Triptolide upregulates NGF synthesis in rat astrocyte cultures

Neurotrophic Natural Products

Neurotrophins (NGF, BDNF, NT3, NT4) can decrease cell death, induce differentiation, as well as sustain the structure and function of neurons, which make them promising therapeutic agents for the treatment of neurodegenerative disorders. However, neurotrophins have not been very effective in clinical trials mostly because they cannot pass through the blood-brain barrier owing to being high-molecular-weight proteins. Thus, neurotrophin-mimic small molecules, which stimulate the synthesis of endogenous neurotrophins or enhance neurotrophic actions, may serve as promising alternatives to neurotrophins. Small-molecular-weight natural products, which have been used in dietary functional foods or in traditional medicines over the course of human history, have a great potential for the development of new therapeutic agents against neurodegenerative diseases such as Alzheimer's disease. In this contribution, a variety of natural products possessing neurotrophic properties such as neurogenesis, neurite outgrowth promotion (neuritogenesis), and neuroprotection are described, and a focus is made on the chemistry and biology of several neurotrophic natural products.

Triptolide induces PANoptosis in macrophages and causes organ injury in mice

Macrophages represent the first lines of innate defense against pathogenic infections and are poised to undergo multiple forms of regulated cell death (RCD) upon infections or toxic stimuli, leading to multiple organ injury. Triptolide, an active compound isolated from Tripterygium wilfordii Hook F., possesses various pharmacological activities including anti-tumor and anti-inflammatory effects, but its applications have been hampered by toxic adverse effects. It remains unknown whether and how triptolide induces different forms of RCD in macrophages. In this study, we showed that triptolide exhibited significant cytotoxicity on cultured macrophages in vitro, which was associated with multiple forms of lytic cell death that could not be fully suppressed by any one specific inhibitor for a single form of RCD. Consistently, triptolide induced the simultaneous activation of pyroptotic, apoptotic and necroptotic hallmarks, which was accompanied by the co-localization of ASC specks respectively with RIPK3 or caspase-8 as well as their interaction with each other, indicating the formation of PANoptosome and thus the induction of PANoptosis. Triptolide-induced PANoptosis was associated with mitochondrial dysfunction and ROS production. PANoptosis was also induced by triptolide in mouse peritoneal macrophages in vivo. Furthermore, triptolide caused kidney and liver injury, which was associated with systemic inflammatory responses and the activation of hallmarks for PANoptosis in vivo. Collectively, our data reveal that triptolide induces PANoptosis in macrophages in vitro and exhibits nephrotoxicity and hepatotoxicity associated with induction of PANoptosis in vivo, suggesting a new avenue to alleviate triptolide's toxicity by harnessing PANoptosis.

The therapeutic potential of triptolide and celastrol in neurological diseases

Neurological diseases are complex diseases affecting the brain and spinal cord, with numerous etiologies and pathogenesis not yet fully elucidated. Tripterygium wilfordii Hook. F. (TWHF) is a traditional Chinese medicine with a long history of medicinal use in China and is widely used to treat autoimmune and inflammatory diseases such as systemic lupus erythematosus and rheumatoid arthritis. With the rapid development of modern technology, the two main bioactive components of TWHF, triptolide and celastrol, have been found to have anti-inflammatory, immunosuppressive and anti-tumor effects and can be used in the treatment of a variety of diseases, including neurological diseases. In this paper, we summarize the preclinical studies of triptolide and celastrol in neurological diseases such as neurodegenerative diseases, brain and spinal cord injury, and epilepsy. In addition, we review the mechanisms of action of triptolide and celastrol in neurological diseases, their toxicity, related derivatives, and nanotechnology-based carrier system.

The Specific Role of Reactive Astrocytes in Stroke

Astrocytes are essential in maintaining normal brain functions such as blood brain barrier (BBB) homeostasis and synapse formation as the most abundant cell type in the central nervous system (CNS). After the stroke, astrocytes are known as reactive astrocytes (RAs) because they are stimulated by various damage-associated molecular patterns (DAMPs) and cytokines, resulting in significant changes in their reactivity, gene expression, and functional characteristics. RAs perform multiple functions after stroke. The inflammatory response of RAs may aggravate neuro-inflammation and release toxic factors to exert neurological damage. However, RAs also reduce excitotoxicity and release neurotrophies to promote neuroprotection. Furthermore, RAs contribute to angiogenesis and axonal remodeling to promote neurological recovery. Therefore, RAs’ biphasic roles and mechanisms make them an effective target for functional recovery after the stroke. In this review, we summarized the dynamic functional changes and internal molecular mechanisms of RAs, as well as their therapeutic potential and strategies, in order to comprehensively understand the role of RAs in the outcome of stroke disease and provide a new direction for the clinical treatment of stroke.

