N-BENZYLOXYCARBONYL-VAL-ALA-ASP-FLUOROMETHYLKETONE REDUCES SEVERITY OF EXPERIMENTAL SPINAL CORD INJURY

Tanshinone IIA attenuates the inflammatory response and apoptosis after traumatic injury of the spinal cord in adult rats

BACKGROUND

Spinal cord injury (SCI), including immediate mechanical injury and secondary injury, is associated with the inflammatory response, apoptosis and oxidative stress in response to traumatic injury. Tanshinone IIA (TIIA) is one of the major extracts obtained from Salvia miltiorrhiza BUNGE, which has anti-inflammatory and anti-apoptotic effects on many diseases. However, little is known about the effects of TIIA treatment on SCI. Therefore, the aim of the present study is to evaluate the pharmacological action of TIIA on secondary damage and the underlying mechanisms of experimental SCI in rats.

METHODOLOGY/PRINCIPAL FINDINGS

SCI was generated using a weight drop device on the dorsal spinal cord via a two-level T9-T11 laminectomy. SCI in rats resulted in severe trauma, characterized by locomotor disturbance, edema, neutrophil infiltration, the production of astrocytes and inflammatory mediators, apoptosis and oxidative stress. TIIA treatment (20 mg/kg, i.p.) after SCI induced significant effects: (1) improved motor function (Basso, Beattie and Bresnahan scores), (2) reduced the degree of tissue injury (histological score), neutrophil infiltration (myeloperoxidase activity) and the expression of astrocytes, (3) inhibited the activation of SCI-related pathways, such as NF-κB and MAPK signaling pathways, (4) decreased the production of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6) and iNOS, (5) reduced apoptosis (TUNEL staining, and Bcl-2 and caspase-3 expression) and (6) reversed the redox state imbalance.

CONCLUSIONS/SIGNIFICANCE

The results clearly show that TIIA has a prominent protective effect against SCI through inhibiting the inflammatory response and apoptosis in the spinal cord tissue after SCI.

Acute toxicity of the antifouling compound butenolide in non-target organisms

Butenolide [5-octylfuran-2(5H)-one] is a recently discovered and very promising anti-marine-fouling compound. In this study, the acute toxicity of butenolide was assessed in several non-target organisms, including micro algae, crustaceans, and fish. Results were compared with previously reported results on the effective concentrations used on fouling (target) organisms. According to OECD's guideline, the predicted no effect concentration (PNEC) was 0.168 µg l⁻¹, which was among one of the highest in representative new biocides. Mechanistically, the phenotype of butenolide-treated Danio rerio (zebrafish) embryos was similar to the phenotype of the pro-caspase-3 over-expression mutant with pericardial edema, small eyes, small brains, and increased numbers of apoptotic cells in the bodies of zebrafish embryos. Butenolide also induced apoptosis in HeLa cells, with the activation of c-Jun N-terminal kinases (JNK), Bcl-2 family proteins, and caspases and proteasomes/lysosomes involved in this process. This is the first detailed toxicity and toxicology study on this antifouling compound.

Activation of GluR6-containing kainate receptors induces ubiquitin-dependent Bcl-2 degradation via denitrosylation in the rat hippocampus after kainate treatment

We previously showed that Bcl-2 (B-cell lymphoma 2) is down-regulated in a kainate (KA)-induced rat epileptic seizure model. The underlying mechanism had remained largely unknown, but we here report for the first time that denitrosylation and ubiquitination are involved. Our results show that the S-nitrosylation levels of Bcl-2 are down-regulated after KA injection and that the GluR6 (glutamate receptor 6) antagonist NS102 can inhibit the denitrosylation of Bcl-2. Moreover, the ubiquitin-dependent degradation of Bcl-2 was found to be promoted after KA treatment, which could be suppressed by the proteasome inhibitor MG132 and the NO donors, sodium nitroprusside and S-nitrosoglutathione. In addition, experiments based on siRNA transfections were performed in the human SH-SY5Y neuroblastoma cell line to verify that the stability of Bcl-2 is causal to neuronal survival. At the same time, it was found that the exogenous NO donor GSNO could protect neurons when Bcl-2 is targeted. Subsequently, these mechanisms were morphologically validated by immunohistochemistry, cresyl violet staining, and in situ TUNEL staining to analyze the expression of Bcl-2 as well as the survival of CA1 and CA3/DG pyramidal neurons. NS102, GSNO, sodium nitroprusside, and MG132 contribute to the survival of CA1 and CA3/DG pyramidal neurons by attenuating Bcl-2 denitrosylation. Taken together, our data reveal that Bcl-2 ubiquitin-dependent degradation is induced by Bcl-2 denitrosylation during neuronal apoptosis after KA treatment.

