Electro-Acupuncture Ameliorated MPTP-Induced Parkinsonism in Mice via TrkB Neurotrophic Signaling

Neurotrophins, such as brain-derived neurotrophic factor (BDNF), have shown promise as neuroprotective agents, indicating their potential in therapeutic strategies for neurodegenerative disease. However, the inherent bioactivity and pharmaceutical limitations of BDNF compromise its clinical efficacy. Research has documented the beneficial effects of electroacupuncture (EA) against neurodegeneration, possibly by BDNF-mediated mechanisms. The present study was designed to clarify whether EA can mount a neuroprotective effect in mice lesioned with MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) via stimulation of the BDNF-TrkB signaling pathway. We found that EA not only ameliorated the motor dysfunction but also restored the dopaminergic neuronal function and upregulated BDNF expression in MPTP-lesioned mice. Interestingly, the TrkB inhibitor K252a abolished the neuroprotective effects of EA. Western blot analyses further demonstrated that EA might recover the level of phospho-Akt, phospho-ERK1/2, and BDNF against MPTP neurotoxicity via reversing the imbalance between TrkB FL and TrkB T1. Taken together, the results of the present study show that EA stimulation can ameliorate MPTP-induced parkinsonism in mice. Such a neuroprotective effect may be partially mediated via restoring TrkB neurotrophic signaling.

Altered N-methyl D-aspartate receptor subunit expression causes changes to the circadian clock and cell phenotype in osteoarthritic chondrocytes

The chondrocyte circadian clock is altered in osteoarthritis. This change is implicated in the disease-associated changes in chondrocyte phenotype and cartilage loss. Why the clock is changed is unknown. N-methyl-D-aspartate receptors (NMDAR) are critical for regulating the hypothalamic clock. Chondrocytes also express NMDAR and the type of NMDAR subunits expressed changes in osteoarthritis.

OBJECTIVE

To determine if NMDAR regulate the chondrocyte clock and phenotype.

DESIGN

Chondrocytes isolated from macroscopically-normal (MN) and osteoarthritic human cartilage were treated with NMDAR antagonists or transfected with GRIN2A or GRIN2B-targetting siRNA. H5 chondrocytes were transfected with GluN2B-expression plasmids. Clock genes and chondrocyte phenotypic markers were measured by RT-qPCR.

RESULTS

PER2 amplitude was higher and BMAL1 amplitude lower in osteoarthritic compared to MN chondrocytes. In osteoarthritic chondrocytes, NMDAR inhibition restored PER2 and BMAL1 expression to levels similar to MN chondrocytes, and resulted in reduced MMP13 and COL10A1. Paradoxically, NMDAR inhibition in MN chondrocytes resulted in increased PER2, decreased BMAL1 and increased MMP13 and COL10A1. Osteoarthritic, but not MN chondrocytes expressed GluN2B NMDAR subunits. GluN2B knockdown in osteoarthritic chondrocytes restored expression of circadian clock components and phenotypic markers to levels similar to MN chondrocytes. Ectopic expression of GluN2B resulted in reduced BMAL1, increased PER2 and altered SOX9, RUNX2 and MMP13 expression. Knockdown of PER2 mitigated the effects of GluN2B on SOX9 and MMP13.

CONCLUSIONS

NMDAR regulate the chondrocyte clock and phenotype suggesting NMDAR may also regulate clocks in other peripheral tissues. GluN2B expression in osteoarthritis may contribute to pathology by altering the chondrocyte clock.

Obesity, osteoarthritis and genetic risk: The rs182052 polymorphism in the ADIPOQ gene is potentially associated with risk of knee osteoarthritis

Objectives

Given the function of adiponectin (ADIPOQ) on the inflammatory condition of obesity and osteoarthritis (OA), we hypothesized that the ADIPOQ gene might be a candidate gene for a marker of susceptibility to OA.