Effects of 7,8-dihydroxycoumarin on the myelin morphological changes and PSD-95 protein expression in Balb/c mice after sciatic nerve injury

OBJECTIVE

To investigate the effects of 7,8-dihydroxycoumarin on the myelin morphological changes and PSD-95 protein expression in mice with sciatic nerve injury, and to explore the relationship between PSD-95 protein and myelin regeneration after nerve myelin injury.

METHODS

One hundred twenty-seven male adult Balb/c mice were selected and randomly divided into high, medium and low 7,8-dihydroxycoumarin dose groups and blank control group. Anastomosis was then carried out for the amputated right sciatic nerve, and intraperitoneal injection of 7,8-dihydroxycoumarin was applied postoperatively. At weeks 1, 2, 4 and 8 after surgery, nervous tissues from the injury side were taken for immunohistochemical Luxol Fast Blue staining, so as to observe the morphological changes of the locally injured nerve myelin. Meanwhile, PSD-95 mRNA and protein expression were determined using real-time PCR and western blotting.

RESULTS

The nerve myelin recovery in injury side of mice at all time points showed a definite dose-effect relationship with the dose of 7,8-dihydroxycoumarin. Moreover, 7,8-dihydroxycoumarin could inhibit the PSD-95 mRNA level and protein expression. At the same time, there was a dose-effect of the inhibition.

CONCLUSIONS

7,8-Dihydroxycoumarin can affect nerve recovery in mice with sciatic nerve injury, which shows a definite dose-effect relationship with its dose. Besides, PSD-95 protein expression can suppress the regeneration of the injured nerve myelin.

Effects of brazilein on PSD-95 protein expression and neurological recovery in mice after sciatic nerve injury

PURPOSE

To evaluate the local nerve myelin recovery and the expression of PSD-95 protein and mRNA in the L4-L6 segment of the spinal cord after applying Brazilein to sciatic nerve injury BALB/c mice model and investigate the regulatory effects of Brazilein on myelin recovery after peripheral nerve injury.

METHODS

A total of 160 BALB/c mice were selected to establish the unilateral sciatic nerve injury model and randomly divided into four groups: saline blank control, Brazilein high-dose, medium-dose, and low-dose. Mice were assessed at different time points (1 w, 2 w, 4 w, 8 w) after sciatic nerve injury for the sciatic functional index (SFI) and sciatic nerve function recovery of the injured side by myelin Luxol Fast Blue (LFB) staining of the sciatic nerve. In addition, immunohistochemistry, real time-PCR, and Western blot were used to detect the PSD-95 expression in the spinal cord L4-L6 segments of the injured sciatic nerve at each time point.

RESULTS

The results of SFI and sciatic nerve function recovery, as well as, myelin LFB staining of the injured side indicated that all indexes of the Brazilein middle- and high-dose groups were significantly better than the low-dose and blank control groups at each time point. The PSD-95 expression in the L4-L6 segment of the spinal cord was statistically lower in the high- and medium-dose groups than in the low-dose and blank control groups at 1 w, 2 w, and 4 w, while the differences between the groups were not significant at 8 w.

CONCLUSION

Brazilein inhibits PSD-95 activation in the corresponding segment of sciatic nerve spinal cord in BALB/c mice after sciatic nerve injury, thereby inhibiting the excessive expression of free radicals and promoting myelin regeneration.

The effects of triptolide on the cellular activity of cryopreserved rat sciatic nerves and nerve regeneration after allotransplantation

Purpose: To investigate the effects of triptolide (T10) on the cellular activity of cryopreserved rat sciatic nerves and nerve regeneration after allotransplantation.Materials and methods: After the optimal T10 concentration was determine, sciatic nerve fragments from Sprague-Dawley (SD) rats were randomly divided into 5 groups: the fresh nerve group (group A), the Dulbecco's modified Eagle's medium (DMEM)-preservation group (group B), the T10-preservation group (group C), the T10-pretreatment, DMEM-preservation group (group D), and the T10-pretreatment, T10-preservation group (group E). The nerves in the preservation groups were preserved at 4 °C for 4 w. Then, either cryopreserved or fresh nerves were used to repair 10-mm sciatic nerve defects in Wistar rats (group A', group B', group C', group D', and group E', which correspond to the nerve groups described above); in addition, one fresh homologous transplantation group (group F') was established.Results: Nerve growth factor (NGF) was expressed at significantly higher levels in the groups treated with the T10 solution at 37 °C. After rat sciatic nerves were cryopreserved for 4 w, group E had increased numbers of live nerve cells and increased levels of biological activity (P < 0.001) and reduced levels of immunogenicity (P < 0.001) when compared with those for the other groups. Sixteen weeks after transplantation, recipient nerve regeneration in group E' was increased compared with that in groups A', B', C', and D' (P < 0.05).Conclusions: The application of T10 in vitro induced the expression of neurotrophic factors in rat sciatic nerves, increased the biological activity of cryopreserved nerves, reduced immunogenicity, and promoted recipient nerve regeneration after allotransplantation.

