myricitrin and Disease-Models--Animal

Parkinson's disease (PD) is characterized by the progressive degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta and decreases in striatal dopamine levels. These changes led to several clinical symptoms: rigidity, resting tremor, and bradykinesia. Although the cause of PD remains unclear, it is widely accepted that oxidative stress, neuroinflammation, mitochondrial dysfunction, and insufficient support of neurotrophic factors are involved in the pathophysiology of the disease. However, novel regimens to prevent neurodegeneration and restore the degenerated nigrostriatal DA system are still required. In recent years, there has been a growing interest in naturally occurring phytochemicals, which are believed to reduce the risk of neurodegenerative diseases. This review provides an overview of the scientific literature concerning the preventive and protective roles of flavonoids, one of the largest families of phytochemicals, against PD. In addition to providing antioxidant and anti-inflammatory effects, flavonoids exhibit a neuroprotective effect by activating antiapoptotic pathways that target mitochondrial dysfunction and induce neurotrophic factors. This review suggests that flavonoids may be promising natural products for the prevention of PD and could potentially be utilized as therapeutic compounds against PD, even though there was no report showing that the treatment with flavonoids could restore the aberrant phenotypes of patients with PD.

Topics: Animals; Anthocyanins; Antioxidants; Antiparkinson Agents; Catechin; Cell Line; Corpus Striatum; Disease Models, Animal; Dopamine; Flavanones; Flavones; Flavonoids; Flavonols; Humans; Isoflavones; Kaempferols; Neuroprotective Agents; Oxidative Stress; Parkinson Disease

The flavonoid myricitrin showed an antidepressant-like effect in the tail suspension test and increased hippocampal neurogenesis, as well as demonstrating anti-inflammatory effects. Interestingly, inflammation has been linked to depression, and anti-inflammatory drugs showed promising results as antidepressant-like drugs. Thus, the present study evaluated the effects of myricitrin in the chronic mild stress (CMS) model, a translational and valid animal model of depression, using the mini-experiment design to improve the reproducibility of the findings. The sucrose preference test (SPT), forced swim test (FST), and tail suspension test (TST) were the readouts of depressive-like phenotypes induced by CMS. Relative adrenal weight was employed as an index of the hypothalamus-pituitary-adrenal (HPA) axis activation. Interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha levels were measured in the hippocampus. Myricitrin (10 mg/kg, intraperitoneally, for 14 days) reversed depressive-like behaviors induced by CMS (increased immobility in the FST, the TST and anhedonia), as well as decreased adrenal hypertrophy and hippocampal levels of IL-6 in stressed mice. Similar results were observed by imipramine (20 mg/kg, intraperitoneally, for 14 days), a serotonin and norepinephrine reuptake inhibitor (positive control). A significant correlation was observed between immobility time in the TST, and hippocampal IL-6 levels. Hippocampal TNF-α levels were not affected by CMS or drug treatment. In conclusion, myricitrin exhibited an antidepressant-like profile in CMS, and this effect may be associated with its anti-inflammatory activity.

Topics: Animals; Anti-Inflammatory Agents; Antidepressive Agents; Behavior, Animal; Depression; Disease Models, Animal; Flavonoids; Hippocampus; Interleukin-6; Mice; Reproducibility of Results; Stress, Psychological

Flavonoids exhibit several biological activities including inhibition of Monoamine oxidase (MAO), an enzyme that metabolizes several neurotransmitters. Thus, MAO inhibitors are well included in traditional therapeutic practices to fine-tune neuromotor behavior. This study aims to isolate flavonoids from a less explored plant of northeast India, named Indian olive (

Topics: Animals; Brain; Disease Models, Animal; Dopamine; Elaeocarpaceae; Flavonoids; Mice; Monoamine Oxidase; Monoamine Oxidase Inhibitors; Olea; Parkinson Disease