Methods

We systematically screened three tagging polymorphisms (rs182052, rs2082940 and rs6773957) in the ADIPOQ gene, and evaluated the association between the genetic variants and OA risk in a case-controlled study that included 196 OA patients and 442 controls in a northern Chinese population. Genotyping was performed using the Sequenom MassARRAY iPLEX platform.

Results

The single nucleotide polymorphism (SNP) rs182052 was found to be potentially associated with knee OA risk (additive model: odds ratio = 1.38; 95% confidence interval 1.07 to 1.76; p = 0.012). Furthermore, a non-significant association was observed for rs182052 and body mass index with regard to OA risk in interaction analyses (p = 0.063). Similarly, no significant interaction was detected for rs182052 and age with regard to OA risk (p = 0.614).

Conclusion

These findings suggest that the SNP rs182052 in the ADIPOQ gene may potentially modify individual susceptibility to knee OA in the Chinese population. Further studies are warranted to investigate our findings in more depth.

Cite this article: L. Jiang, X. Zhu, J. Rong, B. Xing, S. Wang, A. Liu, M. Chu, G. Huang. Obesity, osteoarthritis and genetic risk: The rs182052 polymorphism in the ADIPOQ gene is potentially associated with risk of knee osteoarthritis. Bone Joint Res 2018;7:494–500. DOI: 10.1302/2046-3758.77.BJR-2017-0274.R1.

N-Propargyl Caffeamide Skews Macrophages Towards a Resolving M2-Like Phenotype Against Myocardial Ischemic Injury via Activating Nrf2/HO-1 Pathway and Inhibiting NF-ĸB Pathway

BACKGROUND/AIMS

Macrophages exhibit dynamic pro-inflammatory and resolving activities in myocardial infarction. The present study investigated whether caffeic acid derivatives could induce macrophage polarization towards a resolving M2 phenotype against myocardial infarction injury.

METHODS

Western blotting, RT-PCR and flow cytometry techniques are used to evaluate macrophage biomarkers expression and specific proteins in the related signaling pathways. Ligation of the left anterior descending artery induced rat model of myocardial infarction, TTC staining and immunohistochemical staining are used to examine cardioprotective effect in vivo.

RESULTS

We initially evaluated the anti-inflammatory activity of four caffeic acid derivatives including n-propargyl caffeamide (PACA) in RAW264.7 macrophages. As result, PACA selectively suppressed the up-regulation of inducible nitric oxide synthase (iNOS) over cyclooxygenase-2 (COX-2) in lipopolysaccharides (LPS)-stimulated cells. We subsequently examined the effects of PACA on macrophage polarization by determining macrophage biomarkers. PACA down-regulated M1 biomarkers (e.g., iNOS, tumor necrosis factor-α (TNF-α), C-X-C motif chemokine 10 (CXCL10) and CD80) but up-regulated M2 biomarkers (e.g., Ym-1 and arginase-1). On the other hand, PACA suppressed macrophage chemotaxis while enhanced macrophage phagocytosis. We further examined the in vivo cardioprotective activity of PACA in a rat model of myocardial infarction. Following ligation of the left anterior descending artery, PACA treatment effectively reduced myocardial infarct size and promoted macrophage M2 polarization. We finally explored the underlying mechanisms. We found that PACA attenuated LPS-induced NF-ĸB activation while activated Nrf2/HO-1 pathway. HO-1 inhibitor SnPP attenuated the effects of PACA on iNOS expression in LPS-challenged macrophages, possibly by regulating the cross-talk between HO-1 and NF-ĸB pathways.

CONCLUSIONS

The key finding from the present study was that PACA promoted timely switch of macrophage phenotypes from pro-inflammatory M1 to resolving M2. We anticipate that PACA is a potential drug candidate for the resolution of inflammation and cardiac repair after myocardial infarction.

