Improved Pharmacokinetic and Pharmacodynamic Profile of Deuterium-Reinforced Tricyclic Antidepressants Doxepin, Dosulepin, and Clomipramine in Animal Models

BACKGROUND AND OBJECTIVES

Doxepin, dosulepin, and clomipramine are tricyclic antidepressants (TCAs) that act as serotonin and noradrenaline reuptake inhibitors. The metabolites formed by N-dealkylation of these tricyclic antidepressants contribute to overall poor pharmacokinetics and efficacy. Deuteration of the methyl groups at metabolically active sites has been reported to be a useful strategy for developing more selective and potent antidepressants. This isotopic deuteration can lead to better bioavailability and overall effectiveness. The objective is to study the effect of site-selective deuteration of TCAs on their pharmacokinetic and pharmacodynamic profile by comparison with their nondeuterated counterparts.

METHODS

In the current study, the pharmacokinetic profile and antidepressant behavior of deuterated TCAs were evaluated using the forced swim test (FST) and tail suspension test (TST), using male Wistar rats and male Swiss albino mice, respectively; additionally, a synaptosomal reuptake study was carried out.

RESULTS

Compared with the nondeuterated parent drugs, deuterated forms showed improved efficacy in the behavior paradigm, indicating improved pharmacological activity. The pharmacokinetic parameters indicated increased maximum concentration in the plasma (Cmax), elimination half-life (t1/2), and area under the concentration-time curve (AUC)  in deuterated compounds. This can have a positive clinical impact on antidepressant treatment. Synaptosomal reuptake studies indicated marked inhibition of the reuptake mechanism of serotonin (5-HT) and norepinephrine.

CONCLUSIONS

Deuterated TCAs can prove to be potentially better molecules in the treatment of neuropsychiatric disorders as compared with nondeuterated compounds. In addition, we have demonstrated a concept that metabolically active, site-selective deuteration can be beneficial for improving the pharmacokinetic and pharmacodynamic profiles of TCAs. A further toxicological study of these compounds is needed to validate their future clinical use.

Tianeptine promotes lasting antiallodynic effects in a mouse model of neuropathic pain

Tricyclic antidepressants (TCAs), such as desipramine (DMI), are effective at managing neuropathic pain symptoms but often take several weeks to become effective and also lead to considerable side effects. Tianeptine (TIAN) is an atypical antidepressant that activates the mu-opioid receptor but does not produce analgesic tolerance or withdrawal in mice, nor euphoria in humans, at clinically-relevant doses. Here, we evaluate the efficacy of TIAN at persistently alleviating mechanical allodynia in the spared nerve injury (SNI) model of neuropathic pain, even well after drug clearance. After finding an accelerated onset of antiallodynic action compared to DMI, we used genetically modified mice to gain insight into RGS protein-associated pathways that modulate the efficacy of TIAN relative to DMI in models of neuropathic pain. Because we observed similar behavioral responses to both TIAN and DMI treatment in RGS4, RGSz1, and RGS9 knockout mice, we performed RNA sequencing on the NAc of TIAN- and DMI-treated mice after prolonged SNI to further clarify potential mechanisms underlying TIANs faster therapeutic actions. Our bioinformatic analysis revealed distinct transcriptomic signatures between the two drugs, with TIAN more directly reversing SNI-induced differentially expressed genes, and further predicted several upstream regulators that may be implicated in onset of action. This new understanding of the molecular pathways underlying TIAN action may enable the development of novel and more efficacious pharmacological approaches for the management of neuropathic pain.

Inhibitory Effects of Tricyclic Antidepressants on Human Liver Microsomal Morphine Glucuronidation: Application of IVIVE to Predict Potential Drug-Drug Interactions in Humans

BACKGROUND

Tricyclic antidepressants (TCAs) are commonly co-administered with morphine as an adjuvant analgesic. Nevertheless, there remains a lack of information concerning metabolic drug-drug interactions (DDIs) resulting from TCA inhibition on morphine glucuronidation.

OBJECTIVE

This study aimed to (i) examine the inhibitory effects of TCAs (viz., amitriptyline, clomipramine, imipramine, and nortriptyline) on human liver microsomal morphine 3- and 6-glucuronidation and (ii) evaluate the potential of DDI in humans by employing in vitro-in vivo extrapolation (IVIVE) approaches.

METHOD

The inhibition parameters for TCA inhibition on morphine glucuronidation were derived from the in vitro system containing 2% BSA. The Ki values were employed to predict the DDI magnitude in vivo by using static and dynamic mechanistic PBPK approaches Results: TCAs moderately inhibited human liver microsomal morphine glucuronidation, with clomipramine exhibiting the most potent inhibition potency. Amitriptyline, clomipramine, imipramine, and nortriptyline competitively inhibited morphine 3- and 6-glucuronide formation with the respective Ki values of 91 ± 7.5 and 82 ± 11 μM, 23 ± 1.3 and 14 ± 0.7 μM, 103 ± 5 and 90 ± 7 μM, and 115 ± 5 and 110 ± 3 μM. Employing the static mechanistic IVIVE, a prediction showed an estimated 20% elevation in the morphine AUC when co-administered with either clomipramine or imipramine, whereas the predicted increase was <5% for amitriptyline or nortriptyline. PBPK modelling predicted an increase of less than 10% in the morphine AUC due to the inhibition of clomipramine and imipramine in both virtual healthy and cirrhotic populations.

CONCLUSION

The results suggest that the likelihood of potential clinical DDIs arising from tricyclic antidepressant inhibition on morphine glucuronidation is low.

Calcium-Dependent Interplay of Lithium and Tricyclic Antidepressants, Amitriptyline and Desipramine, on N-methyl-D-aspartate Receptors

The facilitated activity of N-methyl-D-aspartate receptors (NMDARs) in the central and peripheral nervous systems promotes neuropathic pain. Amitriptyline (ATL) and desipramine (DES) are tricyclic antidepressants (TCAs) whose anti-NMDAR properties contribute to their analgetic effects. At therapeutic concentrations <1 µM, these medicines inhibit NMDARs by enhancing their calcium-dependent desensitization (CDD). Li+, which suppresses the sodium−calcium exchanger (NCX) and enhances NMDAR CDD, also exhibits analgesia. Here, the effects of different [Li+]s on TCA inhibition of currents through native NMDARs in rat cortical neurons recorded by the patch-clamp technique were investigated. We demonstrated that the therapeutic [Li+]s of 0.5−1 mM cause an increase in ATL and DES IC50s of ~10 folds and ~4 folds, respectively, for the Ca2+-dependent NMDAR inhibition. The Ca2+-resistant component of NMDAR inhibition by TCAs, the open-channel block, was not affected by Li+. In agreement, clomipramine providing exclusively the NMDAR open-channel block is not sensitive to Li+. This Ca2+-dependent interplay between Li+, ATL, and DES could be determined by their competition for the same molecular target. Thus, submillimolar [Li+]s may weaken ATL and DES effects during combined therapy. The data suggest that Li+, ATL, and DES can enhance NMDAR CDD through NCX inhibition. This ability implies a drug−drug or ion−drug interaction when these medicines are used together therapeutically.

Association of mental disorders and psychotropic medications with bone texture as measured with trabecular bone score

INTRODUCTION

Mental disorders and psychotropic medications are known to increase the risk of osteoporosis and fractures. However, current evidence is mostly limited to studies that used bone mineral density (BMD), which does not provide information about the texture of bone tissue and can underestimate fracture risk.

METHODS

We tested the association between bone texture, as measured with lumbar spine trabecular bone score (TBS), and both diagnosed mental disorders and psychotropic medication use in a large population-based BMD registry from Manitoba, Canada. General linear and logistic regression models were used to test the association of TBS with mental disorders (anxiety, depression, schizophrenia, and alcohol use disorder) and psychotropic medications use (selective serotonin reuptake inhibitors [SSRI], tricyclic antidepressants [TCA], other antidepressants, lithium, non‑lithium mood stabilizers, antipsychotics, and benzodiazepines), adjusted for comorbidities and confounding factors.

RESULTS

The study population contained 45,716 women (mean age = 64.1, SD = 10.4), which included 21.1 % with diagnoses for mental disorders and 18.7 % using psychotropic medications. We observed significant negative covariate-adjusted effects on TBS from diagnosed alcohol use disorder (3.1 % reduction in TBS, p < 0.001) and exposure to SSRI (0.6 % reduction, p < 0.001), TCA (0.8 % reduction, p < 0.001), other antidepressants (0.8 % reduction, p < 0.001), and lithium (3 % reduction, p < 0.001). Logistic regression revealed that TBS in the lowest (versus highest) tertile was associated with alcohol use disorder (adjusted odds ratio [OR] = 2.87, 95 % confidence interval [CI]: 1.95, 4.21), exposure to SSRI (OR = 1.21; 95 % CI: 1.08, 1.35), TCA (OR = 1.18, 95 % confidence interval [CI]: 1.04, 1.35), other antidepressants (OR = 1.26; 95 % CI: 1.09, 1.45), and lithium (OR = 1.97; 95 % CI: 1.09, 3.57).