The present study screened the effect of Myricitrin on cognitive deficits post-cerebral ischemic stroke and the involved mechanism. The rats were submitted to middle cerebral artery occlusion (MCAO) and were treated with sodium butyrate or Myricitrin (15 and 30 mg/kg) for 28 days. The spatial memory was studied by Morris water maze (MWM). After 4 weeks, the rats were euthanized and hippocampus region was utilized for neurochemical and biochemical changes. The extent of histone acetylation was studied by ELISA. Protein levels were analyzed by Western blot analysis. The mRNA levels were analyzed by polymerase chain reaction (PCR). In silico bioinformatics docking studies were done for target confirmation of Myricitrin. The treatment of Myricitrin showed improved memory in MWM compared to rats treated with vehicle, and the effects of Myricitrin were similar to sodium butyrate-treated rats. At a dose of 30 mg/kg Myricitrin, the histone deacetylase content was decreased, the expression levels of BDNF were increased, the levels of acetylated H3 and H4 along with Syn-I in the hippocampus region were over-expressed compared to control vehicle-treated rats. However, at low dose, i.e., 15 mg/kg Myricitrin failed to show alterations in biochemical as well as neurochemical markers. Docking studies suggested the BDNF and Sun-I as potential target proteins of Myricitrin. The cognitive ameliorating effect of Myricitrin post-cerebral ischemia stroke can be attributed to increased expression of BDNF and Syn-I and modulation of histone acetylation.

Topics: Acetylation; Animals; Brain-Derived Neurotrophic Factor; Butyric Acid; Cerebral Cortex; Cognitive Dysfunction; Disease Models, Animal; Flavonoids; Histamine Antagonists; Histone Deacetylases; Histones; Infarction, Middle Cerebral Artery; Rats; Rats, Sprague-Dawley; Spatial Memory; Stroke

Cisplatin could result in a wide range of kidney injuries. During the pathogenetic process, the excessive generation of reactive oxygen species (ROS) induced by cisplatin has been regarded as the initial and critical role, by which DNA damage and cell death could subsequently come up. Therefore the elimination of ROS has long been considered as effective mean to prevent cisplatin-induced kidney injury. Myricitrin is a newfound natural polyphenol hydroxy flavonoid glycoside compound, whose forceful anti-oxidative properties had been confirmed. Thus, we aim to investigate if myricitrin could protect against cisplatin-induced kidney injury.. A cisplatin-induced kidney injury model was established in mice by intraperitoneal injection of cisplatin. The protective effect of myricitrin on kidney injury was evaluated by serum BUN and Cre level. The Kidney pathology was observed with H&E and TUNEL staining. Then cell viability and apoptosis rate were measured using MMT assay and flow cytometry to assess if myricitrin could protect KH-2 cells against cisplatin-induced injury. The intracellular ROS was detected by ROS fluorogenic probe and quantitatively analyzed by flow cytometry. Finally, the expression of Bcl-2 and Bax was investigated by western blotting to indicate the influence in apoptosis pathway.. Myricitrin could significantly remit kidney injury induced by cisplatin and inhibit apoptosis of KH-2 cells. In mechanism, myricitrin could eliminate ROS and subsequently block activation of apoptosis pathway.. Myricitrin protects against cisplatin-induced kidney injury by eliminating excessive ROS.

Topics: Acute Kidney Injury; Animals; Antineoplastic Agents; Apoptosis; Cell Survival; Cisplatin; Disease Models, Animal; Flavonoids; Male; Mice; Mice, Inbred C57BL; Reactive Oxygen Species

