Neuroprotective Effects Of Paeoniflorin Research Articles

The neuroprotective effects of paeoniflorin against MPP+-induced damage to dopaminergic neurons via the Akt/Nrf2/GPX4 pathway

Paeoniflorin (PF), a water-soluble monoterpene glycoside extracted from the root of Paeonia lactiflora Pall, has been shown to exert neuroprotective effects against neurodegenerative diseases such as Parkinson’s disease (PD). However, its underlying mechanisms remain unknown. Our results showed that at certain concentrations, PF alleviated 1-methyl-4-phenylpyridinium (MPP+)-induced morphological damage and inhibited neuronal ferroptosis. Moreover, our research indicated that the neuroprotective effect of PF could be partially blocked by ML385 (a nuclear factor erythroid-2-related factor 2 (Nrf2) inhibitor) and LY29400 (an Akt inhibitor). These findings suggest that PF protects against MPP+-induced neurotoxicity by preventing ferroptosis via activation of the Akt/Nrf2/Gpx4 pathway in vitro.

Neuroprotective effects of paeoniflorin against neuronal oxidative stress and neuroinflammation induced by lipopolysaccharide in mice

Neuroprotective effects of paeoniflorin against neuronal oxidative stress and neuroinflammation induced by lipopolysaccharide in mice

Paeoniflorin ameliorates oxidase stress in Glutamate-stimulated SY5Y and prenatally stressed female offspring through Nrf2/HO-1 signaling pathway

BackgroundPrenatal stress (PS) can cause brain retardation, reduce the learning and memory ability of the offspring and significantly increase the incidence of depression in offspring. Paeoniflorin (PF), a kind of monoterpenoid glycoside, is one of the main active ingredients of Chinese Medicine Paeonia lactiflora Pall, has anti-inflammation and potential neuroprotective effects. However, few reports have shown that the neuroprotective effects of PF are exerted through ameliorating Glutamate toxicity in vivo and in vitro. MethodsHere, we used a prenatal restraint stress model and Glu-induced excitotoxic neurotoxicity in SH-SY5Y cells to study the effects of PF. ResultsOur results showed that PF can ameliorate learning and memory impairments and increases the density of hippocampal neurons, typical Golgi-positive pyramidal cells, and neuronal Neurogranin (Ng) expression in PS rat offspring. Furthermore, PF can significantly up-regulate the decrease of Glu-induced SH-SY5Y cell viability. At the same time, PF can significantly reduce apoptosis, ROS, NO levels, and intracellular Ca2+ concentration, and significantly inhibit the increase of mitochondrial membrane potential. Besides, PF significantly increased the expression of Nrf2 and iNOS, decreased p-JNK/JNK, p-P38/P38, Bax/Bcl-2, active-caspase-3, and active-caspase-9. ConclusionsOur results demonstrate that PF may be an effective treatment in preventing the development of PS-induced learning and memory impairment and have therapeutic potential in Glu-related neurological diseases.

An In Vitro Verification of the Effects of Paeoniflorin on Lipopolysaccharide-Exposed Microglia.

Background The neuroprotective effects of Paeoniflorin (PF) are well known. Most of the evidence was verified in vivo. We attempted to perform an in vitro verification of the effects of PF in microglia. Methods A lipopolysaccharide- (LPS-) exposed microglia model was employed. An enzyme-linked immunosorbent assay was used to measure the levels of cytokines in the culture supernatants. A real-time polymerase chain reaction was performed to measure the mRNA expression of cytokines and M1- and M2-like genes. A western blot analysis was used to examine the expression of proteins associated with the nuclear factor-kappa B (NF-κB) signaling pathway. Results We found that the administration of PF reversed the inflammatory response induced by LPS. It downregulated proinflammatory cytokines and upregulated anti-inflammatory cytokines. This, in turn, alleviated the oxidative injuries, downregulated the expression of M1-like genes, and upregulated the expression of M2-like genes. PF can also reverse the changes in proteins associated with the NF-κB signaling pathway induced by LPS. Conclusions We provided evidence obtained in vitro concerning the neuroprotective effects of PF via suppressing activation of microglia, which might be associated with the NF-κB signaling pathway. These findings contribute to obtaining a deeper understanding of PF, a potential new treatment for brain injuries.

