The neurotoxic mechanism of Jack Bean Urease in insects involves the interplay between octopaminergic and dopaminergic pathways.

In the last decades, the entomotoxicity of JBU and its derived peptides became an object of study, due mainly to the ubiquitous interaction of these compounds with different species of insects and their potential as natural insecticides. In this work, we investigated the neurotoxic effects of JBU in Nauphoeta cinerea cockroaches by dissecting pharmacologically the monoaminergic pathways involved. Selective pharmacological modulators for monoaminergic pathways in in vivo and ex vivo experimental models were employed. Thus, the analysis of N. cinerea neurolocomotory behavior demonstrated that JBU (1.5 and 3 µg/g) induces a significant decrease in the exploratory activity. In these assays, pretreatment of animals with phentolamine, SCH23390 or reserpine, interfered significantly with the response of JBU. Using in vivo abductor metathoracic preparations JBU (1.5 µg/g) induced progressive neuromuscular blockade, in 120 min recordings. In this set of experiments, the previous treatment of the animals with phentolamine, SCH23390 or reserpine, completely inhibited JBU-induced neuromuscular blockade. The recordings of spontaneous compound neural action potentials in N. cinerea legs showed that JBU, only in the smallest dose, significantly decreased the number of potentials in 60 min recordings. When the animals were pretreated with phentolamine, SCH23390, or reserpine, but not with mianserin, there was a significant prevention of the JBU-inhibitory responses on the action potentials firing. Meanwhile, the treatment of the animals with mianserin did not affect JBU's inhibitory activity. The data presented in this work strongly suggest that the neurotoxic response of JBU in N. cinerea involves a cross talking between OCTOPAMIN-ergic and DOPAMIN-ergic nerve systems, but not the SEROTONIN-ergic neurotransmission. Further molecular biology studies with expression of insect receptors associated with voltage clamp techniques will help to discriminate the selectivity of JBU over the monoaminergic transmission.

Treatment-Resistant Depression (TRD): Is the Opioid System Involved?

About 30% of major depression disorder patients fail to achieve remission, hence being diagnosed with treatment-resistant major depression (TRD). Opium had been largely used effectively to treat depression for centuries, but when other medications were introduced, its use was discounted due to addiction and other hazards. In a series of previous studies, we evaluated the antinociceptive effects of eight antidepressant medications and their interaction with the opioid system. Mice were tested with a hotplate or tail-flick after being injected with different doses of mianserin, mirtazapine, trazodone, venlafaxine, reboxetine, moclobemide, fluoxetine, or fluvoxamine to determine the effect of each drug in eliciting antinociception. When naloxone inhibited the antinociceptive effect, we further examined the effect of the specific opioid antagonists of each antidepressant drug. Mianserin and mirtazapine (separately) induced dose-dependent antinociception, each one yielding a biphasic dose-response curve, and they were antagonized by naloxone. Trazodone and venlafaxine (separately) induced a dose-dependent antinociceptive effect, antagonized by naloxone. Reboxetine induced a weak antinociceptive effect with no significant opioid involvement, while moclobemide, fluoxetine, and fluvoxamine had no opioid-involved antinociceptive effects. Controlled clinical studies are needed to establish the efficacy of the augmentation of opiate antidepressants in persons with treatment-resistant depression and the optimal dosage of drugs prescribed.

Antidepressants Differentially Regulate Intracellular Signaling from α1-Adrenergic Receptor Subtypes In Vitro.

