Mn porphyrin-based SOD mimic, MnTnHex-2-PyP5+, and non-SOD mimic, MnTBAP3-, suppressed rat spinal cord ischemia/reperfusion injury via NF-κB pathways

Document Type

Article

Abstract

Herein we have demonstrated that both superoxide dismutase (SOD) mimic, cationic Mn(III) meso-tetrakis(N-n-hexylpyridinium-2-yl)porphyrin (MnTnHex-2-PyP5+), and non-SOD mimic, anionic Mn(III) meso-tetrakis(4-carboxylatophenyl)porphyrin (MnTBAP3-), protect against oxidative stress caused by spinal cord ischemia/reperfusion via suppression of nuclear factor kappa B (NF-κB) pro-inflammatory pathways. Earlier reports showed that Mn(III) N-alkylpyridylporphyrins were able to prevent the DNA binding of NF-κB in an aqueous system, whereas MnTBAP3- was not. Here, for the first time, in a complex in vivo system--animal model of spinal cord injury--a similar impact of MnTBAP3-, at a dose identical to that of MnTnHex-2-PyP5+, was demonstrated in NF-κB downregulation. Rats were treated subcutaneously at 1.5 mg/kg starting at 30 min before ischemia/reperfusion, and then every 12 h afterward for either 48 h or 7 days. The anti-inflammatory effects of both Mn porphyrins (MnPs) were demonstrated in the spinal cord tissue at both 48 h and 7 days. The downregulation of NF-κB, a major pro-inflammatory signaling protein regulating astrocyte activation, was detected and found to correlate well with the suppression of astrogliosis (as glial fibrillary acidic protein) by both MnPs. The markers of oxidative stress, lipid peroxidation and protein carbonyl formation, were significantly reduced by MnPs. The favorable impact of both MnPs on motor neurons (Tarlov score and inclined plane test) was assessed. No major changes in glutathione peroxidase- and SOD-like activities were demonstrated, which implies that none of the MnPs acted as SOD mimic. Increasing amount of data on the reactivity of MnTBAP3- with reactive nitrogen species (RNS) (.NO/HNO/ONOO-) suggests that RNS/MnTBAP3--driven modification of NF-κB protein cysteines may be involved in its therapeutic effects. This differs from the therapeutic efficacy of MnTnHex-2-PyP5+ which presumably occurs via reactive oxygen species and relates to NF-κB thiol oxidation; the role of RNS cannot be excluded.

Keywords

Ischemia reperfusion, MnTBAP 3-, MnTnHex-2-PyP 5+, NF-kappa B, Oxidative stress, Superoxide dismutase mimetics

Publication Date

12-1-2014

Publication Title

Free Radical Research

ISSN

10715762

E-ISSN

10292470

Volume

48

Issue

12

First Page

1426

Last Page

1442

PubMed ID

25185063

Digital Object Identifier (DOI)

10.3109/10715762.2014.960865

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