Antidepressant fluoxetine alleviates colitis by reshaping intestinal microenvironment.

BACKGROUND: The impact of antidepressants on Inflammatory bowel diseases (IBD) has been extensively studied. However, the biological effects and molecular mechanisms of antidepressants in alleviating colitis remain unclear. METHODS: We systematically assessed how antidepressants (fluoxetine, fluvoxamine and venlafaxine) affected IBD and chose fluoxetine, the most effective one, for mechanism studies. We treated the C56BL/6 mice of the IBD model with fluoxetine and their controls. We initially assessed the severity of intestinal inflammation in mice by body weight loss, disease Activity Index scores and the length of the colon. The H&E staining and immunohistochemical staining of MUC2 of colon sections were performed to observe the pathological changes. RT-qPCR and western blot were conducted to assess the expression level of the barrier and inflammation-associated genes. Then, single-cell RNA sequencing was performed on mouse intestinal mucosa. Seurat was used to visualize the data. Uniform Manifold Approximation and Projection (UMAP) was used to perform the dimensionality reduction. Cell Chat package was used to perform cell-cell communication analysis. Monocle was used to conduct developmental pseudotime analysis. Last, RT-qPCR, western blot and immunofluorescence staining were conducted to test the phenomenon discovered by single-cell RNA sequencing in vitro. RESULTS: We found that fluoxetine treatment significantly alleviated colon inflammation. Notably, single-cell RNA sequencing analysis revealed that fluoxetine affected the distribution of different cell clusters, cell-cell communication and KEGG pathway enrichment. Under the treatment of fluoxetine, enterocytes, Goblet cells and stem cells became the dominating cells. The pseudotime analysis showed that there was a trend for M1 macrophages to differentiate into M2 macrophages. Lastly, we tested this phenomenon in vitro, which exhibited anti-inflammatory effects on enterocytes. CONCLUSIONS: Fluoxetine exhibited anti-inflammatory effects on intestinal mucosa via remodeling of the intestinal cells and macrophages, which reveals that fluoxetine is a promising therapeutic drug for the treatment of IBD and psychiatric comorbidities.

Fluoxetine exerts anti-inflammatory effects on human epidermal keratinocytes and suppresses their endothelin release.

Fluoxetine is a safe antidepressant with remarkable anti-inflammatory actions; therefore, we aimed to investigate its effects on immortalized (HaCaT) as well as primary human epidermal keratinocytes in a polyinosinic-polycytidylic acid (p(I:C))-induced inflammatory model. We found that a non-cytotoxic concentration (MTT-assay, CyQUANT-assay) of fluoxetine significantly suppressed p(I:C)-induced expression and release of several pro-inflammatory cytokines (Q-PCR, cytokine array, ELISA), and it decreased the release of the itch mediator endothelins (ELISA). These effects were not mediated by the inhibition of the NF-κB or p38 MAPK pathways (western blot), or by the suppression of the p(I:C)-induced elevation of mitochondrial ROS production (MitoSOX Red labeling). Instead, unbiased activity profiling revealed that they were most likely mediated via the inhibition of the phosphoinositide 3-kinase (PI3K) pathway. Importantly, the PI3K-inhibitor GDC0941 fully mimicked the effects of fluoxetine (Q-PCR, ELISA). Although fluoxetine was able to occupy the binding site of GDC0941 (in silico molecular docking), and exerted direct inhibitory effect on PI3K (cell-free PI3K activity assay), it exhibited much lower potency and efficacy as compared to GDC0941. Finally, RNA-Seq analysis revealed that fluoxetine deeply influenced the transcriptional alterations induced by p(I:C)-treatment, and exerted an overall anti-inflammatory activity. Collectively, our findings demonstrate that fluoxetine exerts potent anti-inflammatory effects, and suppresses the release of the endogenous itch mediator endothelins in human keratinocytes, most likely via interfering with the PI3K pathway. Thus, clinical studies are encouraged to explore whether the currently reported beneficial effects translate in vivo following its topical administration in inflammatory and pruritic dermatoses.

Repetitive transcranial magnetic stimulation and fluoxetine attenuate astroglial activation and benefit behaviours in a chronic unpredictable mild stress mouse model of depression.