Treatment of Neurodegenerative Diseases with Bioactive Components of Tripterygium wilfordii

Tripterygium wilfordii Hook F. (TWHF), a traditional Chinese medicine, has been widely used to treat autoimmune and inflammatory diseases including rheumatoid arthritis, systemic lupus erythematosus and dermatomyositis in China. Recently, studies have demonstrated that the bioactive components of TWHF have effective therapeutic potential for neurodegenerative diseases including Alzheimer's disease, Parkinson's disease and Multiple Sclerosis. In this paper, we summarize the research progress of triptolide and celastrol (the two major TWHF components) as well as their analogues in the treatment of neurodegenerative diseases. In addition, we review and discuss the molecular mechanisms and structure features of those two bioactive TWHF components, highlighting their therapeutic promise in neurodegenerative diseases.

Efficacy and safety of Tripterygium wilfordii Hook F for CKD in Mainland China: A systematic review and meta-analysis

Tripterygium wilfordii Hook F (TwHF) is a promising Chinese traditional medicine used to significantly reduce proteinuria and improve renal function. However, its efficacy and safety in treatment of chronic kidney disease need to be further explored in order to promote its application in clinics. This review compared the efficacy and safety of TwHF with the placebo, conventional Western medicine and other immunosuppressive medicine in a range of kidney disorders. One hundred three randomized controlled trials were included. TwHF therapy decreased 24-hr proteinuria by 0.59 g/day (95% confidence interval [CI; -0.68, -0.50]), serum creatinine level by 1.93 μmol/L (95% CI [-3.69, -0.17]), and blood urea nitrogen level by 0.24 mmol/L (95% CI [-0.41, -0.07]); increased the total effective rate by 27% (95% CI [1.24, 1.30]); and decreased the incidence of adverse reactions by 19% (95% CI [0.68, 0.96]) overall. Meta regression results showed that the duration of therapy and mean age of participants were the major sources of high heterogeneity. Sensitivity analysis demonstrated that our statistic results were relatively stable and credible. The present findings suggested that TwHF possibly has nephroprotective effects by decreasing proteinuria, serum creatinine level, and blood urea nitrogen level and no more adverse reactions compared with control group in most kidney disorders. However, these findings still need to be further confirmed by high-quality trials.

The Medicinal Chemistry of Natural and Semisynthetic Compounds against Parkinson's and Huntington's Diseases

Among the diseases affecting the central nervous system (CNS), neurodegenerations attract the interest of both the clinician and the medicinal chemist. The increasing average age of population, the growing number of patients, and the lack of long-term effective remedies push ahead the quest for novel tools against this class of pathologies. We present a review on the state of the art of the molecules (or combination of molecules) of natural origin that are currently under study against two well-defined pathologies: Parkinson's disease (PD) and Huntington's disease (HD). Nowadays, very few tools are available for preventing or counteracting the progression of such diseases. Two major parameters were considered for the preparation of this review: particular attention was reserved to these research works presenting well-defined molecular mechanisms for the studied compounds, and where available, papers reporting in vivo data were preferred. A literature search for peer-reviewed articles using PubMed, Scopus, and Reaxys databases was performed, exploiting different keywords and logical operators: 91 papers were considered (preferentially published after 2015). The review presents a brief overview on the etiology of the studied neurodegenerations and the current treatments, followed by a detailed discussion of the natural and semisynthetic compounds dividing them in different paragraphs considering their several mechanisms of action.

