The opposite effects of fluvoxamine and sertraline in the treatment of psychotic major depression: a case report

Sigma-1 receptor activation mediates the sustained antidepressant effect of ketamine in mice via increasing BDNF levels

Sigma-1 receptor (S1R) is a unique multi-tasking chaperone protein in the endoplasmic reticulum. Since S1R agonists exhibit potent antidepressant-like activity, S1R has become a novel target for antidepression therapy. With a rapid and sustained antidepressant effect, ketamine may also interact with S1R. In this study, we investigated whether the antidepressant action of ketamine was related to S1R activation. Depression state was evaluated in the tail suspension test (TST) and a chronic corticosterone (CORT) procedure was used to induce despair-like behavior in mice. The neuronal activities and structural changes of pyramidal neurons in medial prefrontal cortex (mPFC) were assessed using fiber-optic recording and immunofluorescence staining, respectively. We showed that pharmacological manipulation of S1R modulated ketamine-induced behavioral effect. Furthermore, pretreatment with an S1R antagonist BD1047 (3 mg·kg-1·d-1, i.p., for 3 consecutive days) significantly weakened the structural and functional restoration of pyramidal neuron in mPFC caused by ketamine (10 mg·kg-1, i.p., once). Ketamine indirectly triggered the activation of S1R and subsequently increased the level of BDNF. Pretreatment with an S1R agonist SA4503 (1 mg·kg-1·d-1, i.p., for 3 consecutive days) enhanced the sustained antidepressant effect of ketamine, which was eliminated by knockdown of BDNF in mPFC. These results reveal a critical role of S1R in the sustained antidepressant effect of ketamine, and suggest that a combination of ketamine and S1R agonists may be more beneficial for depression patients.

[Fluvoxamine in the treatment of anxiety-depressive spectrum disorders]

The RSCI and PubMed search databases have requested publications over the past 40 years on the search queries «fluvoxamine», «anxiety-depressive disorders», «anxiety», «depression», «comorbidity», devoted to the effectiveness of fluvoxamine in various variants of disorders of the anxiety-depressive spectrum, anxiety depressions. The data of the above studies indicate that fluvoxamine (Zovart San) in doses of 50-300 mg / day is a highly effective remedy for the treatment of not only anxiety depressions and genesis (psychogenic, organic, mixed, autochthonous-endogenous) and severity (up to psychotic), but also a wider range of anxiety-depressive disorders, including adaptation disorders, obsessive-compulsive disorder, somatized, dysmorphic, insomniac symptom complexes and eating disorders. A wide range of clinical effects of fluvoxamine is due to its main and additional mechanisms of action: blockade of serotonin reuptake, σ1-agonist activity and the effect on the metabolism of melatonin and neurosteroids catabolism.

Selective serotonin reuptake inhibitors: New hope in the fight against COVID-19

The emerging COVID-19 pandemic led to a dramatic increase in global mortality and morbidity rates. As in most infections, fatal complications of coronavirus affliction are triggered by an untrammeled host inflammatory response. Cytokine storms created by high levels of interleukin and other cytokines elucidate the pathology of severe COVID-19. In this respect, repurposing drugs that are already available and might exhibit anti-inflammatory effects have received significant attention. With the in vitro and clinical investigation of several studies on the effect of antidepressants on COVID-19 prognosis, previous data suggest that selective serotonin reuptake inhibitors (SSRIs) might be the new hope for the early treatment of severely afflicted patients. SSRIs' low cost and availability make them potentially eligible for COVID-19 repurposing. This review summarizes current achievements and literature about the connection between SSRIs administration and COVID-19 prognosis.

Mechanistic insights into the role of plant polyphenols and their nano-formulations in the management of depression