CONCLUSION

Our results suggest that alcohol use disorder, antidepressants, and lithium are associated with poorer bone texture in women. These findings add to the current literature on the link of bone pathology with mental disorders and psychotropic medications.

Cyclooxygenase-2 inhibition affects the expression of down syndrom cell adhesion molecule via interaction with metabotropic glutamate receptor 5

Since we previously discovered that simultaneous inhibition of cyclooxygenase-2 (COX-2; a highly inducible enzyme, crucial for the conversion of arachidonic acid to prostaglandin G2, which plays a predominant role in the CNS) by NS398 and metabotropic glutamate receptor 5 (mGluR5) through the use of its antagonist [3-((2-methyl-4-thiazolyl)ethyl)pyridine; MTEP] alters mouse behavior (e.g., affects spatial learning, and induces/intensifies the antidepressant effect), our aim was to discover the mechanism responsible for these changes. Down syndrome cell adhesion molecule (DSCAM), a member of the immunoglobulin cell adhesion molecule (Ig-CAM) superfamily, is involved in developing the central and peripheral nervous system by influencing cell adhesion mechanisms necessary for synaptic activity and plasticity. Since COX-2 has been implicated in several neuropsychiatric diseases (e.g., major depressive disorder) resulting from neuroplasticity disorders, and on the other hand, its expression is regulated by synaptic activity, we hypothesized that cognitive changes after administration of COX-2 inhibitor and mGluR5 antagonist might be a consequence of impaired DSCAM expression. Importantly, DSCAM deficiency leads to dysregulation of glutamatergic transmission and plasticity. In previous studies, we have demonstrated glutamatergic changes after NS398 and MTEP administration, further supporting the validity of our hypothesis. Due to the different effects observed in behavioral tests, this study used the prefrontal cortex (PFC) and hippocampus (HC) of C57BL/6J mice, which received NS398 and MTEP alone, or in combination, for 7 or 14 days. Among many properties, we also previously investigated the antidepressant potential of these compounds, so we used imipramine (a tricyclic antidepressant) as the reference drug. DSCAM mRNA expression was determined by qRT-PCR. Our results indicate that DSCAM expression after administration of MTEP and NS398 and imipramine along with NS398 is structure- and time-dependent.

Tianeptine, but not fluoxetine, decreases avoidant behavior in a mouse model of early developmental exposure to fluoxetine

Depression and anxiety, two of the most common mental health disorders, share common symptoms and treatments. Most pharmacological agents available to treat these disorders target monoamine systems. Currently, finding the most effective treatment for an individual is a process of trial and error. To better understand how disease etiology may predict treatment response, we studied mice exposed developmentally to the selective serotonin reuptake inhibitor (SSRI) fluoxetine (FLX). These mice show the murine equivalent of anxiety- and depression-like symptoms in adulthood and here we report that these mice are also behaviorally resistant to the antidepressant-like effects of adult SSRI administration. We investigated whether tianeptine (TIA), which exerts its therapeutic effects through agonism of the mu-opioid receptor instead of targeting monoaminergic systems, would be more effective in this model. We found that C57BL/6J pups exposed to FLX from postnatal day 2 to 11 (PNFLX, the mouse equivalent in terms of brain development to the human third trimester) showed increased avoidant behaviors as adults that failed to improve, or were even exacerbated, by chronic SSRI treatment. By contrast, avoidant behaviors in these same mice were drastically improved following chronic treatment with TIA. Overall, this demonstrates that TIA may be a promising alternative treatment for patients that fail to respond to typical antidepressants, especially in patients whose serotonergic system has been altered by in utero exposure to SSRIs.

Kir4.1 Dysfunction in the Pathophysiology of Depression: A Systematic Review

A serotonergic dysfunction has been largely postulated as the main cause of depression, mainly due to its effective response to drugs that increase the serotonergic tone, still currently the first therapeutic line in this mood disorder. However, other dysfunctional pathomechanisms are likely involved in the disorder, and this may in part explain why some individuals with depression are resistant to serotonergic therapies. Among these, emerging evidence suggests a role for the astrocytic inward rectifier potassium channel 4.1 (Kir4.1) as an important modulator of neuronal excitability and glutamate metabolism. To discuss the relationship between Kir4.1 dysfunction and depression, a systematic review was performed according to the PRISMA statement. Searches were conducted across PubMed, Scopus, and Web of Science by two independent reviewers. Twelve studies met the inclusion criteria, analyzing Kir4.1 relationships with depression, through in vitro, in vivo, and post-mortem investigations. Increasing, yet not conclusive, evidence suggests a potential pathogenic role for Kir4.1 upregulation in depression. However, the actual contribution in the diverse subtypes of the disorder and in the comorbid conditions, for example, the epilepsy-depression comorbidity, remain elusive. Further studies are needed to better define the clinical phenotype associated with Kir4.1 dysfunction in humans and the molecular mechanisms by which it contributes to depression and implications for future treatments.

Inhibition by Imipramine of the Voltage-Dependent K+ Channel in Rabbit Coronary Arterial Smooth Muscle Cells

Imipramine, a tricyclic antidepressant, is used in the treatment of depressive disorders. However, the effect of imipramine on vascular ion channels is unclear. Therefore, using a patch-clamp technique we examined the effect of imipramine on voltage-dependent K+ (Kv) channels in freshly isolated rabbit coronary arterial smooth muscle cells. Kv channels were inhibited by imipramine in a concentration-dependent manner, with an IC50 value of 5.55 ± 1.24 µM and a Hill coefficient of 0.73 ± 0.1. Application of imipramine shifted the steady-state activation curve in the positive direction, indicating that imipramine-induced inhibition of Kv channels was mediated by influencing the voltage sensors of the channels. The recovery time constants from Kv-channel inactivation were increased in the presence of imipramine. Furthermore, the application of train pulses (of 1 or 2 Hz) progressively augmented the imipramine-induced inhibition of Kv channels, suggesting that the inhibitory effect of imipramine is use (state) dependent. The magnitude of Kv current inhibition by imipramine was similar during the first, second, and third depolarizing pulses. These results indicate that imipramine-induced inhibition of Kv channels mainly occurs in the closed state. The imipramine-mediated inhibition of Kv channels was associated with the Kv1.5 channel, not the Kv2.1 or Kv7 channel. Inhibition of Kv channels by imipramine caused vasoconstriction. From these results, we conclude that imipramine inhibits vascular Kv channels in a concentration- and use (closed-state)-dependent manner by changing their gating properties regardless of its own function.

Gastroparesis: New insights into an old disease

Gastroparesis (Gp) is a chronic disease characterized by a delayed gastric emptying in the absence of mechanical obstruction. Although this condition has been reported in the literature since the mid-1900s, only recently has there been renewed clinical and scientific interest in this disease, which has a potentially great impact on the quality of life. The aim of this review is to explore the pathophysiological, diagnostic and therapeutical aspects of Gp according to the most recent evidence. A comprehensive online search for Gp was carried out using MEDLINE and EMBASE. Gp is the result of neuromuscular abnormalities of the gastric motor function. There is evidence that patients with idiopathic and diabetic Gp may display a reduction in nitrergic inhibitory neurons and in interstitial cells of Cajal and/or telocytes. As regards diagnostic approach, 99-Technetium scintigraphy is currently considered to be the gold standard for Gp. Its limits are a lack of standardization and a mild risk of radiation exposure. The C13 breath testing is a valid and safe alternative method. ¹³C acid octanoic and the ¹³C Spirulina platensis recently approved by the Food and Drug Administration are the most commonly used diagnostic kits. The wireless motility capsule is a promising technique, but its use is limited by costs and scarce availability in many countries. Finally, therapeutic strategies are related to the clinical severity of Gp. In mild and moderate Gp, dietary modification and prokinetic agents are generally sufficient. Metoclopramide is the only drug approved by the Food and Drug Administration for Gp. However, other older and new prokinetics and antiemetics can be considered. As a second-line therapy, tricyclic antidepressants and cannabinoids have been proposed. In severe cases the normal nutritional approach can be compromised and artificial nutrition may be needed. In drug-unresponsive Gp patients some alternative strategies (endoscopic, electric stimulation or surgery) are available.