Currently utilized antidepressants have limited effectiveness and frequently incur undesired effects. Most antidepressants are thought to act via the inhibition of monoamine reuptake; however, direct binding to monoaminergic receptors has been proposed to contribute to both their clinical effectiveness and their side effects, or lack thereof. Among the target receptors of antidepressants, α1­adrenergic receptors (ARs) have been implicated in depression etiology, antidepressant action, and side effects. However, differences in the direct effects of antidepressants on signaling from the three subtypes of α1-ARs, namely, α1A-, α1B- and α1D­ARs, have been little explored. We utilized cell lines overexpressing α1A-, α1B- or α1D-ARs to investigate the effects of the antidepressants imipramine (IMI), desipramine (DMI), mianserin (MIA), reboxetine (REB), citalopram (CIT) and fluoxetine (FLU) on noradrenaline-induced second messenger generation by those receptors. We found similar orders of inhibition at α1A-AR (IMI < DMI < CIT < MIA < REB) and α1D­AR (IMI = DMI < CIT < MIA), while the α1B-AR subtype was the least engaged subtype and was inhibited with low potency by three drugs (MIA < IMI = DMI). In contrast to their direct antagonistic effects, prolonged incubation with IMI and DMI increased the maximal response of the α1B-AR subtype, and the CIT of both the α1A- and the α1B-ARs. Our data demonstrate a complex, subtype-specific modulation of α1-ARs by antidepressants of different groups.

LPA1 is a key mediator of intracellular signalling and neuroprotection triggered by tetracyclic antidepressants in hippocampal neurons.

Both lysophosphatidic acid (LPA) and antidepressants have been shown to affect neuronal survival and differentiation, but whether LPA signalling participates in the action of antidepressants is still unknown. In this study, we examined the role of LPA receptors in the regulation of extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) activity and neuronal survival by the tetracyclic antidepressants, mianserin and mirtazapine in hippocampal neurons. In HT22 immortalized hippocampal cells, antidepressants and LPA induced a time- and concentration-dependent stimulation of ERK1/2 phosphorylation. This response was inhibited by either LPA1 and LPA1/3 selective antagonists or siRNA-induced LPA1 down-regulation, and enhanced by LPA1 over-expression. Conversely, the selective LPA2 antagonist H2L5186303 had no effect. Antidepressants induced cyclic AMP response element binding protein phosphorylation and this response was prevented by LPA1 blockade. ERK1/2 stimulation involved pertussis toxin-sensitive G proteins, Src tyrosine kinases and fibroblast growth factor receptor (FGF-R) activity. Tyrosine phosphorylation of FGF-R was enhanced by antidepressants through LPA1 . Serum withdrawal induced apoptotic death, as indicated by increased annexin V staining, caspase activation and cleavage of poly-ADP-ribose polymerase. Antidepressants inhibited the apoptotic cascade and this protective effect was curtailed by blockade of either LPA1 , ERK1/2 or FGF-R activity. Moreover, in primary mouse hippocampal neurons, mianserin acting through LPA1 increased phospho-ERK1/2 and protected from apoptosis induced by removal of growth supplement. These data indicate that in neurons endogenously expressed LPA1 receptors mediate intracellular signalling and neuroprotection by tetracyclic antidepressants.

Modulation of TGF-ß/Smad and ERK signaling pathways mediates the anti-fibrotic effect of mirtazapine in mice.

Serotonin (5-HT) has been implicated as a key driver of liver fibrosis, acting via 5-HT2 receptor activation in the hepatic stellate cells. The current study was conducted to investigate the effects of mirtazapine, a 5-HT2A antagonist, in a mouse model of liver fibrosis. Mice received thioacetamide (TAA, 150mg/kg/biweekly, ip) for nine successive weeks for induction of liver fibrosis. Administration of mirtazapine significantly improved the plasma aminotransferases, reduced hepatic 5-HT concentration and ameliorated TAA-induced liver fibrosis, as demonstrated by reduced portal blood pressure, liver procollagen I content and α alpha smooth muscle actin expression. Moreover, hepatic collagen deposition was markedly decreased in mirtazapine-treated mice as evaluated by Masson's trichrome staining. Mirtazapine provided an antifibrotic environment by decreasing the liver content of transforming growth factor-ß1 (TGF-ß1), and protein kinase C as well as the expression of phosphorylated-Smad3 (p-Smad) and phosphorylated extracellular signal-regulated kinases 1 and 2 (p-ERK1/2). Additionally, oxidative stress was largely mitigated by mirtazapine as manifested by decreased liver lipid peroxidation and NADPH oxidase 1 along with glutathione replenishment. The current study indicates that mirtazapine suppressed 5-HT-mediated TGF-ß1/Smad3 and ERK1/2 signaling pathways as well as oxidative stress that contribute to the progression of liver fibrosis.

