Sanguinarine Attenuates Neuropathic Pain in a Rat Model of Chronic Constriction Injury.

OBJECTIVE: There is still no effective treatment of neuropathic pain. Sanguinarine is a natural plant medicine with anti-inflammatory effects, but its effect on neuropathic pain remains unclear. This study was aimed at investigating the potential of sanguinarine to attenuate neuropathic pain. METHODS: Neuropathic pain was induced by chronic constriction injury (CCI) of the sciatic nerve. Rats were randomly divided into several groups: sham, CCI, CCI+SG (1.00 mg/kg), CCI+SG (2.50 mg/kg), and CCI+SG (6.25 mg/kg). SG was injected intraperitoneally from the day of surgery every three days. The mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were recorded before surgery and on days 1, 3, 7, and 14 after surgery. The microglia in the spinal dorsal horn were examined by immunofluorescence. p38 MAPK expression in the spinal dorsal horn was detected by PCR and Western blot analysis. Cytokine levels in the spinal dorsal horn were measured by ELISA. RESULTS: MWT and TWL were significantly reduced in the CCI group, but sanguinarine recovered MWT and TWL in the CCI group. In addition, sanguinarine inhibited the activation of microglia and decreased the expression of p-p38 and TNF-α, IL-1ß, and IL-6 in the spinal dorsal horn of the CCI group in a dose-dependent manner. CONCLUSIONS: Our results suggest that sanguinarine can attenuate neuropathic pain via inhibiting the activation of microglia and the activation of the p38 MAPK signaling pathway.

Selenium-containing protein from selenium-enriched Spirulina platensis antagonizes oxygen glucose deprivation-induced neurotoxicity by inhibiting ROS-mediated oxidative damage through regulating MPTP opening.

CONTEXT: Selenium-containing protein from selenium-enriched Spirulina platensis (Se-SP) (syn. Arthrospira platensis [Microcoleaceae]) showed novel antioxidant activity. However, the protective effect of Se-SP against oxygen glucose deprivation (OGD)-induced neural apoptosis has not been reported yet. OBJECTIVE: To verify whether Se-SP can inhibit OGD-induced neural apoptosis and explore the underlying mechanism. MATERIALS AND METHODS: Primary hippocampal neurons were separated from Sprague-Dawley (SD) rats. 95% N2 + 5% CO2 were employed to establish OGD model. Neurons were treated with 5 and 10 µg/mL Se-SP under OGD condition for 6 h. Neurons without treatment were the control group. Neural viability and apoptosis were detected by MTT, immunofluorescence and western blotting methods. RESULTS: Se-SP significantly improved neuronal viability (from 57.2% to 94.5%) and inhibited apoptosis in OGD-treated primary neurons (from 45.6% to 6.3%), followed by improved neuronal morphology and caspases activation. Se-SP co-treatment also effectively suppressed OGD-induced DNA damage by inhibiting ROS accumulation in neurons (from 225.6% to 106.3%). Additionally, mitochondrial dysfunction was also markedly improved by Se-SP co-treatment via balancing Bcl-2 family expression. Moreover, inhibition of mitochondrial permeability transition pore (MPTP) by CsA (an MPTP inhibitor) dramatically attenuated OGD-induced ROS generation (from 100% to 56.2%), oxidative damage, mitochondrial membrane potential (MPP) loss (from 7.5% to 44.3%), and eventually reversed the neuronal toxicity and apoptosis (from 57.4% to 79.6%). DISCUSSION AND CONCLUSIONS: Se-SP showed enhanced potential to inhibit OGD-induced neurotoxicity and apoptosis by inhibiting ROS-mediated oxidative damage through regulating MPTP opening, indicating that selenium-containing protein showed broad application in the chemoprevention and chemotherapy against human ischaemic brain injury.

Transplantation of olfactory ensheathing cells promotes the therapeutic effect of neural stem cells on spinal cord injury by inhibiting necrioptosis.