Depression is a condition characterized by low mood and an aversion to activity, that causes behavioral problems, poor quality of life and limits daily life activities. It is considered as the fourth leading cause of disability worldwide. Selective Serotonin Reuptake Inhibitors (SSRIs) Monoamine Oxidase (MAO) inhibitors, Tricyclic Antidepressants (TCAs), and atypical antidepressants are some of the conventional medications used to treat depression. However, only about half of patients with major depressive disorder (MDD) respond effectively to first-line antidepressant therapy. Additionally, there are a number of drawbacks to standard antidepressants, such as anti-cholinergic side effects, drug-drug interactions, and food-drug interactions, which prompts researchers to look at alternative approaches to the treatment of depression. Medicinal plants and their metabolites are extensively tested for their efficacy against depression. Electronic databases such as Google scholar, Science Direct, SciFinder and PubMed were used to search relevant literature on the role of polyphenols in depression. Plants-derived Polyphenols represent a major class of compounds extensively distributed in plants. Number of polyphenols have demonstrated antidepressant activity, among which berberine, piperine, curcumin, naringenin, ascorbic acid and ginsenosides are extensively evaluated. The medicinal plants and their derived compounds mediated synthesized green nanoparticles have also exhibited considerable efficacy in the management of depression. The therapeutic effects of these phytochemicals is mediated via differentiation and inhibition of neuronal cell apoptosis, promotion of neuronal cell survival and modulation of key neurotransmitters. The aim of this study is to review compressively the chemical, pharmacological and neurological evidence showing the potential of polyphenols in depression.

Chaperone Sigma1R and Antidepressant Effect

This review analyzes the current scientific literature on the role of the Sigma1R chaperone in the pathogenesis of depressive disorders and pharmacodynamics of antidepressants. As a result of ligand activation, Sigma1R is capable of intracellular translocation from the endoplasmic reticulum (ER) into the region of nuclear and cellular membranes, where it interacts with resident proteins. This unique property of Sigma1R provides regulation of various receptors, ion channels, enzymes, and transcriptional factors. The current review demonstrates the contribution of the Sigma1R chaperone to the regulation of molecular mechanisms involved in the antidepressant effect.

Sertraline inhibits nerve growth factor-induced neurite outgrowth in PC12 cells via a mechanism involving the sigma-1 receptor

The selective serotonin reuptake inhibitors (SSRIs) fluvoxamine and sertraline show a high affinity for sigma-1 receptors. Fluvoxamine enhances nerve growth factor (NGF)-induced neurite outgrowth in PC12 cells via a sigma-1 receptor-mediated mechanism, which suggests that neurogenesis may be involved in the antidepressant action of fluvoxamine. However, the effects of sertraline on neurite outgrowth remain unclear. Here, we report the effects of sertraline on NGF-induced neurite outgrowth in PC12 cells. At concentrations above 0.3 μM, sertraline inhibited neurite outgrowth induced by NGF (50 ng/mL) in PC12 cells in a concentration-dependent manner. At 0.3-3 μM, sertraline inhibited NGF-induced neurite outgrowth; however, had no effect on cell viability. This suggests that at these concentrations, sertraline inhibits NGF-induced neurite outgrowth without causing cell toxicity. Because sertraline has a high affinity for the sigma-1 receptor, we investigated whether this receptor is involved in sertraline's inhibitory effect on NGF-induced neurite outgrowth. The effect was reversed by both the sigma-1 receptor agonist PRE-084 and the sigma-1 receptor antagonist NE-100. These results suggest that sertraline inhibits NGF-induced neurite outgrowth in PC12 cells by acting as an inverse agonist of the sigma-1 receptor in this system.

Anti-anhedonic effect of selective serotonin reuptake inhibitors with affinity for sigma-1 receptors in picrotoxin-treated mice

BACKGROUND AND PURPOSE

Prefrontal dopamine release by the combined activation of 5-HT1A and sigma-1 (σ1 ) receptors is enhanced by the GABAA receptor antagonist picrotoxin in mice. Here, we examined whether this neurochemical event was accompanied by behavioural changes.

EXPERIMENTAL APPROACH

Male mice were treated with picrotoxin to decrease GABAA receptor function. Their anhedonic behaviour was measured using the female encounter test. The expression of c-Fos was determined immunohistochemically.

KEY RESULTS

Picrotoxin caused an anxiogenic effect on three behavioural tests, but it did not affect the immobility time in the forced swim test. Picrotoxin decreased female preference in the female encounter test and attenuated the female encounter-induced increase in c-Fos expression in the nucleus accumbens. Picrotoxin-induced anhedonia was ameliorated by fluvoxamine and S-(+)-fluoxetine, selective serotonin reuptake inhibitors with high affinity for the σ1 receptor. The effect of fluvoxamine was blocked by a 5-HT1A or a σ1 receptor antagonist, and co-administration of the σ1 receptor agonist (+)-SKF-10047 and the 5-HT1A receptor agonist osemozotan mimicked the effect of fluvoxamine. By contrast, desipramine, duloxetine and paroxetine, which have little affinity for the σ1 receptor, did not affect picrotoxin-induced anhedonia. The effect of fluvoxamine was blocked by a dopamine D2/3 receptor antagonist. Methylphenidate, an activator of the prefrontal dopamine system, ameliorated picrotoxin-induced anhedonia.