Plant-Derived Natural Products for Parkinson's Disease Therapy

Plant-derived natural products have made their own niche in the treatment of neurological diseases since time immemorial. Parkinson's disease (PD), the second most prevalent neurodegenerative disorder, has no cure and the treatment available currently is symptomatic. This chapter thoughtfully and objectively assesses the scientific basis that supports the increasing use of these plant-derived natural products for the treatment of this chronic and progressive disorder. Proper considerations are made on the chemical nature, sources, preclinical tests and their validity, and mechanisms of behavioural or biochemical recovery observed following treatment with various plants derived natural products relevant to PD therapy. The scientific basis underlying the neuroprotective effect of 6 Ayurvedic herbs/formulations, 12 Chinese medicinal herbs/formulations, 33 other plants, and 5 plant-derived molecules have been judiciously examined emphasizing behavioral, cellular, or biochemical aspects of neuroprotection observed in the cellular or animal models of the disease. The molecular mechanisms triggered by these natural products to promote cell survivability and to reduce the risk of cellular degeneration have also been brought to light in this study. The study helped to reveal certain limitations in the scenario: lack of preclinical studies in all cases barring two; heavy dependence on in vitro test systems; singular animal or cellular model to establish any therapeutic potential of drugs. This strongly warrants further studies so as to reproduce and confirm these reported effects. However, the current literature offers scientific credence to traditionally used plant-derived natural products for the treatment of PD.

Anti-Inflammatory and Neuroprotective Effects of Triptolide via the NF-κB Signaling Pathway in a Rat MCAO Model

Stroke is the leading cause of neurological disability in humans. Middle cerebral artery occlusion (MCAO) followed by reperfusion is widely accepted to mimic stroke in basic medical research. Triptolide is one of the major active components of the traditional Chinese herb Tripterygium wilfordii Hook F, and has been reported to have potent anti-inflammatory and immunosuppressive properties. Since its preclinical effects on stroke were still unclear, we decided to study the effects of Triptolide on focal cerebral ischemia/reperfusion injury in this study. The results showed that Triptolide treatment significantly attenuates brain infarction volume, water content, neurological deficits, and neuronal cell death rate, which were increased in the MCAO model rats. Immunohistochemistry was used to analyze the expression of glial fibrillary acidic protein (GFAP), Cyclooxygenase-2 (COX-2), inducible nitric oxide (iNOS), and NF-κB in the ischemic brains. The administration of Triptolide showed down-regulation of the iNOS, COX-2, GFAP, and NF-κB expression in MCAO rats. It also increased the expression of bcl-2, and suppressed levels of bax and caspase-3 compared with the MCAO group. Our findings revealed that Triptolide exerts its neuroprotective effects against inflammation with the involvement of inhibition of NF-κB activation.

C6 Glioma-Secreted NGF and FGF2 Regulate Neuronal APP Processing Through Up-Regulation of ADAM10 and Down-Regulation of BACE1, Respectively

Excessive accumulation of amyloid-β (Aβ) caused by cleavage of amyloid precursor protein (APP) is thought to be the primary cause of Alzheimer's disease (AD). Two key enzymes ADAM10 and BACE1 are involved in the initial cleavage of APP, resulting in the onset of two pathways, the amyloidogenic pathway and the non-amyloidogenic pathway, respectively. Altering APP metabolism towards the non-amyloidogenic pathway is thought to reduce Aβ production. It has been reported that, in vivo, exogenous neurotrophic factors make APP apt to entering the non-amyloidogenic pathway. Since astrocytes secrete a battery of neurotrophic factors, we investigated the role of astrocyte-derived factors in the dynamics of Aβ generation in neural cells. Results show that C6 glioma cell-conditioned medium (GCM), obtained from cultured astrocyte-derived C6 glioma cells, inhibit Aβ1-42 production and shift APP processing towards the non-amyloidogenic pathway in APPswe-HEK293 cells. Such effect is attributed to two key APP cleavage enzymes, ADAM10 and BACE1. Two neurotrophic factors in the GCM, nerve growth factor and fibroblast growth factor 2, are responsible for the up-regulation of ADAM10 and down-regulation of BACE1, respectively. Our findings enhance our understanding of the relationship between astrocytes and Aβ generation, indicating that stimulation of astrocytic neurotrophic factors could slow AD progression.

Triptolide treatment reduces Alzheimer's disease (AD)-like pathology through inhibition of BACE1 in a transgenic mouse model of AD

The complex pathogenesis of Alzheimer’s disease (AD) involves multiple contributing factors, including amyloid β (Aβ) peptide accumulation, inflammation and oxidative stress. Effective therapeutic strategies for AD are still urgently needed. Triptolide is the major active compound extracted from Tripterygium wilfordii Hook.f., a traditional Chinese medicinal herb that is commonly used to treat inflammatory diseases. The 5-month-old 5XFAD mice, which carry five familial AD mutations in the β-amyloid precursor protein (APP) and presenilin-1 (PS1) genes, were treated with triptolide for 8 weeks. We observed enhanced spatial learning performances, and attenuated Aβ production and deposition in the brain. Triptolide also inhibited the processing of amyloidogenic APP, as well as the expression of βAPP-cleaving enzyme-1 (BACE1) both in vivo and in vitro. In addition, triptolide exerted anti-inflammatory and anti-oxidative effects on the transgenic mouse brain. Triptolide therefore confers protection against the effects of AD in our mouse model and is emerging as a promising therapeutic candidate drug for AD.