Myricitrin has been reported to exert protective effects on liver diseases, but the protective effects of myricitrin against liver ischemia reperfusion (I/R) injury and the underlying mechanisms remain unexplored. This study aimed to investigate the effects of myricitrin on liver I/R injury and elucidate the underlying mechanisms.. Mice were pretreated with myricitrin before liver I/R injury modeling. The mice were pretreated with either myricitrin or vehicle prior to liver ischemia. Some mice were further pretreated with the PI3K inhibitor LY294002. Liver tissues and blood samples were collected after 6 h of reperfusion. The degree of liver damage was determined by the serum levels of alanine aminotransferase (ALT), aspartate transaminase (AST), and lactic dehydrogenase (LDH) and histological examinations. The tumour necrosis factor-α (TNF-α), interleukin--1β (IL-1β), IL-4 and IL-10 expression levels were assessed by qRT-PCR and enzyme-linked immunosorbent assays (ELISAs). Serum superoxide dismutase (SOD) activity, catalase (CAT) activity, and contents of malondialdehyde (MDA), glutathione (GSH) and nitric oxide (NO) contents were measured. Western blotting and caspase-3 activity were conducted to determine the effect of myricitrin on apoptosis. The expression levels of proliferation related genes (Cyclin D1 and Cyclin E1) were determined by qRT-PCR and western-blotting. The expression of p-Akt, p-mTOR and p-eNOS in liver tissue were investigated by western-blotting.. Myricitrin not only significantly decreased the ALT, AST and LDH levels but also reduced the necrotic areas in the liver tissue compared with liver I/R injury group. In addition, myricitrin pretreatment alleviated liver injury by inhibiting the inflammatory response and suppressing oxidative stress. Western blotting and caspase-3 activity revealed that myricitrin inhibited liver I/R induced-apoptosis. Myricitrin promoted hepatocyte proliferation following liver I/R injury by upregulating the expression levels of Cyclin D1 and Cyclin E1. Further experiments indicated that the myricitrin pretreatment increased nitric oxide (NO) production by activating the PI3K/Akt signaling pathway. However, myricitrin triggered the hepatocyte proliferation and NO synthase activation was blocked by LY294002.. These results demonstrate that myricitrin alleviates liver I/R injury by suppressing oxidative stress, the inflammatory response, and apoptosis, improving liver proliferation and upregulating p-eNOS expression.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; Apoptosis; Apoptosis Regulatory Proteins; Cell Proliferation; Disease Models, Animal; Flavonoids; Liver; Liver Diseases; Male; Mice, Inbred C57BL; Nitric Oxide Synthase Type III; Oxidative Stress; Phosphatidylinositol 3-Kinase; Phosphorylation; Proto-Oncogene Proteins c-akt; Reperfusion Injury; Signal Transduction

In the present study, the protective effects of myricitrin against vascular endothelial growth factor (VEGF)-induced angiogenesis of vascular endothelial cells were characterized. Cells were induced with 50 ng/mL VEGF in the presence or absence of various concentrations of myricitrin for 24 h. Myricitrin treatment significantly reduced cell proliferation by more than 50 %. Cells treated with myricitrin showed significantly increased caspase 3/7 activity and apoptosis in a dose-dependent manner. Treatment with 1, 10, or 100 μM myricitrin significantly reduced matrix metalloproteinase (MMP) activity by 23.3 %, 46.2 %, or 64.3 %, respectively. Myricitrin significantly reduced MMP1 and MMP2 mRNA expression. Similarly, treatment with 1, 10, or 100 μM myricitrin reduced MMP1 protein expression by 10.5 %, 31.6 %, or 52.6 %, respectively, and MMP2 protein expression by 10.9 %, 28.2 %, or 43.5 %, respectively. Cells treated with myricitrin showed significant inhibition of cell migration as well as capillary tube and sprouting formation. Myricitrin treatment significantly reduced the VEGF level. Immune-deficient nude mice bearing U251 xenograft tumors were used to investigate the antiangiogenic effects of myricitrin in vivo. The results demonstrated that myricitrin treatment in vivo significantly inhibited U251 cell xenograft tumor growth, as confirmed by the decreases in tumor volume and tumor weight. VEGF expression is a key proangiogenic factor. Myricitrin treatment significantly reduced mRNA and protein VEGF expression. Taken together, these results indicate that myricitrin is a potential inhibitor of VEGF-induced angiogenesis.

Topics: Angiogenesis Inhibitors; Animals; Apoptosis; Biomarkers; Caspases; Cell Line, Tumor; Disease Models, Animal; Flavonoids; Human Umbilical Vein Endothelial Cells; Humans; Matrix Metalloproteinases; Mice; Neovascularization, Pathologic; Neovascularization, Physiologic; Vascular Endothelial Growth Factors; Xenograft Model Antitumor Assays

