Antidepressant-like effect of the extract from leaves of Schinus molle L. in mice: evidence for the involvement of the monoaminergic system

Phytochemical characterization and nutritional value of vegetable oils from ripe berries of Schinus terebinthifolia raddi and Schinus molle L., through extraction methods

The aims of this study are the phytochemical exploration and food valorization of Schinus molle L. (S. molle) and Schinus terebinthifolia Raddi (S. terebinthifolia) from the Rabat, Morocco. Gas chromatography (GC) and high-performance liquid chromatography (HPLC) were used to analyze the chemical composition of the oils extracted from both species by soxhlet and maceration. Moreover, physicochemical characteristics such as lipid quality indexes such as thrombogenic index (TI), atherogenic index (AI), oxidation susceptibility (OS), and calculated oxidability (Cox) were determined. These characteristics included percentage acidity, peroxide, saponification, iodine, specific extinction values, chlorophyll, and carotenoid pigments. As results, the oil yields varied from 7% (S. molle) to 13% (S. terebinthifolia). In addition, unsaturated fatty acids represented the major fraction for S. terebinthifolia (79%) and S. molle (81%). However, S. terebinthifolia contains more saturated fatty acids (20%) than S. molle (16%) with a predominance of linoleic acid (59.53% and 55%, C18,2), oleic acid (19.29% and 21.69%, C18,1), and palmitic acid (12.56% and 15.48%, C16,0) in S. molle and S. terebinthifolia, respectively. Moreover, the main sterols are β-sitosterol followed by campesterol and then Δ-5-avenasterol, while β-sitosterol varies according to the species and the extraction method. Results revealed also that campesterol is influenced by the extraction results in a content of 179.66 mg/kg (soxhlet) and 63.48 mg/kg (maceration) for S. molle, while S. terebinthifolia yeilds concentrations of 170 mg/kg and 138 mg/kg, then Δ-5-avenasterol, which present with (117 mg/kg and 136 mg/kg), (34 mg/kg and 80 mg/kg) of the total amount of sterols for the oils extracted by soxhlet and maceration, respectively. In addition, there are favorable physicochemical properties for all oils, such as chlorophylls (0.4 to 0.8 mg/kg) and carotenoids (0.7 to 2 mg/kg). However, further investigations are needed to determine other chemical compounds of both extracts as well as to evaluate their biological and health benefits.

Acute toxicity and genotoxicity of Schinus molle L. aqueous extract/ethanol-soluble fraction in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Schinus molle L. is a medicinal species belonging to the Anacardiaceae family. It is commonly referred to as "aroeira" and its leaves and roots are utilized for treating different pathological conditions. However, despite its widespread use in traditional medicine, there is a lack of in-depth toxicological studies.

AIM

To evaluate the acute toxicity and genotoxicity of S. molle aqueous extract/ethanol-soluble fraction in rats.

MATERIAL AND METHODS

First, a purified aqueous extract was obtained from the leaves of S. mole through infusion (referred to as EESM) and its compounds were identified using LC-DAD-MS data. Female rats were then subjected to acute oral toxicity tests using doses of 5, 50, 300, and 2000 mg/kg of ESSM. Studies on genetic material, including the micronucleus test and comet assay, were conducted on male and female Wistar rats using the same doses as in the acute toxicity test. For both assays, ESSM was administered orally.

RESULTS

The main metabolites annotated from ESSM were dimeric proanthocyanidins, phenylpropanoids acids, flavan-3-ols, simple organic acids (C6-C1), a flavonol di-O-glycosylated (rutin), and O-glycosylated megastigmane. The ESSM did not exhibit any acute toxic effects, such as changes in biochemical, hematologic, or histopathological analysis. Furthermore, no changes were observed in comet assay or micronucleus tests when rats were given doses of 5, 50, 300, or 2000 mg/kg of ESSM.

CONCLUSION

The results showed that the ESSM does not induce acute toxicity or exhibit genotoxicity up to a dose of 2000 mg/kg.

Phytoconstituents Targeting the Serotonin 5-HT3 Receptor: Promising Therapeutic Strategies for Neurological Disorders

The 5-hydroxytryptamine-3 receptor (5-HT3R), a subtype of serotonin receptor, is a ligand-gated ion channel crucial in mediating fast synaptic transmission in the central and peripheral nervous systems. This receptor significantly influences various neurological activities, encompassing neurotransmission, mood regulation, and cognitive processing; hence, it may serve as an innovative target for neurological disorders. Multiple studies have revealed promising results regarding the beneficial effects of these phytoconstituents and extracts on conditions such as nausea, vomiting, neuropathic pain depression, anxiety, Alzheimer's disease, cognition, epilepsy, sleep, and dyskinesia via modulation of 5-HT3R in the pathophysiology of neurological disorder. The review delves into a detailed exploration of in silico, in vitro, and in vivo studies and clinical studies that discussed phytoconstituents acting on 5-HT3R and attenuates difficulties in neurological diseases. The diverse mechanisms by which plant-derived phytoconstituents influence 5-HT3R activity offer exciting avenues for developing innovative therapeutic interventions. Besides producing an agonistic or antagonistic effect, some phytoconstituents exert modulatory effects on 5-HT3R activity through multifaceted mechanisms. These include γ-aminobutyric acid and cholinergic neuronal pathways, interactions with neurokinin (NK)-1, NK2, serotonergic, and γ-aminobutyric acid(GABA)ergic systems, dopaminergic influences, and mediation of calcium ions release and inflammatory cascades. Notably, the phytoconstituent's capacity to reduce oxidative stress has also emerged as a significant factor contributing to their modulatory role. Despite the promising implications, there is currently a dearth of exploration needed to understand the effect of phytochemicals on the 5-HT3R. Comprehensive preclinical and clinical research is of the utmost importance to broaden our knowledge of the potential therapeutic benefits associated with these substances.

Antidepressant Effects of South African Plants: An Appraisal of Ethnobotanical Surveys, Ethnopharmacological and Phytochemical Studies

Globally, the search for safe and potent natural-based treatment for depression is receiving renewed interest given the numerous side-effects associated with many existing drugs. In South Africa, the use of plants to manage depression and related symptoms is fairly documented among different ethnic groups. In the current study, we reviewed existing ethnobotanical, ethnopharmacological and phytochemical studies on South African medicinal plants used to manage depression. Electronic databases were accessed for scientific literature that meets the inclusion criteria. Plants with ethnobotanical evidence were subjected to a further pharmacological review to establish the extent (if any) of their effectiveness as antidepressants. Critical assessment resulted in 20 eligible ethnobotanical records, which generated an inventory of 186 plants from 63 plant families. Due to the cultural differences observed in the definition of depression, or lack of definition in some cultures, most plants are reported to treat a wide range of atypical symptoms related to depression. Boophone disticha, Leonotis leonurus and Mentha longifolia were identified as the three most popular plants, with over eight mentions each from the ethnobotanical records. The dominant families were Asteraceae (24), Fabaceae (16), Amaryllidaceae (10), and Apocynaceae (10) which accounted for about 32% of the 186 plants. Only 27 (≈14.5%) of the plants have been screened for antidepressant activity using in vitro and in vivo models. Agapanthus campanulatus, Boophone disticha, Hypericum perforatum, Mondia whitei and Xysmalobium undulatum, represent the most studied plants. Phytochemical investigation on nine out of the 27 plants revealed 24 compounds with antidepressant-like effects. Some of these included buphanidrine and buphanamine which were isolated from the leaves of Boophone disticha, Δ⁹-tetrahydrocannabinol, cannabidiol and cannabichromene obtained from the buds of Cannabis sativa and carnosic acid, rosmarinic acid and salvigenin from Rosmarinus officinalis, A significant portion (≈85%) of 186 plants with ethnobotanical records still require pharmacological studies to assess their potential antidepressant-like effects. This review remains a valuable reference material that may guide future ethnobotanical surveys to ensure their robustness and validity as well as database to identify promising plants to screen for pharmacology efficacy.