Objectives: Repetitive transcranial magnetic stimulation (rTMS) has been considered as an effective antidepressant treatment; however, the mechanism of its antidepressant effect is still unclear. Fluoxetine, a selective serotonin reuptake inhibitor antidepressant, may be neuroprotective. The objective of the present study was to evaluate the effect and underlying possible neuroprotective mechanism of rTMS and fluoxetine on abnormal behaviours in a depressive mouse model induced by chronic unpredictable mild stress (CUMS).Methods: After 28 days of CUMS exposure, mice were chronically treated with rTMS (10 Hz for 5 s per train, total 20 trains per day) and (or) fluoxetine (5 mg/kg/day, intraperitoneally) for 28 days targeting on the frontal cortex. After the behavioural tests, the protein expressions of glial fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and tyrosine kinase B (TrkB) were measured by immunohistochemistry and (or) Western Blot.Results: The results showed rTMS and (or) fluoxetine attenuated the locomotion decrease, anxiety and depressive like behaviours in the CUMS-exposed mice.Conclusion: Our results suggest that both rTMS and fluoxetine could benefit the CUMS-induced abnormal behaviours including depressive-like behaviours, and the beneficial effects of rTMS as well as fluoxetine on depression might be partly related to their neuroprotective effect on attenuating astroglial activation and BDNF decrease.

Fluoxetine Promotes Longevity via Reactive Oxygen Species in Caenorhabditis elegans.

Although several antidepressants have been identified as potential geroprotectors, the effect and mechanism of fluoxetine, a representative selective serotonin reuptake inhibitor, on longevity have not been fully elucidated. Here, we found that fluoxetine promoted longevity in Caenorhabditis elegans with a concomitant extension of a healthy life span as indicated by increasing mobility, reducing fertility and lipofuscin accumulation, and enhanced resistance to different abiotic stresses. Fluoxetine increased the level of reactive oxygen species (ROS), and antioxidant N-acetylcysteine abolished ROS elevation and the pro-longevity effect of fluoxetine. Additionally, fluoxetine extended life span through the daf-2-sod-3 pathway in daf-16-dependent and -independent manners, and fluoxetine-induced life-span extension was abolished in C. elegans sod-3, daf-2, and daf-16 mutants. In conclusion, these findings suggest that fluoxetine can promote health and longevity in C. elegans via the interaction of ROS and insulin signaling.

Prophylactic Effects of Hemp Seed Oil on Perimenopausal Depression: A Role of HPA Axis.

Hemp seed, the dried fruit of Cannabis sativa L. (Moraceae), has been extensively documented as a folk source of food due to its nutritional and functional value. This study evaluated the antidepressant effect of hemp seed oil (HSO) during its estrogen-like effect in Perimenopausal depression (PMD) rats induced by ovariectomy combined with chronic unpredictable mild stress (OVX-CUMS). Female SD rats (SPF, 10 weeks, sham operated group, ovariectomy (OVX) model group, ovariectomy - chronic unpredictable mild stress (OVX-CUMS) group, HSO + OVX-CUMS group, fluoxetine (FLU) + OVX-CUMS group, n=8) were subjected to treatment with HSO (4.32 g/kg) or fluoxetine (10 mg/kg) for 28 days (20 mL/kg by ig). Sucrose preference test (SPT), forced swimming test (FST), open field test (OFT), estrogen receptor α (ERα) and estrogen receptor ß (ERß) expression, estradiol (E2), follicle stimulating hormone (FSH), luteinizing hormone (LH), cortisol (CORT), adrenocorticotropic hormone (ACTH), corticotropin releasing hormone (CRH), norepinephrine (NE), 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5HIAA) levels are measured to evaluate the function of the hypothalamic-pituitary-ovarian (HPO) and hypothalamic-pituitary-adrenal (HPA) axis. The results showed that OVX-CUMS significantly decrease sucrose preference rate in SPT, increase immobility time in FST and OFT, and decrease movement distance and stand-up times in OFT. HSO treatment significantly improves depression-like behaviors, upregulates the expression of ERα and ERß, improves HPO axis function by increasing E2 levels and decreasing FSH and LH levels, reverses HPA axis hyperactivation by decreasing CORT, ACTH, and CRH levels, and upregulates NE, 5-HT, and 5HIAA levels in model rats. The findings suggested that HSO could improve depression-like behavior in OVX-CUMS rats by regulating HPO/HPA axis function and neurotransmitter disturbance.

