Antidepressant-like behavioral, neurochemical and neuroendocrine effects of naringenin in the mouse repeated tail suspension test

New insights into anti-depression effects of bioactive phytochemicals

Depression is one of the most common psychological disorders, and due to its high prevalence and mortality rates, it imposes a significant disease burden. Contemporary treatments for depression involve various synthetic drugs, which have limitations such as side effects, single targets, and slow onset of action. Unlike synthetic medications, phytochemicals offer the benefits of a multi-target and multi-pathway mode of treatment for depression. In this literature review, we describe the pharmacological actions, experimental models, and clinical trials of the antidepressant effects of various phytochemicals. Additionally, we summarize the potential mechanisms by which these phytochemicals prevent depression, including regulating neurotransmitters and their receptors, the HPA axis, inflammatory responses, managing oxidative stress, neuroplasticity, and the gut microbiome. Phytochemicals exert therapeutic effects through multiple pathways and targets, making traditional Chinese medicine (TCM) a promising adjunctive antidepressant for the prevention, alleviation, and treatment of depression. Therefore, this review aims to provide robust evidence for subsequent research into developing phytochemical resources as effective antidepressant agents.

The Potential Role of Polyphenol Supplementation in Preventing and Managing Depression: A Review of Current Research

Depression is a common mental illness that affects 5% of the adult population globally. The most common symptoms of depression are low mood, lack of pleasure from different activities, poor concentration, and reduced energy levels for an extended period, and it affects the emotions, behaviors, and overall well-being of an individual. The complex pathophysiology of depression presents challenges for current therapeutic options involving a biopsychosocial treatment plan. These treatments may have a delayed onset, low remission and response rates, and undesirable side effects. Researchers in nutrition and food science are increasingly addressing depression, which is a significant public health concern due to the association of depression with the increased incidence of cardiovascular diseases and premature mortality. Polyphenols present in our diet may significantly impact the prevention and treatment of depression. The primary mechanisms include reducing inflammation and oxidative stress, regulating monoamine neurotransmitter levels, and modulating the microbiota-gut-brain axis and hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. This review summarizes recent advances in understanding the effects of dietary polyphenols on depression and explores the underlying mechanisms of these effects for the benefit of human health. It also highlights studies that are looking at clinical trials to help future researchers incorporate these substances into functional diets, nutritional supplements, or adjunctive therapy to prevent and treat depression.

Flavonoids against depression: a comprehensive review of literature

Background

Depression is a state of low mood and aversion to activity, which affects a person's thoughts, behavior, motivation, feelings, and sense of wellbeing. Pharmacologic therapies are still the best effective treatment of depression. Still, most antidepressant drugs have low efficacy and delayed onset of therapeutic action, have different side effects, and even exacerbate depression. Such conditions make it possible to look for alternatives. Consequently, we decided to summarize the impact of flavonoids on depression in this review.

Methods

We searched scientific databases such as SCOPUS, PubMed, and Google Scholar to find relevant studies until July 2022.

Results

A wide variety of natural components have been shown to alleviate depression, one of which is flavonoids. Due to the growing tendency to use natural antidepressant drugs, scientific studies are increasingly being conducted on flavonoids. This study aims to review the latest scientific researches that indicate the antidepressant potential of flavonoids. Various mechanisms include neurotransmitter system modulation and dopaminergic, noradrenergic, and serotonergic pathways regulation in the central nervous system. Different compounds of flavonoids have antidepressant properties in vivo or in vitro experiments or clinical trials and can be used as alternative and complementary treatments for depression. In general, it was observed that there were no severe side effects.

Conclusion

Our study proves the antidepressant potential of flavonoids, and considering the limited side effects, they can be used as complementary medicine for depressed patients.

Naringenin: its chemistry and roles in neuroprotection

According to epidemiological research, as the population ages, neurological illnesses are becoming a bigger issue. Despite improvements in the treatment of these diseases, there are still widespread worries about how to find a long-lasting remedy. Several neurological diseases can be successfully treated with natural substances. As a result, current research has been concentrated on finding effective neuroprotective drugs with improved efficacy and fewer side effects. Naringenin is one potential treatment for neurodegenerative diseases. Many citrus fruits, tomatoes, bergamots, and other fruits are rich in naringenin, a flavonoid. This phytochemical is linked to a variety of biological functions. Naringenin has attracted a lot of interest for its ability to exhibit neuroprotection through several mechanisms. In the current article, we present evidence from the literature that naringenin reduces neurotoxicity and oxidative stress in brain tissues. Also, the literatures that are currently accessible shows that naringenin reduces neuroinflammation and other neurological anomalies. Additionally, we found several studies that touted naringenin as a promising anti-amyloidogenic, antidepressant, and neurotrophic treatment option. This review's major goal is to reflect on advancements in knowledge of the molecular processes that underlie naringenin's possible neuroprotective effects. Furthermore, this article also provides highlights of Naringenin with respect to its chemistry and pharmacokinetics.

Liraglutide and Naringenin relieve depressive symptoms in mice by enhancing Neurogenesis and reducing inflammation

Depression is a debilitating mental disease that negatively impacts individuals' lives and society. Novel hypotheses have been recently proposed to improve our understanding of depression pathogenesis. Impaired neuroplasticity and upregulated neuro-inflammation add-on to the disturbance in monoamine neurotransmitters and therefore require novel anti-depressants to target them simultaneously. Recent reports demonstrate the antidepressant effect of the anti-diabetic drug liraglutide. Similarly, the natural flavonoid naringenin has shown both anti-diabetic and anti-depressant effects. However, the neuro-pharmacological mechanisms underlying their actions remain understudied. The study aims to evaluate the antidepressant effects and neuroprotective mechanisms of liraglutide, naringenin or a combination of both. Depression was induced in mice by administering dexamethasone (32 mcg/kg) for seven consecutive days. Liraglutide (200 mcg/kg), naringenin (50 mg/kg) and a combination of both were administered either simultaneously or after induction of depression for twenty-eight days. Behavioral and molecular assays were used to assess the progression of depressive symptoms and biomarkers. Liraglutide and naringenin alone or in combination alleviated the depressive behavior in mice, manifested by decrease in anxiety, anhedonia, and despair. Mechanistically, liraglutide and naringenin improved neurogenesis, decreased neuroinflammation and comparably restored the monoamines levels to that of the reference drug escitalopram. The drugs protected mice from developing depression when given simultaneously with dexamethasone. Collectively, the results highlight the usability of liraglutide and naringenin in the treatment of depression in mice and emphasize the different pathways that contribute to the pathogenesis of depression.