Effects of dihydroxylphenyl lactic acid on inflammatory responses in spinal cord injury

The initial mechanical tissue disruption of spinal cord injury (SCI) is followed by a period of secondary injury that increases the size of the lesion. Secondary injuries are associated with edema, inflammation, excessive cytokine release, excitotoxicity and cell apoptosis. 3,4-dihydroxyphenyl lactic acid (DLA) is one of the major water-soluble components of chemical constituents from Salvia miltiorrhiza (SM). To investigate the inhibition effects of DLA on secondary injury of SCI, focusing especially on suppression of inflammatory responses and the mechanism of this effect, the following studies were performed: Basso, Beattie, and Bresnahan (BBB) scores to assess motor functions till 10 days after SCI; Nissl and Fast Blue histological staining and immunohistochemistry of inhibitory-kappa B-alpha (IκB-α) and nuclear factor-kappa B (NF-κB) p65 subunit protein; levels of myeloperoxidase (MPO) activity analysis as an indicator of polymorphonuclear infiltration; IL-6 production in plasma 10 days after SCI; Western blot analysis to determine cytoplasm levels of IκB-α and NF-κB p65 subunit proteins in the nuclear fractions 10 days after SCI. DLA significantly attenuated the motor function and tissue damage following SCI in rats, significant reduced polymorphonuclear cell infiltration and IL-6 production, as well as reduced cytoplasm IκB-α degradation and the nuclear translocation of NF-κB p65 subunit protein after SCI. In conclusion, the results clearly demonstrate that DLA inhibit the inflammation responses induced by SCI via inhibiting effect of production of IL-6 and nuclear translocation of NF-κB.

Effect of cyclopentanone prostaglandin 15-deoxy-delta12,14PGJ2 on early functional recovery from experimental spinal cord injury

Peroxisome proliferator-activated receptor (PPAR) gamma is a member of the nuclear-receptor superfamily that binds to DNA with retinoid X receptors as PPAR-retinoid X receptor heterodimers. Recent evidence also suggests that the cyclopentenone prostaglandin 15-deoxy-DeltaPGJ2 (15d-PGJ2), which is a metabolite of the prostaglandin D2, functions as an endogenous ligand for PPAR-gamma We postulated that 15d-PGJ2 would attenuate inflammation, investigating the effects on the degree of experimental spinal cord trauma induced by the application of vascular clips (force of 24 g) to the dura via a four-level T5-T8 laminectomy. Spinal cord injury in mice resulted in severe trauma characterized by edema, neutrophil infiltration, production of a range of inflammatory mediators, tissue damage, and apoptosis. Furthermore, 15d-PGJ2 reduced (1) spinal cord inflammation and tissue injury (histological score), (2) neutrophil infiltration (myeloperoxidase activity), (3) nuclear factor-kappaB activation, (4) expression of iNOS, nitrotyrosine and TNF-alpha, and (5) apoptosis (terminal deoxynucleotidyltransferase-mediated uridine triphosphate end labeling staining, Bax, Bcl-2, and FAS-L expression). In a separate set of experiments, 15d-PGJ2 significantly ameliorated the recovery of limb function (evaluated by motor recovery score). To elucidate whether the protective effects of 15d-PGJ2 are related to activation of the PPAR-gamma receptor, we also investigated the effect of a PPAR-gamma antagonist, GW 9662, on the protective effects of 15d-PGJ2. GW9662 (1 mg/kg administered i.p. 30 min before treatment with 15d-PGJ2) significantly antagonized the effect of the PPAR-gamma agonist and, thus, abolished the protective effect. Taken together, our results clearly demonstrate that treatment with 15d-PGJ2 reduces the development of inflammation and tissue injury associated with spinal cord trauma.