Mood, stress and longevity: convergence on ANK3.

Antidepressants have been shown to improve longevity in C. elegans. It is plausible that orthologs of genes involved in mood regulation and stress response are involved in such an effect. We sought to understand the underlying biology. First, we analyzed the transcriptome from worms treated with the antidepressant mianserin, previously identified in a large-scale unbiased drug screen as promoting increased lifespan in worms. We identified the most robust treatment-related changes in gene expression, and identified the corresponding human orthologs. Our analysis uncovered a series of genes and biological pathways that may be at the interface between antidepressant effects and longevity, notably pathways involved in drug metabolism/degradation (nicotine and melatonin). Second, we examined which of these genes overlap with genes which may be involved in depressive symptoms in an aging non-psychiatric human population (n=3577), discovered using a genome-wide association study (GWAS) approach in a design with extremes of distribution of phenotype. Third, we used a convergent functional genomics (CFG) approach to prioritize these genes for relevance to mood disorders and stress. The top gene identified was ANK3. To validate our findings, we conducted genetic and gene-expression studies, in C. elegans and in humans. We studied C. elegans inactivating mutants for ANK3/unc-44, and show that they survive longer than wild-type, particularly in older worms, independently of mianserin treatment. We also show that some ANK3/unc-44 expression is necessary for the effects of mianserin on prolonging lifespan and survival in the face of oxidative stress, particularly in younger worms. Wild-type ANK3/unc-44 increases in expression with age in C. elegans, and is maintained at lower youthful levels by mianserin treatment. These lower levels may be optimal in terms of longevity, offering a favorable balance between sufficient oxidative stress resistance in younger worms and survival effects in older worms. Thus, ANK3/unc-44 may represent an example of antagonistic pleiotropy, in which low-expression level in young animals are beneficial, but the age-associated increase becomes detrimental. Inactivating mutations in ANK3/unc-44 reverse this effect and cause detrimental effects in young animals (sensitivity to oxidative stress) and beneficial effect in old animals (increased survival). In humans, we studied if the most significant single nucleotide polymorphism (SNP) for depressive symptoms in ANK3 from our GWAS has a relationship to lifespan, and show a trend towards longer lifespan in individuals with the risk allele for depressive symptoms in men (odds ratio (OR) 1.41, P=0.031) but not in women (OR 1.08, P=0.33). We also examined whether ANK3, by itself or in a panel with other top CFG-prioritized genes, acts as a blood gene-expression biomarker for biological age, in two independent cohorts, one of live psychiatric patients (n=737), and one of suicide completers from the coroner's office (n=45). We show significantly lower levels of ANK3 expression in chronologically younger individuals than in middle age individuals, with a diminution of that effect in suicide completers, who presumably have been exposed to more severe and acute negative mood and stress. Of note, ANK3 was previously reported to be overexpressed in fibroblasts from patients with Hutchinson-Gilford progeria syndrome, a form of accelerated aging. Taken together, these studies uncover ANK3 and other genes in our dataset as biological links between mood, stress and longevity/aging, that may be biomarkers as well as targets for preventive or therapeutic interventions. Drug repurposing bioinformatics analyses identified the relatively innocuous omega-3 fatty acid DHA (docosahexaenoic acid), piracetam, quercetin, vitamin D and resveratrol as potential longevity promoting compounds, along with a series of existing drugs, such as estrogen-like compounds, antidiabetics and sirolimus/rapamycin. Intriguingly, some of our top candidate genes for mood and stress-modulated longevity were changed in expression in opposite direction in previous studies in the Alzheimer disease. Additionally, a whole series of others were changed in expression in opposite direction in our previous studies on suicide, suggesting the possibility of a "life switch" actively controlled by mood and stress.