Natural Products for the Treatment of Post-stroke Depression

Post-stroke depression (PSD) is the most frequent and important neuropsychiatric consequence of stroke. It is strongly associated with exacerbated deterioration of functional recovery, physical and cognitive recoveries, and quality of life. However, its mechanism is remarkably complicated, including the neurotransmitters hypothesis (which consists of a monoaminergic hypothesis and glutamate-mediated excitotoxicity hypothesis), inflammation hypothesis, dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis, and neurotrophic hypothesis and neuroplasticity. So far, the underlying pathogenesis of PSD has not been clearly defined yet. At present, selective serotonin reuptake inhibitors (SSRIs) have been used as the first-line drugs to treat patients with PSD. Additionally, more than SSRIs, a majority of the current antidepressants complied with multiple side effects, which limits their clinical application. Currently, a wide variety of studies revealed the therapeutic potential of natural products in the management of several diseases, especially PSD, with minor side effects. Accordingly, in our present review, we aim to summarize the therapeutic targets of these compounds and their potential role in-clinic therapy for patients with PSD.

Translational Informatics for Natural Products as Antidepressant Agents

Depression, a neurological disorder, is a universally common and debilitating illness where social and economic issues could also become one of its etiologic factors. From a global perspective, it is the fourth leading cause of long-term disability in human beings. For centuries, natural products have proven their true potential to combat various diseases and disorders, including depression and its associated ailments. Translational informatics applies informatics models at molecular, imaging, individual, and population levels to promote the translation of basic research to clinical applications. The present review summarizes natural-antidepressant-based translational informatics studies and addresses challenges and opportunities for future research in the field.

Medicinal Plants in the Treatment of Depression: Evidence from Preclinical Studies

Medicinal plants and their extracts are natural remedies with enormous potential for treating various diseases, including depression and anxiety. In the case of depression, hundreds of plants have traditionally been used in folk medicine for generations. Different plant extracts and natural products have been analyzed as potential antidepressant agents with validated models to test for antidepressant-like effects in animals, although other complementary studies have also been employed. Most of these studies focus on the possible mediators implicated in these potential effects, with dopamine, serotonin, and noradrenaline being the principal neurotransmitters implicated, both through interference with receptors and with their metabolism by monoamino oxidases, as well as through neuro-endocrine and neuroprotective effects. There are approximately 650 reports of antidepressant-like medicinal plants in PubMed; 155 of them have been compiled in this review, with a relevant group yielding positive results. Saffron and turmeric are the most relevant species studied in both preclinical and clinical studies; St. John's wort or kava have also been tested extensively. To the best of our knowledge, no review to date has provided a comprehensive understanding of the biomolecular mechanisms of action of these herbs or of whether their potential effects could have real benefits. The purpose of this narrative review is to provide an update regarding medicinal plants from the year 2000 to the present to examine the therapeutic potential of these antidepressant-like plants in order to contribute to the development of new therapeutic methods to alleviate the tremendous burden that depression causes worldwide.

Antispasmodic, antidepressant and anxiolytic effects of extracts from Schinus lentiscifolius Marchand leaves

Schinus lentiscifolius (Anacardiaceae) is widely used in folk medicine for treating gastrointestinal and emotional complaints but there are no scientific studies that support these uses. This work aims at evaluating the antispasmodic and central effects of S. lentiscifolius as well as the flavonoids presence in the tincture (SchT) and the composition of the essential oil (SchO). SchT inhibited the concentration-response curves (CRC) of carbachol and calcium in a non-competitive way in isolated rat intestine, bladder and uterus. SchT also non-competitively inhibited the CRC of histamine in guinea-pig intestine and the CRCs of serotonin and oxytocin in rat uterus. Isoquercetin and rutin were identified in SchT. The behavioral effects of SchT, SchO and infusion of S. lentiscifolius leaves (SchW) were tested in mice. These extracts showed an anxiolytic-like effect in the novelty-suppressed feeding test, which was reversed by flumazenil except in SchO-treated mice. Only SchO reduced the spontaneous locomotor function in the open field test. Also, SchT and SchW decreased immobility time in both, the tail suspension (TST) and forced swimming tests, while SchO produced the same effect in the TST. d-limonene and α-santalol were the main components found in SchO. The results demonstrated that extracts obtained from S. lentiscifolius leaves were effective as intestinal, urinary and uterine antispasmodics. SchT and SchW exhibited anxiolytic and antidepressant properties without sedation, whereas SchO showed also sedative properties. Therefore, the present study gives preclinical support to the traditional use of this plant for gastrointestinal and depressive or emotional symptoms.

•

Schinus lentiscifolius is popularly consumed for its medicinal properties but there are no scientific studies in this regard.

•We evaluated its effects on visceral smooth muscle and central nervous system. Our findings reinforce its traditional uses.

•In addition, we propose possible new therapeutic applications.

HPLC-ESI-QTOF-MS/MS profiling and therapeutic effects of Schinus terebinthifolius and Schinus molle fruits: investigation of their antioxidant, antidiabetic, anti-inflammatory and antinociceptive properties

The aim of the current work was to study the phytochemical variability among Schinus terebinthifolius (STE) and Schinus molle (SME) fruit extracts. The in vitro antioxidant, antihemolytic, antidiabetic, and macromolecule damage protective activities, as well as, the in vivo anti-inflammatory and antinociceptive capacities were assessed. Using the HPLC-ESI-QTOF/MS analysis, the chemical profile of fruit extract varied between S. terebinthifolius (30 compounds) and S. molle (16 compounds). The major compound was masazino-flavanone (5774.98 and 1177.65 μg/g sample for STE and SME, respectively). The investigations highlighted significant antioxidant proprieties when using ABTS radical (IC₅₀; 0.12 and 0.14 mg/ml for STE and SME, respectively), superoxide (IC₅₀; 0.17 and 0.22 mg/ml for STE and SME, respectively) and hydrogen peroxide (IC₅₀; 014 and 0.17 mg/ml for STE and SME, respectively). In addition, STE and SME proved preventive effects against H₂O₂-induced hemolysis (IC₅₀; 0.22 and 0.14 mg/ml for STE and SME, respectively). The in vitro antidiabetic effect revealed that STE and SME exhibited important inhibitory effects against α-amylase (IC₅₀; 0.13 and 0.19 mg/ml for STE and SME, respectively) and α-glycosidase (IC₅₀; 0.21 and 0.18 mg/ml for STE and SME, respectively) when compared with acarbose. Furthermore, the extracts showed potent inhibitory activity against AAPH-induced plasmid DNA damage, and protein oxidation. In vivo study revealed that STE and SME presented interesting antinociceptive and anti-inflammatory capacities. All observed effects highlighted the potential application of Schinus fruit extract in food and pharmaceutical industries against ROS-induced damage.