Natural product celastrol suppressed macrophage M1 polarization against inflammation in diet-induced obese mice via regulating Nrf2/HO-1, MAP kinase and NF-κB pathways

Macrophage polarization is implicated in the inflammation in obesity. The aim of the present study was to examine the anti-inflammatory activities of botanical triterpene celastrol against diet-induced obesity. We treated diet-induced obese C57BL/6N male mice with celastrol (5, 7.5 mg/kg/d) for 3 weeks, and investigated macrophage M1/M2 polarization in adipose and hepatic tissues. Celastrol reduced fat accumulation and ameliorated glucose tolerance and insulin sensitivity. Celastrol down-regulated the mRNA levels of macrophage M1 biomarkers (e.g., IL-6, IL-1β, TNF-α, iNOS) in cell culture and in mice. The underlying mechanisms were investigated in murine macrophage RAW264.7 cells. Our results demonstrated that celastrol might control macrophage polarization through modulating the cross-talk between the following three mechanisms: 1) suppressing LPS-induced activation of MAP kinases (e.g., ERK1/2, p38, JNK) in a concentration dependent manner; 2) attenuating LPS-induced nuclear translocation of NF-κB p65 subunit in a time dependent manner; 3) activating Nrf2 and subsequently inducing HO-1 expression. HO-1 inhibitor SnPP diminished the inhibitory effects of celastrol on the activation of NF-κB pathway and the pro-inflammatory M1 macrophage polarization. Taken together, celastrol exhibited anti-obesity effects via suppressing pro-inflammatory M1 macrophage polarization. Thus, our results provide new evidence for the potential of celastrol in the treatment of obesity.

Therapeutic Potential of Heme Oxygenase-1/carbon Monoxide System Against Ischemia-Reperfusion Injury

BACKGROUND

Ischemia-reperfusion (I/R) injury causes the dysfunctions of different major organs, leading to morbidity and mortality on the global scale. Among a battery of therapeutic targets, the heme oxygenase- 1 (HO-1)/carbon monoxide (CO) system has been evaluated for the development of new therapies against I/R injury. The enzyme HO-1 catalyzes the degradation of heme into three biologically active end products, namely biliverdin/bilirubin, CO and ferrous ion. Interestingly, CO is one of a few bioactive gaseous molecules with the capability of regulating inflammation, cell survival and growth. In fact, several CO-releasing compounds have been developed for directly reprogramming the intracellular apoptotic, inflammatory and proliferative signaling networks. In parallel, chemical and genetic approaches have also been evaluated for up-regulating HO-1 expression as an endogenous mechanism to ameliorate I/R injury and heal wounds.

METHODS

In this review, we discussed the recent studies on the therapeutic potential of HO-1/CO system in the treatment of I/R injury in the heart, brain, liver, kidney, lung, intestine and retina. We focused on the activities and underlying mechanisms of various therapeutic strategies to regulate HO-1/CO system against I/R injury.

RESULTS

A large number of studies have demonstrated that HO-1/CO system exhibits potent anti-oxidative, antiapoptotic, anti-inflammatory and cytoprotective activities against I/R injury. The regulation of HO-1/CO expression has been achieved either by genetic overexpression of HO-1 cDNA or pharmacological induction with drugs including curcumin and resveratrol.

CONCLUSION

The HO-1/CO system is a potential target for treating I/R injury. Further studies should be directed to in vivo efficacy and clinical application of HO-1/CO system in the therapy of I/R injury.

Identification of Steroidogenic Components Derived From Gardenia jasminoides Ellis Potentially Useful for Treating Postmenopausal Syndrome