Add-on mirtazapine improves orgasmic functioning in patients with schizophrenia treated with first-generation antipsychotics.

AIM: Sexual dysfunction, common in schizophrenia, may be further exaggerated by antipsychotics, especially those of First Generation (FGAs), and antidepressants, such as Selective Serotonin Reuptake Inhibitors (SSRs). Mirtazapine, an antidepressant characterized by its different action mechanism compared with that of the majority of other antidepressants, may improve SSRI-induced sexual dysfunction in patients with depression. It is unknown, however, whether mirtazapine improves sexual functioning in schizophrenia. METHODS: This study randomly assigned FGA-treated patients with schizophrenia to receive either an add-on mirtazapine (n = 20) or a placebo (n = 19) for 6 weeks. Sexual functioning was prospectively measured using five relevant items from the Udvalg for Kliniske Undersogelser side-effect rating scale (UKU-SERS). RESULTS: Orgasmic function improved with statistical significance in the mirtazapine group (p = .03), with no changes in any other sexual functions in either group. CONCLUSION: Add-on mirtazapine appears to relieve orgasmic dysfunction in FGA-treated patients with schizophrenia.

Mianserin affects alarm reaction to conspecific chemical alarm cues in Nile tilapia.

In this study, I show that mianserin, a chemical with serotonin and adrenoceptor antagonist activities, increases fish vulnerability to a potential predator threat, when prey fish must deal with this threat based on conspecific chemical alarm cues. For that, I evaluated whether mianserin, diluted in the water, influences the behavioral responses of Nile tilapia (Oreochromis niloticus) to conspecific skin extract (chemical alarm cues). I found that, while mianserin did not abolished antipredator responses, this drug mitigates some components of this defensive reaction. Thus, a potential decrease in serotonin and adrenergic activities reduces the ability of dealing with predators when perceiving conspecific chemical alarm cues.

LPA1 Mediates Antidepressant-Induced ERK1/2 Signaling and Protection from Oxidative Stress in Glial Cells.

Antidepressants have been shown to affect glial cell functions and intracellular signaling through mechanisms that are still not completely understood. In the present study, we provide evidence that in glial cells the lysophosphatidic acid (LPA) receptor LPA1 mediates antidepressant-induced growth factor receptor transactivation, ERK1/2 signaling, and protection from oxidative stress. Thus, in C6 glioma cells and rat cortical astrocytes, ERK1/2 activation induced by either amitriptyline or mianserin was antagonized by Ki16425 and VPC 12249 (S), which block LPA1 and LPA3 receptors, and by AM966, which selectively blocks LPA1 Cell depletion of LPA1 with siRNA treatment markedly reduced antidepressant- and LPA-induced ERK1/2 phosphorylation. LPA1 blockade prevented antidepressant-induced phosphorylation of the transcription factors CREB and Elk-1. Antidepressants and LPA signaling to ERK1/2 was abrogated by cell treatment with pertussis toxin and by the inhibition of fibroblast growth factor (FGF) receptor (FGF-R) and platelet-derived growth factor receptor (PDGF-R) tyrosine kinases. Both Ki16425 and AM966 suppressed antidepressant-induced phosphorylation of FGF-R. Moreover, blockade of LPA1 or inhibition of FGF-R and PDGF-R activities prevented antidepressant-stimulated Akt and GSK-3ß phosphorylations. Mianserin protected C6 glioma cells and astrocytes from apoptotic cell death induced by H2O2, as indicated by increased cell viability, decreased expression of cleaved caspase 3, reduced cleavage of poly-ADP ribose polymerase and inhibition of DNA fragmentation. The protective effects of mianserin were antagonized by AM966. These data indicate that LPA1 constitutes a novel molecular target of the regulatory actions of tricyclic and tetracyclic antidepressants in glial cells.