Adenylyl Cyclase (AC) Mediates the Antidepressant-Like Effects of Tropisetron on a Mouse Model of Maternal Separation Stress

The adenylyl cyclase (AC) pathway is involved in the pathophysiology of depression. Finding new antidepressants with high medicinal properties and low side effects is warranted. Therefore, this study was designed to determine the antidepressant-like effect of tropisetron on a maternal separation (MS) model in mice, considering the possible role of AC. NMRI male mice were divided into eleven groups. The control group was treated with saline and MS groups were treated with saline, tropisetron (a 5-HT3 receptor antagonist) at doses of 1, 3, and 5 mg/kg; forskolin (an activator of AC) at doses of 5, 10, and 25 mg/kg; a subeffective dose of forskolin with a subeffective dose of tropisetron; and an effective dose of tropisetron plus an effective dose of NB001 (3 mg/kg) (an AC inhibitor). After treatment, animals were subjected to behavioral tests including the forced swimming test (FST), splash test, and open field test (OFT). We showed that MS caused depressive-like behaviors determined as an increase in the immobility time in the forced swimming test (FST) and decreased grooming time in the splash test. Our results showed that administration of tropisetron, as well as forskolin, mitigated the depressive-like behaviors in MS mice. We found that coadministration of a subeffective dose of tropisetron plus a subeffective dose of forskolin potentiated the antidepressant-like effect of tropisetron. However, coadministration of an effective dose of NB001 with an effective dose of tropisetron did not significantly affect the antidepressant-like effect of tropisetron. We concluded that the antidepressant-like effects of tropisetron on MS mice are partially mediated through the adenylyl cyclase pathway.

Antidepressant-like effect of a selenopropargylic benzamide in mice: involvement of the serotonergic system

RATIONALE

Major depressive disorder is a psychiatric disorder that requires considerable attention, since it dramatically impairs the quality of life of the sufferers. The available treatments do not have the efficacy needed, often presenting several side effects. Organoselenium compounds and benzamides have presented some pharmacological properties, among them an antidepressant-like effect.

OBJECTIVES AND METHODS

This study evaluated the antidepressant-like effect of N-(3-(phenylselanyl)prop-2-yn-1-yl)benzamide (SePB), an organoselenium compound containing a benzamide moiety, on the forced swimming test (FST) and the tail suspension test (TST) in mice, as well as the involvement of the serotonergic system in its effect.

RESULTS

SePB, tested after different times (15-120 min) and doses (1-50 mg/kg, intragastrically (i.g.)), reduced immobility of male mice during FST and TST, without changing locomotor activity in the open-field test (OFT), demonstrating its antidepressant-like effect. SePB (10 mg/kg) also produced an antidepressant-like effect in female mice in the TST. The preadministration of the serotonin (5-HT) depletor p-chlorophenylalanine (pCPA; 100 mg/kg, intraperitoneal route (i.p.) once daily for 4 days) prevented the anti-immobility effect of SePB, indicating that the serotonergic system is involved in the SePB antidepressant-like effect. The preadministration of the selective serotonergic receptor antagonists WAY100635 (0.1 mg/kg, subcutaneous route (s.c.), a selective 5-HT_1A receptor antagonist), ketanserin (1 mg/kg, i.p., a 5-HT_2A/2C receptor antagonist), and ondansetron (1 mg/kg, i.p., a selective 5-HT₃ receptor antagonist) also prevented the anti-immobility effect of SePB, demonstrating that these receptors are involved in the antidepressant-like effect of SePB.

CONCLUSION

The search for new antidepressants drugs is a noteworthy goal. This study has described a new compound with an antidepressant-like effect, whose mechanism of action is related to modulation of the serotonergic system.

Absence of Glia Maturation Factor Protects from Axonal Injury and Motor Behavioral Impairments after Traumatic Brain Injury

Traumatic brain injury (TBI) causes disability and death, accelerating the progression towards Alzheimer's disease and Parkinson's disease (PD). TBI causes serious motor and cognitive impairments, as seen in PD that arise during the period of the initial insult. However, this has been understudied relative to TBI induced neuroinflammation, motor and cognitive decline that progress towards PD. Neuronal ubiquitin-C-terminal hydrolase- L1 (UCHL1) is a thiol protease that breaks down ubiquitinated proteins and its level represents the severity of TBI. Previously, we demonstrated the molecular action of glia maturation factor (GMF); a proinflammatory protein in mediating neuroinflammation and neuronal loss. Here, we show that the weight drop method induced TBI neuropathology using behavioral tests, western blotting, and immunofluorescence techniques on sections from wild type (WT) and GMF-deficient (GMF-KO) mice. Results reveal a significant improvement in substantia nigral tyrosine hydroxylase and dopamine transporter expression with motor behavioral performance in GMF-KO mice following TBI. In addition, a significant reduction in neuroinflammation was manifested, as shown by activation of nuclear factor-kB, reduced levels of inducible nitric oxide synthase, and cyclooxygenase- 2 expressions. Likewise, neurotrophins including brain-derived neurotrophic factor and glial-derived neurotrophic factor were significantly improved in GMF-KO mice than WT 72 h post-TBI. Consistently, we found that TBI enhances GFAP and UCHL-1 expression and reduces the number of dopaminergic TH-positive neurons in WT compared to GMF-KO mice 72 h post-TBI. Interestingly, we observed a reduction of THpositive tanycytes in the median eminence of WT than GMF-KO mice. Overall, we found that absence of GMF significantly reversed these neuropathological events and improved behavioral outcome. This study provides evidence that PD-associated pathology progression can be initiated upon induction of TBI.

Schinus terebinthifolius Essential Oil Attenuates Scopolamine-Induced Memory Deficits via Cholinergic Modulation and Antioxidant Properties in a Zebrafish Model

Schinus terebinthifolius is a plant well recognized for its therapeutic profile such as anti-inflammatory and antitumor activities, promoting antibacterial activity and antioxidant and antidiabetic properties. This study aimed at examining whether Schinus terebinthifolius memory-enhancing activities are mediated by cholinergic and brain antioxidant systems in a scopolamine zebrafish model. Schinus terebinthifolius essential oil (10, 25, and 50 μL/L) was delivered to zebrafish by immersion in water for 8 days. Memory deficits were induced by scopolamine (100 μM) administration. Zebrafish were divided into seven groups (n = 15/group): vehicle group, scopolamine (100 μM) group, Schinus terebinthifolius essential oil groups (STF; 10, 25, and 50 μL/L), the imipramine group (IMP; 20 mg/L, as the positive control in the NTT test), and the donepezil group (DP; 10 mg/L, as the positive control in the Y-maze test). Memory status was estimated by the novel tank diving test (NTT) and the Y-maze test and finally was validated by comparison with imipramine (20 mg/L) and donepezil (10 mg/L). Gas chromatography-mass spectrometry (GC-MS) was used to detect oil compounds. Brain levels of acetylcholinesterase (AChE) and antioxidant enzymes were measured. After being exposed to Schinus terebinthifolius essential oil, the scopolamine zebrafish exhibited an improvement of memory processes in the NTT and Y-maze tests. The essential oil attenuated the elevated level of AChE and brain oxidative stress. Schinus terebinthifolius essential oil was found to support memory formation through the inhibition of the AChE activity and decreasing oxidative stress in the scopolamine-treated zebrafish brains.