Protective role of paeoniflorin from hydrogen peroxide-mediated oxidative damage in C6 glial cells

Oxidative stress is one of the pathogenic mechanisms of various neurodegenerative diseases, such as Alzheimer’s disease. Neuroglia, the most abundant cells in the brain, is thought to play an important role in the antioxidant defense system and neuronal metabolic support against neurotoxicity and oxidative stress. We investigated the protective effect of paeoniflorin (PF) against oxidative stress in C6 glial cells. Exposure of C6 glial cells to hydrogen peroxide (H2O2, 500 μM) significantly decreased cell viability and increased amounts of lactate dehydrogenase (LDH) release, indicating H2O2-induced cellular damage. However, treatment with PF significantly attenuated H2O2-induced cell death as shown by increased cell survival and decreased LDH release. The H2O2- stimulated reactive oxygen species production was also suppressed, and it may be associated with improvement of superoxide dismutase activity by treatment with PF. In addition, an increase in ratio of Bcl-2/Bax protein expression was observed after treatment with PF. In particular, the down-stream of the apoptotic signaling pathway was inhibited in the presence of PF, mostly by reduction of cleaved-poly ADP ribose polymerase, cleaved caspase-3, and -9 protein expression. Furthermore, H2O2-induced phosphorylation of c-Jun N-terminal kinase and extracellular signal-regulated kinase 1/2 was attenuated by treatment with PF. Taken together, neuroprotective effect of PF against oxidative stress probably result from the regulation of apoptotic pathway in C6 glial cells. In conclusion, our findings suggest that PF may be a potent therapeutic agent for neurodegenerative disorders.

Paeoniflorin Ameliorates Chronic Stress-Induced Depression-Like Behaviors and Neuronal Damages in Rats via Activation of the ERK-CREB Pathway.

Neuronal damage is related to the onset and treatment of depressive disorders. Antidepressant-like effects have been elicited by paeoniflorin on animal models. The aim of this study is to demonstrate whether the neuroprotective effect of paeoniflorin on rats suffered from chronic unpredictable mild stress (CUMS) was regulated by the ERK-CREB signaling pathway. Results showed that paeoniflorin not only ameliorated depressive-like behavior with low locomotor activity and prolonged immobility duration in our forced swimming test but also reduced sucrose consumption. Paeoniflorin treatment decreased the degree of neuronal damage in the hippocampus of the model rats. Conversely, it markedly increased the mRNA levels of ERK1, ERK2, and CREB and the levels of ERK, p-ERK, CREB, and p-CREB protein expression in the hippocampus. Blockade of the ERK-CREB axis with the ERK-specific inhibitor U0126 repressed the neuroprotective and antidepressant-like effects of paeoniflorin on rats in the setting of chronic-mild-stress and abolished the recoveries of p-ERK mediated by paeoniflorin treatment. Thus, paeoniflorin possibly exerted a neuroprotective effect modulated by the ERK-CREB signaling pathway on CUMS-induced hippocampal damage in rats.

Neuroprotection by Paeoniflorin against Nuclear Factor Kappa B-Induced Neuroinflammation on Spinal Cord Injury.