Stereoselective study of fluoxetine and norfluoxetine across the blood-brain barrier mediated by organic cation transporter 1/3 in rats using an enantioselective UPLC-MS/MS method.

Fluoxetine (FLT) is a widely used antidepressant in clinical practice, which can be metabolized into active norfluoxetine (NFLT) in vivo. The stereoselectivity of FLT and NFLT enantiomers across the blood-brain barrier (BBB) is still to be clarified. In this study, accurate and reliable UPLC-MS/MS enantioselective analysis was established in rat plasma and brain. The characteristics of FLT and NFLT enantiomers across the BBB were studied by chemical knockout of rat transporters. We found that the dominant enantiomers of FLT and NFLT were S-FLT and R-NFLT, respectively, both in plasma and in brain. The FLT and NFLT enantiomers showed significant stereoselectivity across the BBB, and S-FLT and S-NFLT were the dominant configurations across the BBB. Chemical knockout of organic cation transporter 1 (OCT1) and OCT3 can affect the ratio of plasma FLT and NFLT enantiomers into the brain, suggesting that OCT1/3 is stereoselective for FLT and NFLT transport across the BBB.

MPFC PV+ interneurons are involved in the antidepressant effects of running exercise but not fluoxetine therapy.

Depression is a complex psychiatric disorder. Previous studies have shown that running exercise reverses depression-like behavior faster and more effectively than fluoxetine therapy. GABAergic interneurons, including the PV+ interneuron subtype, in the medial prefrontal cortex (MPFC) are involved in pathological changes of depression. It was unknown whether running exercise and fluoxetine therapy reverse depression-like behavior via GABAergic interneurons or the PV+ interneurons subtype in MPFC. To address this issue, we subjected mice with chronic unpredictable stress (CUS) to a 4-week running exercise or fluoxetine therapy. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that running exercise enriched GABAergic synaptic pathways in the MPFC of CUS-exposed mice. However, the number of PV+ interneurons but not the total number of GABAergic interneurons in the MPFC of CUS-exposed mice reversed by running exercise, not fluoxetine therapy. Running exercise increased the relative gene expression levels of the PV gene in the MPFC of CUS-exposed mice without altering other subtypes of GABAergic interneurons. Moreover, running exercise and fluoxetine therapy both significantly improved the length, area and volume of dendrites and the spine morphology of PV+ interneurons in the MPFC of mice exposed to CUS. However, running exercise but not fluoxetine therapy improved the dendritic complexity level of PV+ interneurons in the MPFC of CUS-exposed mice. In summary, the number and dendritic complexity level of PV+ interneurons may be important therapeutic targets for the mechanism by which running exercise reverses depression-like behavior faster and more effectively than fluoxetine therapy.

Chronic fluoxetine treatment in socially-isolated rats modulates the prefrontal cortex synaptoproteome.

Exposure to chronic social isolation (CSIS) and synapse dysfunction have been implicated in the etiology of major depressive disorder (MDD). Fluoxetine (Flx) has been widely used to treat MDD, but its mechanisms of action remain elusive. We employed comparative synaptoproteomics to investigate the changes in the levels of proteins and molecular signaling pathways in prefrontal cortical samples of adult male Wistar rats exposed to CSIS, a rat model of depression, and CSIS rats treated with chronic Flx and controls, using liquid chromatography coupled to tandem mass spectrometry. Flx-treated control rats showed a decreased level of proteins involved in vesicle-mediated transport, and a predominantly increased level of exocytosis-associated proteins. CSIS significantly reduced the level of proteins involved in the ATP metabolic process, clathrin-dependent endocytosis, and proteolysis. Flx treatment in CSIS rats stimulated synaptic vesicle trafficking by increasing the regulation of exo/endocytosis-associated proteins, proteins involved in synaptic plasticity including neurogenesis, Cox5a, mitochondria-associated proteins involved in oxidative phosphorylation, and ion transport proteins (Slc8a2, Atp1b2). Flx treatment resulted in an increased synaptic vesicle dynamic, plasticity and mitochondrial functionality, and a suppression of CSIS-induced impairment of these processes. BIOLOGICAL SIGNIFICANCE: Identifying biomarkers of MDD and treatment response is the goal of many studies. Contemporary studies have shown that many molecular alterations associated with the pathophysiology of MDD reside within the synapse. As part of this research, a growing importance is the use of proteomics, as monitoring the changes in protein levels enables the identification of (possible) biochemical pathways and processes of importance for the development of depressive-like behavior and the efficacy of antidepressant treatments. We profiled proteomic changes representative of the development of CSIS-induced depressive-like behavior and the antidepressant effects of Flx. Our study has identified synaptosomal proteins and altered molecular pathways that may be potential markers of prefrontal cortical synaptic dysfunction associated with depressive-like behavior, and further clarified the mechanisms of depressive-like behavior and mode of action of Flx. Our findings indicate potential PFC synaptic targets for antidepressant treatment.