Chemodiversity and Antiproliferative Activity of the Essential Oil of Schinus molle Growing in Jordan

The leaves and unripe and fully-grown fruits of Schinus molle were collected from three geographical regions of Jordan: Amman (the Mediterranean), Madaba (Irano-Turanean), and Sahab (Saharo-Arabian). The hydrodistilled volatile oils of fresh and dried leaves and fruits were analyzed by gas chromatography-mass spectrometry (GC/MS). The actual composition of the emitted volatiles was determined using Solid Phase Micro-Extraction (SPME). α- and β-Phellandrenes were the major components in all the analyzed samples. Quantitative differences were observed in the obtained essential oils (0.62-5.25 %). Additionally, cluster analysis was performed. Biologically, the antiproliferative activity of the essential oil, ethanol, and water extracts of the fruits and leaves was screened on Caco2, HCT116, MCF7, and T47D cell lines. The essential oil and ethanol extracts exhibited a dose-dependent inhibition of cell growth with IC₅₀ ranging between 21 and 65 μg/mL. The water extract did not exhibit any antiproliferative activity against the investigated cell lines.

Schinus molle essential oil as a potential source of bioactive compounds: antifungal and antibacterial properties

AIMS

The study was focused on the evaluation of antimicrobial activity in vitro of the essential oil (EO) of leaves from Schinus molle against bacteria and fungi of clinical importance in the search for the discovery of new active compounds.

METHODS AND RESULTS

The chemical composition of the S. molle EO was determined by gas chromatography/mass spectrometry and its antimicrobial effect was verified by broth microdilution method. The major compounds found were β-pinene (25·23%), epi-α-cadinol (21·29%), α-pinene (18·72%), myrcene (11·54%) and sabinene (5·02%). The EO showed significant antifungal activity against Paracoccidioides brasiliensis (39·06 μg ml^-1 ), weak action against Cryptococcus neoformans (625 μg ml^-1 ) and Trichophyton quinckeanum (625 μg ml^-1 ) and was inactive against Candida sp. In the analysis of the antibacterial action, the micro-organisms tested did not show sensitivity.

CONCLUSIONS

This study showed a promising result of S. molle volatiles against the fungus P. brasiliensis, which causes paracoccidioidomycosis (PCM), a systemic mycosis of great clinical importance in Latin America.

SIGNIFICANCE AND IMPACT OF THE STUDY

The results found here are novel and encourage investigations of the compounds present in this EO, which represents a source of molecules with potential use in the treatment of PCM.

Phytochemistry and pharmacology of anti-depressant medicinal plants: A review

Stress renders an individual to experience mental pressure and exhaustion which brings about feelings of anxiety, depression, anger and/or other negative emotions. Depression affects a person's state of mind, behaviour, health and is often associated with suicide. The use of anti-depressant drugs as therapeutic agents is associated with symptoms such as, delayed onset of action, side-effects, drug-drug and dietary interactions, sexual dysfunction, cardiac toxicity, etc. Thus, there is need to target these issues and improve current treatment options. Medicinal plants have long been used in discovering novel treatment strategies and compounds with promising roles in treating various disease conditions. There has been an increase, worldwide, in the use of medicinal plants and herbs for developing nutraceuticals for treatment of depression and other psychiatric disorders. Medicinal plants in their natural forms are valuable as they are rich in various phytochemical compounds. These phytochemical compounds have pharmacological roles in treating various diseases conditions; apart from being widely available in nature and commercially beneficial. The phytochemical compounds in plants are constantly being explored through various experimental studies to determine the molecular basis of how medicinal plants work in relation to drugs and diseases and to develop neutraceuticals for improving conditions. This review summarizes 110 medicinal plants and their phytochemical constituents that have been shown to possess anti-depressant activity. This review also highlights the various mechanisms of anti-depressant action of some of these plants and their plant parts like roots, stem, leaves, flowers, fruit or whole plant; phytochemical compounds showing anti-depressant activity such flavanoids, steroids, saponins, sugars, lectins, alkaloids, etc.; and various anti-depressant screening models used such as tail suspension test, forced swim test, chronic unpredictable stress test, sucrose preference test, monoamine oxidase inhibition assay, learned helplessness test, open field test, hole board test, etc. However, mechanistic evaluation of many of these plants still needs to be investigated and explored.

In Vitro Anthelmintic Activity of Crude Extracts of Aerial Parts of Cissus quadrangularis L. and Leaves of Schinus molle L. against Haemonchus contortus

BACKGROUND

Haemonchus contortus, the causative agent of Haemonchosis, is the most economically important parasite in small ruminant production. Control with chemotherapy has not been successful due to rapid emergence of drug-resistant strains. There is a continuous search for alternative leads particularly from plants. The study aimed to evaluate the anthelmintic activity of crude methanolic extracts of leaves of Schinus molle and aerial parts of Cissus quadrangularis against H. contortus. Methods. Adult motility test and egg hatching inhibition assay were employed to investigate the in vitro adulticidal and egg hatching inhibitory effects of the extracts.

RESULTS

Higher concentrations of the extracts (10 and 5 mg/ml) had a significantly superior adulticidal activity (p < 0.05) compared to the negative control and lower concentration levels, which was comparable to albendazole. Similarly, the relative egg hatch inhibition efficacy of S. molle and C. quadrangularis extracts indicated a maximum of 96% and 88% egg hatch inhibition, respectively, within the 48 hrs of exposure at 1 mg/ml.

CONCLUSION

The current study evidenced that the crude methanolic extracts of the plants have promising adulticidal and egg hatching inhibitory effects against H. contortus.

Antidepressant-like deliverables from the sea: evidence on the efficacy of three different brown seaweeds via involvement of monoaminergic system

Brown seaweeds exhibit several health benefits in treating and managing wide array of ailments. In this study, the antidepressant-like effect of methaolic extracts from Sargassum swartzii (SS), Stoechospermum marginatum (SM), and Nizamuddinia zanardinii (NZ) was examined in forced swimming test (FST), in rats. Oral administration of SS, SM, and NZ extract (30-60 mg/kg) exhibited antidepressant-like activity in FST by reducing immobility time as compared to control group, without inducing significant change in ambulatory behavior in open field test. In order to evaluate the involvement of monoaminergic system, rats were pretreated with the inhibitor of brain serotonin stores p-chlorophenylalanin (PCPA), dopamine (SCH23390 and sulpiride), and adrenoceptor (prazosin and propranolol) antagonists. Rats receiving treatment for 28 days were decapitated and brains were analyzed for monoamine levels. It may be concluded that the extracts of SS, SM, and NZ produces antidepressant-like activity via modulation of brain monoaminergic system in a rat model.