Background Acute spinal cord injury (SCI) is one of the most common and devastating causes of sensory or motor dysfunction. Nuclear factor-kappa B(NF-κB)-mediated neuroinflammatory responses, in addition to nitric oxide (NO), are key regulatory pathways in SCI. Paeoniflorin (PF), a major active component extracted from Paeonia roots, has been suggested to exert neuroprotective effects in the central nervous system. However, whether PF could improve the motor function after SCI in vivo is still unclear. Method Immunohistochemical analysis, western blot, real-time quantitative PCR, immunofluorescence staining, and histopathological and behavioral evaluation were used to explore the effects of paeoniflorin after SCI for 14 days. Results In this study, PF treatment significantly inhibited NF-κB activation and downregulated the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2(COX-2), and Nogo-A. Comparing behavioral and histological changes in SCI and PF treatment groups, we found that PF treatment improved motor function recovery, attenuated the histopathological damage, and increased neuronal survival in the SCI model. PF treatment also reduced expression levels of Bax and c-caspase-3 and increased the expression level of Bcl-2 and cell viabilities. Upregulation of TNF-α, IL-6, and IL-1β after injury was also prevented by PF. Conclusion These results suggest that the neuroprotective effects of PF are related to the inhibition of the NF-κB signaling pathway. And PF may be a therapeutic strategy in spinal cord injury.

Neuroprotective effect of paeoniflorin on okadaic acid-induced tau hyperphosphorylation via calpain/Akt/GSK-3β pathway in SH-SY5Y cells

Abnormal phosphorylation of tau, one of the most common symptoms of dementia, has become increasingly important in the study of the etiology and development of Alzheimer’s disease. Paeoniflorin, the main bioactive component of herbaceous peony, is a monoterpene glycoside, which has been reported to exert beneficial effects on neurodegenerative disease. However, the effect of paeoniflorin on tauopathies remains ambiguous. SH-SY5Y cells were treated with okadaic acid (OA) for 8 h to induce tau phosphorylation and no cell death was observed. Optical microscopy results showed that paeoniflorin ameliorated okadaic acid induced morphological changes, including cell swelling and synapsis shortening. Western blotting data illustrated that paeoniflorin reversed okadaic acid induced tau hyperphosphorylation, which was enhanced by inhibiting the activities of calpain, Akt and GSK-3β. Transmission electron microscopy results showed that paeoniflorin alone can reduce the number of autophagosomes and stabilize the microtubule structure. In addition, calpastain and paeoniflorin enhance the effect of paeoniflorin on stabilizing microtubules. In addition, calpastain markedly enhanced the effect of paeoniflorin on reversing okadaic acid-lowered fluorescence intensity of both MAP-2 and β III-tubulin, two microtubule-associated proteins. This study shows that paeoniflorin protected SH-SY5Y cells against okadaic acid assault by interfering with the calpain/Akt/GSK-3β-related pathways, in which autophagy might be involved. Besides, paeoniflorin is found to relieve the stress response of the microtubule structure system caused by okadaic acid treatment. The results presented in this study suggest that paeoniflorin potentially plays an important role in tauopathies.

Neuroprotective effects of paeoniflorin in neurodegenerative diseases of the central nervous system

Paeoniflorin is a monoterpene glycoside, the β-glucoside of paeoniflorigenin. It is one of the major components of Radix Paeoniae, the herbal product obtained from Paeonia lactiflora Pall., a medicinal plant used in folk medicine, especially in Chinese Traditional Medicine, to treat several human ailments, including dementia and cognitive decline. The neuroprotective effects of paeoniflorin have been studied by many investigations showing that its beneficial effects may derive from its anti-inflammatory and anti-apoptotic properties, and its ability to promote neuronal survival. This review evaluates scientific evidence on the neuroprotective properties of paeoniflorin. On the basis of literature data, paeoniflorin seems to be a promising compound for the prevention and treatment of neurodegenerative disorders, though definitive recommendation requires further studies.

Paeoniflorin attenuates the neuroinflammatory response in a rat model of chronic constriction injury.

