatine's antidepressant actions are attributed to its sleep-promoting and chronobiotic actions mediated by MT1 and MT2 receptors present in the suprachiasmatic nucleus, as well as to its effects on the blockade of 5-HT2c receptors. Blockade of 5-HT2c receptors causes release of both noradrenaline and dopamine at the fronto-cortical dopaminergic and noradrenergic pathways. The combined actions of agomelatine on MT1/MT2 and 5-HT2c receptors facilitate the resynchronization of altered circadian rhythms and abnormal sleep patterns. Agomelatine appeared to be effective in treating major depression. Moreover, evidence exists that points out a possible efficacy of such drug in the treatment of bipolar depression, anxiety disorders, alcohol dependence, migraines etc. Thus, the aim of this narrative review was to elucidate current evidences on the role of agomelatine in disorders other than major depression.