Chronic fatigue patients experience various neuropsychological symptoms, including fatigue behaviors, chronic pain, and depression. They also display immune system dysregulation. Polygonum aviculare L. extract (PAE) is a traditional herbal medicine used to treat inflammatory diseases by reportedly decreasing pro-inflammatory cytokine production.. We hypothesized that the anti-inflammatory properties of PAE would attenuate fatigue symptoms in a mouse model of restraint stress.. We evaluated the effects of PAE on fatigue using three experimental groups: unstressed, vehicle-treated stressed, and PAE-treated stressed mice. This restraint stress paradigm, comprised of restraint for 3 h daily for 15 days, was used to model chronic fatigue.. We compared lethargy-like behavior between our experimental groups using forced-swim, sucrose preference, and open-field tests once per week on days 7 and 14 of restraint stress. We also used histology and western blotting to evaluate pro-inflammatory cytokine expression in the brain and serum, and microglial activation in the brain. Finally, we used liquid chromatography/mass spectroscopy (LC/MS) to identify individual components of PAE, and applied cell culture techniques to test the effects of these components on neuronal cells in vitro.. In restraint-stressed mice, PAE treatment decreased lethargy-like behavior relative to vehicle-treated animals. PAE treatment also reduced expression of fatigue-related factors such as corticosterone, serotonin, and catecholamines (adrenaline and noradrenaline) in the brain and serum, and decreased expression of CD68, Ibal-1, and the inflammatory cytokines TNF-α, IL-6, and IL-1β in the brain. Together, these data indicate that PAE reduced fatigue and is anti-inflammatory. Furthermore, histopathological analyses indicated that PAE treatment recovered atrophic volumes and hepatic injuries. Finally, LC/MS analysis of PAE identified four individual chemicals: myricitrin, isoquercitrin, avicularin, and quercitrin. In neuronal cell cultures, treatment with these PAE components inhibited TNF-α production, confirming that PAE treatment reduces neuroinflammation.. PAE treatment may reduce fatigue by suppressing neuroinflammation and the expression of fatigue-related hormones.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Brain; Corticosterone; Cytokines; Disease Models, Animal; Drugs, Chinese Herbal; Fatigue; Flavonoids; Inflammation; Male; Mice, Inbred C57BL; Plant Extracts; Polygonum; Serotonin; Stress, Physiological

Type 2 diabetes mellitus (T2DM) may occur via oxidative stress. Myricitrin is a plant-derived antioxidant, and its solid lipid nanoparticle (SLN) may be more potent. Hence, the present study was conducted to evaluate the effects of myricitrin SLN on streptozotocin-nicotinamide- (STZ-NA-) induced T2DM of the mouse and hyperglycemic myotube. In this experimental study, cold homogenization method was used to prepare SLN. Then, 120 adult male NMRI mice were divided into 7 groups: control, vehicle, diabetes (received STZ 65 mg/kg 15 min after injected NA 120 mg/kg), diabetes + SLN containing myricitrin 1, 3, and 10 mg/kg, and diabetes + metformin. For in vitro study, myoblast (C2C12) cell line was cultured and divided into 6 groups (

Topics: Animals; Antioxidants; Disease Models, Animal; Flavonoids; Humans; Hypoglycemic Agents; Male; Mice; Middle Aged; Muscle Fibers, Skeletal; Nanoparticles; Niacinamide; Streptozocin

Myricitrin has multiple effects, including antagonism of platelet activating factor, regulation of blood sugar levels, oxidation resistance, protection of the liver and the relieving of ethylism. The present study evaluated how myricitrin weakens traumatic injury of the spinal cord (TISC), and exhibits antioxidant and anti‑inflammatory activities in a rat model. TISC model rats were injected intraperitoneally with 5, 10 or 30 mg/kg/day of myricitrin for 5 days. Basso‑Beattie‑Bresnahan evaluation of locomotion and water content of spinal cord were used to analyze the effects of myricitrin on TISC. Myricitrin significantly inhibited the TISC‑induced oxidative stress and inflammatory reactions. In addition, cyclooxygenase‑2 (COX‑2), transforming growth factor (TGF)‑β1 and p53 were significantly reduced and Bcl‑2/Bax rate was significantly increased by treatment with myricitrin. The results of the current study suggested that the neuroprotective effect of myricitrin exhibits significant antioxidant and anti‑inflammatory activities, and a remarkable trauma protection activity in TISC rats through inhibition of COX‑2, TGF‑β1, p53 and elevation of Bcl‑2/Bax signaling pathway.

