Beneficial effect of fluoxetine treatment aganist psychological stress is mediated by increasing BDNF expression in selected brain areas

Promising new pharmacological targets for depression: The search for efficacy

Pharmacological treatment of major depressive disorder (MDD) still relies on the use of serotonergic drugs, despite their limited efficacy. A few mechanistically new drugs have been developed in recent years, but many fail in clinical trials. Several hypotheses have been proposed to explain MDD pathophysiology, indicating that physiological processes such as neuroplasticity, circadian rhythms, and metabolism are potential targets. Here, we review the current state of pharmacological treatments for MDD, as well as the preclinical and clinical evidence for an antidepressant effect of molecules that target non-serotonergic systems. We offer some insights into the challenges facing the development of new antidepressant drugs, and the prospect of finding more effectiveness for each target discussed.

Antidepressant-like effects of the Punica granatum and citalopram combination are associated with structural changes in dendritic spines of granule cells in the dentate gyrus of rats

Introduction: Natural products such as phytoestrogens-enriched foods or supplements have been considered as an alternative therapy to reduce depressive symptoms associated with menopause. It is known that the aqueous extract of Punica granatum (AE-PG) exerts antidepressant-like effects by activating β-estrogen receptors and facilitates the antidepressant response of the clinical drug citalopram (CIT). However, the effects on neuroplasticity are unknown. Objectvie investigated the antidepressant-like response of combining AE-PG and CIT at sub-optimal doses, analyzing their effects on the formation and maturation of dendrite spines in granule cells as well as on the dendrite complexity. Methods: Ovariectomized Wistar rats (3-month-old) were randomly assigned to one of the following groups: A) control (saline solution as vehicle of CIT and AE-PG, B) AE-PG at a sub-threshold dose (vehicle of CIT plus AE-PG at 0.125 mg/kg), C) CIT at a sub-threshold dose (0.77 mg/kg plus vehicle of AE-PG), and D) a combination of CIT plus AE-PG (0.125 mg/kg and 0.77 mg/kg, respectively). All rats were treated intraperitoneally for 14 days. Antidepressant-like effects were evaluated using the force swimming test test (FST). The complexity of dendrites and the number and morphology of dendrite spines of neurons were assessed in the dentate gyrus after Golgi-Cox impregnation. The expressions of the mature brain-derived neurotrophic factor (mBDNF) in plasma and of mBDNF and synaptophysin in the hippocampus, as markers of synaptogenesis, were also determined. Results: Administration of CIT combined with AE-PG, but not alone, induced a significant antidepressant-like effect in the FST with an increase in the dendritic complexity and the number of dendritic spines in the dentate gyrus (DG) of the hippocampus, revealed by the thin and stubby categories of neurons at the granular cell layer. At the same time, an increase of mBDNF and synaptophysin expression was observed in the hippocampus of rats that received the combination of AE-PG and CIT.

Saffron carotenoids reversed the UCMS-induced depression and anxiety in rats: Behavioral and biochemical parameters, and hippocampal BDNF/ERK/CREB and NR2B signaling markers

BACKGROUND

Depression is a debilitating condition that affects the mind and the individual's body. The improving effects of saffron on depression and anxiety have long been discussed, with limited information about the molecular mechanism of action.

HYPOTHESIS/PURPOSE

Investigating the effect of saffron carotenoids, Crocin and Crocetin, on depression and anxiety in rats by emphasizing some signaling pathways involved.

STUDY DESIGN

Depression and anxiety were induced in rats via unpredictable chronic mild stress (UCMS). Then different rat groups were treated with Crocin, Crocetin, Fluoxetine, and vehicle. Behavioral tests were done before and after treatment.

METHODS

The serum Serotonin and Corticosterone and the expression of some hippocampal signaling proteins were studied. Furthermore, bioinformatics tools were used to predict the interactions of Crocin/ Crocetin with the Serotonin transporter and NMDA receptor subunit NR2B. Then, the patch-clamp was used to study the interaction of Crocetin with the NMDA receptor.

RESULTS

Various behavioral tests confirmed the induction of depression and the improvement of depression by these natural carotenoids. In addition, Crocin/ Crocetin significantly increased the decreased serum Serotonin and reduced the increased serum Corticosterone in the depressed groups. They also increased or caused a trend of increase in the CREB, ERK, BAD, BDNF, p11, and 5-HT1B expression in the hippocampus of the depressed groups. In addition, there were an increase or a trend in p-CREB/CREB, p-ERK1/2 /ERK1/2, and p-BAD/BAD ratios in the Crocin/ Crocetin treated depressed groups. However, the NR2B and FOXO3a expression showed a trend of decrease in depressed groups after treatment. The bioinformatics data indicated that Crocin/ Crocetin could bind to the Serotonin transporter (SLC6A4) and NR2B subunit of the NMDA receptor. Both carotenoids bind to the same site as Fluoxetine in the SLC6A4. However, they bound to different sites on the NR2B. So, Crocetin binds to NR2B at the same site as Ifenprodil. But Crocin bound to another site. The whole cell patch-clamp recording on the normal rat hippocampus revealed a significant decrease in the NMDA peak amplitude after Crocetin treatment, indicating its inhibitory effect on this receptor.