Selective inhibition of MAO-A activity results in an antidepressant-like action of 2-benzoyl 4-iodoselenophene in mice

Depression is a leading cause of disability worldwide. For this reason, the aim of this study was to investigate the possible antidepressant-like activity of 2-benzoyl-4-iodoselenophene (C₁₇H₁₁IOSe), a selenophene compound, in two well-consolidated behavioral assays for screening antidepressant activity (forced swimming test and tail suspension test) in mice. In order to investigate the mechanism of action of C₁₇H₁₁IOSe, it was investigated the activities of cerebral enzymes: monoamine oxidase MAO A and B and Na⁺, K⁺ ATPase, and if an inhibitor of serotonin synthesis, p-chlorophenylalanine (pCPA) (100mg/kg) blocks the antidepressant-like effect of C₁₇H₁₁IOSe. Swiss mice received (C₁₇H₁₁IOSe) (5-50mg/kg) or canola oil by the intragastric (i.g.) route before behavioral tests. The results showed that C₁₇H₁₁IOSe at dose range of 5-50mg/kg decreased immobility time in the tail suspension test. In the forced swimming test, C₁₇H₁₁IOSe reduced the immobility time at the doses of 10 and 50mg/kg. C₁₇H₁₁IOSe differently affected the cerebral cortical Na⁺, K⁺ ATPase; the effects on this enzyme were dependent of the dose tested. At a dose of 10mg/kg, the compound increased Na⁺, K⁺ ATPase activity, while the activity was inhibited at a dose of 50mg/kg. pCPA blocked the antidepressant-like action of C₁₇H₁₁IOSe in mice. Therefore, C₁₇H₁₁IOSe (5-50mg/kg) selectively inhibited MAO-A activity in cerebral cortices of mice. The modulation of serotonergic system contributed to the antidepressant-like action of C₁₇H₁₁IOSe in mice.

Alpha-phellandrene-induced apoptosis in mice leukemia WEHI-3 cells in vitro

Although reports have shown that α-phellandrene (α-PA) is one of the monoterpenes and is often used in the food and perfume industry, our previous studies have indicated that α-PA promoted immune responses in normal mice in vivo. However, there is no available information to show that α-PA induced cell apoptosis in cancer cells, thus, we investigated the effects of α-PA on the cell morphology, viability, cell cycle distribution, and apoptosis in mice leukemia WEHI-3 cells in vitro. Results indicated that α-PA induced cell morphological changes and decreased viability, induced G0/G1 arrest and sub-G1 phase (apoptosis) in WEHI-3 cells. α-PA increased the productions of reactive oxygen species (ROS) and Ca²⁺ and decreased the levels of mitochondrial membrane potential (ΔΨ_m ) in dose- and time-dependent manners in WEHI-3 cells that were analyzed by flow cytometer. Results from confocal laser microscopic system examinations show that α-PA promoted the release of cytochrome c, AIF, and Endo G from mitochondria in WEHI-3 cells. These results are the first findings to provide new information for understanding the mechanisms by which α-PA induces cell cycle arrest and apoptosis in WEHI-3 cells in vitro. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1640-1651, 2016.

Modulation of muscarinic system with serotonin-norepinephrine reuptake inhibitor antidepressant attenuates depression in mice

Objective:

Several studies suggest that muscarinic receptor antagonist scopolamine is a rapidly acting antidepressant for the treatment-resistant depression. Therefore, this study was carried out to investigate the possibility of synergistic potential of scopolamine with antidepressants for the treatment of depression without memory impairment in mice.

Materials and Methods:

Antidepressants such as citalopram, duloxetine, fluvoxamine, and venlafaxine at their median effective dose that is 12.5, 42.8, 17.5, 15.7 mg/kg p.o., respectively, were evaluated in combination with scopolamine 0.2 mg/kg intraperitoneally for the synergistic potential for ameliorating depression in Swiss albino mice. A battery of tests including forced swim test (FST) and tail suspension test (TST) were performed in all the groups comprising vehicle control, scopolamine, antidepressants per se, and the combinations of antidepressants with scopolamine. This was followed by the locomotor activity and memory tests.

Results:

Behavioral studies indicated that only antidepressant venlafaxine with scopolamine resulted in 95.5% and 93.6% reduction in immobility time compared to the vehicle control in FST and TST, respectively. This is significant (P < 0.0001) synergistic hyper-additive antidepressive-like effect compared to scopolamine per se and venlafaxine per se treatment effects in antidepressant paradigms. All the data were evaluated using the one-way analysis of variance followed by individual comparisons using Tukey's post-hoc test. Control open field studies demonstrated no significant increase in general locomotion after co-administration of the compounds. Step down avoidance paradigm confirmed that scopolamine at the selected dose has no cognition deficit in any mice.

Conclusions:

The dose of scopolamine selected for synergistic potential has no detrimental effect on memory. The present results suggest the concoction of scopolamine with venlafaxine for enhanced synergistic antidepressive effects with the reduction of dose.

Reduced vasopressin receptors activation mediates the anti-depressant effects of fluoxetine and venlafaxine in bulbectomy model of depression

RATIONALE

In response to stress, corticotropin releasing hormone (CRH) and vasopressin (AVP) are released from the hypothalamus, activate their receptors (CRHR1, CRHR2 or AVPr1b), and synergistically act to induce adrenocorticotropic hormone (ACTH) release from the anterior pituitary. Overstimulation of this system has been frequently associated with major depression states.

OBJECTIVE

The objective of the study is to assess the role of AVP and CRH receptors in fluoxetine and venlafaxine effects on the expression of depression-related behavior.

METHODS

In an animal model of depression (olfactory bulbectomy in mice, OB), we evaluated the effects of fluoxetine or venlafaxine (both 10 mg/kg/day) chronic administration on depression-related behavior in the tail suspension test. Plasma levels of AVP, CRH, and ACTH were determined as well as participation of their receptors in the expression of depression related-behavior and gene expression of AVP and CRH receptors (AVPr1b, CRHR1, and CRHR2) in the pituitary gland.

RESULTS

The expression of depressive-like behavior in OB animals was reversed by treatment with both antidepressants. Surprisingly, OB-saline mice exhibited increased AVP and ACTH plasma levels, with no alterations in CRH levels when compared to sham mice. Chronic fluoxetine or venlafaxine reversed these effects. In addition, a significant increase only in AVPr1b gene expression was found in OB-saline.

CONCLUSION

The antidepressant therapy used seems to be more likely related to a reduced activation of AVP rather than CRH receptors, since a positive correlation between AVP levels and depressive-like behavior was observed in OB animals. Furthermore, a full restoration of depressive behavior was observed in OB-fluoxetine- or venlafaxine-treated mice only when AVP was centrally administered but not CRH.

Alpha-phellandrene-induced DNA damage and affect DNA repair protein expression in WEHI-3 murine leukemia cells in vitro

Although there are few reports regarding α-phellandrene (α-PA), a natural compound from Schinus molle L. essential oil, there is no report to show that α-PA induced DNA damage and affected DNA repair associated protein expression. Herein, we investigated the effects of α-PA on DNA damage and repair associated protein expression in murine leukemia cells. Flow cytometric assay was used to measure the effects of α-PA on total cell viability and the results indicated that α-PA induced cell death. Comet assay and 4,6-diamidino-2-phenylindole dihydrochloride staining were used for measuring DNA damage and condensation, respectively, and the results indicated that α-PA induced DNA damage and condensation in a concentration-dependent manner. DNA gel electrophoresis was used to examine the DNA damage and the results showed that α-PA induced DNA damage in WEHI-3 cells. Western blotting assay was used to measure the changes of DNA damage and repair associated protein expression and the results indicated that α-PA increased p-p53, p-H2A.X, 14-3-3-σ, and MDC1 protein expression but inhibited the protein of p53, MGMT, DNA-PK, and BRCA-1.