CONCLUSION AND IMPLICATIONS

Picrotoxin-treated mice show anhedonic behaviour that is ameliorated by simultaneous activation of 5-HT1A and σ1 receptors. These findings suggest that the increased prefrontal dopamine release is associated with the anti-anhedonic effect observed in picrotoxin-treated mice.

Sigma-1 Receptor Agonists and Their Clinical Implications in Neuropsychiatric Disorders

Accumulating evidence suggests that sigma-1 receptors play a role in the pathophysiology of neuropsychiatric diseases, as well as in the mechanisms of some selective serotonin reuptake inhibitors (SSRIs). Among the SSRIs, the order of affinity for sigma-1 receptors is as follows: fluvoxamine > sertraline > fluoxetine > escitalopram > citalopram >> paroxetine. Some SSRIs (e.g., fluvoxamine, fluoxetine and escitalopram) and other drugs (donepezil , ifenprodil , dehydroepiandeterone (DHEA)) potentiate nerve-growth factor (NGF)-induced neurite outgrowth in PC12 cells, and these effects could be antagonized by the selective sigma-1 receptor antagonist NE-100. Furthermore, fluvoxamine, donepezil, and DHEA, but not paroxetine or sertraline, improved phencyclidine-induced cognitive deficits in mice, and these effects could be antagonized by NE-100. Several clinical studies showed that sigma-1 receptor agonists such as fluvoxamine and ifenprodil could have beneficial effects in patients with neuropsychiatric disorders. In this chapter, the authors will discuss the role of sigma-1 receptors in the mechanistic action of some SSRIs, donepezil, neurosteroids, and ifenprodil, and the clinical implications for sigma-1 receptor agonists .

Evaluation of sigma (σ) receptors in the antidepressant-like effects of ketamine in vitro and in vivo

Ketamine is an NMDA antagonist and dissociative anesthetic that has been shown to display rapid acting and prolonged antidepressant activity in small-scale human clinical trials. Ketamine also binds to σ receptors, which are believed to be protein targets for a potential new class of antidepressant medications. The purpose of this study was to determine the involvement of σ receptors in the antidepressant-like actions of ketamine. Competition binding assays were performed to assess the affinity of ketamine for σ(1) and σ(2) receptors. The antidepressant-like effects of ketamine were assessed in vitro using a neurite outgrowth model and PC12 cells, and in vivo using the forced swim test. The σ receptor antagonists, NE-100 and BD1047, were evaluated in conjunction with ketamine in these assays to determine the involvement of σ receptors in the antidepressant-like effects of ketamine. Ketamine bound to both σ(1) and σ(2) receptors with μM affinities. Additionally, ketamine potentiated NGF-induced neurite outgrowth in PC12 cells and this effect was attenuated in the presence of NE-100. Ketamine also displayed antidepressant-like effects in the forced swim test; however, these effects were not attenuated by pretreatment with NE-100 or BD1047. Taken together, these data suggest that σ receptor-mediated neuronal remodeling may contribute to the antidepressant effects of ketamine.

Dextromethorphan as a potential rapid-acting antidepressant

Dextromethorphan shares pharmacological properties in common with antidepressants and, in particular, ketamine, a drug with demonstrated rapid-acting antidepressant activity. Pharmacodynamic similarities include actions on NMDA, μ opiate, sigma-1, calcium channel, serotonin transporter, and muscarinic sites. Additional unique properties potentially contributory to an antidepressant effect include actions at ß, alpha-2, and serotonin 1b/d receptors. It is therefore, hypothesized that dextromethorphan may have antidepressant efficacy in bipolar, unipolar, major depression, psychotic, and treatment-resistant depressive disorders, and may display rapid-onset of antidepressant response. An antidepressant response may be associated with a positive family history of alcoholism, prediction of ketamine response, increased AMPA-to-NMDA receptor activity ratio, antidepressant properties in animal models of depression, reward system activation, enhanced erythrocyte magnesium concentration, and correlation with frontal μ receptor binding potential. Clinical trials of dextromethorphan in depressive disorders, especially treatment-resistant depression, now seem warranted.