Agonist-specific voltage-dependent gating of lysosomal two-pore Na+ channels

Mammalian two-pore-channels (TPC1, 2; TPCN1, TPCN2) are ubiquitously- expressed, PI(3,5)P2-activated, Na+-selective channels in the endosomes and lysosomes that regulate luminal pH homeostasis, membrane trafficking, and Ebola viral infection. Whereas the channel activity of TPC1 is strongly dependent on membrane voltage, TPC2 lacks such voltage dependence despite the presence of the presumed 'S4 voltage-sensing' domains. By performing high-throughput screening followed by lysosomal electrophysiology, here we identified a class of tricyclic anti-depressants (TCAs) as small-molecule agonists of TPC channels. TCAs activate both TPC1 and TPC2 in a voltage-dependent manner, referred to as Lysosomal Na+ channel Voltage-dependent Activators (LyNa-VAs). We also identified another compound which, like PI(3,5)P2, activates TPC2 independent of voltage, suggesting the existence of agonist-specific gating mechanisms. Our identification of small-molecule TPC agonists should facilitate the studies of the cell biological roles of TPCs and can also readily explain the reported effects of TCAs in the modulation of autophagy and lysosomal functions.

Preliminary Biochemical Description of Brain Oxidative Stress Status in Irritable Bowel Syndrome Contention-Stress Rat Model

Background and objectives: Oxidative stress and inflammation have been implicated in the etiology of irritable bowel syndrome (IBS), a common gastrointestinal functional disease. This study aimed to further characterize the contention-stress rat model by exploring a possible correlation between oxidative stress markers measured in brain tissues with behavioral components of the aforementioned model. Thus, it is hereby proposed a possible IBS animal model relevant to pharmacological and complementary medicine studies. Materials and Methods: Wild-type male Wistar rats (n = 5/group) were chronically exposed to 6-hour/day contention, consisting of isolating the animals in small, vital space-granting plastic devices, for seven consecutive days. Following contention exposure, temporal lobes were extracted and subjected to biochemical analyses to assess oxidative stress-status parameters. Results: Our results show increased brain oxidative stress in contention-stress rat model: decreased superoxide dismutase and glutathione peroxidase activities and increased malondialdehyde production in the IBS group, as compared to the control group. Furthermore, the biochemical ratios which are used to evaluate the effectiveness of an antioxidant system on oxidative stress could be described in this model. Conclusions: The correlations between the behavioral patterns and biochemical oxidative stress features could suggest that this may be a complex model, which can successfully mimic IBS symptomatology further providing evidence of a strong connection between the digestive system, enteric nervous system, and the central nervous system.

mRNA expression of antioxidant and biotransformation enzymes in zebrafish (Danio rerio) embryos after exposure to the tricyclic antidepressant amitriptyline

Now-a-days, the occurrence of antidepressant residues in surface waters has become a major concern. Amitriptyline (AMI) has been described to treat depression and other disorders for decades. However, little is known about its effect on non-target organisms. The aim of this study was to assess the potential impact of AMI on the mRNA expression of antioxidant and detoxification enzymes during the early embryonic development of zebrafish (Danio rerio). Fertilized D. rerio embryos were exposed to AMI at concentrations of 300 ng/L and 30 μg/L and sampled 24, 48, 96, and 144 h post fertilization (hpf) to assess the mRNA expressions of cytochrome P450 1A1, glutathione-S-transferase, glutathione peroxidase, superoxide dismutase, and catalase. The time courses of the mRNA expressions of antioxidant and detoxification enzymes revealed characteristic changes during embryonic development causing generally transient changes post hatching; however, AMI did not cause any significant impact except in the case of CAT after 144 h, which was significantly upregulated by the AMI concentration of 30 μg/L. The results suggest that the antidepressant AMI causes only moderate to minor impacts on antioxidant and detoxification enzymes during early embryonic development of the non-target organism D. rerio and that CAT is the only biomarker affected by AMI.

The Use of Antidepressive Agents and Bone Mineral Density in Women: A Meta-Analysis

Antidepressive agents are one of the fastest-growing classes of prescribed drugs. However, the effects of antidepressive agents on bone density are controversial. The aim of this meta-analysis is to evaluate the state of research on the relationship between the use of tricyclic antidepressants (TCAs) or selective serotonin reuptake inhibitors (SSRIs) and bone mineral density (BMD) in women. The database searched was Pubmed. The meta-analysis included human studies in women fulfilling the following criteria: (i) an assessment of bone mineral density in the lumbar spine, the femoral neck or the total hip; (ii) a comparison of the BMD of depressed individuals using antidepressive agents (SSRIs or TCAs), and a control group that did not use antidepressive agents; (iii) measurement of BMD using dual-energy X-ray absorptiometry (DXA); and (iv) calculations of the mean BMD and standard deviation or standard error. Four studies were identified, which, in total, included 934 women using antidepressive agents and 5767 non-using individuals. The results showed that no significant negative composite weighted mean effect sizes were identified for the comparisons between SSRI users and non-users. Similarly, no significant negative composite weighted mean effect sizes were identified for the comparisons between TCA users and non-users, indicating similar BMD in SSRI or TCA users and non-users. The meta-analysis shows that the association between antidepressant medication and bone mineral density has not been extensively researched. Only four studies fulfilled the inclusion criteria. The global result of the literature review and meta-analysis was that the use of antidepressive agents was not associated with lower or higher BMD. This result applies to both SSRIs and TCAs and to all measurement locations (lumbar spine, femoral neck and total hip).

How does early maternal separation and chronic stress in adult rats affect the immunoreactivity of serotonergic neurons within the dorsal raphe nucleus?

Vulnerability to emotional disorders like depression derives from interactions between early and late environments, including stressful conditions. The serotonin (5HT) system is strongly affected by stress and chronic unpredictable stress can alter the 5HT system. We evaluated the distribution of active serotonergic neurons in the dorsal raphe nucleus (DR) through immunohistochemistry in maternally separated and chronically stressed rats treated with an antidepressant, tianeptine, whose mechanism of action is still under review. Male Wistar rats were subjected to daily maternal separation (MS) for 4.5 h between postnatal days (PND) 1-21, or to animal facility rearing (AFR). Between (PND) days 50-74, rats were exposed to chronic unpredictable stress and were treated daily with tianeptine (10 mg/kg) or vehicle. We found an interaction between the effects of MS and chronic unpredictable stress on Fos-5HT immunoreactive cells at mid-caudal level of the DR. MS-chronically stressed rats showed an increase of Fos-5HT immunoreactive cells compared with AFR-chronically stressed rats. The ventrolateral (DRL/VLPAG) and dorsal (DRD) subdivisions of the DR were significantly more active than the ventral part (DRV). At the rostral level of the DR, tianeptine decreased the number of Fos-5HT cells in DR in the AFR groups, both unstressed and stressed. Overall, our results support the idea of a match in phenotype exhibited when the early and the adult environment correspond.

Tricyclic Antidepressants Modulate Stressed Mitochondria in Glioblastoma Multiforme Cells

A common feature of solid tumors, including glioblastoma multiforme (GBM), is mitochondrial dysfunction. However, it is reported that the current standard of anti-GBM therapies may potentiate mitochondrial damage and, in effect, support the aggressive character of cancer. As mitochondria are implicated in the modulation of cellular drug sensitivity and chemoresistance mechanisms, activation-stressed mitochondria in GBM cells may represent a new target for anti-GBM therapy that is nontoxic for normal cells.

METHODS

As mitochondria are possible targets for antidepressant drugs used as adjuvant therapy in patients with GBM, we examined their influence on mitochondrial volume and activity, reactive oxygen species level, extracellular lactate concentration, and p65 NF-κB gene expression in GBM cells.

RESULTS

Our investigation showed, for the first time, that tricyclic antidepressants, imipramine and amitriptyline, partially reverse GBM abnormalities.

CONCLUSION

In the light of reported studies, the mitochondrial disturbance observed in glioma cells is a dynamic process that can be reversed or silenced. Moreover, imipramine and amitriptyline are attractive cellular metabolic modulators and can potentially be used to restoring a proper function of mitochondria in GBM cells.

Methyl jasmonate attenuated lipopolysaccharide-induced depressive-like behaviour in mice

Depression is a recurrent neuropsychiatric disorder that affects millions of individuals worldwide and impact negatively on the patients' social functions and quality of life. Studies have shown that i.p injection of lipopolysaccharide (LPS) induces depressive-like behavior in rodents via induction of oxidative stress and neuroinflammation. Methyl jasmonate (MJ), an isolated compound from jasmine plant has gained reputation in aromatherapy for treatment of depression, nervousness and memory deficits. This study was designed to evaluate the effects of MJ on LPS-induced depressive-like behavior in mice. Mice were given MJ (5-20 mg/kg), imipramine (10 mg/kg) or vehicle (10 mL/kg) intraperitoneally for 7 consecutive days. On day 7, treatment was carried out 30 min prior to i.p injection of LPS (830 μg/kg). Twenty four hours after LPS administration, tail suspension, forced swim and sucrose preference tests were carried out. Thereafter, serum corticosterone levels were determined using ELISA. The levels of malondialdehyde (MDA), glutathione (GSH) and tumor necrosis factor-alpha (TNF-α) were determined in brain tissue homogenates. LPS significantly increased immobility time in the tail suspension and forced swim tests when compared with vehicle (p < 0.05), which indicates depressive-like syndromes. However, the increased immobility time was significantly reduced by MJ (5-20 mg/kg) when compared with LPS-treated group. LPS administration also altered the levels of MDA, GSH, corticosterone and TNF alpha in mice, which was significantly reversed by MJ. These findings suggest that attenuation of LPS-induced depressive-like behavior by MJ may be related to suppression of oxidative stress and release of TNF alpha.