Potential Beneficial Effects of Naringin and Naringenin on Long COVID-A Review of the Literature

Coronavirus disease 2019 (COVID-19) caused a severe epidemic due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Recent studies have found that patients do not completely recover from acute infections, but instead, suffer from a variety of post-acute sequelae of SARS-CoV-2 infection, known as long COVID. The effects of long COVID can be far-reaching, with a duration of up to six months and a range of symptoms such as cognitive dysfunction, immune dysregulation, microbiota dysbiosis, myalgic encephalomyelitis/chronic fatigue syndrome, myocarditis, pulmonary fibrosis, cough, diabetes, pain, reproductive dysfunction, and thrombus formation. However, recent studies have shown that naringenin and naringin have palliative effects on various COVID-19 sequelae. Flavonoids such as naringin and naringenin, commonly found in fruits and vegetables, have various positive effects, including reducing inflammation, preventing viral infections, and providing antioxidants. This article discusses the molecular mechanisms and clinical effects of naringin and naringenin on treating the above diseases. It proposes them as potential drugs for the treatment of long COVID, and it can be inferred that naringin and naringenin exhibit potential as extended long COVID medications, in the future likely serving as nutraceuticals or clinical supplements for the comprehensive alleviation of the various manifestations of COVID-19 complications.

Naringenin mitigates reserpine-induced anxiety-like behavior, neurodegeneration, and oxidative stress in male rats

Reserpine (Res) induces anxiety-like behaviors, orofacial dyskinesia, and neurodegeneration in animals, the pathophysiology of which has been related to oxidative stress. The purpose of this study was to investigate whether naringenin (NG) could prevent reserpine-induced anxiety-like behaviors, orofacial dyskinesia, and neurodegeneration in male rats. Twenty-eight male rats were distributed into different groups as follows: Control rats; vehicle rats, which received the vehicles (normal saline, orally; acetic acid, intraperitoneally); Res rats (1 mg/kg/day) every other day for 3 days; and Res + NG rats, which received NG (50 mg/kg, orally, pre-treatment for 7 days), followed by Res. Administration of Res significantly increased chewing frequency compared with the control group (P < 0.01) and NG reversed the effect of Res on this factor (P < 0.05). Res induced an anxiety-like behavior in rats in the plus maze, and pre-treatment with NG improved this behavior. In addition, Res significantly increased the level of oxidative stress markers and degenerated neurons in the striatum; NG was able to ameliorate these damages. The results of this study demonstrated that Res caused behavioral disorders and increased the levels of oxidative stress in male rats; the use of NG was effective in treating these disorders. Therefore, NG should be considered as a preventive agent for reserpine-induced brain damage in male rats.

The ethanolic extract of peanut shell attenuates the depressive-like behaviors of mice through modulation of inflammation and gut microbiota

Peanut shell is an agricultural byproduct being wasted on a large scale, which is in urgent need to be recycled. To fully utilize its pharmacological ingredients, e.g. luteolin, eriodyctiol, and 5,7-dihydroxychromone, we evaluated the curative effect of ethanol extract deriving from peanut shell (PSE) in treating chronic unpredictable mild stress (CUMS)-induced depressive mice. The chronic stress lasted for 10 weeks, and PSE at 100-900 mg/kg/day was gavaged to mice in the last 2 weeks of modeling. The depressive behaviors were assessed by analyses of sucrose preference, tail suspension, and forced swimming. The brain injury was demonstrated by Hematoxylin and Eosin (H&E), Nissl body, and TdT-mediated dUTP nick end labeling (TUNEL) stainings in the mouse hippocampus. Biochemical indicators were analyzed, including levels of neurotrophic factors, neurotransmitters, stress hormones, and inflammatory mediators. The feces were collected for the 16S rDNA sequencing of gut microbiome. Administration of PSE improved the sucrose water consumption of depressive mice, while it decreased the immobile time in tail suspension and forced swimming tests. Meanwhile, the anti-depressive effect of PSE was supported by ameliorated histochemical staining, increased levels of neurotrophic factors and neurotransmitters, as well as down-regulated stress hormones. Furthermore, the treatment of PSE was able to mitigate the levels of inflammatory cytokines in brain, serum, and small intestine. Besides, the tight junction proteins, e.g., occludin and ZO-1, of gut showed elevated expressions, which coincided with the elevated abundance and diversity of gut microbiota upon PSE treatment. This study validated the therapeutic efficacy of PSE in fighting against depression, as well as its modulatory action on inflammation and gut microbiota, which promoted the recycling of this agricultural waste to be health supplements of added value.

Natural Phytochemicals for the Treatment of Major Depressive Disorder: A Mini-Review of Pre- and Clinical Studies

Major Depressive Disorder (MDD) is a common mental illness that causes significant disability and declining quality of life. An overlap of multiple factors can be involved in the pathophysiology of this mood disorder, including increased inflammation and oxidative stress, change in neurotransmitters, decreased brain-derived neurotrophic factor (BDNF), activation of the hypothalamicpituitary- adrenal (HPA) axis, and changes in the microbiota-gut-brain axis. Although the classic treatment for MDD is safe, it is far from ideal, with delay to start the best clinic, side effects, and a large number of non-responses or partial-responses. Therefore, other alternatives are being studied to improve depressive symptoms, and, among them, the role of phytochemicals in food stands out. This mini-review will discuss the main phytochemicals present in foods with clinical and preclinical studies showing benefits for MDD treatment. In addition, the main mechanisms of action that are being proposed for each of these compounds will be addressed.