Neuropathic pain remains the most frequent cause of suffering and disability worldwide. Paeoniflorin (PF), a water‑soluble monoterpene glycoside extracted from the roots of Paeonialactiflora Pall, has a wide range of pharmacological functions. Although the neuroprotective effect of PF has been reported in animal models of neuropathology, no systematic investigation has reported on the analgesic properties of PF in neuropathic pain. The aim of the present study was to investigate whether PF can alleviate neuropathic pain and to examine its possible mechanism. Neuropathic pain was induced by chronic constriction injury (CCI) of the sciatic nerve in rats. Following CCI surgery, the rats were administered with PF for 11days. Mechanical withdrawal threshold and thermal withdrawal latency were assessed prior to surgery, and on days 3, 7 and 11 post‑surgery. The levels of interleukin (IL)‑1β and tumor necrosis factor (TNF)‑α in the spinal cord were analyzed using enzyme‑linked immunosorbent assays. The activation of astrocytes and microglia were observed using immunostaining. In addition, the phosphorylation of p38 mitogen‑activated protein kinase (p‑p38MAPK) and nuclear factor‑κB (NF‑κB) were examined using western blot analysis. The results indicated that PF significantly attenuated CCI‑induced neuropathic pain and decreased the levels of TNF‑α and IL‑1β proinflammatory cytokines in the spinal cord. Furthermore, PF inhibited the over‑activation of microglia and reduced the elevated expression levels of p‑p38 MAPK and NF‑κB in the spinal cord. These results indicated that PF offers potential as a therapeutic agent for neuropathic pain, which merits further investigation.

Paeoniflorin and Albiflorin Attenuate Neuropathic Pain via MAPK Pathway in Chronic Constriction Injury Rats.

Neuropathic pain remains as the most frequent cause of suffering and disability around the world. The isomers paeoniflorin (PF) and albiflorin (AF) are major constituents extracted from the roots of Paeonia (P.) lactiflora Pall. Neuroprotective effect of PF has been demonstrated in animal models of neuropathologies. However, only a few studies are related to the biological activities of AF and no report has been published on analgesic properties of AF about neuropathic pain to date. The aim of this study was to compare the effects of AF and PF against CCI-induced neuropathic pain in rat and explore the underlying mechanism. We had found that both PF and AF could inhibit the activation of p38 mitogen-activated protein kinase (p38 MAPK) pathway in spinal microglia and subsequent upregulated proinflammatory cytokines (interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α)). AF further displayed remarkable effects on inhibiting the activation of astrocytes, suppressing the overelevated expression of phosphorylation of c-Jun N-terminal kinases (p-JNK) in astrocytes, and decreasing the content of chemokine CXCL1 in the spinal cord. These results suggest that both PF and AF are potential therapeutic agents for neuropathic pain, which merit further investigation.

Neuroprotective effect of paeoniflorin on H2O2-induced apoptosis in PC12 cells by modulation of reactive oxygen species and the inflammatory response.

Paeoniflorin (PF) is a product derived from Paeoniae Radix and is commonly prescribed in traditional Chinese medicine. PF has been reported to exhibit neuroprotective, anti-ischemic, antioxidant, anti-inflammatory and anticancer effects. The neuroprotective properties of PF have been demonstrated in animal models of various neuropathologies. The present study investigated the effects of PF on hydrogen peroxide (H2O2)-induced apoptosis in PC12 cells, to improve the understanding of the mechanisms underlying its neuroprotective properties. The H2O2-induced apoptosis of PC12 cells resulted in a reduction in the B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein ratio and the activation of caspase-3. PF treatment was observed to reverse the apoptotic process and to modulate the expression levels of a number of apoptosis-associated proteins. Furthermore, PF significantly mitigated the H2O2-induced reduction in cell viability, in addition to scavenging reactive oxygen species and preventing the release of lactate dehydrogenase from the PC12 cells. In addition, the apoptosis-associated activation of nuclear factor (NF)-κB was inhibited in the PF-treated cells, and the expression levels of tumor necrosis factor α and interleukin (IL)-1β were reduced. In conclusion, the present study demonstrated that PF was able to reduce H2O2-induced toxicity by blocking the activation of the neuroinflammatory factor NF-κB. These results suggest that PF may be a valuable neuroprotective agent for the treatment of neurological disease and injury.