Antidepressants inhibit Nav1.3, Nav1.7, and Nav1.8 neuronal voltage-gated sodium channels more potently than Nav1.2 and Nav1.6 channels expressed in Xenopus oocytes

Tricyclic antidepressants (TCAs) and duloxetine are used to treat neuropathic pain. However, the mechanisms underlying their analgesic effects remain unclear. Although many investigators have shown inhibitory effects of antidepressants on voltage-gated sodium channels (Na_v) as a possible mechanism of analgesia, to our knowledge, no one has compared effects on the diverse variety of sodium channel α subunits. We investigated the effects of antidepressants on sodium currents in Xenopus oocytes expressing Na_v1.2, Na_v1.3, Na_v1.6, Na_v1.7, and Na_v1.8 with a β₁ subunit by using whole-cell, two-electrode, voltage clamp techniques. We also studied the role of the β₃ subunit on the effect of antidepressants on Na_v1.3. All antidepressants inhibited sodium currents in an inactivated state induced by all five α subunits with β₁. The inhibitory effects were more potent for Na_v1.3, Na_v1.7, and Na_v1.8, which are distributed in dorsal root ganglia, than Na_v1.2 and Na_v1.6, which are distributed primarily in the central nervous system. The effect of amitriptyline on Na_v1.7 with β₁ was most potent with a half-maximal inhibitory concentration (IC₅₀) 4.6 μmol/L. IC₅₀ for amitriptyline on Na_v1.3 coexpressed with β₁ was lowered from 8.4 to 4.5 μmol/L by coexpression with β₃. Antidepressants predominantly inhibited the sodium channels expressed in dorsal root ganglia, and amitriptyline has the most potent inhibitory effect. This is the first evidence, to our knowledge, showing the diverse effects of antidepressants on various α subunits. Moreover, the β₃ subunit appears important for inhibition of Na_v1.3. These findings may aid better understanding of the mechanisms underlying the pain relieving effects of antidepressants.

Antidepressants for irritable bowel syndrome-A systematic review

BACKGROUND

According to the multifactorial etiology of Irritable bowel syndrome (IBS), psychological factors play an important role. It is possible that antidepressant therapy may be more effective for patients with IBS. The aim of this study was a systematic review of the best available antidepressant therapies for IBS.

METHODS

The databases Medline, PubMed, EMBASE, and the Cochrane Controlled Trials Register for randomized controlled trials were searched for studies published before September 2016. Meta-analyses, randomized controlled trials, controlled trials, uncontrolled trials, cohort studies, and open-label studies were analyzed.

RESULTS

Of 513 articles, 29 fulfilled the inclusion criteria: 6 meta-analyses, 18 randomized controlled trials, and 5 studies without randomization. In these studies, the efficacy of tricyclics, selective serotonin reuptake inhibitors or serotonin-noradrenaline reuptake inhibitors, were analyzed in IBS. Different interventions were used, though in most studies their effect on global symptom relief in IBS as a primary outcome was investigated. Generally, patients' tolerance of the therapies was good. Only severe adverse events were observed as a result of the nature of the drug.

CONCLUSIONS

Generally, antidepressants improved IBS symptoms. In comparison with placebo, tricyclic therapy for IBS was more effective than selective serotonin reuptake inhibitors. Antidepressants might be an alternative therapy for patients suffering from IBS, especially diarrhea-predominant IBS.

Antidepressant imipramine diminishes stress-induced inflammation in the periphery and central nervous system and related anxiety- and depressive- like behaviors

In order to relieve anxiety and depression accompanying stress, physicians resort to tricyclic antidepressants, such as imipramine. We had previously shown that imipramine reversed stress-induced social avoidance behavior, and down-regulated microglial activation 24days after stress cessation. To further characterize the effects of imipramine on stress induced neuroimmune dysregulation and associated changes in behavior, the aims of this study were to determine if imipramine 1) ameliorated stress-induced inflammation in the periphery and central nervous system, and 2) prevented stress related anxiety- and depressive-like behaviors. C57BL/6 mice were treated with imipramine (15mg/kg) in their drinking water, and exposed to repeated social defeat (RSD). Imipramine attenuated stress-induced corticosterone and IL-6 responses in plasma. Imipramine decreased the percentage of monocytes and granulocytes in the bone marrow and circulation. However, imipramine did not prevent splenomegaly, stress-related increased percentage of granulocytes in this organ, and the production of pro-inflammatory cytokines in the spleen, following RSD. Moreover, imipramine abrogated the accumulation of macrophages in the brain in mice exposed to RSD. Imipramine blocked neuroinflammatory signaling and prevented stress-related anxiety- and depressive-like behaviors. These data support the notion that pharmacomodulation of the monoaminergic system, besides exerting anxiolytic and antidepressant effects, may have therapeutic effects as a neuroimmunomodulator during stress.

Role of Acid Sphingomyelinase in the Regulation of Social Behavior and Memory

Major depressive disorder is often associated with deficits in social and cognitive functioning. Mice transgenic for acid sphingomyelinase (t-ASM) were previously shown to have a depressive-like phenotype, which could be normalized by antidepressant treatment. Here, we investigated whether t-ASM mice show deficits in social behavior and memory performance, and whether these possible deficits might be normalized by amitriptyline treatment. Our results revealed that ASM overexpression altered the behavior of mice in a sex-dependent manner. As such, t-ASM female, but not male, mice showed an impaired social preference and a depressive- and anxiogenic-like phenotype, which could be normalized by amitriptyline treatment. Both male and female t-ASM mice showed unaltered preference for social novelty, novel object recognition, and social and object discrimination abilities. Amitriptyline treatment impaired novel object recognition and object discrimination abilities in female, but not in male, wild-type mice, while female t-ASM mice showed unaltered novel object recognition and object discrimination abilities. This study suggests that female t-ASM mice represent a model of depression with comorbid anxiety and social deficits, without memory impairments. It further suggests that ASM overexpression has a protective role against the detrimental effects of amitriptyline on female, but not on male, non-social (object) memory.

Tianeptine induces mTORC1 activation in rat hippocampal neurons under toxic conditions

RATIONALE

Recent studies have demonstrated that mTORC1 activation may be related to antidepressant action. However, the relationship between mTORC1 signaling activation and currently prescribed antidepressants remains unclear.

OBJECTIVE

The aim of the present study was to determine whether alterations in mTORC1 signaling are observable following treatment with tianeptine under toxic conditions induced by B27 deprivation. Additionally, we investigated whether this drug affects synaptic proteins, neurite outgrowth, and spine density via mTORC1 signaling.

METHODS

Using Western blotting, we measured the phosphorylation levels of mTORC1, 4E-BP-1, p70S6K, Akt, and ERK in rat primary hippocampal neurons. Changes in BDNF, dendritic outgrowth, spine density, and synaptic proteins (PSD-95, synaptophysin, and GluR1) were measured.

RESULTS

Tianeptine significantly increased the phosphorylation of mTORC1, 4E-BP-1, p70S6K, Akt, and ERK. The increase in mTOR phosphorylation was blocked by the PI3K, MEK, and mTORC1 inhibitors. Tianeptine increased BDNF, dendritic outgrowth, spine density, and synaptic proteins; all of these effects were blocked by the mTORC1 inhibitor.

CONCLUSIONS

In this study, we demonstrated that tianeptine activates the mTORC1 signaling pathway and increases dendritic outgrowth, spine density, and synaptic proteins through mTORC1 signaling under toxic conditions in rat primary hippocampal neurons.