Effects of palatable cafeteria diet on cognitive and noncognitive behaviors and brain neurotrophins' levels in mice

The consumption of palatable high-fat and high-sugar foods have increased dramatically over the past years. Overconsumption of calorically dense food contributes to increasing rates of overweight and obesity that are associated with psychiatry disorders, in particular mood and anxiety disorders. This study evaluated the impact of palatable cafeteria diet (CAF) intake on cognitive and noncognitive behaviors, as well as identified factors related to these behaviors through an evaluation of brain neurotrophic factor (BDNF, NGF, and GDNF) levels in hippocampus of mice. Male Swiss mice received two different diets during 13 weeks: standard chow (STA) and highly CAF. Posteriorly, forced swimming test (FST), tail suspension test (TST), plus-maze test (PMT), open-field tests (OFT), and object recognition task (ORT) were utilized as behavioral tests. In addition, brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), and nerve growth factor (NGF) neurotrophins' levels were evaluated in hippocampus of mice. The results demonstrated that mice from the CAF group showed a decrease in the immobility time in the FST and TST. Besides, mice in the CAF group spent more time in the open arms of the PMT. No significant differences were observed in the cognitive behaviors, which were evaluated in the OFT and ORT. In addition, the CAF group showed that BDNF and NGF protein levels increased in the hippocampus of mice. In conclusion, our data suggest that the consumption of palatable high-fat and high-sugar foods induces antidepressant- and anxiolytic-like behaviors, which can be related with BDNF and NGF expression increases in hippocampus of mice in the CAF group.

Flavonoid-rich fraction of the Monodora tenuifolia seed extract attenuates behavioural alterations and oxidative damage in forced-swim stressed rats

The antidepressant effects of the flavonoid-rich fraction of Monodora tenuifolia seed extract were examined by assessing the extent of attenuation of behavioural alterations and oxidative damage in the rats that were stressed by forced swim test. Compared with the model control group, the altered behavioural parameters were attenuated significantly (P < 0.05) in the group treated with the flavonoid-rich fraction (100 and 200 mg·kg(-1)), comparable to the group treated with the standard drug, fluoxetine (10 mg·kg(-1)). The flavonoid-rich fraction and fluoxetine improved significantly (P < 0.05) the activities of the antioxidant enzymes such as superoxide dismutase and catalase as well as other biochemical parameters such as reduced glutathione, protein, and nitrite in the brain of the stressed rats. These results suggested that the flavonoid-rich fraction of Monodora tenuifolia seed extract exerted the antidepressant-like effects which could be useful in the management of stress induced disease.

Plant-derived natural medicines for the management of depression: an overview of mechanisms of action

Depression is a serious widespread psychiatric disorder that affects approximately 17% of people all over the world. Exploring the neurological mechanisms of the antidepressant activity of plant-derived agents could have a crucial role in developing natural drugs for the management of depression. The aim of the present study is to review the neurological mechanisms of action of antidepressant plants and their constituents. For this purpose, electronic databases, including PubMed, Science Direct, Scopus, and Cochrane Library, were searched from 1966 to October 2013. The results showed that several molecular mechanisms could be proposed for the antidepressant activity of medicinal plants and their constituents.

Anti-depressant-like effect of kaempferitrin isolated from Justicia spicigera Schltdl (Acanthaceae) in two behavior models in mice: evidence for the involvement of the serotonergic system

We evaluated the antidepressant-like effect of kaempferitrin (Km) isolated from the plant Justicia spicigera (Asteraceae), which is used in traditional medicine for relieving emotional disorders, such as "la tristeza" (sadness or dysthymia) and "el humor" (mood changes). The actions of Km were evaluated in a forced swimming test (FST) and a suspension tail test (TST) in mice. We explored the involvement of the serotonergic system and the hypothalamic-hypophysis-adrenal axis (HPA) in the antidepressant-like effect of Km. To evaluate nonspecific effects of Km on general activity, the open field test (OFT) was performed. Km at 5, 10, and 20 mg/kg induced an antidepressant-like effect. Sub-effective dose of Km (1 mg/kg) produced a synergistic effect with imipramine (6.25 mg/kg) and fluoxetine (10 mg/kg) but not with desipramine (3.12 mg/kg). Pretreatment with p-chlorophenylalanine methyl ester (PCPA), a serotonin synthesis inhibitor, N-{2-(4-(2-methoxyphenyl)-1-piperazinyl}-N-(2-pyridinyl)cyclohexecarboxamide (WAY-100635), a selective 5-HT1A receptor antagonist, and 8OH-DPAT, a selective 5-HT1A agonist, but not pindolol (10 mg/kg) blocked the anti- immobility effect induced by Km. Taken together, these results indicate that the antidepressant-like effect of Km is related to the serotonergic system, principally 5-HT1A. This effect was not related to changes in locomotor activity.

Antidepressant-like effect of Hoodia gordonii in a forced swimming test in mice: evidence for involvement of the monoaminergic system

Hoodia gordonii is a plant species used traditionally in southern Africa to suppress appetite. Recently, it has been associated with a significant increase in blood pressure and pulse rate in women, suggesting sympathomimetic activity. The present study investigated the possible antidepressant-like effects of acute and repeated (15 days) administration of H. gordonii extract (25 and 50 mg/kg, po) to mice exposed to a forced swimming test (FST). Neurochemical analysis of brain monoamines was also carried out to determine the involvement of the monoaminergic system on these effects. Acute administration of H. gordonii decreased the immobility of mice in the FST without accompanying changes in general activity in the open-field test during acute treatment, suggesting an antidepressant-like effect. The anti-immobility effect of H. gordonii was prevented by pretreatment of mice with PCPA [an inhibitor of serotonin (5-HT) synthesis], NAN-190 (a 5-HT1A antagonist), ritanserin (a 5-HT2A/2C antagonist), ondansetron (a 5-HT3A antagonist), prazosin (an α1-adrenoceptor antagonist), SCH23390 (a D1 receptor antagonist), yohimbine (an α2-adrenoceptor antagonist), and sulpiride (a D2 receptor antagonist). A significant increase in 5-HT levels in the striatum was detected after acute administration, while 5-HT, norepinephrine and dopamine were significantly elevated after chronic treatment. Results indicated that H. gordonii possesses antidepressant-like activity in the FST by altering the dopaminergic, serotonergic, and noradrenergic systems.

The antidepressant-like effect of 7-fluoro-1,3-diphenylisoquinoline-1-amine in the mouse forced swimming test is mediated by serotonergic and dopaminergic systems

The aim of the present study was to investigate the role of monoaminergic system in the antidepressant-like action of 7-fluoro-1,3-diphenylisoquinoline-1-amine (FDPI), a derivative of isoquinoline class, in Swiss mice. The antidepressant-like effect of FDPI was characterized in the modified forced swimming test (FST) and the possible mechanism of action was investigated by using serotonergic, dopaminergic and noradrenergic antagonists. Monoamine oxidase (MAO) activity and [(3)H]serotonin (5-HT) uptake were determined in prefrontal cortices of mice. The results showed that FDPI (1, 10 and 20mg/kg, i.g.) reduced the immobility time and increased the swimming time but did not alter climbing time in the modified FST. These effects were similar to those of paroxetine (8mg/kg, i.p.), a positive control. Pretreatments with p-chlorophenylalanine (100mg/kg, i.p., an inhibitor of 5-HT synthesis), WAY100635 (0.1mg/kg, s.c., 5-HT1A antagonist), ondansetron (1mg/kg, i.p., a 5-HT3 receptor antagonist), haloperidol (0.2mg/kg, i.p., a non-selective D2 receptor antagonist) and SCH23390 (0.05mg/kg, s.c., a D1 receptor antagonist) were effective to block the antidepressant-like effect of FDPI at a dose of 1mg/kg in the FST. Ritanserin (1mg/kg, i.p., a 5-HT2A/2C receptor antagonist), sulpiride (50mg/kg, i.p., a D2 and D3 receptor antagonist), prazosin (1mg/kg, i.p., an α1 receptor antagonist), yohimbine (1mg/kg, i.p., an α2 receptor antagonist) and propranolol (2mg/kg, i.p., a β receptor antagonist) did not modify the effect of FDPI in the FST. FDPI did not change synaptosomal [(3)H]5-HT uptake. At doses of 10 and 20mg/kg FDPI inhibited MAO-A and MAO-B activities. These results suggest that antidepressant-like effect of FDPI is mediated mostly by serotonergic and dopaminergic systems.