Topics: Animals; Anti-Inflammatory Agents; Antioxidants; bcl-2-Associated X Protein; Cyclooxygenase 2; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Female; Flavonoids; Gene Expression Regulation; Injections, Intraperitoneal; Neuroprotective Agents; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Signal Transduction; Spinal Cord; Spinal Cord Injuries; Transforming Growth Factor beta1; Tumor Suppressor Protein p53

Blood vessel endothelial dysfunction induced by oxidized low-density lipoprotein (ox-LDL) has been implicated in the pathogenesis of atherosclerosis and vasculopathy. The ox-LDL-elicited reactive oxygen species (ROS) release has been assumed to serve a critical function in endothelial damage. Myricitrin (from Myrica cerifera) is a natural antioxidant that has strong anti-oxidative, anti-inflammatory, and anti-nociceptive activities. However, the protective effect of myricitrin on ROS-induced endothelial cell injury and its related molecular mechanisms have never been investigated. This study demonstrates that myricitrin can inhibit ox-LDL-induced endothelial apoptosis and prevent plaque formation at an early stage in an atherosclerotic mouse model. The administration of myricitrin in vivo decreases the thickness of the vascular wall in the aortic arch of ApoE-/- mice. In vitro study shows that ox-LDL-induced human umbilical vein endothelial cell apoptosis can be reduced upon receiving myricitrin pre-treatment. Treatment with myricitrin significantly attenuated ox-LDL-induced endothelial cell apoptosis by inhibiting LOX-1 expression and by increasing the activation of the STAT3 and PI3K/Akt/eNOS signaling pathways. At the same time, our result demonstrates that myricitrin treatment optimizes the balance of pro/anti-apoptosis proteins, including Bax, Bad, XIAP, cIAP-2, and survivin. Our study suggests that myricitrin treatment can effectively protect cells from ox-LDL-induced endothelial cell apoptosis, which results in reduced atherosclerotic plaque formation. This result indicates that myricitrin can be used as a drug candidate for the treatment of cardiovascular diseases.

Topics: Animals; Aortic Diseases; Apolipoproteins E; Apoptosis; Apoptosis Regulatory Proteins; Atherosclerosis; Biopsy; Cardiovascular Agents; Cells, Cultured; Diet, High-Fat; Disease Models, Animal; Dose-Response Relationship, Drug; Enzyme Activation; Flavonoids; Human Umbilical Vein Endothelial Cells; Humans; Lipoproteins, LDL; Male; Mice, Inbred C57BL; Mice, Knockout; Nitric Oxide Synthase Type III; Phosphatidylinositol 3-Kinase; Plaque, Atherosclerotic; Proto-Oncogene Proteins c-akt; Scavenger Receptors, Class E; Signal Transduction; STAT3 Transcription Factor; Time Factors; X-Ray Microtomography

Animal models aimed to mimic mania have in common the lack of genuine affective parameters. Although rodent amphetamine-induced hyperlocomotion is a frequently used behavioral model of mania, locomotor activity is a rather unspecific target for developing new pharmacological therapies, and does not necessarily constitute a cardinal symptom in bipolar disorder (BD). Hence, alternative behavioral markers sensitive to stimulants are required.. Since D-amphetamine induces appetitive 50-kHz ultrasonic vocalizations (USV) in rats, we asked whether established or potential antimanic drugs would inhibit this effect, thereby possibly complementing traditional analysis of locomotor activity.. Amphetamine-treated rats (2.5 mg/kg) were systemically administered with the antimanic drugs lithium (100 mg/kg) and tamoxifen (1 mg/kg). Since protein kinase C (PKC) activity has been implicated in the pathophysiology of bipolar disorder and the biochemical effects of mood stabilizers, the new PKC inhibitor myricitrin (10, 30 mg/kg) was also evaluated.. We demonstrate for the first time that drugs with known or potential antimanic activity were effective in reversing amphetamine-induced appetitive 50-kHz calls. Treatments particularly normalized amphetamine-induced increases of frequency-modulated calls, a subtype presumably indicative of positive affect in the rat.. Our findings suggest that amphetamine-induced 50-kHz calls might constitute a marker for communicating affect that provides a useful model of exaggerated euphoric mood and pressured speech. The antimanic-like effects of the PKC inhibitors tamoxifen and myricitrin support the predictive and etiological validity of both drugs in this model and highlight the role of PKC signaling as a promising target to treat mania and psychosis-related disorders.