Naringin and Naringenin Polyphenols in Neurological Diseases: Understandings from a Therapeutic Viewpoint

The glycosides of two flavonoids, naringin and naringenin, are found in various citrus fruits, bergamots, tomatoes, and other fruits. These phytochemicals are associated with multiple biological functions, including neuroprotective, antioxidant, anticancer, antiviral, antibacterial, anti-inflammatory, antiadipogenic, and cardioprotective effects. The higher glutathione/oxidized glutathione ratio in 3-NP-induced rats is attributed to the ability of naringin to reduce hydroxyl radical, hydroperoxide, and nitrite. However, although progress has been made in treating these diseases, there are still global concerns about how to obtain a solution. Thus, natural compounds can provide a promising strategy for treating many neurological conditions. Possible therapeutics for neurodegenerative disorders include naringin and naringenin polyphenols. New experimental evidence shows that these polyphenols exert a wide range of pharmacological activity; particular attention was paid to neurodegenerative diseases such as Alzheimer's and Parkinson's diseases, as well as other neurological conditions such as anxiety, depression, schizophrenia, and chronic hyperglycemic peripheral neuropathy. Several preliminary investigations have shown promising evidence of neuroprotection. The main objective of this review was to reflect on developments in understanding the molecular mechanisms underlying the development of naringin and naringenin as potential neuroprotective medications. Furthermore, the configuration relationships between naringin and naringenin are discussed, as well as their plant sources and extraction methods.

Effects of Huolisu Oral Solution on Depression-Like Behavior in Rats: Neurotransmitter and HPA Axis

Background: Depression is a common mental disorder, and its morbidity rate is expected to rank second among all mental disorders by 2020. Hence, traditional Chinese medicines gradually attract the attention of many researchers because of their various targets and low toxicity. Huolisu oral solution (HLS) is a Chinese medicine compound preparation, which is present in the Chinese Pharmacopoeia. It is used clinically mainly for the treatment of neurasthenia, perimenopausal syndrome, and insomnia, or depression associated with cerebrovascular disease. Despite the fact that HLS has been used as an antidepressant in clinics, the underlying mechanism is still an untouched domain. To provide a theoretical basis for the clinical application, a series of assessment methods, such as the tail suspension test (TST), forced swim test (FST), and locomotor activity test in mice and rat models of chronic unpredictable mild stress (CUMS), have been conducted in our study.

Objective: The aim of the study was to explore the antidepressive effect and mechanism of HLS.

Methods: CUMS was induced in rats to simulate a depression-like behavior. Neurotransmitters and hormones were detected by enzyme-link immunosorbent assay (ELISA). Pathomorphology examination of the hippocampus was obtained by using the TSView 7 image analysis system. The active ingredients of HLS were also determined by high-performance liquid chromatography (HPLC).

Results: HLS could alleviate the depression-like behavior of the model rats. Biochemical analysis showed that HLS enhanced the levels of 5-hydroxytryptamine (5-HT), norepinephrine (NE), and dopamine (DA) in the hippocampus and diminished these in the serum of the CUMS rats. HLS could also decrease the concentration of corticosterone (CORT), adrenocorticotropic hormone (ACTH), and β-endorphin (β-EP) in blood. The pathohistological examination revealed that the hippocampus and adrenal gland were improved after treatment with HLS.

Conclusions: This study concluded that HLS could alleviate depression-like behaviors in the rats exposed to CUMS, and the potential mechanism may be related to the regulation of the monoamine neurotransmitters, the hypothalamic–pituitary–adrenal (HPA) axis, and the β-EP. These findings hint that HLS is likely to be a potentially effective agent for treating depression.

Prospective multifunctional roles and pharmacological potential of dietary flavonoid narirutin

Plant-based phytochemicals are now being used to treat plenty of physiological diseases. Herbal drugs have gained popularity in recent years because of their strength, purity, and cheap cost-effectiveness. Citrus fruits contain significant amounts of flavanones, which falls to the category of polyphenols. Flavanones occupy a major fraction of the total polyphenols present in the plasma when orange juice is taken highly or in moderate states. Narirutin is a disaccharide derivative available in citrus fruits, primarily dihydroxy flavanone. From a pharmacological viewpoint, narirutin is a bioactive phytochemical with therapeutic efficacy. Many experimental researches were published on the use of narirutin. Anticancer activity, neuroprotection, stress relief, hepatoprotection, anti-allergic activity, antidiabetic activity, anti-adipogenic activity, anti-obesity action, and immunomodulation are a couple of the primary pharmacological properties. Narirutin also has antioxidant, and anti-inflammatory activities. The ultimate goal of this review is to provide the current scenario of pharmacological research with narirutin; to make a better understanding for therapeutic potential of narirutin, as well as its biosynthesis strategies and side effects. Extensive literature searches and studies were undertaken to determine the pharmacological properties of narirutin.

Biologically Active Compounds Present in Tobacco Smoke: Potential Interactions Between Smoking and Mental Health

Tobacco dependence remains one of the major preventable causes of premature morbidity and mortality worldwide. There are well over 8,000 compounds present in tobacco and tobacco smoke, but we do not know what effect, if any, many of them have on smokers. Major interest has been on nicotine, as well as on toxic and carcinogenic effects and several major and minor components of tobacco smoke responsible for the negative health effects of smoking have been elucidated. Smokers themselves report a variety of positive effects from smoking, including effects on depression, anxiety and mental acuity. Smoking has also been shown to have protective effects in Parkinson’s Disease. Are the subjective reports of a positive effect of smoking due to nicotine, of some other components of tobacco smoke, or are they a manifestation of the relief from nicotine withdrawal symptoms that smoking provides? This mini-review summarises what is currently known about the components of tobacco smoke with potential to have positive effects on smokers.