Estrogen-stimulating principles have been demonstrated to relieve postmenopausal syndrome effectively. Gardenia jasminoides Ellis (GJE) is an herbal medicine possessing multiple pharmacological effects on human health with low toxicity. However, the therapeutic effects of GJE on the management of postmenopausal syndrome and its mechanism of action have not been fully elucidated. In this study, network pharmacology-based approaches were employed to examine steroidogenesis under the influence of GJE. In addition, the possibility of toxicity of GJE was ruled out and four probable active compounds were predicted. In parallel, a chromatographic fraction of GJE with estrogen-stimulating effect was identified and nine major compounds were isolated from this active fraction. Among the nine compounds, four of them were identified by network pharmacology, validating the use of network pharmacology to predict active compounds. Then the phenotypic approaches were utilized to verify that rutin, chlorogenic acid (CGA) and geniposidic acid (GA) exerted an estrogen-stimulating effect on ovarian granulosa cells. Furthermore, the results of target-based approaches indicated that rutin, CGA, and GA could up-regulate the FSHR-aromatase pathway in ovarian granulosa cells. The stimulation of estrogen production by rat ovarian granulosa cells under the influence of the three compounds underwent a decline when the follicle-stimulating hormone receptor (FSHR) was blocked by antibodies against the receptor, indicating the involvement of FSHR in the estradiol-stimulating activity of the three compounds. The effects of the three compounds on estrogen biosynthesis- related gene expression level were further confirmed by Western blot assay. Importantly, the MTT results showed that exposure of breast cancer cells to the three compounds resulted in reduction of cell viability, demonstrating the cytotoxicity of the three compounds. Collectively, rutin, chlorogenic acid and geniposidic acid may contribute to the therapeutic potential of GJE for the treatment of postmenopausal syndrome.

Skin resistance to UVB-induced oxidative stress and hyperpigmentation by the topical use of Lactobacillus helveticus NS8-fermented milk supernatant

AIMS

In this study, we investigated the preventive properties of the supernatant of Lactobacillus helveticus NS8-fermented milk (NS8-FS) against UV light-induced skin oxidative damage and hyperpigmentation.

METHODS AND RESULTS

NS8-FS exhibited significant radical scavenging activity in tests with ABST⁺ and DPPH scavenging methods, and as well strongly inhibited 3-morpholinosydnonimine (Sin-1)-induced ROS generation in HaCat keratinocytes. Unexpectedly, NS8-FS was found to inhibit melanin production in B16F10 melanoma cells and to exhibit inhibitory effects both to the enzymatic activity of tyrosinase (TYR) and the expression of proteins required for melanin synthesis. In SKH-1 hairless mice, topical application of NS8-FS alleviated UVB-induced skin photodamage, including the improvement of the appearance of epidermal thickness, transepidennal water loss and lipid peroxidation levels. In the tanning guinea pig model, the whitening effect of NS8-FS was demonstrated using Masson-Fontana staining and TYR staining. Furthermore, NS8-FS was shown to stimulate the nuclear translocation and activation of the Nrf2 protein, along with recovery of antioxidant enzyme activities.

CONCLUSION

NS8-FS exhibits the protective capacities against UV light-induced skin oxidative damage and hyperpigmentation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our findings indicate the potential of cell-free fermented products of lactic acid bacteria in topical photoprotection.

Molecular Diversity and Potential Anti-neuroinflammatory Activities of Cyathane Diterpenoids from the Basidiomycete Cyathus africanus

Ten new polyoxygenated cyathane diterpenoids, named neocyathins A–J (1–10), together with four known diterpenes (11–14), were isolated from the liquid culture of the medicinal basidiomycete fungus Cyathus africanus. The structures and configurations of these new compounds were elucidated through comprehensive spectroscopic analyses including 1D NMR, 2D NMR (HSQC, HMBC, NOESY) and HRESIMS, and electronic circular dichroism (ECD) data. Neuroinflammation is implicated in the pathogenesis of various neurodegenerative diseases, such as Alzheimers’ disease (AD). All isolated compounds were evaluated for the potential anti-neuroinflammatory activities in BV2 microglia cells. Several compounds showed differential effects on the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in lipopolysaccharide (LPS)-stimulated and Aβ_1–42-treated mouse microglia cell line BV-2. Molecular docking revealed that bioactive compounds (e.g., 11) could interact with iNOS protein other than COX-2 protein. Collectively, our results suggested that this class of cyathane diterpenoids might serve as important lead compounds for drug discovery against neuroinflammation in AD.