CONCLUSION

The antidepressant activities of Crocin/ Crocetin are possibly due to their effects on Serotonin and Corticosterone serum concentrations, NR2B expression, and the downstream signaling pathways. Furthermore, these natural carotenoids, like Fluoxetine, induced an increasing tendency in p11 and 5HT1B in depressed rats.

The Effects of Four Compounds That Act on the Dopaminergic and Serotonergic Systems on Working Memory in Animal Studies; A Literature Review

The dopaminergic and serotonergic systems are two of the most important neuronal pathways in the human brain. Almost all psychotropic medications impact at least one neurotransmitter system. As a result, investigating how they affect memory could yield valuable insights into potential therapeutic applications or unanticipated side effects. The aim of this literature review was to collect literature data from animal studies regarding the effects on memory of four drugs known to act on the serotonergic and dopaminergic systems. The studies included in this review were identified in the PubMed database using selection criteria from the PRISMA protocol. We analyzed 29 articles investigating one of four different dopaminergic or serotonergic compounds. Studies conducted on bromocriptine have shown that stimulating D2 receptors may enhance working memory in rodents, whereas inhibiting these receptors could have the opposite effect, reducing working memory performance. The effects of serotonin on working memory are not clearly established as studies on fluoxetine and ketanserin have yielded conflicting results. Further studies with better-designed methodologies are necessary to explore the impact of compounds that affect both the dopaminergic and serotonergic systems on working memory.

Neurotrophic Factors and Dendritic Spines

Dendritic spines are highly dynamic structures that play important roles in neuronal plasticity. The morphologies and the numbers of dendritic spines are highly variable, and this diversity is correlated with the different morphological and physiological features of this neuronal compartment. Dendritic spines can change their morphology and number rapidly, allowing them to adapt to plastic changes. Neurotrophic factors play important roles in the brain during development. However, these factors are also necessary for a variety of processes in the postnatal brain. Neurotrophic factors, especially members of the neurotrophin family and the ephrin family, are involved in the modulation of long-lasting effects induced by neuronal plasticity by acting on dendritic spines, either directly or indirectly. Thereby, the neurotrophic factors play important roles in processes attributed, for example, to learning and memory.

Antidepressant-like activity of oroxylin A in mice models of depression: A behavioral and neurobiological characterization

Depression is a mood disorder which causes a huge economic burden to both families and societies. However, those monoamine-based antidepressants used in clinical practice have been found to have various limitations. Therefore, currently it is very necessary to explore novel antidepressant targets and medications. As a main active component extracted from Scutellariae radix, oroxylin A possesses many pharmacological functions such as anti-cancer, anti-inflammation and neuroprotection. Here, the present study aims to investigate whether oroxylin A possess antidepressant-like actions using the chronic unpredictable mild stress (CUMS) and chronic restraint stress (CRS) models of depression, forced swim test, tail suspension test, open field test, sucrose preference test, western blotting, immunofluorescence and viral-mediated gene interference. Our results revealed that treatment of oroxylin A fully prevented both the CUMS-induced and CRS-induced depressive-like behaviors in mice. Moreover, the protecting effects of oroxylin A against CUMS and CRS on mice behaviors were accompanied with a significant enhancement on the levels of brain-derived neurotrophic factor (BDNF), phosphorylated tyrosine kinase B (pTrkB), phosphorylated cAMP-response element binding protein (pCREB) and neurogenesis in the hippocampus. Furthermore, genetic knockdown of BDNF and TrkB in the hippocampus remarkably abolished the antidepressant-like efficacy of oroxylin A in both the CUMS and CRS models of depression, proving that the hippocampal BDNF-TrkB system participates in the antidepressant mechanism of oroxylin A. In summary, our findings are the first evidence showing that oroxylin A possesses potential of being an antidepressant candidate.

Achyranthes aspera ameliorates stress induced depression in mice by regulating neuroinflammatory cytokines

Background and aim

Achyranthes aspera Linn. (A. aspera) (family: Amaranthaceae) is highly recognized in ethnomedicine and traditional systems of Indian medicine as a nervine restorative for several psychiatric disorders. Study presented here was designed to appraise the antidepressant-like effects of A. aspera in murine model of chronic unpredictable mild stress (CUMS) induced depression.