Central nervous system effects and chemical composition of two subspecies of Agastache mexicana; an ethnomedicine of Mexico

ETHNOPHARMACOLOGICAL RELEVANCE

Agastache mexicana subspecies mexicana (Amm) and xolocotziana (Amx) are used in Mexican traditional medicine to relief cultural affiliation syndromes known as "susto" or "espanto", for "nervous" condition, and as a sleep aid. Despite its intensive use, neuropharmacological studies are scarce, and the chemical composition of the aqueous extracts has not been described. Aims of the study are: (1) To analyze the chemical composition of aqueous extracts from aerial parts of Amm and Amx. (2) To evaluate the anxiolytic-like, sedative, antidepressant-like effects. (3) Analyze the general toxic effects of different doses.

MATERIALS AND METHODS

Anxiolytic-like and sedative effects were measured in the avoidance exploratory behavior, burying behavior and the hole-board tests. The antidepressant-like actions were studied in the forced swimming and tail suspension tests. Finally, general activity and motor coordination disturbances were evaluated in the open field, inverted screen and rota-rod tests. The acute toxicity of Amm and Amx was determined by calculating their LD50 (mean lethal dose). The chemical analyses were performed employing chromatographic, photometric and HPLC-ESI-MS techniques.

RESULTS

Low doses of Amm and Amx (0.1σ1.0mg/kg) induced anxiolytic-like actions; while higher doses (over 10mg/kg) induced sedation and reduced the locomotor activity, exerting a general inhibition in the central nervous system (CNS).

CONCLUSIONS

Results support the use of Amm and Amx in traditional medicine as tranquilizers and sleep inducers. Additionally, this paper contributes to the knowledge of the chemical composition of the aqueous extracts of these plants.

Escin attenuates behavioral impairments, oxidative stress and inflammation in a chronic MPTP/probenecid mouse model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder that results mainly due to the death of dopaminergic neurons in the substantia nigra (SN), and subsequently has an effect on one's motor function and coordination. The current investigation explored the neuroprotective potential of escin, a natural triterpene-saponin on chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine/probenecid (MPTP/p) induced mouse model of PD. Administration of MPTP led to the depleted striatal dopamine content, impaired patterns of behavior, enhanced oxidative stress and diminished expression of tyrosine hydroxylase (TH), dopamine transporter (DAT) and vesicular monoamine transporter-2 (VMAT-2). The expressions of interleukin-6 and -10, glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor protein-1 (IBA-1), tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) in SN were also enhanced. Oral treatment of escin significantly attenuated MPTP/p induced dopaminergic markers depletion, physiological abnormalities, oxidative stress and inhibit neuroinflammatory cytokine expressions in SN. The result of our study confirmed that escin mediated its protection against experimental PD through its antioxidant and anti-inflammatory properties.

Antioxidant, antimicrobial and toxicological properties of Schinus molle L. essential oils

ETHNOPHARMACOLOGICAL RELEVANCE

Schinus molle L. has been used in folk medicine as antibacterial, antiviral, topical antiseptic, antifungal, antioxidant, anti-inflammatory, anti-tumoural as well as antispasmodic and analgesic; however, there are few studies of pharmacological and toxicological properties of Schinus molle essential oils. The aim of this study was to evaluate the antioxidant and antimicrobial activities of Schinus molle leaf and fruit essential oils, correlated with their chemical composition and evaluate their acute toxicity.

MATERIALS AND METHODS

The chemical composition of Schinus molle leaf and fruit essential oils were evaluated by GC-FID and GC-MS. Antioxidant properties were determined using the 2,2-diphenyl-1-picryl-hydrazyl (DPPH) free radical and β-carotene/linoleic acid methods. Antimicrobial properties were evaluated by the agar disc diffusion method and minimal inhibitory concentration assay. Toxicity in Artemia salina and acute toxicity with behavioural screening in mice were evaluated.

RESULTS

The dominant compounds found in leaf and fruit essential oils (EOs) were monoterpene hydrocarbons, namely α-phellandrene, β-phellandrene, β-myrcene, limonene and α-pinene. EOs showed low scavenging antioxidant activity by the DPPH free radical method and a higher activity by the β-carotene/linoleic acid method. Antimicrobial activity of EOs was observed for Gram+, Gram- pathogenic bacteria and food spoilage fungi. EOs showed totoxicity for Artemia salina and lower toxicity in Swiss mice.

CONCLUSIONS

The result showed that EOs of leaves and fruits of Schinus molle demonstrated antioxidant and antimicrobial properties, suggesting their potential use in food or pharmaceutical industries.

Evidence of the involvement of the monoaminergic systems in the antidepressant-like effect of Aloysia gratissima

ETHNOPHARMACOLOGICAL RELEVANCE

Aloysia gratissima (Verbenaceae) is an aromatic plant distributed in South America and, employed in folk medicine for the treatment of nervous systems illness, including depression. The neuroprotective and antidepressant-like activities of the aqueous extract of Aloysia gratissima (AE) administered orally has already been demonstrated.In this study the involvement of monoaminergic systems in the antidepressant-like effect of the AE was investigated.

MATERIALS AND METHODS

The implication of the monoaminergic systems in the antidepressant-like activity of Aloysia gratissima was evaluated using different pharmacological antagonists that were administered previously to the acute oral administration of AE (10 mg/kg). The antidepressant-like effect was assessed in the TST and locomotor activity was evaluated in the open-field test in mice.

RESULTS

The anti-immobility effect elicited by AE in the TST was prevented by the pre-treatment of mice with the antagonists, NAN-190 (5-HT(1A) receptor), ketanserin (5-HT(2A/2C) receptor), prazosin (α1-adrenoceptor), yohimbine (α2-adrenoceptor), SCH23390 (dopamine D1 receptor), or sulpiride (dopamine D2 receptor).

CONCLUSIONS

These results indicate that the antidepressant-like effect of AE in the TST is dependent on its interaction with the serotonergic (5-HT(1A) and 5-HT(2A/2C)), noradrenergic (α1 and α2-adrenoceptors) and dopaminergic (D1 and D2 receptors) systems, suggesting that this specie might act as a new potential resource for developing antidepressants to treat depressive disorders.