Amitriptyline Activates TrkA to Aid Neuronal Growth and Attenuate Anesthesia-Induced Neurodegeneration in Rat Dorsal Root Ganglion Neurons

Tricyclic antidepressant amitriptyline (AM) has been shown to exert neurotrophic activity on neurons. We thus explored whether AM may aid the neuronal development and protect anesthesia-induced neuro-injury in young spinal cord dorsal root ganglion (DRG) neurons.The DRG explants were prepared from 1-day-old rats. The effect of AM on aiding DRG neural development was examined by immunohistochemistry at dose-dependent manner. AM-induced changes in gene and protein expressions, and also phosphorylation states of tyrosine kinases receptor A (TrkA) and B (TrkB) in DRG, were examined by quantitative real-time polymerase chain reaction and western blot. The effect of AM on attenuating lidocaine-induced DRG neurodegeneration was examined by immunohistochemistry, and small interfering RNA (siRNA)-mediated TrkA/B down-regulation.Amitriptyline stimulated DRG neuronal development in dose-dependent manner, but exerted toxic effect at concentrations higher than 10 M. AM activated TrkA in DRG through phosphorylation, whereas it had little effect on TrkB-signaling pathway. AM reduced lidocaine-induced DRG neurodegeneration by regenerating neurites and growth cones. Moreover, the neuroprotection of AM on lidocaine-injured neurodegeneration was blocked by siRNA-mediated TrkA down-regulation, but not by TrkB down-regulation.Amitriptyline facilitated neuronal development and had protective effect on lidocaine-induced neurodegeneration, very likely through the activation of TrkA-signaling pathway in DRG.

Role of TrkB in the anxiolytic-like and antidepressant-like effects of vagal nerve stimulation: Comparison with desipramine

A current hypothesis regarding the mechanism of antidepressant (AD) action suggests the involvement of brain-derived neurotrophic factor (BDNF). Consistent with this hypothesis, the receptor for BDNF (and neurotrophin 4/5 (NT-4/5)), Tropomyosin-related kinase B (TrkB), is activated in rodents by treatment with classical AD drugs. Vagal nerve stimulation (VNS), a therapy for treatment resistant depression (TRD), also activates TrkB in rodents. However, the role of this receptor in the therapeutic effects of VNS is unclear. In the current study, the involvement of TrkB in the effects of VNS was investigated in rats using its inhibitor, K252a. Anxiolytic-like and AD-like effects were analyzed using the novelty suppressed feeding test (NSFT) and forced swim test (FST), respectively. K252a blocked the anxiolytic-like effect of chronic VNS treatment and the AD-like effect of acute VNS treatment. By contrast, blocking TrkB did not prevent either the anxiolytic-like or AD-like effect of chronic treatment with desipramine (DMI), a selective noradrenergic reuptake inhibitor; it did, however, block the acute effect of DMI in the FST. To examine whether the activation of TrkB caused by either VNS or DMI is ligand-dependent, use was made of TrkB-Fc, a molecular scavenger for ligands of TrkB. Intraventricular administration of TrkB-Fc blocked the acute activation of TrkB induced by either treatment, indicating that treatment-induced activation of this receptor is ligand-dependent. The behavioral results highlight differences in the involvement of TrkB in the chronic effects of an AD drug and a stimulation therapy as well as its role in acute versus chronic effects of DMI.

Amitriptyline induces brain-derived neurotrophic factor (BDNF) mRNA expression through ERK-dependent modulation of multiple BDNF mRNA variants in primary cultured rat cortical astrocytes and microglia

A significant role of brain-derived neurotrophic factor (BDNF) has been previously implicated in the therapeutic effect of antidepressants. To ascertain the contribution of specific cell types in the brain that produce BDNF following antidepressant treatment, the effects of the tricyclic antidepressant amitriptyline on rat primary neuronal, astrocytic and microglial cortical cultures were examined. Amitriptyline increased the expression of BDNF mRNA in astrocytic and microglial cultures but not neuronal cultures. Antidepressants with distinct mechanisms of action, such as clomipramine, duloxetine and fluvoxamine, also increased BDNF mRNA expression in astrocytic and microglial cultures. There are multiple BDNF mRNA variants (exon I, IIA, IV and VI) expressed in astrocytes and microglia and the variant induced by antidepressants has yet to be elaborated. Treatment with antidepressants increased the expression of exon I, IV and VI in astrocyte and microglia. Clomipramine alone significantly upregulated expression of exon IIA. The amitriptyline-induced expression of both total and individual BDNF mRNA variants (exon I, IV and VI) were blocked by MEK inhibitor U0126, indicating MEK/ERK signaling is required in the expression of BDNF. These findings indicate that non-neural cells are a significant target of antidepressants and further support the contention that glial production of BDNF is crucial role in the therapeutic effect of antidepressants. The current data suggest that targeting of glial function could lead to the development of antidepressants with a truly novel mechanism of action.

Maternal separation in early life modifies anxious behavior and Fos and glucocorticoid receptor expression in limbic neurons after chronic stress in rats: effects of tianeptine

Early-life adversity can lead to long-term consequence persisting into adulthood. Here, we assess the implications of an adverse early environment on vulnerability to stress during adulthood. We hypothesized that the interplay between early and late stress would result in a differential phenotype regarding the number of neurons immunoreactive for glucocorticoid receptor (GR-ir) and neuronal activity as assessed by Fos immunoreactivity (Fos-ir) in brain areas related to stress responses and anxiety-like behavior. We also expected that the antidepressant tianeptine could correct some of the alterations induced in our model. Male Wistar rats were subjected to daily maternal separation (MS) for 4.5 h during the first 3 weeks of life. As adults, the rats were exposed to chronic stress for 24 d and they were treated daily with tianeptine (10 mg/kg intraperitoneal) or vehicle (isotonic saline). Fos-ir was increased by MS in all structures analyzed. Chronic stress reduced Fos-ir in the hippocampus, but increased it in the paraventricular nucleus. Furthermore, chronic stress increased GR-ir in hippocampus (CA1) and amygdala in control non-MS rats. By contrast, when MS and chronic stress were combined, GR-ir was decreased in these structures. Additionally, whereas tianeptine did not affect Fos-ir, it regulated GR-ir in a region-dependent manner, in hippocampus and amygdala opposing in some cases the stress or MS effects. Furthermore, tianeptine reversed the MS- or stress-induced anxious behavior. The interplay between MS and chronic stress observed indicates that MS rats have a modified phenotype, which is expressed when they are challenged by stress in later life.

[Tricyclic antidepressant therapy in headache]

The two most important representatives of the primary headaches are migraine and tension-type headache. More than 10% of the population suffer from migraine and even a greater part, approximately 30-40% from tension-type headache. These two headache types have a great effect both on the individual and on the society. There are two types of therapeutic approaches to headaches: the abortive and the prophylactic therapy. Prophylactic treatment is used for frequent and/or difficult-to-treat headache attacks. Although both migraine and tension-type headache are often associated with depression, for their treatment - in contrast to the widespread medical opinion - not all antidepressants were found to be effective. Amitriptyline, which is a tricyclic antidepressant, is used as a prophylactic therapy for headache since 1968. Its efficacy has been demonstrated in several double-blind, placebo-controlled studies. Although the newer types of antidepressant, such as selective serotonin reuptake inhibitors and selective serotonin-norepinephrine reuptake inhibitor, have a more favorable side-effect profile than tricyclic antidepressants, their headache prophylactic effect has not been proven yet.

Dual Targeting of the Autophagic Regulatory Circuitry in Gliomas with Repurposed Drugs Elicits Cell-Lethal Autophagy and Therapeutic Benefit

The associations of tricyclic antidepressants (TCAs) with reduced incidence of gliomas and elevated autophagy in glioma cells motivated investigation in mouse models of gliomagenesis. First, we established that imipramine, a TCA, increased autophagy and conveyed modest therapeutic benefit in tumor-bearing animals. Then we screened clinically approved agents suggested to affect autophagy for their ability to enhance imipramine-induced autophagy-associated cell death. The anticoagulant ticlopidine, which inhibits the purinergic receptor P2Y12, potentiated imipramine, elevating cAMP, a modulator of autophagy, reducing cell viability in culture, and increasing survival in glioma-bearing mice. Efficacy of the combination was obviated by knockdown of the autophagic regulatory gene ATG7, implicating cell-lethal autophagy. This seemingly innocuous combination of TCAs and P2Y12 inhibitors may have applicability for treating glioma.

Integrated theory to unify status among schizophrenia and manic depressive illness

Tryptophan hydroxylase 1 is primarily expressed in the gastrointestinal tract, and has been associated with both schizophrenia and depression. Although decreased serotonin activity has been reported in both depression and mania, it is important to investigate the interaction between serotonin and other neurotransmitter systems. There are competitive relationships between branched-chain amino acids, and tryptophan and tyrosine that relate to physical activity, and between L-3,4-dihydroxyphenylalanine (L-DOPA) and 5-hydroxytryptophan (5-HTP), both highly dependent on intracellular tetrahydrobiopterin concentrations. Here, I propose a chaos theory for schizophrenia, mania, and depression using the competitive interaction between tryptophan and tyrosine with regard to the blood-brain barrier and coenzyme tetrahydrobiopterin. Mania may be due to the initial conditions of physical hyperactivity and hypofunctional 5-HTP-producing cells inducing increased dopamine. Depression may be due to the initial conditions of physical hypoactivity and hypofunctional 5-HTP-producing cells inducing decreased serotonin. Psychomotor excitation may be due to the initial conditions of physical hyperactivity and hyperfunctional 5-HTP-producing cells inducing increased serotonin and substantially increased dopamine. The hallucinatory-paranoid state may be due to the initial conditions of physical hypoactivity and hyperfunctional 5-HTP-producing cells inducing increased serotonin and dopamine.