7, 8-dihydroxycoumarin improves neurological function in a mouse model of sciatic nerve injury

In the present study, a mouse model of sciatic nerve injury was treated with intraperitoneal injection of 7, 8-dihydroxycoumarin (10, 5, or 2.5 mg/kg per day). Western blot and real-time PCR results showed that growth associated protein 43 expression was significantly increased in the L_4-6 segments of the spinal cord. The amplitude and velocity of motor nerve conduction in the sciatic nerve were significantly increased in model mice. In addition, the appearance of the myelin sheath in the injured sciatic nerve was regular, with an even thickness and clear outline, and the surrounding fibroplasia was not obvious. Our results indicate that 7, 8-dihydroxycoumarin can promote the repair of injured nerve by upregulating growth associated protein 43 expression in the corresponding spinal cord segments of mice with sciatic nerve injury.

Computational prediction and experimental validation of low-affinity target of triptolide and its analogues

ERα as a novel low affinity target for triptolide and its analogues triptonide and triptriolide.

Triptolide preserves cognitive function and reduces neuropathology in a mouse model of Alzheimer's disease

Triptolide, a major bioactive ingredient of a widely used herbal medicine, has been shown to possess multiple pharmacological functions, including potential neuroprotective effects pertinent to Alzheimer's disease (AD) in vitro. However, the therapeutic potential of triptolide for AD in vivo has not been thoroughly evaluated. In the present study, we investigated the impact of peripherally administered triptolide on AD-related behavior and neuropathology in APP_swe/PS1_ΔE9 (APP/PS1) mice, an established model of AD. Our results showed that two-month treatment with triptolide rescued cognitive function in APP/PS1 mice. Immunohistochemical analyses indicated that triptolide treatment led to a significant decrease in amyloid-β (Aβ) deposition and neuroinflammation in treated mice. In contrast to previous findings in vitro, biochemical analyses showed that triptolide treatment did not significantly affect the production pathway of Aβ in vivo. Intriguingly, further analyses revealed that triptolide treatment upregulated the level of insulin-degrading enzyme, a major Aβ-degrading enzyme in the brain, indicating that triptolide treatment reduced Aβ pathology by enhancing the proteolytic degradation of Aβ. Our findings demonstrate that triptolide treatment ameliorates key behavioral and neuropathological changes found in AD, suggesting that triptolide may serve as a potential therapeutic agent for AD.

The mechanism of astragaloside IV promoting sciatic nerve regeneration

3-O-beta-D-xylopyranosyl-6-O-beta-D-glucopyranosyl-cycloastragenol (astragaloside IV), the main active component of the traditional Chinese medicine astragalus membranaceus, has been shown to be neuroprotective. This study investigated whether astragaloside IV could promote the repair of injured sciatic nerve. Denervated sciatic nerve of mice was subjected to anastomosis. The mice were intraperitoneally injected with 10, 5, 2.5 mg/kg astragaloside IV per day for 8 consecutive days. Western blot assay and real-time PCR results demonstrated that growth-associated protein-43 expression was upregulated in mouse spinal cord segments L_4–6 after intervention with 10, 5, 2.5 mg/kg astragaloside IV per day in a dose-dependent manner. Luxol fast blue staining and electrophysiological detection suggested that astragaloside IV elevated the number and diameter of myelinated nerve fibers, and simultaneously increased motor nerve conduction velocity and action potential amplitude in the sciatic nerve of mice. These results indicated that astragaloside IV contributed to sciatic nerve regeneration and functional recovery in mice. The mechanism underlying this effect may be associated with the upregulation of growth-associated protein-43 expression.

Puerarin accelerates neural regeneration after sciatic nerve injury

Puerarin is a natural isoflavone isolated from plants of the genus Pueraria and functions as a protector against cerebral ischemia. We hypothesized that puerarin can be involved in the repair of peripheral nerve injuries. To test this hypothesis, doses of 10, 5, or 2.5 mg/kg per day puerarin (8-(β-D-Glucopyranosyl-7-hydroxy-3-(4-hydroxyphenyl)-4H-1-benzopyran-4-one) were injected intraperitoneally into mouse models of sciatic nerve injury. Puerarin at the middle and high doses significantly up-regulated the expression of growth-associated protein 43 in the L_4–6 segments of the spinal cord from mice at 1, 2, and 4 weeks after modeling, and reduced the atrophy of the triceps surae on the affected side and promoted the regeneration of nerve fibers of the damaged spinal cord at 8 weeks after injury. We conclude that puerarin exerts an ongoing role to activate growth-associated protein 43 in the corresponding segment of the spinal cord after sciatic nerve injury, thus contributing to neural regeneration after sciatic nerve injuries.