Fluoxetine alleviates postoperative cognitive dysfunction by attenuating TLR4/MyD88/NF-κB signaling pathway activation in aged mice.

OBJECTIVE AND DESIGN: Postoperative cognitive dysfunction (POCD) is a common complication following surgery among elderly patients. Emerging evidence demonstrates that neuroinflammation plays a pivotal role in the pathogenesis of POCD. This study tested the hypothesis that fluoxetine can protect against POCD by suppressing hippocampal neuroinflammation through attenuating TLR4/MyD88/NF-κB signaling pathway activation. SUBJECTS: Aged C57BL/6 J male mice (18 months old) were studied. TREATMENT: Aged mice were intraperitoneally injected with fluoxetine (10 mg/kg) or saline for seven days before splenectomy. In addition, aged mice received an intracerebroventricular injection of a TLR4 agonist or saline seven days before splenectomy in the rescue experiment. METHODS: On postoperative days 1, 3, and 7, we assessed hippocampus-dependent memory, microglial activation status, proinflammatory cytokine levels, protein levels related to the TLR4/MyD88/NF-κB signaling pathway, and hippocampal neural apoptosis in our aged mouse model. RESULTS: Splenectomy induced a decline in spatial cognition, paralleled by parameters indicating exacerbation of hippocampal neuroinflammation. Fluoxetine pretreatment partially restored the deteriorated cognitive function, downregulated proinflammatory cytokine levels, restrained microglial activation, alleviated neural apoptosis, and suppressed the increase in TLR4, MyD88, and p-NF-κB p65 in microglia. Intracerebroventricular injection of LPS (1 µg, 0.5 µg/µL) before surgery weakened the effect of fluoxetine. CONCLUSION: Fluoxetine pretreatment suppressed hippocampal neuroinflammation and mitigated POCD by inhibiting microglial TLR4/MyD88/NF-κB pathway activation in aged mice.

Effect of Bromelain on Chronic Unpredictable Stress-induced Behavioral, Biochemical, and Monoamine Changes in Wistar Albino Rat Model of Depression.

BACKGROUND: Bromelain is a complex mixture of protease enzyme extract from the fruit or stem of the pineapple plant and it has a history of folk medicine use. It is known to have a wide range of biological actions and it is most commonly used as an anti-inflammatory agent, though scientists have also discovered its potential as an anticancer and antimicrobial agent, it has been reported to have positive effects on the respiratory, digestive, circulatory systems and potentially on the immune system. OBJECTIVE: This study was designed to investigate the antidepressant potential of Bromelain in the chronic unpredictable stress (CUS) model of depression. METHODS: We studied the antioxidant activity, and neuroprotective effect of Bromelain by analyzing the fear and anxiety behavior, antioxidants, and neurotransmitter levels, and also by analyzing the histopathological changes. Adult male Wistar albino rats were divided into 5 groups, Control; Bromelain; CUS; CUS + Bromelain, CUS + fluoxetine. Animals of the CUS group, CUS + Bromelain group, and CUS + Fluoxetine group were exposed to CUS for 30 days. Animals of the Bromelain group and CUS + Bromelain group were treated orally with 40 mg/kg Bromelain throughout the period of CUS whereas, the positive control group was treated with fluoxetine. RESULTS: Results showed a significant decrease in oxidative stress marker (lipid peroxidation), and the stress hormone cortisol, in Bromelain-treated CUS-induced depression. Bromelain treatment in CUS has also resulted in a significant increase in neurotransmitter levels, which indicates the efficacy of Bromelain to counteract the monamine neurotransmitter changes in depression by increasing their synthesis and reducing their metabolism. In addition, the antioxidant activity of Bromelain prevented oxidative stress in depressed rats. Also, hematoxylin and eosin staining of hippocampus sections has revealed that Bromelain treatment has protected the degeneration of nerve cells by chronic unpredictable stress exposure. CONCLUSION: This data provides evidence for the antidepressant-like action of Bromelain by preventing neurobehavioral, biochemical, and monoamine alterations.