Role of PI3K/Akt pathway in effect of paeoniflorin against Aβ25-35-induced PC12 cell injury

To study the role of PI3K/Akt pathway in the neuroprotective effect of paeoniflorin on PC12 cells. The paeoniflorin group (5, 10, 20 μmol · L(-1)) was pretreated for 30 min, and then added with Aβ25-35 (20 μmol · L(-1)) for interaction for 24 h. Inhibitor LY294002 (10 μmol · L(-1)) was pretreated for 30 min before the action of paeoniflorin (10 μmol · L(-1)). The MTT colorimetric method was used to detect the cell viability. The apoptosis rate was tested by the FITC-Annexin V/PI staining. The protein expression of p-AKT, Bax, Bcl-2 and cleaved caspase-3 protein were detected by Western blot analysis. Paeoniflorin could significantly inhibit the Aβ25-35-induced PC12 cell toxicity and apoptosis. Its protection effect may be achieved by up- regulating AKT phosphorylation level, increasing Bcl-2 protein expression, reducing Bax protein expression, inhibiting the activation of caspase-3. Inhibitor LY294002 could weaken the above protective effects of paeoniflorin. Paeoniflorin could activate PI3K/Akt signaling pathway to protect the PC12 cell injury induced by Aβ25-35.

Original article Paeoniflorin attenuates Aβ 25-35 -induced neurotoxicity in PC12 cells by preventing mitochondrial dysfunction

The pathogenic mechanism of neurodegenerative brain disorder such as Alzheimer's disease (AD) has been still far from clearly understood. Previous research has identified that mitochondrial dysfunction induced by Aβ has been recognized as a hallmark in AD. Therefore, the effective agents targeting β-amyloid (Aβ)-induced mitochondrial dysfunction may be useful for the treatment or prevention of AD. In the present study, the neuroprotective effect of paeoniflorin (PF), one monoterpene glycoside isolated from the Chinese herb Radix Paeoniae alba, on Aβ25-35-induced toxicity in PC12 cells was investigated for the first time. The results showed that PF could attenuate or restore the cell injury induced by Aβ25-35 in PC12 cells through preventing mitochondrial dysfunction, including decreased mitochondrial membrane potential, increased cytochrome c release as well as activity of caspase-3 and caspase-9. Therefore, our data provide the evidence that PF could protect PC12 cells against Aβ25-35-induced neurotoxicity and might be a potentially therapeutic approach for AD in the future.

Paeoniflorin, a Natural Neuroprotective Agent, Modulates Multiple Anti-Apoptotic and Pro-apoptotic Pathways in Differentiated PC12 Cells

Numerous studies have shown robust neuroprotective effects of paeoniflorin (PF), a natural compound derived from the herbal medicine Paeony radix. In the present study, we determined associations of PF neuroprotection with its modulation of various apoptotic and anti-apoptotic pathways. PF (50-400μM) pretreatment significantly improved viability of differentiated PC12 cells exposed to methyl-4-phenylpyridine ion (MPP(+)), a neurotoxin, and inhibited over-release of lactate dehydrogenase, a biomarker of neuronal cell death. PF also ameliorated MPP(+)-induced nuclear and mitochondrial apoptotic alteration and intracellular calcium overload. PF treatment reversed MPP(+) suppression of activity of B cell lymphoma-extra large, which is a mitochondrial membrane molecule that protects cells from DNA damage-induced apoptosis, and strikingly inhibited the enhanced level of cleaved poly(ADP-ribose)polymerase, which is involved in the process of apoptosis. PF alone and coadministration with MPP(+) enhanced phospho activation of extracellular signal-regulated kinases, Akt, and its downstream element glycogen synthase kinase-3, but the effects were completely abolished in the presence of their blockers PD98059 and LY294002. The presence of the blockers also diminished the potency of PF in improving viability of MPP(+)-exposed cells. These results indicate that neuroprotective effects of PF are related to its modulation of multiple anti-apoptotic and pro-apoptotic pathways, including blockade of intracellular calcium overload, prevention of mitochondrial membrane integrity, inhibition of pro-apoptotic molecules, and up-regulation of anti-apoptotic proteins associated with cell survival and proliferation. The study provides evidence supporting PF as a potential therapeutic agent used for the treatment of neurodegenerative diseases and neural injury.