Experimental procedures-

Rodents were exposed to different stressor in unpredictive manner during CUMS protocol once a day for 4 weeks. Mice were intraperitoneally injected with A. aspera extract (2.5, 5 and 10 mg/kg) or fluoxetine (10 mg/kg) or betaine (20 mg/kg) once daily during day 15–28 of the CUMS protocol. Sucrose preference, motivation and self-care, immobility latency and plasma corticosterone were evaluated after 24 h of last stressor. After behavioral assessments TNF-α, Il-6 and BDNF immunocontent was determined in hippocampus and prefrontal cortex.

Results and conclusion

A. aspera extract as well as betaine improved sucrose preference, increased grooming frequency and latency in splash test and ameliorated depression-like condition in CUMS mice in Porsolt test. A. aspera treatment decreased the elevated plasma corticosterone and reversed the effect of CUMS on TNF-α, Il-6 and BDNF immunocontent in mice. The results of the present study suggest A. aspera as a promising indigenous medicine for stress associated neurobehavioral and comorbid complications.

•

Achyranthes aspera is a recognized medicine for psychiatric disorders.

•

A. aspera improved sucrose preference, increased grooming frequency and latency in splash test in CUMS mice.

•

A. aspera ameliorated depression-like condition in CUMS mice.

•

A. aspera treatment decreased the elevated plasma corticosterone and reversed the effect of CUMS on TNF-α, Il-6 and BDNF immunocontent in mice.

•

Results suggest A. aspera as a medicine for stress associated neurobehavioral and comorbid complications.

Comparison of Brain-derived Neurotrophic Factor Level in Depressed Patients Treated with Fluoxetine and Sertraline

Background: The Brain-Derived NeurotrophicFactor (BDNF) is the main neuronal growth factor in the brain that regulates neurogenesis, neuronal maturity, synaptic formation and plasticity. Studies showed BDNF level decreased in depression and the administration of anti depressant drugs increased BDNF level. In this study, we used fluoxetine and sertraline, which are Selective Serotonin Reuptake Inhibitor (SSRI) but had a different mechanism in influencing the BDNF levels. The purpose of this study was to compare the effect of fluoxetine and sertraline administration tothe BDNF level in depressed subjects. This study was conducted at Wahidin Sudirohusodo Hospital, Makassar, Indonesia and its affiliates from January to February 2019. Twenty outpatient subjects were diagnosed with depression based on DSM-V. The subjects were either antidepressant naïve, or dropping out of antidepressant therapy for at least 3 months since the last administration. Blood samples from each subject were taken by consecutive sampling, and BDNF levels were analyzed before and after administration of fluoxetine and sertraline for six weeks. Also, Hamilton Depression Rating Scale (HDRS) scores are measured before and after administration. The BDNF serum was significantly increased by 100.6% (p<0,001) from the baseline level in the fluoxetine group and 75.4% in the sertraline group. HDRS score was decreased by39.5%  (p<0,001) in the fluoxetine group and 30.1% in the sertraline group after six weeks of administration. This study suggests that fluoxetine was superior to sertraline in increasing the BDNF level in depression.

Testing the efficacy of a brief exercise intervention for enhancing exposure therapy outcomes

Recently, it has been hypothesized that a brief bout of exercise could cognitively enhance extinction learning processes theorized to underlie exposure therapy for pathological anxiety. The present study tested the exercise enhancement hypothesis in a sample of speech-anxious undergraduates (n = 84). During the first laboratory session, participants engaged in either 30 min of moderate-intensity exercise on a cycling ergometer (n = 37) or seated rest (n = 47) immediately following a brief speech exposure trial. They returned approximately one week later to give a follow-up speech. Contrary to expectation, there were no significant between-group differences in memory of a brief word list across four recall trials, which served as a manipulation check. Further, all main effects and interactions involving condition were nonsignificant. Post hoc tests revealed that participants who reported higher average perceived exertion during exercise demonstrated increases in an average anxiety composite across speeches relative to those who reported lower average perceived exertion, indicating that trying hard during the intervention predicted worse exposure trial outcomes. The implications of these findings, as well as future directions for this line of research, are explored.