The activation of α1-adrenoceptors is implicated in the antidepressant-like effect of creatine in the tail suspension test

The antidepressant-like activity of creatine in the tail suspension test (TST) was demonstrated previously by our group. In this study we investigated the involvement of the noradrenergic system in the antidepressant-like effect of creatine in the mouse TST. In the first set of experiments, creatine administered by i.c.v. route (1 μg/site) decreased the immobility time in the TST, suggesting the central effect of this compound. The anti-immobility effect of peripheral administration of creatine (1 mg/kg, p.o.) was prevented by the pretreatment of mice with α-methyl-p-tyrosine (100 mg/kg, i.p., inhibitor of tyrosine hydroxylase), prazosin (1 mg/kg, i.p., α1-adrenoceptor antagonist), but not by yohimbine (1 mg/kg, i.p., α2-adrenoceptor antagonist). Creatine (0.01 mg/kg, subeffective dose) in combination with subeffective doses of amitriptyline (1 mg/kg, p.o., tricyclic antidepressant), imipramine (0.1 mg/kg, p.o., tricyclic antidepressant), reboxetine (2 mg/kg, p.o., selective noradrenaline reuptake inhibitor) or phenylephrine (0.4 μg/site, i.c.v., α1-adrenoceptor agonist) reduced the immobility time in the TST as compared with either drug alone. These results indicate that the antidepressant-like effect of creatine is likely mediated by an activation of α1-adrenoceptor and that creatine produces synergistic effects in the TST with antidepressants that modulate noradrenaline transporter, suggesting that an improvement in the response to the antidepressant therapy may occur when creatine is combined with these antidepressants. Furthermore, the synergistic effect of creatine (0.01 mg/kg, p.o.) and reboxetine (2 mg/kg, p.o.) combination was abolished by the α1-adrenoceptor antagonist prazosin, indicating that the antidepressant-like effect of combined therapy is likely mediated by an activation of α1-adrenoceptor.

Antidepressant-like effect of ursolic acid isolated from Rosmarinus officinalis L. in mice: evidence for the involvement of the dopaminergic system

Ursolic acid, a constituent from Rosmarinus officinalis, is a triterpenoid compound which has been extensively known for its anticancer and antioxidant properties. In the present study, we investigated the antidepressant-like effect of ursolic acid isolated from this plant in two predictive tests of antidepressant property, the tail suspension test (TST) and the forced swimming test (FST) in mice. Furthermore, the involvement of dopaminergic system in its antidepressant-like effect was investigated in the TST. Ursolic acid reduced the immobility time in the TST (0.01 and 0.1mg/kg, p.o.) and in the FST (10mg/kg, p.o.), similar to fluoxetine (10mg/kg, p.o.), imipramine (1mg/kg, p.o.) and bupropion (10mg/kg, p.o.). The effect of ursolic acid (0.1mg/kg, p.o.) in the TST was prevented by the pretreatment of mice with SCH23390 (0.05mg/kg, s.c., a dopamine D(1) receptor antagonist) and sulpiride (50mg/kg, i.p., a dopamine D(2) receptor antagonist). The administration of a sub-effective dose of ursolic acid (0.001mg/kg, p.o.) in combination with sub-effective doses of SKF38393 (0.1mg/kg, s.c., a dopamine D(1) receptor agonist), apomorphine (0.5μg/kg, i.p., a preferential dopamine D(2) receptor agonist) or bupropion (1mg/kg, i.p., a dual dopamine/noradrenaline reuptake inhibitor) reduced the immobility time in the TST as compared with either drug alone. Ursolic acid and dopaminergic agents alone or in combination did not cause significant alterations in the locomotor and exploratory activities. These results indicate that the antidepressant-like effect of ursolic acid in the TST is likely mediated by an interaction with the dopaminergic system, through the activation of dopamine D(1) and D(2) receptors.

Antidepressant-like effect of creatine in mice involves dopaminergic activation

Creatine has been shown to play a significant role in health and disease. However, studies concerning its effect on mood are scarce. This study investigated the effect of creatine (p.o.) in the tail suspension test, a predictive test of antidepressant activity. Creatine reduced the immobility time in the tail suspension test (0.1-1000 mg/kg, male and female mice), without affecting locomotor activity. Furthermore, the involvement of the dopaminergic system in creatine-induced antidepressant-like effect in male mice in the tail suspension test was investigated. The anti-immobility effect of creatine (1 mg/kg) was prevented by the pre-treatment of mice with haloperidol (0.2 mg/kg, intraperitoneal (i.p.) route, non-selective dopamine receptor antagonist), (R)-(+)-7-chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH23390; 0.05 mg/kg, subcutaneous (s.c.) route, dopamine D₁ receptor antagonist) and sulpiride (50 mg/kg, i.p., dopamine D₂ receptor antagonist). Creatine (0.01 mg/kg, sub-effective dose) in combination with sub-effective doses of (1-phenyl-7,8-dihydroxy-2,3,4,5-tetrahydro-1H-3-benzazepine) hydrochloride (SKF38393; 0.1 mg/kg, s.c., dopamine D₁ receptor agonist), apomorphine (0.5 µg/kg, i.p., preferential dopamine D₂ receptor agonist) or bupropion (1 mg/kg, p.o., dopamine reuptake inhibitor with subtle activity on noradrenergic reuptake) reduced the immobility time in the tail suspension test as compared with either drug alone. These results indicate that the antidepressant-like effect of creatine is likely mediated by an activation of dopamine D₁ and D₂ receptors.

Antidepressant-like effect of the novel MAO inhibitor 2-(3,4-dimethoxy-phenyl)-4,5-dihydro-1H-imidazole (2-DMPI) in mice

Monoamine oxidase (MAO) inhibitors were the first antidepressant drugs to be prescribed and are still used today with great success, especially in patients resistant to other antidepressants. In this study, we evaluated the MAO inhibitory properties and the potential antidepressant action of 2-(3,4-dimethoxy-phenyl)-4,5-dihydro-1H-imidazole (2-DMPI) in mice. We found that 2-DMPI inhibited both MAO isoforms (K(i) values were 1.53 (1.3-1.8) μM and 46.67 (31.8-68.4) μM for MAO-A and MAO-B, respectively) with 30-fold higher selectivity toward MAO-A. In relation to the nature of MAO-A inhibition, 2-DMPI showed to be a mixed and reversible inhibitor. The treatment with 2-DMPI (100-1000 μmol/kg, s.c.) caused a significant decrease in immobility time in the tail suspension test (TST) without affecting locomotor activity, motor coordination or anxiety-related activities. Conversely, moclobemide (1000 μmol/kg, s.c.) caused a significant increase in immobility time in the TST, which appeared to be mediated by a nonspecific effect on motor coordination function. 2-DMPI (300 μmol/kg, s.c.) decreased serotonin turnover in the cerebral cortex, hippocampus and striatum, whereas dopamine turnover was diminished only in the striatum, and norepinephrine turnover was not changed. The antidepressant-like effect of 2-DMPI was inhibited by the pretreatment of mice with methysergide (2 mg/kg, s.c., a non-selective serotonin receptor antagonist), WAY100635 (0.1 mg/kg, s.c., a selective 5-HT(1A) receptor antagonist) or haloperidol (0.05 mg/kg, i.p., a non-selective dopamine receptor antagonist). These results suggest that 2-DMPI is a prototype reversible and preferential MAO-A inhibitor with potential antidepressant activity, due to its modulatory effect on serotonergic and dopaminergic systems.