Non-psychoactive Cannabidiol Prevents Osteoporosis in an Animal Model and Increases Cell Viability, Proliferation, and Osteogenic Gene Expression in Human Skeletal Stem and Progenitor Cells.

Cannabidiol (CBD), the non-psychoactive component of the Cannabis sativa plant, is marketed as a potential therapeutic agent and has been studied for its roles in reducing inflammation and managing neuropathic pain. Some studies have reported that CB1 and CB2 receptor activation can attenuate and reverse bone loss in experimental animal models. Despite this, little is known about the impact of CBD on fracture healing. We investigated the effects of CBD in vitro using human osteoprogenitor cells and in vivo via murine femur fracture and osteoporosis models. In vitro mesenchymal stem cells were treated with increasing concentrations of crystalized pharmaceutical grade CBD or vehicle solution. Cell viability and proliferation were significantly increased in cells treated with CBD compared to vehicle control. Osteocalcin expression was also significantly higher in the CBD-treated human stem cells compared to vehicle control. In vivo the effect of CBD on bone mineral density and fracture healing in mice was examined using a two-phase experimental approach. Fluoxetine was used for pharmacologic induction of osteoporosis and surgical oophorectomy (OVX) was used for hormonal induction of osteoporosis. X-ray and microCT analysis showed that CBD prevented both fluoxetine- and OVX-induced osteoporosis. We found that while OVX resulted in delayed bone healing in control mice, CBD-pretreated mice exhibited normal bone healing. Collectively these in vitro and in vivo findings suggest that CBD exerts cell-specific effects which can be exploited to enhance bone metabolism. These findings also indicate that CBD usage in an osteoporotic population may positively impact bone morphology, warranting further research.

Protective effect of Nr4a2 (Nurr1) against LPS-induced depressive-like behaviors via regulating activity of microglia and CamkII neurons in anterior cingulate cortex.

Neuroinflammation is tightly associated with onset of depression. The nuclear receptor related 1 protein (Nurr1, also called Nr4a2), its roles in dopaminergic neurons is well understood, which can alleviate inflammation. Nevertheless, potential effects of Nr4a2 on neuroinflammation associated with depression still remains unclear. Chronic lipopolysaccharides (LPS) stress induced depressive-behaviors were confirmed via behavioral tests. Differentially expressed genes were detected by using RNA-sequencing. The anterior cingulate cortex (ACC) tissues were collected for biochemical experiments. The Golgi-Cox staining and virus labeling were used to evaluate the dendritic spines. We applied fluoxetine (FLX) and amodiaquine dihydrochloride (AQ, a highly selective agonist of Nr4a2) in mice. Overexpression experiments were performed by injecting with AAV-Nr4a2-EGFP into ACC. Chemogenetic activation of CamkII neurons via injecting the hM3Dq virus. Mice treated with LPS displayed depressive- and anxiety-like behaviors. The reduction of Nr4a2 and FosB induced by LPS were rescued by pretreatment with FLX or AQ. More importantly, LPS-induced behavior deficits in mice were also alleviated via fluoxetine treatment and pharmacological activation the expression of Nr4a2. Meanwhile, enhancing the level of Nr4a2 could improve dendritic spines loss of neuron and morphological changes in microglia. Overexpression of Nr4a2 in ACC reversed the depressive- and anxiety-like behaviors caused by LPS administration. Activation of CamkII neurons in ACC could robustly increase the expression of Nr4a2 and improve LPS-induced behavior deficits. Our findings demonstrate that the Nr4a2 may regulate depressive-like behaviors via alleviating the impairment of morphology and function on microglia and CamkII neurons induced by chronic neuroinflammation.

The metabolites could not be ignored: A comparative study of the metabolite norfluoxetine with its parent fluoxetine on zebrafish (Danio rerio).