Transplantation of neural stem cells (NSCs) is one of the most promising treatments for spinal cord injury (SCI). However, the limited survival of transplanted NSCs reduces their therapeutic effects. The aim of the present study was to examine whether a co-transplantation of olfactory ensheathing cells (OECs) may enhance the survival of NSCs and improve the beneficial effects of NSCs in rats with SCI, as well as to investigate potential mechanisms underlying such efficacies. Co-transplantation of OECs and NSCs was used to treat rats with SCI. Sympathetic nerve function was determined by measuring sympathetic skin responses. The results showed that OEC/NSC co-transplantation improved motor function and autonomic nerve function in rats with SCI. Co-transplantation of OECs promoted NSC-induced neuroprotection and inhibited programmed necrosis of NSCs, which was mediated by receptor-interacting protein kinase 3 (RIP3) and mixed lineage kinase domain-like protein (MLKL). Furthermore, OECs increased the proliferation and differentiation of NSCs in vitro, and improved the survival rate of NSCs in vivo. Taken together, we conclude that transplantation of OECs inhibited programmed necrosis of co-transplanted NSCs to promote therapeutic effects on SCI. Therefore, co-transplantation of OECs and NSCs may represent a promising strategy for treating patients with SCI.

Conditioned Media of Choroid Plexus Epithelium Cells Attenuates High Pi-Induced Calcification of MOVAS Cells by Inhibiting ROS-Mediated Signal Pathways.

Vascular calcification was an independent risk of cardiovascular and cerebrovascular diseases (CCDs). Studies reported that conditioned media of choroid plexus epithelium cells (CPECs-CM) showed potential neuroprotective effects. However, the protective effect of CPECs-CM against vascular calcification (VC) has not been reported yet. Herein, high phosphate (HPi)-induced calcification model in mouse aortic vascular smooth muscle cells (MOVAS) was established, and the protective effects and underlying mechanism of CPECs-CM against HPi-induced calcification were explored. The results indicated that CPEC cells were successfully isolated and cultured, and CPECs-CM co-treatment significantly inhibited HPi-induced calcification of MOVAS cells through blocking alkaline phosphatase activity and expression. CPECs-CM co-treatment also suppressed reactive oxide species-mediated DNA damage in HPi-treated MOVAS cells. Moreover, dysfunction of MAPKs and PI3K/AKT pathways both contributed to HPi-induced calcification of MOVAS cells, and CPECs-CM co-treatment attenuated HPi-induced calcification by normalizing MAPKs and PI3K/AKT expression. Taken together, our findings provide evidence that CPECs-CM had the potential to inhibit vascular calcification with potent application in chemoprevention and chemotherapy of human CCD.

Neural stem cell transplantation inhibits glial cell proliferation and P2X receptor-mediated neuropathic pain in spinal cord injury rats.

P2X4 and P2X7 receptors play an important role in neuropathic pain after spinal cord injury. Regulation of P2X4 and P2X7 receptors can obviously reduce pain hypersensitivity after injury. To investigate the role of neural stem cell transplantation on P2X receptor-mediated neuropathic pain and explore related mechanisms, a rat model of spinal cord injury was prepared using the free-falling heavy body method with spinal cord segment 10 as the center. Neural stem cells were injected into the injured spinal cord segment using a micro-syringe. Expression levels of P2X4 and P2X7 receptors, neurofilament protein, and glial fibrillary acidic protein were determined by immunohistochemistry and western blot assay. In addition, sensory function was quantitatively assessed by current perception threshold. The Basso-Beattie-Bresnahan locomotor rating scale was used to assess neuropathological pain. The results showed that 4 weeks after neural stem cell transplantation, expression of neurofilament protein in the injured segment was markedly increased, while expression of glial fibrillary acidic protein and P2X4 and P2X7 receptors was decreased. At this time point, motor and sensory functions of rats were obviously improved, and neuropathic pain was alleviated. These findings demonstrated that neural stem cell transplantation reduced overexpression of P2X4 and P2X7 receptors, activated locomotor and sensory function reconstruction, and played an important role in neuropathic pain regulation after spinal cord injury. Therefore, neural stem cell transplantation is one potential option for relieving neuropathic pain mediated by P2X receptors.