The rs4238326 polymorphism in ALDH1A2 gene potentially associated with non-post traumatic knee osteoarthritis susceptibility: a two-stage population-based study

OBJECTIVE

A recent genome-wide association study reported significant associations of genetic variants within the ALDH1A2 gene with osteoarthritis (OA) of the hand in European populations. However, these findings have not been well generalized to other joints, or to other populations.

METHODS

We performed a two-stage population-based case-control study including 196 non-post traumatic knee OA cases and 442 controls in the first stage and independent 143 non-post traumatic knee OA cases and 238 controls in the second stage in a Chinese population by genotyping eight tagging polymorphisms in ALDH1A2.

RESULTS

In the first stage, the single nucleotide polymorphism (SNP) rs4238326 was found to be potentially associated with knee OA risk (additive model: odds ratio [OR] = 0.70; 95% confidence interval [95% CI] = 0.49-1.01; P = 0.055), which was further confirmed in the second stage with similar effect (additive model: OR = 0.60; 95% CI = 0.38-0.95; P = 0.029). After combining the two stages, we found that the variant C allele of rs4238326 was probably associated with decreased risk of knee OA (additive model: OR = 0.65; 95% CI = 0.49-0.86; P = 0.003). Furthermore, interaction analyses showed that rs4238326 interacted multiplicatively with age to contribute to knee OA risk (interaction P = 0.041).

CONCLUSIONS

These findings indicate that the SNP rs4238326 in ALDH1A2 gene may potentially modify individual susceptibility to knee OA in the Chinese population. Beyond that, further studies are warranted to validate and extend our findings, and future functional studies are required to clarify the possible mechanisms.

Plant-derived triterpene celastrol ameliorates oxygen glucose deprivation-induced disruption of endothelial barrier assembly via inducing tight junction proteins

BACKGROUND

The integrity and functions of blood-brain barrier (BBB) are regulated by the expression and organization of tight junction proteins.

OBJECTIVE

The present study was designed to explore whether plant-derived triterpenoid celastrol could regulate tight junction integrity in murine brain endothelial bEnd3 cells.

METHODS

We disrupted the tight junctions between endothelial bEnd3 cells by oxygen glucose deprivation (OGD). We investigated the effects of celastrol on the permeability of endothelial monolayers by measuring transepithelial electrical resistance (TEER). To clarify the tight junction composition, we analyzed the expression of tight junction proteins by RT-PCR and Western blotting techniques.

RESULTS

We found that celastrol recovered OGD-induced TEER loss in a concentration-dependent manner. Celastrol induced occludin, claudin-5 and zonula occludens-1 (ZO-1) in endothelial cells. As a result, celastrol effectively maintained tight junction integrity and inhibited macrophage migration through endothelial monolayers against OGD challenge. Further mechanistic studies revealed that celastrol induced the expression of occludin and ZO-1) via activating MAPKs and PI3K/Akt/mTOR pathway. We also observed that celastrol regulated claudin-5 expression through different mechanisms.

CONCLUSION

The present study demonstrated that celastrol effectively protected tight junction integrity against OGD-induced damage. Thus, celastrol could be a drug candidate for the treatment of BBB dysfunction in various diseases.

Clinical interrogation and application of super-selective intracranial artery infusion chemotherapy for lung cancer patients with brain metastases

OBJECTIVE

The purpose of this study was to evaluate the clinical efficacy of super-selective intracranial artery infusion chemotherapy and to determine correlated prognostic parameters for advanced lung cancer patients with brain metastases.

PATIENTS AND METHODS

Fifty-four lung cancer patients with brain metastasis who had no previous treatment were enrolled for the study. These patients received super-selective intracranial artery infusion chemotherapy, as well as arterial infusion chemotherapy for primary and metastatic lesions. The procedure was performed once every 4 weeks. Patients were monitored to evaluate short-term clinical outcomes 4 weeks after the first 2 treatments, and follow-up visits performed every 4 weeks after the first 4 treatments until the appearance of disease progression or intolerable toxicity.