The ubiquitous pharmaceuticals in aquatic environments have attracted huge attention due to their significant risks to humans and ecosystems. However, even though the knowledge of the negative effects induced by the parent pharmaceuticals is quite extensive, little is known about their metabolites for a long time. This study provides systematical knowledge about the potential toxicity of metabolite norfluoxetine and its parent fluoxetine on zebrafish (Danio rerio) at the early life stage. The results showed that the metabolite norfluoxetine had similar acute toxicity in fish with the parent fluoxetine. For the altered fish development, there was no significant difference in most cases between the two pharmaceuticals. Compared to the control, the metabolite markedly inhibited the locomotor behavior under light-to-dark transitions, which was comparable to the parent. Norfluoxetine could easily accumulate but hardly eliminate from fish, relative to fluoxetine. In addition, the accumulated fluoxetine in zebrafish may rapidly metabolize to norfluoxetine and then be eliminated through different metabolic pathways. The functional genes related to serotonergic process (5-ht1aa, 5-ht2c, slc6a4b, and vmat), early growth (egr4), and circadian rhythm (per2) were downregulated by both the norfluoxetine and fluoxetine, indicative of the same mode-of-action of norfluoxetine with its parent in these functions. Meanwhile, the alterations caused by norfluoxetine were more pronounced than that of fluoxetine in the genes of 5-ht2c, slc6a4b, vmat, and per2. The molecular docking also confirmed that norfluoxetine could bind with serotonin transporter protein in the same as fluoxetine with a lower binding free energy. Overall, the metabolite norfluoxetine could induce similar and even more toxic effects on zebrafish with the same mode of action. The different and binding energy of the metabolite norfluoxetine and its parent fluoxetine on zebrafish may be responsible for the differentiated effects. It highlights the risks of the metabolite norfluoxetine in the aquatic environment could not be ignored.

Traxoprodil Produces Antidepressant-Like Behaviors in Chronic Unpredictable Mild Stress Mice through BDNF/ERK/CREB and AKT/FOXO/Bim Signaling Pathway.

Traxoprodil is a selective N-methyl-d-aspartate receptor subunit 2B (NR2B) receptor inhibitor with rapid and long-lasting antidepressant effects. However, the appropriate dosage, duration of administration, and underlying mechanism of traxoprodil's antidepressant effects remain unclear. The purpose of this study is to compare the antidepressant effects of traxoprodil in different doses and different durations of administration and to explore whether traxoprodil exerts antidepressant effects via the brain-derived neurotrophic factor/extracellular signal-regulated kinase/cAMP-response element binding protein (BDNF/ERK/CREB) and protein kinase B/Forkhead box O/building information modelling (AKT/FOXO/Bim) signaling pathway. Mice were randomly divided into control group, chronic unpredictable mild stress (CUMS) + vehicle group, CUMS + traxoprodil (10 mg/kg, 20 mg/kg, and 40 mg/kg) groups, and CUMS + fluoxetine (5 mg/kg) group, followed by a forced swimming test, tail suspension test, and sucrose preference test. Western blotting and immunohistochemistry were used to measure the protein expression of BDNF, p-ERK1/2, p-CREB, NR2B, AKT, FOXO1, FOXO3a, and Bim. Compared with the control group, CUMS treatment increased immobility time; decreased sucrose preference; reduced expression of BDNF, p-ERK1/2, and p-CREB; and increased expression of AKT, FOXO, and Bim in the hippocampus. These alterations were ameliorated by administration of 20 mg/kg or 40 mg/kg of traxoprodil after 7 or 14 days of administration and with 10 mg/kg of traxoprodil or 5 mg/kg of fluoxetine after 21 days of administration. At the 7-day and 14-day timepoints, traxoprodil displayed dose-dependent antidepressant effects, with 20 and 40 mg/kg doses of traxoprodil producing rapid and strong antidepressant effects. However, at 21 days of administration, 10 and 20 mg/kg doses of traxoprodil exerted more pronounced antidepressant effects. The mechanism of traxoprodil's antidepressant effects may be closely related to the BDNF/ERK/CREB and AKT/FOXO/Bim signaling pathway.

Baicalin Ameliorates Corticosterone-Induced Depression by Promoting Neurodevelopment of Hippocampal via mTOR/GSK3ß Pathway.