A Phase 2 Randomized Dose-Finding Study With Esmirtazapine in Patients With Primary Insomnia.

The antidepressant mirtazapine is an alternative to classical hypnotics, and this study investigated the efficacy and safety of esmirtazapine (Org 50081, the maleic acid salt of S-mirtazapine) in patients given a diagnosis of primary insomnia after acute (2-day) treatment. Patients aged 18 to 65 years with primary insomnia were randomized to receive placebo or 1.5-, 3.0-, or 4.5-mg esmirtazapine in a balanced 4-way crossover study; 2 sleep laboratory nights with polysomnography were separated by 5-day, single-blind placebo washout periods. Polysomnography-determined total sleep time (primary end point) and patient-reported total sleep time improved by at least 25 minutes with all 3 doses of esmirtazapine (P ≤ 0.001 vs placebo). Polysomnography-measured wake time after sleep onset (P ≤ 0.0001) and latency to persistent sleep also improved vs placebo (P ≤ 0.01, 3.0 and 4.5 mg). Patient-reported sleep quality improved with 3.0- and 4.5-mg esmirtazapine (P ≤ 0.01 and P ≤ 0.05, respectively, vs placebo). Morning alertness and contentment were not altered after esmirtazapine, and calmness increased with 4.5-mg esmirtazapine vs placebo. Evening questionnaires showed no difference in duration of daytime naps but reduced energy and ability to work/function after esmirtazapine treatment periods vs placebo (P < 0.05), although this effect was limited to the first night of each 2-night period. There were few adverse events, no serious adverse events, or clinically relevant treatment differences in vital signs, laboratory values, or electrocardiogram. Esmirtazapine doses of 1.5 to 4.5 mg/day significantly improved quantity and quality of sleep and were generally well tolerated, with no evidence of safety concerns or consistent pattern of residual effects.

Effect of Mirtazapine Treatment on Serum Levels of Brain-Derived Neurotrophic Factor and Tumor Necrosis Factor-α in Patients of Major Depressive Disorder with Severe Depression.

BACKGROUND: This study evaluated the clinical efficacy of mirtazapine and its effect on serum brain-derived neurotrophic factor (BDNF) and tumor necrosis factor-α (TNF-α) levels in patients of major-depressive disorder (MDD) with severe depression. METHODS: Patients (aged 18-60) with MDD diagnosed by DSM-IV criteria, and Hamilton Rating Scale for Depression (HAM-D) score ≥25 were included (n = 30). Mirtazapine was given in the doses of 30 mg/day. All patients were followed up for 12 weeks for the evaluation of clinical efficacy, safety along with serum BDNF and TNF-α levels. RESULTS: HAM-D score at the start of treatment was 30.1 ± 1.92, which significantly (p < 0.05) reduced to 13.47 ± 1.77 at 12 weeks of treatment. In responders, mean serum BDNF levels at the start of treatment were 2.32 ± 0.3 ng/ml, which significantly (p < 0.05) increased to 2.79 ± 0.33 ng/ml at 12 weeks of treatment and mean serum TNF-α levels at the start were 5.18 ± 0.67 pg/ml, which significantly decreased to 4.36 ± 0.72 pg/ml (p < 0.05) at 12 weeks of treatment. CONCLUSION: Our results suggest that mirtazapine is effective and well tolerated in severely depressed patients and treatment response is associated with an increase in serum BDNF and a decrease in serum TNF-α levels.

COMBINED MIRTAZAPINE AND SSRI TREATMENT OF PTSD: A PLACEBO-CONTROLLED TRIAL.