The Role of Natural Products in Treatment of Depressive Disorder

Depressive disorder is one of the most common psychiatric syndromes that, if left untreated, can cause many disturbances in a person's life. Numerous factors are involved in depression, including inflammation, brain-derived neurotrophic factor (BDNF), GABAergic system, hypothalamic- pituitary-adrenal (HPA) Axis, monoamine neurotransmitters (serotonin (5-HT), noradrenaline, and dopamine). Common treatments for depression are selective serotonin reuptake inhibitors, tricyclic antidepressants, and monoamine oxidase inhibitors, but these drugs have several side effects such as anxiety, diarrhea, constipation, weight loss, and sexual dysfunctions. These agents only reduce the symptoms and temporarily reduce the rate of cognitive impairment associated with depression. As a result, extensive research has recently been conducted on the potential use of antidepressant and sedative herbs. According to the available data, herbs used in traditional medicine can be significantly effective in reducing depression, depressive symptoms and improving patients' performance. The present study provides a summary of biomarkers and therapeutic goals of depression and shows that natural products such as saffron or genipin have antidepressant effects. Some of the useful natural products and their mechanisms were evaluated. Data on various herbs and natural isolated compounds reported to prevent and reduce depressive symptoms is also discussed.

Emerging Role of Flavonoids as the Treatment of Depression

Depression is one of the most frequently observed psychological disorders, affecting thoughts, feelings, behavior and a sense of well-being in person. As per the WHO, it is projected to be the primitive cause of various other diseases by 2030. Clinically, depression is treated by various types of synthetic medicines that have several limitations such as side-effects, slow-onset action, poor remission and response rates due to complicated pathophysiology involved with depression. Further, clinically, patients cannot be given the treatment unless it affects adversely the job or family. In addition, synthetic drugs are usually single targeted drugs. Unlike synthetic medicaments, there are many plants that have flavonoids and producing action on multiple molecular targets and exhibit anti-depressant action by affecting multiple neuronal transmissions or pathways such as noradrenergic, serotonergic, GABAnergic and dopaminergic; inhibition of monoamine oxidase and tropomyosin receptor kinase B; simultaneous increase in nerve growth and brain-derived neurotrophic factors. Such herbal drugs with flavonoids are likely to be useful in patients with sub-clinical depression. This review is an attempt to analyze pre-clinical studies, structural activity relationship and characteristics of reported isolated flavonoids, which may be considered for clinical trials for the development of therapeutically useful antidepressant.

Acetylcholinesterase Inhibitors in the Treatment of Neurodegenerative Diseases and the Role of Acetylcholinesterase in their Pathogenesis

Acetylcholinesterase (AChE) plays an important role in the pathogenesis of neurodegenerative diseases by influencing the inflammatory response, apoptosis, oxidative stress and aggregation of pathological proteins. There is a search for new compounds that can prevent the occurrence of neurodegenerative diseases and slow down their course. The aim of this review is to present the role of AChE in the pathomechanism of neurodegenerative diseases. In addition, this review aims to reveal the benefits of using AChE inhibitors to treat these diseases. The selected new AChE inhibitors were also assessed in terms of their potential use in the described disease entities. Designing and searching for new drugs targeting AChE may in the future allow the discovery of therapies that will be effective in the treatment of neurodegenerative diseases.

Naringenin mitigates behavioral alterations and provides neuroprotection against 3-nitropropinoic acid-induced Huntington's disease like symptoms in rats

BACKGROUND

Naringenin is a powerful antioxidant and anti-inflammatory flavonoid which has been widely used as a therapeutic agent in various toxic models. However, few studies have clearly discussed the neuromodulatory effects of naringenin against different neurodegenerative disorders.

AIM

We investigated the neuroprotective efficacy of naringenin against 3-nitropropionic acid (3-NP)-induced neurobehavioral, biochemical and histopathological alterations in rats.

METHODS

Albino Wistar rats were randomly divided into three experimental groups. Group 1, the vehicle administered group, received saline. Group 2 received 3-NP (20 mg/kg body weight, i.p.) for 4 consecutive days. Group 3 received naringenin (50 mg/kg body weight, p.o.) twice daily for a period of 4 days, 30 min before and 6 h after the 3-NP administration. On the 5th day, neurobehavioral experiments were performed to access the behavioral outcomes and the striatum tissue was used for analysis of the monoamine oxidase (MAO) activity and serotonin (5-HT) levels. In addition, astrocytes activation was observed by glial fibrillary acidic protein (GFAP) immunostaining.

RESULTS

Our results showed that naringenin co-treatment provides neuroprotection against 3-NP-induced neurological disorders. Naringenin also increased the MAO activity and 5-HT levels in the striatum. Moreover, co-treatment with naringenin reduced the expression of GFAP protein in the striatal part and significantly attenuated the neuronal cell death. The findings of the present study suggest that naringenin provides neuroprotection and mitigates neurobehavioral alterations in experimental rats.

CONCLUSION

The results show that co-treatment with naringenin ameliorates 3-NP-induced HD-like symptoms in rats.

A review on the protective effects of naringenin against natural and chemical toxic agents

Naringenin (NRG), as a flavanone from flavonoids family, is widely found in grapefruit, lemon tomato, and Citrus fruits. NRG has shown strong anti-inflammatory and antioxidant activities in body organs via mechanisms such as enhancement of glutathione S-transferase (GST), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) activity, but reduction of serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and malondialdehyde (MDA). Furthermore, NRG anti-apoptotic potential was indicated to be mediated by regulating B-cell lymphoma (Bcl-2), Bcl-2-associated X protein (Bax) and caspase3/9. Overall, these properties make NRG a highly fascinating compound with beneficial pharmacological effects. Based on the literature, NRG-induced protective effects against toxicities produced by natural toxins, pharmaceuticals, heavy metals, and environmental chemicals, were mainly mediated via suppression of lipid peroxidation, oxidative stress (through boosting the antioxidant arsenal), and inflammatory factors (e.g., TNF-α, interleukin [IL]-6, IL-10, and IL-12), and activation of PI3K/Akt and MAPK survival signaling pathways. Despite considerable body of evidence on protective properties of NRG against a variety of toxic compounds, more well-designed experimental studies and particularly, clinical trials are required before reaching a concrete conclusion. The present review discusses how NRG protects against the above-noted toxic compounds.

Augmentation of morphine-conditioned place preference by food restriction is associated with alterations in the oxytocin/oxytocin receptor in rat models

BACKGROUND

Studies indicate that food restriction (FR) reinforces the effects of morphine. The exact mechanisms by which FR influences the reward circuitry of morphine have not yet been determined.