Toxicity of ayahuasca after 28 days daily exposure and effects on monoamines and brain-derived neurotrophic factor (BDNF) in brain of Wistar rats

Ayahuasca is a hallucinogenic beverage that affects the serotonergic system and have therapeutic potential for many diseases and disorders, including depression and drug addiction. The objectives of this study were to evaluate the potential toxic effects of ayahuasca on rats after chronic exposure, and the levels of monoamines, their metabolites and the brain-derived neurotrophic factor (BDNF) in the brain. Female and male rats were treated orally for 28 days with H₂O (control), fluoxetine (FLX), a selective serotonin reuptake inhibitor antidepressant, or ayahuasca (Aya) at doses of 0.5X, 1X and 2X the ritualistic dose (7 to 10 animals/group). Clinical, hematological and macroscopic results showed that ayahuasca was safe to the rats. Behavior tests conducted one hour after the last treatment showed that male rats from the Aya1 group explored the open field central area less than the control group, and the number of entries in the central area compared to total locomotion was also significantly lower in this group and in the FLX group. The hippocampus was removed for BDNF analysis and the remaining brain was used for monoamine analysis by HPLC-FL. Serotonin levels were significantly higher than control only in the Aya2 female group, while a significant reduction of its metabolite 5-HIAA was observed in the FLX group. Dopamine levels were similar among the experimental groups, but the levels of its metabolite DOPAC increased significantly in the Aya1 and Aya2 groups compared to controls, especially in females, and the DOPAC/dopamine turnover was significantly higher in Aya2 group. The levels of HVA, another dopamine metabolite, did not change with the treatments compared to controls, but HVA/DOPAC ratio was significantly lower in all ayahuasca male groups. Norepinephrine was not detected in any brain sample, and the levels of its metabolite MHPG did not change significantly among the groups. BDNF levels in the hippocampus were significantly higher in the FLX and Aya2 female groups compared to controls when expressed in relation to the total brain weight. The mechanisms involved in the increase in serotonin, dopamine turnover and BDNF levels observed in ayahuasca treated animals should be further investigated in specific brain areas.

Vitamin E prevents the cognitive impairments in post-traumatic stress disorder rat model: behavioral and molecular study

RATIONALE

Post-traumatic stress disorder (PTSD) is a psychiatric disorder developed after an exposure to severe traumatic events. Patients with PTSD suffer from different symptoms including memory impairment. In addition, PTSD is associated with oxidative stress. Vitamin E, a fat-soluble vitamin, possesses cognition protective effects via its antioxidative properties.

OBJECTIVES

To investigate the impact of vitamin E on memory impairment induced by PTSD in animals.

METHODS

A rat model of PTSD-like behavior and the radial arm water maze (RAWM) for testing of learning and memory paradigm were used. Rats were divided into 4 groups: control, vitamin E, PTSD, and vitamin E + PTSD.

RESULTS

In the learning phase, results showed no significant differences among experimental groups, indicating that PTSD-like behavior did not impair learning ability in rats. However, memory tests in the RAWM showed that PTSD-like animals had impairment in both short-term and long-term memories. Vitamin E, on the other hand, prevented this impairment of memory. With respect to oxidative stress, significant decreases were detected in reduced glutathione/oxidized glutathione (GSH/GSSG) ratio, glutathione peroxidase (GPx) and catalase enzyme activities, global histone 3 acetylation, and brain derived neurotrophic factor (BDNF) levels in the PTSD-like animals group compared with other groups (P < 0.05). Vitamin E protected the reduction of these oxidative stress biomarkers, global histone 3 acetylation, and BDNF levels.

CONCLUSIONS

Vitamin E prevented memory impairment associated with PTSD-like behavior in animals, probably via its antioxidative properties, and preservation of epigenetic changes induced in PTSD-like animals.

Antidepressant-like activity of hyperforin and changes in BDNF and zinc levels in mice exposed to chronic unpredictable mild stress

Chronic unpredictable mild stress (CUMS) - a rodent model of depression mimics a variety of neurochemical and behavioral alterations similar to those seen in human depression. This study evaluated the antidepressant activity of hyperforin in the CUMS model using fluoxetine (FLX) as a reference drug. The antidepressant-like effects of hyperforin and FLX were evaluated in the tail suspension test (TST), forced swim test (FST), and splash test (SPT). CUMS induced an increase in immobility time in mice (pro-depressive effects) in the FST and TST. CUMS-induced changes were reversed by chronic treatment with hyperforin (2.5 and 5 mg/kg), as well as FLX (10 mg/kg). SPT results revealed a decrease in the frequency and duration of grooming in stressed mice. These effects were normalized by hyperforin (5 mg/kg) and FLX treatment. Hyperforin (2.5 mg/kg) only reversed the CUMS-induced deficits related to the frequency of grooming. CUMS also caused a decrease in zinc concentration in the frontal cortex (FC) and hippocampus (Hp) of mice; hyperforin (2.5 mg/kg) increased zinc concentration in the Hp of control rats. CUMS also induced a decrease in BDNF protein levels in the FC and Hp, while decreasing the pCREB/CREB ratio only in the Hp. Hyperforin (2.5 and 5 mg/kg) reversed the CUMS-induced reduction of BDNF only in the Hp. Our results demonstrate the antidepressant-like activity of hyperforin in the CUMS model in mice and the possible involvement of hippocampal BDNF/zinc alterations in this activity.