Tricyclic Antidepressants Amitriptyline and Desipramine Induced Neurotoxicity Associated with Parkinson's Disease

Recent studies report that a history of antidepressant use is strongly correlated with the occurrence of Parkinson's disease (PD). However, it remains unclear whether antidepressant use can be a causative factor for PD. In the present study, we examined whether tricyclic antidepressants amitriptyline and desipramine can induce dopaminergic cell damage, both in vitro and in vivo. We found that amitriptyline and desipramine induced mitochondria-mediated neurotoxicity and oxidative stress in SH-SY5Y cells. When injected into mice on a subchronic schedule, amitriptyline induced movement deficits in the pole test, which is known to detect nigrostriatal dysfunction. In addition, the number of tyrosine hydroxylase-positive neurons in the substantia nigra pars compacta was reduced in amitriptyline-injected mice. Our results suggest that amitriptyline and desipramine may induce PD-associated neurotoxicity.

Depressive behavior induced by social isolation of predisposed female rats

Depression is a mood disorder that is more prevalent in women and has been closely associated with chronic stress. Many models of depression have been suggested that consider different forms of stress. In fact, stress is present in the life of every human being, but only a few develop depression. Accordingly, it seems wrong to consider all stressed animals to be depressed, emphasizing the importance of predisposition for this mood disorder. Based on this finding, we evaluated a predisposition to depressive behavior of female rats on the forced swim test (FST), and the more immobile the animal was during the FST, the more predisposed to depression it was considered to be. Then, animals were subjected to the stress of social isolation for 21 days and were re-evaluated by the FST. The Predisposed/Isolated rats presented higher immobility times. Once all the rats had prior experience in the FST, we calculated an Index of Increase by Isolation, confirming the previous results. Based on this result, we considered the Predisposed/Isolated group as presenting depressive behavior ('Depressed') and the Nonpredisposed/Nonisolated group as the control group ('Nondepressed'). The animals were distributed into 4 new groups: Nondepressed/Vehicle, Nondepressed/Amitriptyline, Depressed/Vehicle, Depressed/Amitriptyline. After 21 days of treatment, only the Depressed/Vehicle group differed from the other 3 groups, demonstrating the efficacy of amitriptyline in treating the depressive behavior of the Depressed animals, validating the model. This study shows that conducting an FST prior to any manipulation can predict predisposition to depressive behavior in female rats and that the social isolation of predisposed animals for 21 days is effective in inducing depressive behavior. This behavior can be considered real depressive behavior because it takes into account predisposition, chronic mild stress, and the prevalent gender.

The loss of NDRG2 expression improves depressive behavior through increased phosphorylation of GSK3β

N-myc downstream-regulated gene 2 (NDRG2) is one of the important stress-inducible genes and plays a critical role in negatively regulating PI3K/AKT signaling during hypoxia and inflammation. Through recruitment of PP2A phosphatase, NDRG2 maintains the dephosphorylated status of PTEN to suppress excessive PI3K/AKT signaling, and loss of NDRG2 expression is frequently seen in various types of cancer with enhanced activation of PI3K/AKT signaling. Because NDRG2 is highly expressed in the nervous system, we investigated whether NDRG2 plays a functional role in the nervous system using Ndrg2-deficient mice. Ndrg2-deficient mice do not display any gross abnormalities in the nervous system, but they have a diminished behavioral response associated with anxiety. Ndrg2-deficient mice exhibited decreased immobility and increased head-dipping and rearing behavior in two behavioral models, indicating an improvement of emotional anxiety-like behavior. Moreover, treatment of wild-type mice with the antidepressant drug imipramine reduced the expression of Ndrg2 in the frontal cortex, which was due to the degradation of HIF-1α through reduced expression of HSP90 protein. Furthermore, we found that the down-regulation of Ndrg2 in Ndrg2-deficient mice and imipramine treatment improved mood behavior with enhanced phosphorylation of GSK3β through activation of PI3K/AKT signaling, suggesting that the expression level of NDRG2 has a causal influence on mood-related phenotypes. Collectively, these results suggest that NDRG2 may be a potential target for mood disorders such as depression and anxiety.

Chronic mild stress and antidepressant treatment alter 5-HT1A receptor expression by modifying DNA methylation of a conserved Sp4 site

The serotonin 1A receptor (5-HT1A), a critical regulator of the brain serotonergic tone, is implicated in major depressive disorder (MDD) where it is often found to be dys-regulated. However, the extent to which stress and antidepressant treatment impact 5-HT1A expression in adults remains unclear. To address this issue, we subjected adult male BALB/c mice to unpredictable chronic mild stress (UCMS) to induce a depression-like phenotype that was reversed by chronic treatment with the antidepressant imipramine. In prefrontal cortex (PFC) and midbrain tissue, UCMS increased 5-HT1A RNA and protein levels, changes that are expected to decrease the brain serotonergic activity. The stress-induced increase in 5-HT1A expression was paralleled by a specific increase in DNA methylation of the conserved -681 CpG promoter site, located within a Sp1-like element. We show that the -681 CpG site is recognized and repressed by Sp4, the predominant neuronal Sp1-like factor and that Sp4-induced repression is attenuated by DNA methylation, despite a stress-induced increase in PFC Sp4 levels. These results indicate that adult life stress induces DNA methylation of a conserved promoter site, antagonizing Sp4 repression to increase 5-HT1A expression. Chronic imipramine treatment fully reversed the UCMS-induced increase in methylation of the -681 CpG site in the PFC but not midbrain of stressed animals and also increased 5-HT1A expression in the PFC of control animals. Incomplete reversal by imipramine of stress-induced changes in 5-HT1A methylation and expression indicates a persistence of stress vulnerability, and that sustained reversal of behavioral impairments may require additional pathways.

Imipramine protects against the deleterious effects of chronic corticosterone on depression-like behavior, hippocampal reelin expression, and neuronal maturation

We have hypothesized that a downregulation of reelin and deficient maturation of adult-born hippocampal neurons are important factors in the pathogenesis of depression. This hypothesis is based on previous work showing that depression-like behavior in rats treated with protracted corticosterone develops in concert with decreased dendritic complexity in newborn hippocampal granule neurons and decreased reelin expression in the proliferative subgranular zone of the dentate gyrus. In addition, heterozygous reeler mice with approximately 50% of normal brain levels of reelin are more vulnerable to the depressogenic effects of corticosterone than wild-type mice. The purpose of this experiment was to provide pharmacological validation for the link between reelin, neuronal maturation, and depression by examining whether the deleterious effects of corticosterone on these measures could be prevented by co-administration of the antidepressant imipramine. Rats received corticosterone injections, corticosterone injections plus either 10 or 15mg/kg imipramine injections, or vehicle injections for 21 consecutive days. They were then subjected to the forced swim test to assess depression-like behavior and sacrificed for immunohistochemical examination of immature neuron number and dendritic complexity and the presence of reelin+cells. We found that corticosterone increases depression-like behavior, decreases the number of reelin+cells in the subgranular zone, and decreases the number and complexity of immature neurons in the granule cell layer. All of these behavioral and cellular phenotypes were prevented by imipramine, providing further support for the idea that reelin is involved in the pathogenesis of depression.

Sexual effects of antidepressents and psychomotor stimulant drugs

Sexual dysfunction is common in depressive illness, most often occuring as loss of sexual interest, impotence, and a decline in the frequency of intercourse. Antidepressant drugs have been documented to improve sexual function in depression; however, adverse effects of sexual function also occur as a result of the drugs' interference with peripheral cholinergic and adrenergic function. MAO inhibitors may also ameliorate depression-related sexual dysfunction. These drugs also improve sperm count and sperm motility and may have a clinical use in moderate oligospermia. Stimulant drugs have been linked to a wide variety of sexual effects. Most dramatic is the increase in sexual arousal reported by many stimulant users. Increases in sexual activity and sexual perversion have both been related to stimulant use. Due to the high rate of pre-drug sexual aberration and the non-specific nature of stimulant arousal, caution should be exercised in postulating a direct effect on sexuality by stimulant drugs.