Topics: Animals; Antimanic Agents; Bipolar Disorder; Central Nervous System Stimulants; Dextroamphetamine; Disease Models, Animal; Dose-Response Relationship, Drug; Flavonoids; Lithium Carbonate; Male; Motor Activity; Protein Kinase C; Rats; Rats, Wistar; Signal Transduction; Tamoxifen; Vocalization, Animal

Atherosclerosis (AS) is a state of heightened oxidative stress characterized by lipid and protein oxidation in vascular walls. Oxidative stress-induced vascular endothelial cell (VEC) injury is a major factor in the pathogenesis of AS. Myricitrin, a natural flavonoid isolated from the root bark of Myrica cerifera, was recently found to have a strong antioxidative effect. However, its use for treating cardiovascular diseases, especially AS is still unreported. Consequently, we evaluated the cytoprotective effect of myricitrin on AS by assessing oxidative stress-induced VEC damage. The in vivo study using an ApoE-/-mouse model of AS demonstrated that myricitrin treatment protects against VEC damage and inhibits early AS plaque formation. This effect is associated with the antioxidative effect of myricitrin, as observed in a hydrogen peroxide (H2O2)-induced rat model of artery endothelial injury and primary cultured human VECs. Myricitrin treatment also prevents and attenuates H2O2-induced endothelial injury. Further investigation of the cytoprotective effects of myricitrin demonstrated that myricitrin exerts its function by scavenging for reactive oxygen species, as well as reducing lipid peroxidation, blocking NO release, and maintaining mitochondrial transmembrane potential. Myricitrin treatment also significantly decreased H2O2-induced apoptosis in VECs, which was associated with significant inhibition of p53 gene expression, activation of caspase-3 and the MAPK signaling pathway, and alteration of the patterns of pro-apoptotic and anti-apoptotic gene expression. The resulting significantly increased bcl-2/bax ratio indicates that myricitrin may prevent the apoptosis induced by oxidative stress injury.

Topics: Animals; Apolipoproteins E; Apoptosis; Atherosclerosis; bcl-2-Associated X Protein; Disease Models, Animal; Endothelial Cells; Flavonoids; Gene Expression Regulation; Humans; Hydrogen Peroxide; Lipid Peroxidation; Male; Membrane Potential, Mitochondrial; Mice; Mice, Inbred C57BL; Mice, Knockout; Myrica; Nitric Oxide; Oxidative Stress; Plaque, Atherosclerotic; Proto-Oncogene Proteins c-bcl-2; Rats; Reactive Oxygen Species

The present work explored the antinociceptive effects of the flavonoid myricitrin in models of overt nociception triggered by intraplantar injection of chemical algogens into the hind paw of mice. The nociception induced by bradykinin (3 nmol/paw i.pl.) was abolished by prior treatment with myricitrin (10-100mg/kg, i.p.) with ID(50) of 12.4 (8.5-18.1)mg/kg. In sharp contrast, myricitrin failed to affect the nociception elicited by prostaglandin E(2) (3 nmol/paw i.pl.). Cinnamaldehyde (10 nmol/paw i.pl.)-induced nociception was reduced by myricitrin (100mg/kg, i.p.) and camphor (7.6 mg/kg,s.c.) in 43±10% and 57±8%, respectively. Myricitrin (30-100mg/kg, i.p.) and amiloride (100mg/kg, i.p.) inhibited nociceptive responses induced by acidified saline (pH 5/paw i.pl.), with ID(50) of 22.0 (16.1-30.0)mg/kg and inhibition of 71±6% and 64±5%, respectively. Moreover, myricitrin (10-30 mg/kg, i.p.) and ruthenium red (3mg/kg, i.p.) significantly reduced the nociception induced by menthol (1.2 μmol/paw i.pl.) with the mean ID(50) of 2.4 (1.5-3.7)mg/kg and inhibition of 95±3% and 51±7%, respectively. In addition, myricitrin administration (30 and 100mg/kg, i.p.) markedly reduced menthol-induced mechanical allodynia. However, myricitrin (100mg/kg, i.p.) prevented (only in time of 60 min) cold allodynia induced by menthol. Collectively, the present results extend prior data and show that myricitrin promotes potent antinociception, an action that is likely mediated by an inhibition of the activation of nociceptors by bradykinin and TRPs agonist (i.e. cinnamaldehyde, acidified saline and menthol), probably via inhibition of PKC pathways. Thus, myricitrin could constitute an attractive molecule of interest for the development of new analgesic drugs.