OBJECTIVE: To investigate the role of hippocampal neurodevelopment in the antidepressant effect of baicalin. METHODS: Forty male Institute of Cancer Research mice were divided into control, corticosterone (CORT, 40 mg/kg), CORT+baicalin-L (25 mg/kg), CORT+baicalin-H (50 mg/kg), and CORT+fluoxetine (10 mg/kg) groups according to a random number table. An animal model of depression was established by chronic CORT exposure. Behavioral tests were used to assess the reliability of depression model and the antidepressant effect of baicalin. In addition, Nissl staining and immunofluorescence were used to evaluate the effect of baicalin on hippocampal neurodevelopment in mice. The protein and mRNA expression levels of neurodevelopment-related factors were detected by Western blot analysis and real-time polymerase chain reaction, respectively. RESULTS: Baicalin significantly ameliorated the depressive-like behavior of mice resulting from CORT exposure and promoted the development of dentate gyrus in hippocampus, thereby reversing the depressive-like pathological changes in hippocampal neurons caused by CORT neurotoxicity. Moreover, baicalin significantly decreased the protein and mRNA expression levels of glycogen synthase kinase 3ß (GSK3ß), and upregulated the expression levels of cell cycle protein D1, p-mammalian target of rapamycin (mTOR), doublecortin, and brain-derived neurotrophic factor (all P<0.01). There were no significant differences between baicalin and fluoxetine groups (P>0.05). CONCLUSION: Baicalin can promote the development of hippocampal neurons via mTOR/GSK3ß signaling pathway, thus protect mice against CORT-induced neurotoxicity and play an antidepressant role.

Decreased serotonin transporter activity in the mitral valve contributes to progression of degenerative mitral regurgitation.

Degenerative mitral valve (MV) regurgitation (MR) is a highly prevalent heart disease that requires surgery in severe cases. Here, we show that a decrease in the activity of the serotonin transporter (SERT) accelerates MV remodeling and progression to MR. Through studies of a population of patients with MR, we show that selective serotonin reuptake inhibitor (SSRI) use and SERT promoter polymorphism 5-HTTLPR LL genotype were associated with MV surgery at younger age. Functional characterization of 122 human MV samples, in conjunction with in vivo studies in SERT-/- mice and wild-type mice treated with the SSRI fluoxetine, showed that diminished SERT activity in MV interstitial cells (MVICs) contributed to the pathophysiology of MR through enhanced serotonin receptor (HTR) signaling. SERT activity was decreased in LL MVICs partially because of diminished membrane localization of SERT. In mice, fluoxetine treatment or SERT knockdown resulted in thickened MV leaflets. Similarly, silencing of SERT in normal human MVICs led to up-regulation of transforming growth factor ß1 (TGFß1) and collagen (COL1A1) in the presence of serotonin. In addition, treatment of MVICs with fluoxetine not only directly inhibited SERT activity but also decreased SERT expression and increased HTR2B expression. Fluoxetine treatment and LL genotype were also associated with increased COL1A1 expression in the presence of serotonin in MVICs, and these effects were attenuated by HTR2B inhibition. These results suggest that assessment of both 5-HTTLPR genotype and SERT-inhibiting treatments may be useful tools to risk-stratify patients with MV disease to estimate the likelihood of rapid disease progression.

The serotonin reuptake inhibitor fluoxetine induces human fetal membrane sterile inflammation through p38 MAPK activation.

Serotonin Reuptake Inhibitors (SRIs) are often used as first line therapy for depression and other psychiatric disorders. SRI use during pregnancy is associated with preterm premature rupture of membranes (PPROM) and subsequent preterm birth. The objective of this study was to investigate the mechanism(s) responsible for SRI-associated PPROM. Putative mechanisms underlying PPROM include fetal membrane (FM) inflammation, increased apoptosis, and/or accelerated senescence, the later which may be reversed by statins. Human FM explants from normal term deliveries without labor, infection, or antidepressant use were treated with or without the SRI, fluoxetine (FLX), either alone or in the presence of a p38 MAPK inhibitor or the statins, simvastatin or rosuvastatin. FMs were also collected from women either unexposed or exposed to FLX during pregnancy. FLX significantly increased FM p38 MAPK activity and secretion of inflammatory IL-6. Inhibition of p38 MAPK reduced FM IL-6 secretion in response to FLX. Statins did not reduce the SRI-induced FM IL-6 production. FMs from women exposed to FLX during pregnancy expressed elevated levels of p38 MAPK activity compared to matched unexposed women. FMs exposed to FLX did not exhibit signs of increased apoptosis and/or accelerated senescence. These results indicate that the SRI, FLX, may induce sterile FM inflammation during pregnancy through activation of the p38 MAPK pathway, and in the absence of apoptosis and senescence. These findings may better inform clinicians and patients as they weigh the risks and benefits of SRI antidepressant treatment during pregnancy.