Ursolic acid induces neural regeneration after sciatic nerve injury

In this study, we aimed to explore the role of ursolic acid in the neural regeneration of the injured sciatic nerve. BALB/c mice were used to establish models of sciatic nerve injury through unilateral sciatic nerve complete transection and microscopic anastomosis at 0.5 cm below the ischial tube-rosity. The successfully generated model mice were treated with 10, 5, or 2.5 mg/kg ursolic acid via intraperitoneal injection. Enzyme-linked immunosorbent assay results showed that serum S100 protein expression level gradually increased at 1-4 weeks after sciatic nerve injury, and significantly decreased at 8 weeks. As such, ursolic acid has the capacity to significantly increase S100 protein expression levels. Real-time quantitative PCR showed that S100 mRNA expression in the L4-6 segments on the injury side was increased after ursolic acid treatment. In addition, the muscular mass index in the soleus muscle was also increased in mice treated with ursolic acid. Toluidine blue staining revealed that the quantity and average diameter of myelinated nerve fibers in the injured sciatic nerve were significantly increased after treatment with ursolic acid. 10 and 5 mg/kg of ursolic acid produced stronger effects than 2.5 mg/kg of ursolic acid. Our findings indicate that ursolic acid can dose-dependently increase S100 expression and promote neural regeneration in BALB/c mice following sciatic nerve injury.

7,8-dihydroxycoumarin may promote sciatic nerve regeneration by suppressing NF-κB expression in mice

Nuclear factor (NF)-κB expression occurs during sciatic injury. In addition, 7,8-dihydroxycoumarin exhibits a neurotrophic effect on peripheral nerve regeneration. To investigate the effects of 7,8-dihydroxycoumarin on the expression levels of NF-κB in L4-6 spinal cord segments of the injured sciatic nerve in mice and on the functional recovery and regeneration following nerve injury, a total of 160 healthy adult male BALB/c mice underwent unilateral sciatic nerve interruption and anastomosis. The mice were separated into groups and subsequently treated with physiological saline (control) or high, medium or low doses of 7,8-dihydroxycoumarin. NF-κB levels were detected by western blot analysis and quantitative polymerase chain reaction (qPCR), and the sciatic functional index (SFI) was measured. Neuronal apoptosis was detected by terminal-deoxynucleotidyl transferase dUTP-mediated nick-end labeling (TUNEL) staining. The results revealed that NF-κB was activated in the L4-6 spinal cord connected to the injured sciatic nerve. qPCR and western-blot analysis results showed that the expression levels of NF-κB in the high- and medium-dose groups were significantly lower compared with the low-dose and control groups at 12 h, one day, three days, five days and one week (P<0.05 for each). SFI and TUNEL results demonstrated that the high- and medium-dose groups exhibited improved functional nerve regeneration and reduced apoptosis compared with the low-dose and control groups. In conclusion, 7,8-dihydroxycoumarin is capable of suppressing the immune activation of NF-κB in the neurons of the L4-6 spinal cord connected with the injured sciatic nerve, thereby reducing the focal filtration of inflammatory cells, producing the optimum environment for nerve regeneration.

Can medical herbs stimulate regeneration or neuroprotection and treat neuropathic pain in chemotherapy-induced peripheral neuropathy?

Chemotherapy-induced neuropathy (CIPN) has a relevant impact on the quality of life of cancer patients. There are no curative conventional treatments, so further options have to be investigated. We conducted a systematic review in English and Chinese language databases to illuminate the role of medical herbs. 26 relevant studies on 5 single herbs, one extract, one receptor-agonist, and 8 combinations of herbs were identified focusing on the single herbs Acorus calamus rhizoma, Cannabis sativa fructus, Chamomilla matricaria, Ginkgo biloba, Salvia officinalis, Sweet bee venom, Fritillaria cirrhosae bulbus, and the herbal combinations Bu Yang Huan Wu, modified Bu Yang Huan Wu plus Liuwei Di Huang, modified Chai Hu Long Gu Mu Li Wan, Geranii herba plus Aconiti lateralis praeparata radix , Niu Che Sen Qi Wan (Goshajinkigan), Gui Zhi Jia Shu Fu Tang (Keishikajutsubuto), Huang Qi Wu Wu Tang (Ogikeishigomotsuto), and Shao Yao Gan Cao Tang (Shakuyakukanzoto). The knowledge of mechanism of action is still limited, the quality of clinical trials needs further improvement, and studies have not yielded enough evidence to establish a standard practice, but a lot of promising substances have been identified. While CIPN has multiple mechanisms of neuronal degeneration, a combination of herbs or substances might deal with multiple targets for the aim of neuroprotection or neuroregeneration in CIPN.