The properties of B-form monoamine oxidase in mitochondria from monkey platelet

The present study was examined the effect of the properties of monkey platelet monoamine oxidase (MAO) based on inhibitor sensitivity. Monkey platelet showed a high MAO activity with beta-phenylethylamine (beta-PEA) as substrate and a very low A-form MAO activity with 5 hydroxytryptamine (5-HT) as substrate. Moreover, monkey platelet MAO was sensitive to the drugs deprenyl as B-form MAO inhibitor and less sensitive to clorgyline and harmaline as A form MAO inhibitor with beta-PEA as the B-form MAO substrate. B-form MAO from monkey platelet was more stable against heat treatment at 55 degrees C than B-form MAO in brain. After digestion with trypsin at 37 degrees C for 4 hrs, it was found that MAO from platelet was inhibited about 70% with beta-PEA as substrate with brain. The tricyclic antidepressant imipramine and nortriptyline inhibited B-form MAO activity more potency than B-form MAO in brain. However, when the noncyclic antidepressant nomifensine was used, monkey platelet B-form MAO activities were less potently inhibited. All these reagents were noncompetitive inhibitors of B form MAO in monkey platelet. The present studies demonstrated that monkey platelet MAO is a single of B-form MAO and sensitive to tricyclic antidepressants.

Reevaluating the role of antidepressants in cancer-related depression: a systematic review and meta-analysis

OBJECTIVE

Prior reviews evaluating the role of antidepressants in cancer-related depression have drawn conflicting conclusions. These reviews have also not explored differences in efficacy and tolerability between antidepressants. We conducted a meta-analysis to address these limitations.

METHOD

We searched Medline (1948-2013), the Cochrane Library (1800-2013), the Cumulative Index to Nursing and Allied Health Literature (1986-2013), ClinicalTrials.gov (2013) and meeting abstracts. We included randomized trials comparing antidepressants to placebo or no treatment for cancer-related depression. We used random effects to calculate standardized mean differences (SMD).

RESULTS

Of 5178 potentially eligible citations, 9 trials (1169 subjects) met inclusion criteria. Trials of mianserin found a robust reduction in depression scores at ≥4 weeks of treatment (SMD: 0.60, 95% confidence interval (CI): 0.24-0.95). Similar, but less robust, results were observed with paroxetine (SMD: 0.22, 95% CI: 0.01-0.42) and fluoxetine (SMD 0.34, 95% CI: 0.02-0.66). Conversely, there was no advantage with amitriptyline or desipramine. Compared to placebo, the odds of dropping out due to side effect were higher with fluoxetine and paroxetine and lower with mianserin. Methodological quality was moderate.

CONCLUSIONS

Paroxetine, fluoxetine and mianserin improve cancer-related depression but may vary in efficacy and tolerability. High-quality, randomized trials of newer antidepressant agents are needed to identify optimal treatments for managing cancer-related depression.

Haloperidol-induced extra pyramidal symptoms attenuated by imipramine in rats

Effects of administration of imipramine (IMI) are determined on haloperidol-induced extrapyramidal symptoms (EPS). Haloperidol is administered orally at a dose of 0.2 mg/rat/day in rats for a period of 5 weeks, by this treatment rats developed vacuous chewing movements (VCMs) after 2 weeks, which increased in a time dependent manner as the treatment continued for 5 weeks. Motor coordination (assess on rota rod activity) impaired maximally after 3 weeks and tolerance was developed in the haloperidol induced motor impairment after 5 weeks of treatment. Motor activity in an open field or activity box was not altered. The administration of IMI (intraperitoneally, for 5 weeks) did not affect motor activity or motor coordination. Co-administration of IMI at a dose of 5 mg/ml/kg/day attenuated the induction of haloperidol elicited VCMs (Quantitative orofacial dyskinesia) as well impairment of motor coordination. Results are discussed in the context of the mechanism involved by which imipramine attenuated haloperidol-induced EPS.

An open-source analytical platform for analysis of C. elegans swimming-induced paralysis

BACKGROUND

The nematode Caenhorhabditis elegans offers great power for the identification and characterization of genes that regulate behavior. In support of this effort, analytical methods are required that provide dimensional analyses of subcomponents of behavior. Previously, we demonstrated that loss of the presynaptic dopamine (DA) transporter, dat-1, evokes DA-dependent Swimming-Induced Paralysis (Swip) (Mcdonald et al., 2007), a behavior compatible with forward genetic screens (Hardaway et al., 2012).

NEW METHOD

Here, we detail the development and implementation of SwimR, a set of tools that provide for an automated, kinetic analysis of C. elegans Swip. SwimR relies on open source programs that can be freely implemented and modified.

RESULTS

We show that SwimR can display time-dependent alterations of swimming behavior induced by drug-treatment, illustrating this capacity with the dat-1 blocker and tricyclic antidepressant imipramine (IMI). We demonstrate the capacity of SwimR to extract multiple kinetic parameters that are impractical to obtain in manual assays.

COMPARISON WITH EXISTING METHODS

Standard measurements of C. elegans swimming utilizes manual assessments of the number of animals exhibiting swimming versus paralysis. Our approach deconstructs the time course and rates of movement in an automated fashion, offering a significant increase in the information that can be obtained from swimming behavior.

CONCLUSIONS

The SwimR platform is a powerful tool for the deconstruction of worm thrashing behavior in the context of both genetic and pharmacological manipulations that can be used to segregate pathways that underlie nematode swimming mechanics.

A double-hit model of stress dysregulation in rats: implications for limbic corticosteroid receptors and anxious behavior under amitriptyline treatment

Adversity during early life can lead to diverging endocrine and behavioral responses to stress in adulthood. In our laboratory, we evaluated the long-term effects of early life adversity and its interaction with chronic stress during adulthood. We propose this as a model of vulnerability to dysregulation of the stress response. We hypothesized that rats subjected to both protocols would show differential expression of corticosteroid receptors measured as number of neurons immunoreactive for glucocorticoid receptors (GR) or mineralocorticoid receptors (MR), in limbic areas related to the control of anxiety-like behavior. We also evaluated the effect of amitriptyline expecting to prevent the outcomes of the model. Male Wistar rats were separated from the mother (MS) for 4.5 h every day for the first 3 weeks of life. From postnatal day 50, rats were subjected to chronic variable stress (CVS) during 24 d (five types of stressor at different times of day). During the stress protocol, the rats were administered amitriptyline (10 mg/kg i.p.) daily. MS evoked lower MR expression in the central amygdaloid nucleus and this was reversed by amitriptyline. Furthermore, CVS increased MR immunoreactivity in the hippocampal area CA2 and increased anxious behavior; both effects were prevented by the antidepressant. When MS was combined with CVS during adulthood, there was a reduction of locomotor activity, with no corrective effect of amitriptyline. The differential effects among groups could mean that MS would promote an alternative phenotype that is expressed when facing CVS (a double hit) later in life.

The selective glucocorticoid receptor antagonist CORT 108297 decreases neuroendocrine stress responses and immobility in the forced swim test

Pre-clinical and clinical studies have employed treatment with glucocorticoid receptor (GR) antagonists in an attempt to limit the deleterious behavioral and physiological effects of excess glucocorticoids. Here, we examined the effects of GR antagonists on neuroendocrine and behavioral stress responses, using two compounds: mifepristone, a GR antagonist that is also a progesterone receptor antagonist, and CORT 108297, a specific GR antagonist lacking anti-progestin activity. Given its well-documented impact on neuroendocrine and behavioral stress responses, imipramine (tricyclic antidepressant) served as a positive control. Male rats were treated for five days with mifepristone (10mg/kg), CORT 108297 (30mg/kg and 60mg/kg), imipramine (10mg/kg) or vehicle and exposed to forced swim test (FST) or restraint stress. Relative to vehicle, imipramine potently suppressed adrenocorticotropin hormone (ACTH) responses to FST and restraint exposure. Imipramine also decreased immobility in the FST, consistent with antidepressant actions. Both doses of CORT 108297 potently suppressed peak corticosterone responses to FST and restraint stress. However, only the higher dose of CORT 108297 (60mg/kg) significantly decreased immobility in the FST. In contrast, mifepristone induced protracted secretion of corticosterone in response to both stressors, and modestly decreased immobility in the FST. Taken together, the data indicate distinct effects of each compound on neuroendocrine stress responses and also highlight dissociation between corticosterone responses and immobility in the FST. Within the context of the present study, our data suggest that CORT 108297 may be an attractive alternative for mitigating neuroendocrine and behavioral states associated with excess glucocorticoid secretion.