OBJECTIVES

We hypothesized that the effects of FR on the oxytocin (OXT) system and HPA axis can be associated with substance abuse disorders. In this study, the serum levels of OXT and corticosterone, and the expression of OXT/OXT receptor (OXTR), glucocorticoid receptor (GR), and brain-derived neurotrophic factor (BDNF) in the hippocampus, prefrontal cortex, and nucleus accumbens were investigated in an FR model.

METHODS

First, the male rats (n = 8 per group) were subjected to FR for 3 weeks. Then, morphine-induced conditioned place preference (CPP) was observed using two doses of morphine (3 and 5 mg/kg). The serum concentrations of corticosterone and OXT were determined by ELISA and the expression of genes was examined by qPCR.

RESULTS

FR induced an enhanced preference in the animals for the 5 mg/kg dose of morphine compared to the controls. Serum corticosterone levels increased after FR but OXT levels decreased. Meanwhile, FR actuated downregulation of GR, BDNF, and OXT genes, while inducing the overexpression of OXTR.

CONCLUSION

We propose the inclusion of OXT and OXTR alterations in the enhancement of morphine-induced CPP and addiction vulnerability following FR. Moreover, we conclude that altered BDNF levels and HPA axis activity may be the mechanisms involved in the effects of FR on morphine-induced behavior.

Antidepressant Potential of Lotus corniculatus L. subsp. corniculatus: An Ethnobotany Based Approach

As a Turkish traditional medicinal plant, aerial parts of Lotus corniculatus L. subsp. corniculatus (Fabaceae) are used as a painkiller, antihemoroidal, diuretic and sedative. In this study, the antidepressant potential of the plant has been attempted to clarify. Extracts with water, n-Hexane, ethyl acetate, and methanol were prepared respectively from the aerial parts. Antidepressant activity of the extracts were researched by using three different in vivo test models namely a tail suspension test, antagonism of tetrabenazine-induced hypothermia, ptosis, and suppression of locomotor activity and forced swimming test on male BALB/c mice and in vitro monoamine oxidase (MAO)-A and B inhibition assays. The results were evaluated through comparing with control and reference groups, and then active compounds of the active extract have been determined. Bioassay-guided fractionation of active fraction led to the isolation of three compounds and structures of the compounds were elucidated by spectroscopic methods. The data of this study demonstrate that the MeOH extract of the aerial parts of the plant showed remarkable in vivo antidepressant effect and the isolated compounds medicarpin-3-O-glucoside, gossypetin-3-O-glucoside and naringenin-7-O-glucoside (prunin) from the active sub-fractions could be responsible for the activity. Further mechanistic and toxicity studies are planned to develop new antidepressant-acting drugs.

Identification of the main active antidepressant constituents in a traditional Turkish medicinal plant, Centaurea kurdica Reichardt

ETHNOPHARMACOLOGICAL RELEVANCE

In Turkish folk medicine, infusions and decoctions prepared from the flowers, fruits and aerial parts of Centaurea kurdica Reichardt (Asteraceae) are used as sedative and antidepressant-like effects of various sedative plants have been identified in many studies. The present study was designed to evaluate the antidepressant activity of this plant.

MATERIALS AND METHODS

n-Hexane, ethyl acetate (EtOAc), and methanol (MeOH) extracts were prepared from the branches with leaves and also flowers of the plant. Antidepressant potentials of these extracts were researched by using the forced swimming test, tail suspension test, and antagonism of tetrabenazine-induced ptosis, hypothermia, and suppression of locomotor activity.

RESULTS

After determination of high antidepressant potentials of MeOH extract prepared from flowers and n-hexane extract prepared from branches with leaves, isolation studies were carried out on these two extracts and the main active components were determined as β-amyrin, mixture of β-sitosterol and stigmasterol and costunolide for the branches with leaves and quercitrin, isoquercetin and naringenin-7-O-glucopyranoside for the flowers.

CONCLUSIONS

As a result of the mechanistic and toxicity studies planned on this plant, it is thought that C. kurdica may be a glimmer of hope for depressed patients.

Therapeutic potential of naringin in neurological disorders

Neurological illnesses are multifactorial incurable debilitating disorders that may cause neurodegeneration. These diseases influence approximately 30 million people around the world. Despite several therapies, effective management of such disorders remains a global challenge. Thus, natural products might offer an alternative therapy for the treatment of various neurological disorders. Polyphenols, such as curcumin, resveratrol, myricetin, mangiferin and naringin (NRG) have been shown to possess promising potential in the treatment of neurogenerative illness. In this review, we have targeted the therapeutic potential of naringin as a neuroprotective agent. The overall neuroprotective effects and different possible underlying mechanisms related to NRG are discussed. In light of the strong evidence for the neuropharmacological efficacy of NRG in various experimental paradigms, it is concluded that this molecule should be further considered and studied as a potential candidate for neurotherapeutics, focusing on mechanistic and clinical trials to ascertain its efficacy.

Assessment of Antidepressant Effect of the Aerial Parts of Micromeria myrtifolia Boiss. & Hohen on Mice

The currently available antidepressant agents necessitate the development of newer alternatives because of their serious adverse effects and costs. Traditional medicinal knowledge is likely the key that opens the door to discover new medicines. In Turkish folk medicine, the infusion prepared from aerial parts of Micromeria myrtifolia Boiss. & Hohen is used as pleasure and medicinal tea for its relaxing action. The present research was conceived to confirm the antidepressant’s potential of this traditional medicinal plant. In this process, first of all, the collected and shade-dried aerial parts of M. myrtifolia were powdered and then, extracted using solvents with different polarity as follows; n-hexane, ethyl acetate (EtOAc), and methanol (MeOH). The antidepressant activity of the extracts was evaluated by using several in vivo and in vitro experimental models of depression. When the data obtained from the control and experimental groups were compared, it was determined that the MeOH extract was the most active. The active components of this extract were isolated and identified utilizing various chromatographic separation techniques. The MeOH extract was applied to reversed phase (RP-18) column chromatography to obtain five main fractions and they were tested on antidepressant activity models. The isolated compounds from the obtained fractions were elucidated as rosmarinic acid (1), myricetin (2), apigenin (3), and naringenin (4) which were assumed to be responsible for the antidepressant activity of the aerial parts. According to the results, rosmarinic acid, myricetin, apigenin, and naringenin showed statistically significant activity on forced swimming test and tetrabenazine-induced ptosis models, whereas only rosmarinic acid showed statistically significant activity on the tail suspension test. Apigenin displayed the highest inhibitory activity on MAO A and B enzymes. Studies in the future should be performed to investigate the antidepressant activity mechanism of these natural compounds. The current research could be an important step in the development of the new agents that can be used in the treatment of depression.