The Inhibition of Spinal Astrocytic JAK2-STAT3 Pathway Activation Correlates with the Analgesic Effects of Triptolide in the Rat Neuropathic Pain Model

Neuropathic pain (NP) is an intractable clinical problem without satisfactory treatments. However, certain natural products have been revealed as effective therapeutic agents for the management of pain states. In this study, we used the spinal nerve ligation (SNL) pain model to investigate the antinociceptive effect of triptolide (T10), a major active component of the traditional Chinese herb Tripterygium wilfordii Hook F. Intrathecal T10 inhibited the mechanical nociceptive response induced by SNL without interfering with motor performance. Additionally, the anti-nociceptive effect of T10 was associated with the inhibition of the activation of spinal astrocytes. Furthermore, intrathecal administration of T10 attenuated SNL-induced janus kinase (JAK) signal transducers and activators of transcription 3 (STAT3) signalling pathway activation and inhibited the upregulation of proinflammatory cytokines, such as interleukin-6, interleukin-1 beta, and tumour necrosis factor-α, in dorsal horn astrocytes. Moreover, NR2B-containing spinal N-methyl D-aspartate receptor (NMDAR) was subsequently inhibited. Above all, T10 can alleviate SNL-induced NP via inhibiting the neuroinflammation in the spinal dorsal horn. The anti-inflammation effect of T10 may be related with the suppression of spinal astrocytic JAK-STAT3 activation. Our results suggest that T10 may be a promising drug for the treatment of NP.

Triptolide with potential medicinal value for diseases of the central nervous system

Tripterygium wilfordii Hook.f. (TWHF) has a long history as a Traditional Chinese Medicine (TCM) herb that aids in treating inflammatory and autoimmune diseases. The major bioactive component of TWHF is triptolide, which has been recognized to possess a broad spectrum of biological profiles including antiinflammatory, immunosuppressive, antifertility, and antitumor activities, as well as neurotrophic and neuroprotective effects. Limitation of triptolide, such as poor water solubility and severe systemic toxicity, has postponed clinical development and trials; however, the wide range of medicinal value of triptolide has been drawing intensive worldwide attention. In particular, triptolide has been shown to have significant effects on central nervous system (CNS) diseases, such as Parkinson's disease, Alzheimer's disease, spinal cord and brain injury, and multiple sclerosis. This review focuses on the potential therapeutic role of triptolide on CNS diseases, and discusses the structural features, potential modifications, and the other pharmacological activities of triptolide.

Triptolide increases transcript and protein levels of survival motor neurons in human SMA fibroblasts and improves survival in SMA-like mice

BACKGROUND AND PURPOSE

Spinal muscular atrophy (SMA) is a progressive neuromuscular disease. Since disease severity is related to the amount of survival motor neuron (SMN) protein, up-regulated functional SMN protein levels from the SMN2 gene are considered a major SMA drug-discovery strategy. In this study, we investigated the possible effects of triptolide, a diterpene triepoxide purified from Tripterygium wilfordii Hook. F., as a new compound for increasing SMN protein.

EXPERIMENTAL APPROACH

The effects and mechanisms of triptolide on the production of SMA protein were determined by cell-based assays using the motor neuronal cell line NSC34 and skin fibroblasts from SMA patients. Wild-type (Smn(+/+) SMN2(-/-) , C57BL/6) and SMA-like (Smn(-/-) SMN2) mice were injected with triptolide (0.01 or 0.1 mg·kg(-1) ·day(-1) , i.p.) and their survival rate and level of change in SMN protein in neurons and muscle tissue measured.

KEY RESULTS

In NSC34 cells and human SMA fibroblasts, pM concentrations of triptolide significantly increased SMN protein expression and the levels of SMN complex component (Gemin2 and Gemin3). In human SMA fibroblasts, triptolide increased SMN-containing nuclear gems and the ratio of full-length transcripts (FL-SMN2) to SMN2 transcripts lacking exon 7 (SMN2Δ7). Furthermore, in SMA-like mice, triptolide significantly increased SMN protein levels in the brain, spinal cord and gastrocnemius muscle. Furthermore, triptolide treatment increased survival and reduced weight loss in SMA-like mice.