BACKGROUND: Combined treatment with a selective serotonin reuptake inhibitor (SSRI) plus mirtazapine has shown superior efficacy in some studies of depression, but has not been studied in posttraumatic stress disorder (PTSD). This study aimed to assess acceptability of combined sertraline plus mirtazapine treatment for PTSD and to estimate its effect size relative to sertraline plus placebo. METHODS: Thirty-six adults with PTSD were randomized to 24 weeks of double-blind treatment with sertraline plus mirtazapine or sertraline plus placebo. Outcomes were analyzed with mixed effects models. RESULTS: The combined treatment group showed a significantly greater remission rate (P = .042) and improvement in depressive symptoms (P = .023) than the sertraline plus placebo group. There were no significant group differences in the two primary outcomes of treatment retention and PTSD severity, or in other secondary outcomes (sleep impairment, sexual functioning, quality of life, and physical and mental functioning), but the combined treatment group showed numerical advantages on all of these outcomes, and effect sizes relative to sertraline plus placebo ranged from small to moderate (d = .26-.63). Both treatments were well-tolerated, with significantly increased appetite but not weight gain in the combined treatment group. CONCLUSION: Findings suggest that combined treatment of PTSD with sertraline plus mirtazapine may have clinically meaningful advantages in symptomatic improvement, relative to SSRI treatment alone, and acceptable tolerability. Combined treatment with an SSRI plus mirtazapine in PTSD deserves additional study as initial treatment or as an augmentation strategy for nonresponders to an SSRI.

Effect of mirtazapine on rat bone tissue after orchidectomy.

OBJECTIVE: Our study aimed to investigate the effect of mirtazapine on bone metabolism in the orchidectomized rat model. METHODS: Rats were divided into three groups. A sham-operated control group (SHAM group) and a control group after orchidectomy (ORX group) received the standard laboratory diet (SLD). An experimental group after orchidectomy (ORX MIRTA group) received SLD enriched with mirtazapine for 12 weeks. Bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry. Bone marker concentrations of osteoprotegerin (OPG), amino-terminal propeptide of procollagen type I, bone alkaline phosphatase (BALP), sclerostin and bone morphogenetic protein 2 were examined in bone homogenate. The femurs were used for biomechanical testing. RESULTS: Compared with the control ORX group, we found a lower BMD in the ORX MIRTA group. The differences were statistically significant, although not in the lumbar vertebrae. BMD was lower in the MIRTA group, suggesting a preferential effect on cortical bone. However, although the thickness of the diaphyseal cortical bone was not different, the fragility in the femoral neck area was statistically significantly different between the groups in biomechanical testing. Regarding the bone metabolism markers, there was a significant decrease in OPG and BALP levels, suggesting a reduction in osteoid synthesis. CONCLUSIONS: The results suggest that prolonged use of mirtazapine may have a negative effect on the synthesis of bone and on its mechanical strength, especially in the femoral neck. Further studies are warranted to establish whether mirtazapine may have a clinically significant adverse effect on bone exclusively in the model of gonadectomized rats, or whether the effect occurs also in the model of gonadally intact animals and in respective human models.

[Allosteric effect of serotonin and mianserin on the kinetics of specific [3H]-ligand binding to adrenergic and muscarinic receptors in the rat cerebral cortex membranes].

The effects of serotonin receptor activation (by serotonin) and inhibition (by mianserin) on the properties of the α1-, α2-adrenoreceptors, and muscarinic cholinergic receptors in subcellular membrane fractions from the rat cerebral cortex were studied. Experimental data on the kinetics of specific antagonists binding to adrenergic and muscarinic receptors were analyzed by graphical and mathematical methods. The results suggest the presence of allosteric (cross-talk) interaction. In the control, α1- and α2-adrenoreceptors were represented by a single pool, and muscarinic receptors, by two pools. Two pools of adrenoreceptors with different affinity were detected against the background of serotonin. It was found that mianserin induces the formation of two pools of only (α2-receptors and muscarinic receptors are represented by two pools differing in the main parameters, such as dissociation constants and adrenoreceptor concentrations, in the control and experimental groups. It was shown that the allosteric effect of serotonin and mianserin is manifested in the inhibition of muscarinic receptors. It was assumed that the adrenergic and cholinergic receptors exist as dimers. The interaction between the adrenergic, cholinergic, and serotonergic systems is likely to be implemented at the cell membrane level.