Fluoxetine increased adult neurogenesis is mediated by 5-HT3 receptor.

Adult neurogenesis is an aspect of structural plasticity that remains active during adulthood in some brain regions. One of them is the subgranular zone (SGZ) of the dentate gyrus of the hippocampus. Adult neurogenesis is reduced by different factors and in disorders of the CNS, including major depression. Antidepressant treatments, such as chronic fluoxetine administration, recover the normal level of adult neurogenesis. Fluoxetine treatment increases the free concentration of the neurotransmitter serotonin and this monoamine is implicated in the regulation of the neurogenic process; however, the target of the action of this neurotransmitter has not been fully elucidated. In this study, we have tried to determine the relevance of the serotonin receptor 3 (5-HT3) in the hippocampal neurogenesis of adult rats. We have used fluorescent immunohistochemistry to study the expression of the 5-HT3 receptor in different neurogenesis stages in the SGZ, identifying its expression in stem cells, amplifying neural progenitors and immature neurons. Moreover, we have studied the impact of a 5-HT3 antagonist (ondansetron) in the fluoxetine-induced adult neurogenesis. We observed that fluoxetine alone increases the number of both proliferating cells (ki67 positive) and immature neurons (DCX positive) in the SGZ. By contrast, co-treatment with ondansetron blocked the increase in proliferation and neurogenesis. This study demonstrates that the activation of 5-HT3 receptors is necessary for the increase of adult neurogenesis induced by fluoxetine.

Protein synergistic action-based development and application of a molecularly imprinted chiral sensor for highly stereoselective recognition of S-fluoxetine.

In order to improve the recognition performance of MIPs sensors in chiral drug enantiomers, a novel a highly selective molecular recognition method based on protein-assisted immobilization of chiral molecular conformation was developed. S-fluoxetine (S-FLX) as the target chiral molecule, human serum albumin (HSA), which has a high affinity and strong interactions with S-FLX, was screened from 11 proteins to serve as an auxiliary recognition unit for the fixation of chiral conformation. By incorporating HSA into the preparation of molecularly imprinted polymers (MIPs), the natural chirality and high stereoselectivity of the protein were leveraged for the induction and fixation of the stereo conformation of S-FLX, refinement of internal structures of the imprinted cavities. The sensor exhibited excellent chiral recognition ability and high detection sensitivity. The changes of probe signal intensity of the MIPs/HSA sensor were positively correlated with the logarithmic concentration of S-FLX in the range of 1.0 × 10-16-1.0 × 10-11 mol L-1, where a detection limit of 6.43 × 10-17 mol L-1 was achieved (DL = 3δb/K). The selectivity of MIPs/HSA sensor in recognizing S-FLX was increased by 18.5 times and the sensitivity was increased by 2.6 times after the incorporation of HSA. The developed sensor was successfully used for the analysis of S-FLX in fluoxetine hydrochloride capsules.

Immunostimulatory activity of fluoxetine in macrophages via regulation of the PI3K and P38 signaling pathways.

Fluoxetine is an antidepressant drug that is heavily preferred in the cure of depression, which is from the selective serotonin reuptake inhibitor (SSRI) group. There are many reports on the effect of fluoxetine on the immune system, and its effect on the macrophage cells has never been looked at before. We aimed to demonstrate the cytokine production potential of fluoxetine antidepressant, which is widely used in the clinic, in the J774.2 cell line and its effect on PI3K and P38 pathways. The use of fluoxetine alone in J774.2 macrophage cells showed immunostimulatory properties by inducing the production of tumor necrosis factor-α (TNF-α), interleukin (IL) IL-6, IL-12p40, and granulocyte-macrophage colony-stimulating factor (GM-CSF) cytokines. It showed anti-inflammatory properties by completely stopping the production of cytokines (IL-6, IL12p40, TNF-α, and GM-CSF) at all concentrations where LPS and fluoxetine were used together. While PI3K and P38 pathways were not effective in the immunostimulatory effect in the presence of the drug agent, we found that the PI3K and P38 pathways were influenced during their anti-inflammatory activity.