Olfactory ensheathing cell transplantation inhibits P2X4 receptor overexpression in spinal cord injury rats with neuropathic pain.

Cell-based therapy is a promising strategy to alleviate neuropathic pain caused by spinal cord injury (SCI). We transplanted olfactory ensheathing cells (OECs) into SCI rats with neuropathic pain and quantitatively detected the sensory nerve function. The expression levels of P2X4 receptor (P2X4R), 200kD neurofilament heavy polypeptide (NF200), and glial fiber acidic protein (GFAP) were measured by immunofluorescence and Western blot analyses. Results showed that NF200 expression significantly increased, GFAP expression decreased, and sensory nerve function improved. In addition, OEC transplantation inhibited the overexpression of P2X4R, which plays an important role in neuropathic pain. Thus, OEC is a candidate target for the treatment of sensory functional loss and P2X4R-mediated neuropathic pain caused by SCI.

Reversal of Beta-Amyloid-Induced Neurotoxicity in PC12 Cells by Curcumin, the Important Role of ROS-Mediated Signaling and ERK Pathway.

Progressive accumulation of beta-amyloid (Aß) will form the senile plaques and cause oxidative damage and neuronal cell death, which was accepted as the major pathological mechanism to the Alzheimer's disease (AD). Hence, inhibition of Aß-induced oxidative damage and neuronal cell apoptosis by agents with potential antioxidant properties represents one of the most effective strategies in combating human AD. Curcumin (Cur) a natural extraction from curcuma longa has potential of pharmacological efficacy, including the benefit to antagonize Aß-induced neurotoxicity. However, the molecular mechanism remains elusive. The present study evaluated the protective effect of Cur against Aß-induced cytotoxicity and apoptosis in PC12 cells and investigated the underlying mechanism. The results showed that Cur markedly reduced Aß-induced cytotoxicity by inhibition of mitochondria-mediated apoptosis through regulation of Bcl-2 family. The PARP cleavage, caspases activation, and ROS-mediated DNA damage induced by Aß were all significantly blocked by Cur. Moreover, regulation of p38 MAPK and AKT pathways both contributed to this protective potency. Our findings suggested that Cur could effectively suppress Aß-induced cytotoxicity and apoptosis by inhibition of ROS-mediated oxidative damage and regulation of ERK pathway, which validated its therapeutic potential in chemoprevention and chemotherapy of Aß-induced neurotoxicity.

Myelin ultrastructure of sciatic nerve in rat experimental autoimmune neuritis model and its correlation with associated protein expression.

To explore the relationship of peripheral nerve ultrastructure and its associated protein expression in experimental autoimmune neuritis (EAN). EAN was established in Lewis rats using an emulsified mixture of P0 peptide 180-199, Mycobacterium tuberculosis, and incomplete Freund's adjuvant. Rats immunized with saline solution were used as a control group. Sciatic nerve ultrastructure and immunofluorescence histopathology were measured at the neuromuscular severity peak on day 18 post-induction. Cell-specific protein markers were used for immunofluorescence histopathology staining to characterize sciatic nerve cells: CD3 (T cell), Iba-1 (microglia), S100 (myelin), and neurofilament 200 (axon). The results showed that swelling of the myelin lamellae, vesicular disorganization, separation of the myelin lamellae, and an attenuation or disappearance of the axon were observed by transmission electron microscopy in the EAN group. CD3 and Iba-1 increased significantly in the structures characterized by separation or swelling of the myelin lamellae, and increased slightly in the structures characterized by vesicular of the myelin lamellae, S100 decreased in the structures characterized by vesicular disorganization or separation of the myelin lamellae. And neurofilament 200 decreased in the structures characterized by separation of the myelin lamellae. Furthermore, we found that Iba1 were positive in the myelin sheath, and overlapped with S100, which significantly indicated that Schwann cells played as macrophage-like cells during the disease progression of ENA. Our findings may be a significant supplement for the knowledge of EAN model, and may offer a novel sight on the treatment of Guillain-Barré syndrome.