Naringenin protects against oxido-inflammatory aberrations and altered tryptophan metabolism in olfactory bulbectomized-mice model of depression

Oxido-inflammatory aberrations play a substantial role in the pathophysiology of depression. Oxido-inflammatory stress increases catabolism of tryptophan into kynurenine which leads to imbalance in kynurenine and serotonin levels in the brain. Naringenin a flavonoid, has been reported to possess antidepressant property by restoring serotonin and noradrenaline levels in the brain. Its effects on oxido-inflammatory aberrations in depression has not been investigated. With this background, the present study was designed to investigate the antidepressant-like potential of naringenin in olfactory bulbectomy (OBX)-induced neuroinflammation, oxidative stress, altered kynurenine pathway, and behavioural deficits in BALB/c mice. OBX-mice showed depression-like behavioural alterations characterized by hyperactivity in open field, increased immobility time in forced swim test and decreased sucrose preference. After 14 days, OBX-mice were treated by gavage with naringenin (25, 50 and 100 mg/kg) and fluoxetine (5 mg/kg) for two weeks. Naringenin significantly ameliorated depression-like behavioural alterations. Naringenin significantly restored corticosterone levels in serum and antioxidant enzymes (Catalase, SOD GSH), nitrite and MDA in cerebral cortex and hippocampus showing its anti-stress and antioxidant property. Naringenin also significantly decreased elevated pro-inflammatory cytokines like IL-1β, IL-6, TNF-α and NF-ҝβ levels. Naringenin also significantly increased neurotrophic growth factor like BDNF. Naringenin reversed altered levels of tryptophan, serotonin, 5-Hydroxyindole acetic acid and kynurenine in hippocampus and cortex. A positive correlation was found between KYN/TRP ratio and proinflammatory parameters while endogenous antioxidants were negatively correlated. In conclusion, naringenin showed potent neuroprotective effect in depression comparable to the fluoxetine by restoring alterations in kynurenine pathway via its antioxidant and anti-inflammatory potential.

Naringenin attenuates behavioral derangements induced by social defeat stress in mice via inhibition of acetylcholinesterase activity, oxidative stress and release of pro-inflammatory cytokines

The effects of naringenin; a dietary flavonoid, with potent anti-oxidant and anti-inflammatory activities on social defeat stress (SDS)-induced neurobehavioral and biochemical changes were evaluated in mice using resident-intruder paradigm. The intruder male mice were distributed into 6 groups (n = 6). Mice in group 1 (control) received vehicle (3% DMSO, i.p), group 2 (SDS-control) were also given vehicle, groups 3-5 received naringenin (10, 25 and 50 mg/kg, i.p.) while group 6 had ginseng (50 mg/kg, i.p) daily for 14 days. However, 30 min after treatment on day 7, mice in groups 2-6 were exposed to SDS for a period of 10 min confrontation with aggressive counterparts for 7 consecutive days. Neurobehavioral phenotypes: spontaneous motor activity (SMA), memory, anxiety and depression were then evaluated on day 14. Malondialdehyde (MDA), glutathione (GSH), catalase and superoxide dismutase (SOD) were then estimated in the brain tissues. Acetylcholinesterase (AChE) activity and the concentrations of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) were also determined. SDS-induced neurobehavioral deficits were significantly (p < 0.05) attenuated by naringenin. The increased brain level of MDA (13.00 ± 0.63 μmol/g tissue) relative to vehicle-control (6.50 ± 0.43 μmol/g tissue) was significantly (p < 0.05) reduced to 5.50 ± 0.22 μmol/g tissue by naringenin (50 mg/kg). Mice exposed to SDS had decreased brain GSH level (5.17 ± 0.40 μmol/g tissue) relative to control (11.67 ± 0.84 μmol/g tissue). However, naringenin (50 mg/kg) significantly (p < 0.05) elevated GSH content (13.33 ± 0.88 μmol/g tissue) in the brains of SDS-mice. Moreover, 50 mg/Kg of naringenin (38.13 ± 2.38 ρg/mL) attenuated (p < 0.05) increased TNF-α level when compared with SDS (49.69 ± 2.81 ρg/mL). SDS-induced increase in brain level of IL-1β (236.5 ± 6.92 ρg/mL) was significantly (p < 0.05) reduced by naringenin (219.90 ± 15.25 ρg/mL). Naringenin also elevated antioxidant enzymes and decreased AChE activity in the brains of mice exposed to SDS (p < 0.05). These findings suggest that naringenin attenuates SDS-induced neurobehavioral deficits through inhibition of acetylcholinesterase activity, oxidative stress and release of pro-inflammatory cytokines.

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.

Antidepressant Flavonoids and Their Relationship with Oxidative Stress

Depression is a serious disorder that affects hundreds of millions of people around the world and causes poor quality of life, problem behaviors, and limitations in activities of daily living. Therefore, the search for new therapeutic options is of high interest and growth. Research on the relationship between depression and oxidative stress has shown important biochemical aspects in the development of this disease. Flavonoids are a class of natural products that exhibit several pharmacological properties, including antidepressant-like activity, and affects various physiological and biochemical functions in the body. Studies show the clinical potential of antioxidant flavonoids in treating depressive disorders and strongly suggest that these natural products are interesting prototype compounds in the study of new antidepressant drugs. So, this review will summarize the chemical and pharmacological perspectives related to the discovery of flavonoids with antidepressant activity. The mechanisms of action of these compounds are also discussed, including their actions on oxidative stress relating to depression.