Fluoxetine pretreatment enhances neurogenic, angiogenic and immunomodulatory effects of MSCs on experimentally induced diabetic neuropathy

Being one of the most debilitating complications among diabetic patients, diabetic polyneuropathy (DPN) is a paramount point of continuous research. Stem cell therapies have shown promising results. However, limited cell survival and paracrine activities hinder its transfer from bench to bedside. We designed this study to evaluate fluoxetine-pretreatment technique of mesenchymal stem cells (MSCs) as an approach to enhance their paracrine and immunomodulatory properties in DPN. Effects of fluoxetine treatment of MSCs were tested in vitro. Forty-two adult Wistar male albino rats were utilized, further subdivided into control, diabetic, MSC-treated and fluoxetine-pretreated MSC groups. Sciatic nerve sections were prepared for light and electron microscope examination and immunohistochemical detection of neurofilament (NF) protein. Also, we assessed in vitro survival and paracrine properties of fluoxetine-pretreated MSCs. Real time PCR of BDNF, VEGF, IL-1β, and IL-10 expression in tissue homogenate was performed. Our results showed restoration of normal neuronal histomorphology and ultrastructure, moreover, immunohistochemical expression of anti-neurofilament protein was significantly elevated in MSC-treated groups compared to the diabetic one. Fluoxetine enhanced the MSC survival and their paracrine properties of MSCs in vitro. Furthermore, the fluoxetine-pretreated MSC group revealed a significant elevation of mRNA expression of BDNF (neurotrophic factor) and VEGF (angiogenic factor), denoting ameliorated MSC paracrine properties. Similarly, improved immunomodulatory functions were evident by a significant reduction of interleukin-1β mRNA expression (pro-inflammatory) and a reciprocal significant increase of interleukin-10 (anti-inflammatory). We concluded that fluoxetine-pretreatment of MSCs boosts their survival, paracrine, and immunomodulatory traits and directly influenced neuronal histomorphology. Hence, it presents a promising intervention of diabetic polyneuropathy. Graphical Abstract.

Advances in the Preclinical Study of Some Flavonoids as Potential Antidepressant Agents

Flavonoids are phenolic compounds found commonly in plants that protect them against the negative effects of environmental insults. These secondary metabolites have been widely studied in preclinical research because of their biological effects, particularly as antioxidant agents. Diverse flavonoids have been studied to explore their potential therapeutic effects in the treatment of disorders of the central nervous system, including anxiety and depression. The present review discusses advances in the study of some flavonoids as potential antidepressant agents. We describe their behavioral, physiological, and neurochemical effects and the apparent mechanism of action of their preclinical antidepressant-like effects. Natural flavonoids produce antidepressant-like effects in validated behavioral models of depression. The mechanism of action of these effects includes the activation of serotonergic, dopaminergic, noradrenergic, and γ-aminobutyric acid-ergic neurotransmitter systems and an increase in the production of neural factors, including brain-derived neurotrophic factor and nerve growth factor. Additionally, alterations in the function of tropomyosin receptor kinase B and activity of the enzyme monoamine oxidase A have been reported. In conclusion, preclinical research supports the potential antidepressant effects of some natural flavonoids, which opens new possibilities of evaluating these substances to develop complementary therapeutic alternatives that could ameliorate symptoms of depressive disorders in humans.

Novel rapid-acting antidepressants: molecular and cellular signaling mechanisms

Depression is a chronic, debilitating, and common illness. Currently available pharmacotherapies can be helpful but have several major drawbacks, including substantial rates of low or no response and a long therapeutic time lag. In pursuit of better treatment options, recent research has focussed on rapid-acting antidepressants, including the N-methyl-d-aspartate (NMDA) receptor (NMDAR) antagonist ketamine, which affects a range of signaling pathways in ways that are distinct from the mechanisms of typical antidepressants. Because ketamine and similar drugs hold the promise of dramatically improving treatment options for depressed patients, there has been considerable interest in developing new ways to understand how these compounds affect the brain. Here, we review the current understanding of how rapid-acting antidepressants function, including their effects on neuronal signaling pathways and neural circuits, and the research techniques being used to address these questions.