Prokinetic effects of mirtazapine on gastrointestinal transit.

Mirtazapine is a noradrenergic and specific serotonergic antidepressant. The aim of this study was to investigate the effects of mirtazapine on gastrointestinal motility in dogs, including solid gastric emptying, antral and small intestinal contractions, and small intestinal and colonic transit. Six dogs were implanted with two cannulas located at the duodenum and the ascending colon; another six dogs were implanted with gastric cannula 6 cm proximal to the pylorus. Mirtazapine 45 mg was administered orally 90 min before the study. We found that 1) Mirtazapine accelerated gastric emptying during the entire 3 h in normal dogs (P < 0.04) and accelerated delayed gastric emptying induced by rectal distention (P < 0.04). 2) Mirtazapine restored impaired gastric tone and accommodation induced by rectal distention (P < 0.05). 3) No significant changes were noted in small intestinal contractions or transit with mirtazapine (P > 0.1). 4) Mirtazapine accelerated colonic transit at 2 and 4 h but not 6 h. The geometric center was increased from 1.9 ± 0.6 to 3.0 ± 0.5 and 3.9 ± 0.5 to 4.7 ± 0.1 at 2 and 4 h respectively (P = 0.04 vs. corresponding control). In conclusion, mirtazapine improves gastric emptying in healthy dogs and normalizes rectal distention-induced delay in gastric emptying and accelerates colon but not small intestinal transit in healthy dogs. Clinical studies are warranted to assess the effects of mirtazapine on gastrointestinal motility and sensory functions in patients with functional gastrointestinal diseases.

Mianserin, an antidepressant kills Leishmania donovani by depleting ergosterol levels.

In the present study, we have investigated the antileishmanial potential of mianserin, an antidepressant. Mianserin was found to inhibit both the promastigote and amastigote forms of the parasite in a dose dependant manner. The IC50 values for promastigotes and amastigotes were 21 µM and 46 µM respectively. Interestingly, mianserin failed to inhibit THP-1 differentiated macrophages up to 100 µM concentration thus, exhibiting parasite selectivity. When mianserin was incubated with recombinant Leishmania donovani 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) enzyme, it exhibited an IC50 value of 19.8 µM. Inhibition kinetics revealed competitive mode of enzyme inhibition as the Km increased with no change in Vmax. Further structural investigation of enzyme-inhibitor interaction revealed quenching of HMGR tryptophan intrinsic fluorescence with a K(sv) value of 3.025±0.37 M(-1) and an apparent binding constant of 0.0954 mM. We further estimated ergosterol levels which is a major component of Leishmania cell membrane. It is synthesized by HMGR enzyme, the first rate limiting enzyme of the sterol biosynthetic pathway. Analysis of ergosterol levels by HPLC revealed ∼2.5-fold depletion in mianserin treated promastigotes with respect to untreated parasites. This data was further validated by exogenous supplementation of mianserin treated cells with ergosterol and cholesterol. Reversal of growth inhibition was observed only upon ergosterol addition though it was refractory to cholesterol supplementation. Overall, our results demonstrate the possibility of repositioning of an antidepressant for the treatment of Visceral Leishmaniasis.

Nummular headache in a patient with ipsilateral occipital neuralgia--a case report.

Nummular headache (NH) is a rarely recognized primary headache, the diagnostic criteria of which are contained in the appendix to the 2nd edition of the International Classification of Headache Disorders (code A13.7.1). We present the case of a 61-year-old female who suffers, regardless of NH, from right-sided occipital neuralgia. The applied treatment - gabapentin and mianserin - had no effect. Injection of bupivacaine twice to the right occipital region resulted in neuralgia resolution up to three months, with no effect on NH. This confirms the independence of two above mentioned head pain conditions.