RESULTS

All 54 cases were treated at least 4 times. The overall response rate was 55.56% (30/54), and the disease control rate was 85.19% (46/54). The median overall survival was 7 months, with a 95% confidence interval (CI) of 5.87-8.13 months, and the median progression-free survival was 4 months, with a 95% CI of 3.20-4.80 months. The 6-month survival rate and 1-year survival rate were 81.48% (44/54) and 18.52% (10/54), respectively.

CONCLUSION

Super-selective intracranial artery infusion chemotherapy provides a clinically efficacious avenue of treatment for lung cancer patients with brain metastases. Pathological classification, Karnofsky performance status, and extracranial metastases may serve as reliable prognostic parameters in determining the clinical outcomes for lung cancer patients with brain metastases.

No association of the single nucleotide polymorphism rs8044769 in the fat mass and obesity-associated gene with knee osteoarthritis risk and body mass index: A population-based study in China

OBJECTIVES

Previous genome-wide association studies (GWAS) have reported significant association of the single nucleotide polymorphism (SNP) rs8044769 in the fat mass and obesity-associated gene (FTO) with osteoarthritis (OA) risk in European populations. However, these findings have not been confirmed in Chinese populations.

METHODS

We systematically genotyped rs8044769 and evaluated the association between the genetic variants and OA risk in a case-controlled study including 196 OA cases and 442 controls in a northern Chinese population. Genotyping was performed using the Sequenom MassARRAY iPLEX platform.

RESULTS

We found that the variant T allele of rs8044769 showed no significant association of OA risk (p = 0.791), or association with body mass index (BMI) (pmeta = 0.786) in an additive genetic model. However, we detected a significant interaction between rs8044769 genotypes and BMI on OA risk (p = 0.037), as well as a borderline interaction between rs8044769 genotypes and age on OA risk (p = 0.062).

CONCLUSIONS

Our findings indicate that rs8044769 in the FTO gene may not modify individual susceptibility to OA or increased BMI in the Chinese population. Further studies are warranted to validate and extend our findings.Cite this article: Prof L. Jiang. No association of the single nucleotide polymorphism rs8044769 in the fat mass and obesity-associated gene with knee osteoarthritis risk and body mass index: A population-based study in China. Bone Joint Res 2016;5:169-174. DOI: 10.1302/2046-3758.55.2000589.

Gallic acid-l-leucine (GAL) conjugate enhances macrophage phagocytosis via inducing leukotriene B4 12-hydroxydehydrogenase (LTB4DH) expression

Timely clearance of apoptotic cells is an important step in the resolution of ongoing inflammation and the restoration of tissue integrity and function after acute myocardial infarction. Natural products gallic acid and l-leucine are well-documented for anti-inflammatory and anabolic effects. We synthesized gallic acid-l-leucine (GAL) conjugate via direct coupling gallic acid and l-leucine. The aim of the present study was to investigate the effect of GAL conjugate on the phagocytotic activity of macrophages. By using murine macrophage cell line RAW264.7 as an in vitro model, we evaluated the effect of GAL conjugate on the phagocytic uptake of fluorescently labeled latex beads and apoptotic cardiomyocyte H9c2 cells. We found that GAL conjugate enhanced the phagocytic activity of macrophage RAW264.7 cells in a concentration-dependent manner. Further mechanistic studies revealed that the effect of GAL conjugate on macrophage phagocytosis was positively correlated with the up-regulation of leukotriene B4 12-hydroxydehydrogenase (LTB4DH) expression at both mRNA and protein levels. By ESI-MS based lipidomics profiling, GAL conjugate increased the enzymatic activities of LTB4DH, leading to the formation of lipid metabolites including 12-oxo-LTB4, 13,14-dh-oxo-PGE2 and 13,14-dh-oxo-PGF2α. Interestingly, GAL conjugate failed to increase macrophage phagocytosis upon silencing of LTB4DH by specific siRNA. Moreover, it appeared that GAL conjugate induced LTB4DH expression via activating the Nrf2/HO-1 pathway. After Nrf-2 was silenced by specific siRNA, GAL conjugate no longer induced LTB4DH expression in the Nrf2-siRNA transfected cells. Taken together, our results suggest that GAL enhances macrophage phagocytosis via sequentially activating Nrf2 and up-regulating LTB4DH expression. Thus, GAL conjugate may serve as a lead compound for the development of new anti-inflammatory drugs.