Evaluation of the antidepressant-like effect of musk in an animal model of depression: how it works

Depression has become a common public health problem that is showing increasing prevalence. Slow onset of action, low response rates and drug resistance are potential limitations of the current antidepressant drugs. Alternative therapy using natural substances, specifically aromatherapy, is currently tried to treat depression. This work aimed to assess the efficacy of musk in relieving the behavioral, biochemical and hippocampal histopathological changes induced by exposure to chronic mild stress in mice and explore the possible mechanism behind this antidepressant-like effect. Forty male albino mice were divided into four groups (n = 10): control, a group exposed to chronic unpredictable mild stress (CUMS) and two groups exposed to CUMS and then treated with fluoxetine or musk. Behavioral changes and serum corticosterone levels were assessed at the end of the experiment. Protein and gene expressions of brain-derived neurotropic factor (BDNF) and glucocorticoid receptors (GRs) in the hippocampus were assessed using ELISA and real-time RT-PCR, respectively. Histopathological examination of the hippocampus and immunohistochemical techniques using glial fibrillary acidic protein (GFAP), Ki67, caspase-3, BDNF and GR were performed. Inhalation of musk had an antidepressant-like effect in an animal model of depression. Musk alleviated the behavioral changes and elevated serum corticosterone levels induced by exposure to chronic stress. It reduced the hippocampal neuronal apoptosis and stimulated neurogenesis in the dentate gyrus. Musk's action may be related to the upregulation of hippocampal GR and BDNF expressions. Musk is considered a potential antidepressant so it is advisable to assess its efficacy in treating depressed patient.

Calcium imaging reveals glial involvement in transcranial direct current stimulation-induced plasticity in mouse brain

Transcranical direct current stimulation (tDCS) is a treatment known to ameliorate various neurological conditions and enhance memory and cognition in humans. tDCS has gained traction for its potential therapeutic value; however, little is known about its mechanism of action. Using a transgenic mouse expressing G-CaMP7 in astrocytes and a subpopulation of excitatory neurons, we find that tDCS induces large-amplitude astrocytic Ca²⁺ surges across the entire cortex with no obvious changes in the local field potential. Moreover, sensory evoked cortical responses are enhanced after tDCS. These enhancements are dependent on the alpha-1 adrenergic receptor and are not observed in IP₃R2 (inositol trisphosphate receptor type 2) knockout mice, in which astrocytic Ca²⁺ surges are absent. Together, we propose that tDCS changes the metaplasticity of the cortex through astrocytic Ca²⁺/IP₃ signalling.

While transcranical direct current stimulation (tDCS) is used in clinical setting, its cellular mechanism of action is unclear. Here, Hajime Hirase and colleagues visualize cellular response in mouse brain to tDCS and show robust astrocyte activation that coincide with plasticity changes.

Antidepressant-like effects of albiflorin extracted from Radix paeoniae Alba

ETHNOPHARMACOLOGY RELEVANCE

Albiflorin, a monoterpene glycoside, is a main component of Radix paeoniae Alba, which could be a Chinese herbal medicine used in the treatment of psychiatric disorders. However, the exact role of albiflorin in depression is poorly understood.

AIM OF THE STUDY

The current study aimed to evaluate the antidepressant effect of albiflorin in mice and rats, and the possible mechanism was also determined.

MATERIALS AND METHODS

The antidepressant-like effects of albiflorin was determined by using animal models of depression including forced swim and tail suspension tests in mice and chronic unpredictable stress (CUS) in rats. The acting mechanism was explored by determining the effect of albiflorin on the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus by western blot and the levels of monoamine in the hippocampus by HPLC.

RESULTS

Our results showed that 7 days treatment with albiflorin significantly decreased immobility time in the forced swimming test (FST) and the tail suspension test (TST) at doses of 3.5, 7.0 and 14.0mg/kg without alter the locomotor activity in mice. Moreover, western blot analysis showed that albiflorin could increase the expression of BDNF in the hippocampus. We further exposed rats to a chronic unpredictable stress (CUS) protocol for a period of 35d to induce depressive-like behaviors. We found that chronic treatment with albiflorin, at doses of 7.0 and 14.0mg (i.g., once daily for 35d), restored the sucrose preference in CUS rats. In the open-field test, albiflorin significantly increased the number of crossings and rearings in the CUS rats at three doses. Moreover, chronic treatment with albiflorin up-regulated the hippocampal BDNF expression levels and the hippocampal 5-HT, 5-HIAA, and NA levels.

CONCLUSION

Albiflorin produced significant antidepressant-like effects, which were closely related to the hippocampal 5-HT/NE increase and BDNF expression. Our data indicated that albiflorin could be a potential anti-depressant drug.

Naringenin Mitigates Iron-Induced Anxiety-Like Behavioral Impairment, Mitochondrial Dysfunctions, Ectonucleotidases and Acetylcholinesterase Alteration Activities in Rat Hippocampus

Studies demonstrated that the iron chelating antioxidant restores brain dysfunction induced by iron toxicity in animals. Earlier, we found that iron overload-induced cerebral cortex apoptosis correlated with oxidative stress could be protected by naringenin (NGEN). In this respect, the present study is focused on the mechanisms associated with the protective efficacy of NGEN, natural flavonoid compound abundant in the peels of citrus fruit, on iron induced impairment of the anxiogenic-like behaviour, purinergic and cholinergic dysfunctions with oxidative stress related disorders on mitochondrial function in the rat hippocampus. Results showed that administration of NGEN (50 mg/kg/day) by gavage significantly ameliorated anxiogenic-like behaviour impairment induced by the exposure to 50 mg of Fe-dextran/kg/day intraperitoneally for 28 days in rats, decreased iron-induced reactive oxygen species formation and restored the iron-induced decrease of the acetylcholinesterase expression level, mitochondrial membrane potential and mitochondrial complexes activities in the hippocampus of rats. Moreover, NGEN was able to restore the alteration on the activity and expression of ectonucleotidases such as adenosine triphosphate diphosphohydrolase and 5'-nucleotidase, enzymes which hydrolyze and therefore control extracellular ATP and adenosine concentrations in the synaptic cleft. These results may contribute to a better understanding of the neuroprotective role of NGEN, emphasizing the influence of including this flavonoid in the diet for human health, possibly preventing brain injury associated with iron overload.