Paeoniflorin suppresses the expression of intercellular adhesion molecule‐1 (ICAM‐1) in endotoxin‐treated human monocytic cells

Paeoniflorin (PF) has ameliorative effects on learning and memory impairment and cerebral ischaemia in rats and has protective effects against the degeneration of dopaminergic neurons in substantia nigra. The neuroprotective effects of PF are most probably derived from its anti-inflammatory property. Abnormally high levels of intercellular adhesion molecule-1 (ICAM-1) have been found to be associated with a wide range of inflammatory and immune responses. Here we studied whether PF regulates the levels of ICAM-1 elevated in LPS-activated differentiated human monocytic U937 cells and TNF-α-stimulated human umbilical vein endothelial cells (HUVECs). mRNA levels were evaluated by RT-PCR. Protein levels were evaluated by Western blot analysis. An immunofluorescence technique was used to estimate NF-κB translocation, and NF-κB binding to nuclear DNA was determined by EMSA. PF inhibited ICAM-1 expression elevated in LPS-induced U937 cells and TNF-α-stimulated HUVECs. Although previous reports showed that PF's action is mediated by activating adenosine A₁ receptors, application of a selective adenosine A₁ receptor antagonist did not change the inhibitory effect of PF in our experiments. To elucidate the underlying mechanisms of the effect of PF, we studied its effect on signalling pathways upstream of ICAM-1 expression. PF suppressed the activation of the NF-κB pathway, which regulates the expression of ICAM-1. The TLR4 and MAPK pathways were shown not to be involved in the effects of PF in these cells. PF inhibits ICAM-1 expression in LPS-treated U937 cells and TNF-α-stimulated HUVECs by suppressing the activation of the NF-κB pathway.

Neuroprotective effect of paeoniflorin on cerebral ischemic rat by activating adenosine A1 receptor in a manner different from its classical agonists

The effects of paeoniflorin (PF), a compound isolated from Paeony radix, on neurological impairment and histologically measured infarction volume following transient and permanent focal ischemia were examined in Sprague-Dawley rats. In transient ischemia model, rats were subjected to a 1.5-h occlusion of the middle cerebral artery (MCA). The administration of PF (2.5 and 5 mg kg(-1), s.c.) produced a dose-dependent decrease in both neurological impairment and the histologically measured infarction volume. Similar results were also obtained when PF (2.5, 5, and 10 mg kg(-1), s.c.) was given in permanent ischemia model. The neuroprotective effect of PF (10 mg kg(-1), s.c.) was abolished by pretreatment of DPCPX (0.25 mg kg(-1), s.c.), a selective adenosine A1 receptor (A1R) antagonist. PF (10, 40, and 160 mg kg(-1), i.v.) had no effect on mean arterial pressure (MAP) and heart rates (HR) in the conscious rat. Additionally, PF (10(-3) mol l(-1)) had no effect on noradrenaline- (NA-) or high K+ concentration-induced contractions of isolated rabbit primary artery. In competitive binding experiments, PF did not compete with the binding of [3H]DPCPX, but displaced the binding of [3H]NECA to the membrane preparation of rat cerebral cortex. This binding manner was distinguished from the classical A1R agonists. The results demonstrated that activation of A1R might be involved in PF-induced neuroprotection in cerebral ischemia in rat. However, PF had no 'well-known' cardiovascular side effects of classical A1R agonists. The results suggest that PF might have the potential therapeutic value as an anti-stroke drug.