CONCLUSION AND IMPLICATIONS

Triptolide enhanced SMN protein production by promoting SMN2 activation, exon 7 inclusion and increasing nuclear gems, and increased survival in SMA mice, which suggests triptolide might be a potential candidate for SMA therapy.

Immune reactions and nerve repair in mice with sciatic nerve injury 14 days after intraperitoneal injection of Brazil

BALB/c mice were intraperitoneally injected with 10, 5 or 2.5 mg/kg Brazil for 14 days after sciatic nerve injury. Results demonstrate that the spleen T/B lymphocyte stimulation index and serum circulating immune complex concentration were significantly reduced, and the morphology of the soleus muscle was restored in mice with sciatic nerve injury. These effects of Brazil were dose-dependent. Our experimental findings indicate that Brazil can regulate immune responses after nerve injury and promote sciatic nerve repair.

[Effects of triptolide-medicated serum on secretion function of adrenocortical cells isolated from rats]

OBJECTIVE

To study the effects of triptolide-medicated serum on secretory function of adrenocortical cells isolated from rats.

METHODS

Thirty SD rats were randomly divided into control group, prednisone group, and low-, medium- and high-dose triptolide groups. Rats were administered with normal saline, prednisone and low-, medium- and high-dose triptolide respectively by gastrogavage to prepare sera containing drugs. Primary adrenocortical cells were isolated from normal male rats and cultured with sera containing drug for 48 hours. Expression of proliferating cell nuclear antigen (PCNA) was observed by immunohistochemical method and number of PCNA-positive cells was counted. Ultrastructure of adrenocortical cells was observed under a transmission electron microscope. Content of corticosterone in supernatant of adrenocortical cell culture was detected by enzyme-linked immunosorbent assay, and real-time fluorescence quantitative polymerase chain reaction (PCR) was employed to investigate the expression of 3beta-hydroxysteroid dehydrogenase (3beta-HSD) mRNA.

RESULTS

As compared with the control group, content of corticosterone in supernatant of adrenocortical cell culture and expression of 3beta-HSD mRNA were significantly increased in the triptolide-treated groups, and the numbers of PCNA-positive cells were increased in the medium- and high-dose triptolide groups, however, they were decreased in the prednisone group.

CONCLUSION

Triptolide-medicated serum can increase the secretion of corticosterone in rat adrenocortical cells in vitro.

Neurotrophic activity of obovatol on the cultured embryonic rat neuronal cells by increase of neurotrophin release through activation of ERK pathway

Previously, we found that obovatol, a lignan compound isolated from Magnolia officinalis, has anti-cancer, anti-inflammatory, and anxiolytic effects. Recent studies showed that honokiol, magnolol, and 4-O-methylhonokiol, lignin compounds isolated from the Magnolia family have neurotrophic activity. In this study, we examined whether or not obovatol also exhibits neurite-promoting effects on rat embryonic neuronal cells. Obovatol increased neurite outgrowth in a concentration-dependent manner. Consistent with the neurite outgrowth effect, the expression of neurite differentiation markers also increased in response to obovatol. We also found that obovatol increased levels of NGF and BDNF released into the culture medium. In addition, the combination of low concentrations of obovatol (1 and 2 μM) with NGF (50 ng/ml) or with BDNF (10 ng/ml) greatly enhanced neurite outgrowth. Subsequently, we found that obovatol increased phosphorylation of ERK. However, the neurite outgrowth, and NGF and BDNF release induced by obovatol were prevented by an ERK-specific inhibitor. These results suggest that obovatol promotes neurite outgrowth due to the increased release of neurotrophic factors via activation of the ERK pathway.

Therapeutic strategies for Parkinson's disease: the ancient meets the future--traditional Chinese herbal medicine, electroacupuncture, gene therapy and stem cells

In China, it has been estimated that there are more than 2.0 million people suffering from Parkinson's disease, which is currently becoming one of the most common chronic neurodegenerative disorders during recent years. For many years, scientists have struggled to find new therapeutic approaches for this disease. Since 1994, our research group led by Drs. Ji-Sheng Han and Xiao-Min Wang of Neuroscience Research Institute, Peking University has developed several prospective treatment strategies for the disease. These studies cover the traditional Chinese medicine-herbal formula or acupuncture, and modern technologies such as gene therapy or stem cell replacement therapy, and have achieved some original results. It hopes that these data may be beneficial for the research development and for the future clinical utility for treatment of Parkinson's disease.