Emodin opposes chronic unpredictable mild stress induced depressive-like behavior in mice by upregulating the levels of hippocampal glucocorticoid receptor and brain-derived neurotrophic factor

Emodin, the major active component of Rhubarb, has shown neuroprotective activity. This study is attempted to investigate whether emodin possesses beneficial effects on chronic unpredictable mild stress (CUMS)-induced behavioral deficits (depression-like behaviors) and explore the possible mechanisms. ICR mice were subjected to chronic unpredictable mild stress for 42 consecutive days. Then, emodin and fluoxetine (positive control drug) were administered for 21 consecutive days at the last three weeks of CUMS procedure. The classical behavioral tests: open field test (OFT), sucrose preference test (SPT), tail suspension test (TST) and forced swimming test (FST) were applied to evaluate the antidepressant effects of emodin. Then plasma corticosterone concentration, hippocampal glucocorticoid receptor (GR) and brain-derived neurotrophic factor (BDNF) levels were tested to probe the mechanisms. Our results indicated that 6 weeks of CUMS exposure induced significant depression-like behavior, with high, plasma corticosterone concentration and low hippocampal GR and BDNF expression levels. Whereas, chronic emodin (20, 40 and 80 mg/kg) treatments reversed the behavioral deficiency induced by CUMS exposure. Treatment with emodin normalized the change of plasma corticosterone level, which demonstrated that emodin could partially restore CUMS-induced HPA axis impairments. Besides, hippocampal GR (mRNA and protein) and BDNF (mRNA) expressions were also up-regulated after emodin treatments. In conclusion, emodin remarkably improved depression-like behavior in CUMS mice and its antidepressant activity is mediated, at least in part, by the up-regulating GR and BDNF levels in hippocampus.

BDNF signaling is necessary for the antidepressant-like effect of naringenin

Previous studies in our laboratory have demonstrated that naringenin produced antidepressant-like action in tail suspension test (TST). However, the underlying mechanisms involved in neurotrophin system by which naringenin works have not been investigated. The present study extends earlier works on the role of brain-derived neurotrophic factor (BDNF) in regulating the antidepressant-like actions of naringenin in chronic unpredictable mild stress (CUMS). We showed that a 21-day regimen with naringenin reversed the decreased sucrose preference in sucrose preference test (SPT) and the prolonged first feeding latency in novelty-suppressed feeding test (NSFT), without affecting home-cage feeding consumption. In addition, we also found that naringenin promoted BDNF expression in the hippocampus but not in the frontal cortex in both non-stressed and CUMS mice. Moreover, the antidepressant-like effect of naringenin in SPT and NSFT induced by naringenin administration were totally abolished by K252a, an inhibitor of BDNF receptor tropomyosin-related kinase receptor B (TrkB). In conclusion, our findings suggest that the antidepressant-like effect of naringenin may be mediated, at least in part, by the activation of BDNF signaling in the hippocampus.

Impaired glucocorticoid production and response to stress in Arntl-deficient male mice

The basic helix-loop-helix transcription factor Aryl Hydrocarbon Receptor Nuclear Translocator-Like (ARNTL, also known as BMAL1 or MOP3) is a core component of the circadian timing system in mammals, which orchestrates 24-hour rhythms of physiology and behavior. Genetic ablation of Arntl in mice leads to behavioral and physiological arrhythmicity, including loss of circadian baseline regulation of glucocorticoids (GCs). GCs are important downstream regulators of circadian tissue clocks and have essential functions in the physiological adaptation to stress. The role of the clock machinery in the regulation of stress-induced GC release, however, is not well understood. Here we show that already under unstressed conditions Arntl-deficient mice suffer from hypocortisolism with impaired adrenal responsiveness to ACTH and down-regulated transcription of genes involved in cholesterol transport in adrenocortical cells. Under stress they show diminished GC and behavioral responses and develop behavioral resistance to acute and subchronic stressors, as shown using forced swim, tail suspension, and sucrose preference tests. These data suggest that the clock gene Arntl regulates circadian and acute secretion of GCs by the adrenal gland. Arntl disruption, probably via its effect on adrenal clock function, modulates stress axis activity and, thus, may promote resistance to both acute and repeated stress.

Citrus aurantium and Rhodiola rosea in combination reduce visceral white adipose tissue and increase hypothalamic norepinephrine in a rat model of diet-induced obesity

Extracts from the immature fruit of Citrus aurantium are often used for weight loss but are reported to produce adverse cardiovascular effects. Root extracts of Rhodiola rosea have notable antistress properties. The hypothesis of these studies was that C aurantium (6% synephrine) and R rosea (3% rosavins, 1% salidroside) in combination would improve diet-induced obesity alterations in adult male Sprague-Dawley rats. In normal-weight animals fed standard chow, acute administration of C aurantium (1-10 mg/kg) or R rosea (2-20 mg/kg) alone did not reduce deprivation-induced food intake, but C aurantium (5.6 mg/kg) + R rosea (20 mg/kg) produced a 10.5% feeding suppression. Animals maintained (13 weeks) on a high-fat diet (60% fat) were exposed to 10-day treatments of C aurantium (5.6 mg/kg) or R rosea (20 mg/kg) alone or in combination. Additional groups received vehicle (2% ethanol) or were pair fed to the C aurantium + R rosea group. Although high-fat diet intake and weight loss were not influenced, C aurantium + R rosea had a 30% decrease in visceral fat weight compared with the other treatments. Only the C aurantium group had an increased heart rate (+7%) compared with vehicle. In addition, C aurantium + R rosea administration resulted in an elevation (+15%) in hypothalamic norepinephrine and an elevation (+150%) in frontal cortex dopamine compared with the pair-fed group. These initial findings suggest that treatments of C aurantium + R rosea have actions on central monoamine pathways and have the potential to be beneficial for the treatment of obesity.