NCS-1 deficiency causes anxiety and depressive-like behavior with impaired non-aversive memory in mice

Sensing and regulating intracellular levels of calcium are essential for proper cellular function. In neurons, calcium sensing plays important roles in neuronal plasticity, neurotransmitter release, long-term synapse modification and ion channel activity. Neuronal calcium sensor-1 (NCS-1) is a member of the highly conserved neuronal calcium sensor family. Although NCS-1 has been associated with psychiatric conditions including autism, bipolar disorder and schizophrenia, it is unclear which role NCS-1 plays in behavior. To understand the involvement of NCS-1 in psychiatric conditions, we provided a comprehensive behavioral characterization of NCS-1 knockout (KO) mice. These mice grow and develop normally without apparent abnormalities in comparison to wild type littermates. However, open field showed that NCS-1 deficiency impairs novelty-induced exploratory activity in both KO and heterozygote (HT) mice. Moreover, NCS-1-deficiency also resulted in anxiety- and depressive-like behaviors as demonstrated by elevated plus maze, large open field, forced swim and tail suspension tasks. Furthermore, based on spontaneous object recognition test, non-aversive long-term memory was impaired in NCS-1 KO mice. In contrast, neither social behavior nor a kind of aversive memory was affected under NCS-1 deficiency. These data implicate NCS-1 in exploratory activity, memory and mood-related behaviors, suggesting that NCS-1 gene ablation may result in phenotypic abnormalities associated with neuropsychiatric disorders.

[In vitro effect of psychotropic drugs on the activity of leukocyte elastase]

OBJECTIVE

To investigate the effect of the neuroleptic aminazine (chlorpromazine) and the antidepressant melipramine on the activity of leukocyte elastase (LE).

METHODS

The LE activity was measured on a spectrophotometer. Different doses of aminazine and melipramine in terms of therapeutic doses were added to the pooled blood serum sampled from 7 healthy people.

RESULTS

Aminazine and melipramine inhibited the LE activity.

CONCLUSIONS

The dose-dependent inhibiting effect of aminazine and melipramine was shown.

[Phenylephrine potentiates antidepressive and eliminates sedative action of amitriptyline in rats]

Single i. m. injection of amitriptyline in rats in high doses of 10-30 mg/kg causes a weak an- tidepressive effect because only in 1.3-1.7 times decrease immobilization in Porsolt test. In the specified doses amitriptyline exhibits appreciable sedative effect because in 3-6 times decrease horizontal activity, and also in 2-2.5 times decrease vertical activity of rats in the open field test. Combined single i.m. injection of amitriptyline in a small dose of 3 mg/kg and high dose of 30 mg/kg with phenylephine in threshold, noneffective alone dose of 0.02 mg/kg, causes the ma- ximal antidepressive effect because decreases immobilization in Porsolt test, accordingly, in 3 and 4.6 times, but does not produce side sedative effect in the open field test. The basis of the mec- hanism of potentiation of antidepressive action and elimination of sedative action of amitriptyline is the stimulation of gastric mucosa afferents by phenylephine.

[Studying the development of imipramine tolerance and prospects of its overcoming with the aid of tianeptine]

Reaction of two groups of mice to sub-chronic imipramine administration has been studied in a series of experiments, where one (control) group received physiological saline instead of imipramine. Then, both groups were randomly divided to receive either tianeptine (two groups) or physiological saline (two groups) for three days. After this period, the reaction of mice to imipramine was assessed again by measuring the immobilization duration in the tail suspension test. It was found that sub-chronic administration of imipramine (6 days) did not reduce sensitivity of the mice to this medication. Tianeptine showed "pro-depressive" action in the tail suspension test, but the administration of tianeptine increased the sensitivity of rodents to imipramine.

Chronic clomipramine treatment reverses core symptom of depression in subordinate tree shrews

Chronic stress is the major cause of clinical depression. The behavioral signs of depression, including anhedonia, learning and memory deficits, and sleep disruption, result from the damaging effects of stress hormones on specific neural pathways. The Chinese tree shrew (Tupaia belangeri chinensis) is an aggressive non-human primate with a hierarchical social structure that has become a well-established model of the behavioral, endocrine, and neurobiological changes associated with stress-induced depression. The tricyclic antidepressant clomipramine treats many of the core symptoms of depression in humans. To further test the validity of the tree shrew model of depression, we examined the effects of clomipramine on depression-like behaviors and physiological stress responses induced by social defeat in subordinate tree shrews. Social defeat led to weight loss, anhedonia (as measured by sucrose preference), unstable fluctuations in locomotor activity, sustained urinary cortisol elevation, irregular cortisol rhythms, and deficient hippocampal long-term potentiation (LTP). Clomipramine ameliorated anhedonia and irregular locomotor activity, and partially rescued the irregular cortisol rhythm. In contrast, weight loss increased, cortisol levels were even higher, and in vitro LTP was still impaired in the clomipramine treatment group. These results demonstrate the unique advantage of the tree shrew social defeat model of depression.

Tricyclic antidepressant amitriptyline indirectly increases the proliferation of adult dentate gyrus-derived neural precursors: an involvement of astrocytes

Antidepressants increase the proliferation of neural precursors in adult dentate gyrus (DG), which is considered to be involved in the therapeutic action of antidepressants. However, the mechanism underlying it remains unclear. By using cultured adult rat DG-derived neural precursors (ADP), we have already shown that antidepressants have no direct effects on ADP. Therefore, antidepressants may increase the proliferation of neural precursors in adult DG via unknown indirect mechanism. We have also shown that amitriptyline (AMI), a tricyclic antidepressant, induces the expressions of GDNF, BDNF, FGF2 and VEGF, common neurogenic factors, in primary cultured astrocytes (PCA). These suggest that AMI-induced factors in astrocytes may increase the proliferation of neural precursors in adult DG. To test this hypothesis, we examined the effects of AMI-induced factors and conditioned medium (CM) from PCA treated with AMI on ADP proliferation. The effects of CM and factors on ADP proliferation were examined with BrdU immunocytochemistry. AMI had no effect on ADP proliferation, but AMI-treated CM increased it. The receptors of GDNF, BDNF and FGF2, but not VEGF, were expressed in ADP. FGF2 significantly increased ADP proliferation, but not BDNF and GDNF. In addition, both of a specific inhibitor of FGF receptors and anti-FGF2 antibody significantly counteracted the increasing effect of CM on ADP proliferation. In addition, FGF2 in brain is mainly derived from astrocytes that are key components of the neurogenic niches in adult DG. These suggest that AMI may increase ADP proliferation indirectly via PCA and that FGF2 may a potential candidate to mediate such an indirect effect of AMI on ADP proliferation via astrocytes.

Structural basis for action by diverse antidepressants on biogenic amine transporters

The biogenic amine transporters (BATs) regulate endogenous neurotransmitter concentrations and are targets for a broad range of therapeutic agents including selective serotonin reuptake inhibitors (SSRIs), serotonin-noradrenaline reuptake inhibitors (SNRIs) and tricyclic antidepressants (TCAs). Because eukaryotic BATs are recalcitrant to crystallographic analysis, our understanding of the mechanism of these inhibitors and antidepressants is limited. LeuT is a bacterial homologue of BATs and has proven to be a valuable paradigm for understanding relationships between their structure and function. However, because only approximately 25% of the amino acid sequence of LeuT is in common with that of BATs, and as LeuT is a promiscuous amino acid transporter, it does not recapitulate the pharmacological properties of BATs. Indeed, SSRIs and TCAs bind in the extracellular vestibule of LeuT and act as non-competitive inhibitors of transport. By contrast, multiple studies demonstrate that both TCAs and SSRIs are competitive inhibitors for eukaryotic BATs and bind to the primary binding pocket. Here we engineered LeuT to harbour human BAT-like pharmacology by mutating key residues around the primary binding pocket. The final LeuBAT mutant binds the SSRI sertraline with a binding constant of 18 nM and displays high-affinity binding to a range of SSRIs, SNRIs and a TCA. We determined 12 crystal structures of LeuBAT in complex with four classes of antidepressants. The chemically diverse inhibitors have a remarkably similar mode of binding in which they straddle transmembrane helix (TM) 3, wedge between TM3/TM8 and TM1/TM6, and lock the transporter in a sodium- and chloride-bound outward-facing open conformation. Together, these studies define common and simple principles for the action of SSRIs, SNRIs and TCAs on BATs.

Using conditioned place preference to identify relapse prevention medications

Stimuli, including contexts, which predict the availability or onset of a drug effect, can acquire conditioned incentive motivational properties. These conditioned properties endure after withdrawal, and can promote drug-seeking which may result in relapse. Conditioned place preference (CPP) assesses the associations between drugs and the context in which they are experienced. Here, we review the potential utility of CPP procedures in rodents and humans to evaluate medications that target conditioned drug-seeking responses. We discuss the translational potential of the CPP procedure from rodents to humans, and review findings with FDA-approved treatments that support the use of CPP to develop relapse-reduction medications. We also discuss challenges and methodological questions in applying the CPP procedure to this purpose. We argue that an efficient and valid CPP procedure in humans may reduce the burden of full clinical trials with drug-abusing patients that are currently required for testing promising treatments.