Topics: Acrolein; Amiloride; Analgesics, Non-Narcotic; Animals; Bradykinin; Camphor; Dinoprostone; Disease Models, Animal; Dose-Response Relationship, Drug; Flavonoids; Functional Laterality; Hyperalgesia; Male; Mice; Models, Chemical; Pain; Pain Measurement; Pain Threshold; Ruthenium Red

Myricitrin is a nitric oxide (NO) and protein kinase C (PKC) inhibitor that has central nervous system activity, including anxiolytic-like action. Nitric oxide inhibitors blocked the behavioral effects of apomorphine, suggesting an antipsychotic-like effect. Furthermore, PKC inhibition reduced psychotic symptoms in acute mania patients and blocked amphetamine-induced hyperlocomotion, suggesting a potential antipsychotic-like effect. The present study evaluated the effects of myricitrin in animal models that assess antipsychotic-like effects (apomorphine-induced stereotypy and climbing and the paw test) and extrapyramidal side effects (catalepsy test and paw test). Olanzapine was used as a positive control. 7-Nitroindazole (7-NI), a NOS inhibitor, and l-arginine, a NO precursor, were used to evaluate nitrergic modulation, and tamoxifen was used to test the effect of PKC inhibition. In mice, myricitrin dose-dependently and olanzapine blocked the stereotypy and climbing induced by apomorphine at doses that did not induce catalepsy. 7-Nitroindazole also blocked apomorphine-induced stereotypy and climbing, which were reversed by l-arginine pretreatment. l-arginine only attenuated the effects of myricitrin on apomorphine's effects. Tamoxifen also blocked apomorphine-induced stereotypy and climbing. In the paw test in rats, myricitrin and olanzapine increased hindlimb retraction time at doses that did not affect forelimb reaction time, whereas haloperidol affected both parameters at the same dose. Myricitrin did not induce catalepsy in the bar test. Tamoxifen did not affect hindlimb retraction time or forelimb retraction time, whereas 7-NI significantly increased hindlimb reaction time. Thus, myricitrin exhibited an antipsychotic-like profile at doses that did not induce catalepsy, and this effect may be related to nitrergic action.

Topics: Animals; Antipsychotic Agents; Apomorphine; Arginine; Catalepsy; Disease Models, Animal; Dopamine Agonists; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Flavonoids; Indazoles; Male; Mice; Motor Activity; Nitric Oxide; Phytotherapy; Plant Leaves; Plant Preparations; Protein Kinase C; Psychotic Disorders; Rats; Rats, Wistar; Stereotyped Behavior; Syzygium; Tamoxifen

The aim of the present study was to investigate the effects of myricitrin, a flavonoid with anti-inflammatory and antinociceptive action, upon persistent neuropathic and inflammatory pain. The neuropathic pain was caused by a partial ligation (2/3) of the sciatic nerve and the inflammatory pain was induced by an intraplantar (i.pl.) injection of 20 microL of complete Freund's adjuvant (CFA) in adult Swiss mice (25-35 g). Seven days after sciatic nerve constriction and 24 h after CFA i.pl. injection, mouse pain threshold was evaluated through tactile allodynia, using Von Frey Hair (VFH) filaments. Further analyses performed in CFA-injected mice were paw edema measurement, leukocytes infiltration, morphological changes and myeloperoxidase (MPO) enzyme activity. The intraperitoneal (i.p.) treatment with myricitrin (30 mg/kg) significantly decreased the paw withdrawal response in persistent neuropathic and inflammatory pain and decreased mouse paw edema. CFA injection increased 4-fold MPO activity and 27-fold the number of neutrophils in the mouse paw after 24 h. Myricitrin strongly reduced MPO activity, returning to basal levels; however, it did not reduce neutrophils migration. In addition, myricitrin treatment decreased morphological alterations to the epidermis and dermis papilar of mouse paw. Together these results indicate that myricitrin produces pronounced anti-allodynic and anti-edematogenic effects in two models of chronic pain in mice. Considering that few drugs are currently available for the treatment of chronic pain, the present results indicate that myricitrin might be potentially interesting in the development of new clinically relevant drugs for the management of this disorder.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Disease Models, Animal; Edema; Female; Flavonoids; Freund's Adjuvant; Inflammation; Mice; Neutrophil Infiltration; Pain; Pain Threshold; Sciatic Neuropathy; Subcutaneous Tissue