Plant Natural Product Puerarin Ameliorates Depressive Behaviors and Chronic Pain in Mice with Spared Nerve Injury (SNI)

Simultaneous relief of the pain from body and brain remains an ongoing challenge. The aim of the present study was to clarify whether plant-derived isoflavone puerarin could ameliorate comorbid depression and pain. We investigated the effects of puerarin on depressive-like behaviors and neuropathic pain in C57BL/6 N mice with spared nerve injury (SNI). After SNI surgery, mice were allowed to recover spontaneously for 7 days and subsequently treated with puerarin, anti-depressant citalopram, and analgesic ibuprofen, alone or in combination, for 8 or 14 days. Forced swim test and tail suspension test were used to assess depressive-like behaviors, whereas von Frey filament test was used to estimate the sensitivity to the mechanical stimulation. Our results suggested that puerarin effectively ameliorated depression and pain in SNI mice although citalopram exhibited anti-depressant activity. In contrast, ibuprofen showed lesser activities against SNI-induced depression and pain. Further mechanistic studies revealed the uniqueness of puerarin as follows: (1) puerarin did not recover SNI-induced depletion of reduced glutathione and loss of superoxide dismutase (SOD), whereas citalopram and ibuprofen showed somewhat antioxidant activities; (2) puerarin markedly promoted the activation of CREB pathway although puerarin and citalopram activated ERK pathway to the same extent; (3) puerarin rapidly and persistently induced brain-derived neurotrophic factor (BDNF) expression whereas citalopram only induced BDNF expression after a prolonged stimulation. Collectively, these results suggest that puerarin may ameliorate the SNI-induced depression and pain via activating ERK, CREB, and BDNF pathways. Puerarin may serve as new lead compound for the development of novel therapeutics for depression and pain comorbidity.

N-Propargyl Caffeate Amide (PACA) Potentiates Nerve Growth Factor (NGF)-Induced Neurite Outgrowth and Attenuates 6-Hydroxydopamine (6-OHDA)-Induced Toxicity by Activating the Nrf2/HO-1 Pathway

Insufficient production of neurotrophic factors is implicated in the pathogenesis of various neurodegenerative disorders. The aim of the present study was to evaluate the potential of N-propargyl caffeate amide (PACA) to enhance nerve growth factor (NGF)-induced neurite outgrowth and the underlying mechanisms. We discovered that PACA not only potentiated NGF-induced neurite outgrowth but also attenuated 6-hydroxydopamine (6-OHDA) neurotoxicity in dopaminergic PC12 cells and primary rat midbrain neurons. To identify the PACA-binding proteins, we introduced a biotin tag to the covalent PACA-protein adducts via "click chemistry" alkyne-azido cycloaddition. As a result, kelch-like ECH-associated protein 1 (Keap1) was isolated as the predominant protein from PACA treated PC12 cells. We demonstrated that the formation of PACA-Keap1 conjugates induced the nuclear translocation of transcription factor Nrf2 and the expression of antioxidant heme oxygenase-1 (HO-1). Importantly, specific HO-1 inhibitor SnPP diminished the neuroprotective and neuritogenic activities of PACA. Moreover, PACA attenuated 6-OHDA-induced production of neurotoxic reactive oxygen species and reactive nitrogen species. PACA also preserved mitochondrial membrane integrity and enhanced the cellular resistance against 6-OHDA neurotoxicity. These results suggest that PACA may exhibit neuroprotective and neuritogenic activities via activating the Nrf2/HO-1 antioxidant pathway.