Structural insights into the unexpected agonism of tetracyclic antidepressants at serotonin receptors 5-HT1eR and 5-HT1FR.

Serotonin [5-hydroxytryptamine (5-HT)] acts via 13 different receptors in humans. Of these receptor subtypes, all but 5-HT1eR have confirmed roles in native tissue and are validated drug targets. Despite 5-HT1eR's therapeutic potential and plausible druggability, the mechanisms of its activation remain elusive. To illuminate 5-HT1eR's pharmacology in relation to the highly homologous 5-HT1FR, we screened a library of aminergic receptor ligands at both receptors and observe 5-HT1eR/5-HT1FR agonism by multicyclic drugs described as pan-antagonists at 5-HT receptors. Potent agonism by tetracyclic antidepressants mianserin, setiptiline, and mirtazapine suggests a mechanism for their clinically observed antimigraine properties. Using cryo-EM and mutagenesis studies, we uncover and characterize unique agonist-like binding poses of mianserin and setiptiline at 5-HT1eR distinct from similar drug scaffolds in inactive-state 5-HTR structures. Together with computational studies, our data suggest that these binding poses alongside receptor-specific allosteric coupling in 5-HT1eR and 5-HT1FR contribute to the agonist activity of these antidepressants.

An antidepressant that extends lifespan in adult Caenorhabditis elegans.

The mechanisms that determine the lifespan of an organism are still largely a mystery. One goal of ageing research is to find drugs that would increase lifespan and vitality when given to an adult animal. To this end, we tested 88,000 chemicals for the ability to extend the lifespan of adult Caenorhabditis elegans nematodes. Here we report that a drug used as an antidepressant in humans increases C. elegans lifespan. In humans, this drug blocks neural signalling by the neurotransmitter serotonin. In C. elegans, the effect of the drug on lifespan is reduced or eradicated by mutations that affect serotonin synthesis, serotonin re-uptake at synapses, or either of two G-protein-coupled receptors: one that recognizes serotonin and the other that detects another neurotransmitter, octopamine. In vitro studies show that the drug acts as an antagonist at both receptors. Testing of the drug on dietary-restricted animals or animals with mutations that affect lifespan indicates that its effect on lifespan involves mechanisms associated with lifespan extension by dietary restriction. These studies indicate that lifespan can be extended by blocking certain types of neurotransmission implicated in food sensing in the adult animal, possibly leading to a state of perceived, although not real, starvation.

Effects of repeated dosing with mirtazapine, trazodone, or placebo on driving performance and cognitive function in healthy volunteers.

OBJECTIVE: This study aimed to evaluate the effects of repeated treatments with the sedative antidepressants mirtazapine and trazodone on driving performance and cognitive function. METHODS: Nineteen healthy men received continuous nocturnal doses of 15-mg mirtazapine , 25-mg trazodone, or placebo for 8 days in a double-blinded, three-way crossover trial. Subjects were asked to perform three driving tasks (road tracking, car following, and harsh braking) using a driving simulator and cognitive tasks (the Wisconsin Card Sorting Test, Continuous Performance Test, and N-back Test) at baseline and on Days 2 and 9. Stanford Sleepiness Scale scores were also assessed. RESULTS: Mirtazapine significantly increased the standard deviation of lateral position in the road-tracking task as compared with trazodone on Day 2. Mirtazapine significantly increased Stanford Sleepiness Scale scores as compared with trazodone and placebo. For the remaining tasks, no significant effects of treatment were observed. CONCLUSIONS: Acute treatment of mirtazapine impaired road-tracking performance and increased sleepiness, but sedative effects disappeared under repeated administrations. Trazodone did not affect driving performance or cognitive function under acute or repeated administrations. Both initial sedative effects and pharmacological profiles should be taken into consideration when using sedative antidepressants.