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Amelioration of Cerebral Ischemic Injury by a Synthetic Seco-nucleoside LMT497.

Ryu S, Kwon J, Park H, Choi IY, Hwang S, Gajulapati V, Lee JY, Choi Y, Varani K, Borea PA, Ju C, Kim WK - Exp Neurobiol (2015)

Bottom Line: LMT497 neither showed A3AR binding activity nor anti-platelet activity.LMT497 significantly reduced the ascending cellular level of reactive oxygen species under ischemic conditions by increasing the superoxide dismutase (SOD) levels.In rats subjected to middle cerebral artery occlusion (MCAO, 1.5 h) followed by reperfusion, LMT497 largely reduced brain infarction volume, and edema, and improved neurological score.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, School of Medicine, Korea University, Seoul 136-705, Korea.

ABSTRACT
Recently, we reported that the A3 adenosine receptor (A3AR) agonist LJ529 (2-chloro-N(6)-(3-iodobnzyl)-5'-N-methylcarbamoyl-4'-thioadenosine) reduces cerebral ischemic injury via inhibition of recruitment of peripheral inflammatory cells into ischemic brain lesion. A3AR agonists, however, are known to possess anti-platelet activity, which may deter the combination therapy with tissue plasminogen activator for the therapy of cerebral ischemic stroke. Thus, the present study investigates the neuroprotective/anti-ischemic effect of a synthetic seco-nucleoside, LMT497 ((S)-2-((R)-1-(2-chloro-6-(3-iodobenzylamino)-9H-purin-9-yl)-2-hydroxyethoxy)-3-hydroxy-N-methylpropanamide) with little anti-platelet activity. LMT497 neither showed A3AR binding activity nor anti-platelet activity. In our present study LMT497 significantly attenuated the injury/death of cortical neurons exposed to oxygen-glucose deprivation (OGD) followed by re-oxygenation (R). LMT497 significantly reduced the ascending cellular level of reactive oxygen species under ischemic conditions by increasing the superoxide dismutase (SOD) levels. LMT497 also inhibited the migration of microglia which mediates inflammatory responses in ischemia. In rats subjected to middle cerebral artery occlusion (MCAO, 1.5 h) followed by reperfusion, LMT497 largely reduced brain infarction volume, and edema, and improved neurological score. Therapeutic efficacy of LMT497 was obtained by twice treatments even at 10 h and 18 h after the onset of ischemia. Collectively, LMT497 could be a therapeutic drug candidate with a wide therapeutic time window for the treatment of cerebral ischemic stroke.

No MeSH data available.


Related in: MedlinePlus

Effects of LMT497 on SOD/catalase activity and ODG/R-induced superoxide generation. SOD (A) and catalase (B) assays were performed 4 h after incubation with vehicle or LMT497 10 µm. Data are presented as medians±interquartile ranges. n=6; *p<0.05 compared with indicated group (C, D) OGD/R-induced intracellular superoxide levels in cortical cells. Cortical cells were treated with LMT497 (10 µm) Or Trolox (T; 10 µm) before OGD. (C) Representative images. Scale bar=50 µm. (D) Quantification of HE fluorescence. n=6; **p<0.01 significantly different from the control group.
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Figure 4: Effects of LMT497 on SOD/catalase activity and ODG/R-induced superoxide generation. SOD (A) and catalase (B) assays were performed 4 h after incubation with vehicle or LMT497 10 µm. Data are presented as medians±interquartile ranges. n=6; *p<0.05 compared with indicated group (C, D) OGD/R-induced intracellular superoxide levels in cortical cells. Cortical cells were treated with LMT497 (10 µm) Or Trolox (T; 10 µm) before OGD. (C) Representative images. Scale bar=50 µm. (D) Quantification of HE fluorescence. n=6; **p<0.01 significantly different from the control group.

Mentions: In regards to anti-oxidative defense mechanisms, enzymes such as SOD and catalase have the abilities to alleviate oxidative damage caused by ischemic stroke [13]. To further investigate the anti-oxidative capabilities of LMT497, the levels of SOD and catalase were tested as representative anti-oxidant enzymes. LMT497 significantly increased SOD activity in cortical cells in non-ischemic conditions, but failed to show significance when tested for catalase activity (Fig. 4A, B). Since SOD catalyzes the dismutation of superoxide to hydrogen peroxide and oxygen [13], it was necessary to examine whether LMT497 could decrease the level of superoxide under ischemic conditions. Similar to Trolox, LMT497 significantly decreased OGD/R-induced HE fluorescence, which indicates the decline of superoxide levels. (Fig. 4C, D)


Amelioration of Cerebral Ischemic Injury by a Synthetic Seco-nucleoside LMT497.

Ryu S, Kwon J, Park H, Choi IY, Hwang S, Gajulapati V, Lee JY, Choi Y, Varani K, Borea PA, Ju C, Kim WK - Exp Neurobiol (2015)

Effects of LMT497 on SOD/catalase activity and ODG/R-induced superoxide generation. SOD (A) and catalase (B) assays were performed 4 h after incubation with vehicle or LMT497 10 µm. Data are presented as medians±interquartile ranges. n=6; *p<0.05 compared with indicated group (C, D) OGD/R-induced intracellular superoxide levels in cortical cells. Cortical cells were treated with LMT497 (10 µm) Or Trolox (T; 10 µm) before OGD. (C) Representative images. Scale bar=50 µm. (D) Quantification of HE fluorescence. n=6; **p<0.01 significantly different from the control group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4363332&req=5

Figure 4: Effects of LMT497 on SOD/catalase activity and ODG/R-induced superoxide generation. SOD (A) and catalase (B) assays were performed 4 h after incubation with vehicle or LMT497 10 µm. Data are presented as medians±interquartile ranges. n=6; *p<0.05 compared with indicated group (C, D) OGD/R-induced intracellular superoxide levels in cortical cells. Cortical cells were treated with LMT497 (10 µm) Or Trolox (T; 10 µm) before OGD. (C) Representative images. Scale bar=50 µm. (D) Quantification of HE fluorescence. n=6; **p<0.01 significantly different from the control group.
Mentions: In regards to anti-oxidative defense mechanisms, enzymes such as SOD and catalase have the abilities to alleviate oxidative damage caused by ischemic stroke [13]. To further investigate the anti-oxidative capabilities of LMT497, the levels of SOD and catalase were tested as representative anti-oxidant enzymes. LMT497 significantly increased SOD activity in cortical cells in non-ischemic conditions, but failed to show significance when tested for catalase activity (Fig. 4A, B). Since SOD catalyzes the dismutation of superoxide to hydrogen peroxide and oxygen [13], it was necessary to examine whether LMT497 could decrease the level of superoxide under ischemic conditions. Similar to Trolox, LMT497 significantly decreased OGD/R-induced HE fluorescence, which indicates the decline of superoxide levels. (Fig. 4C, D)

Bottom Line: LMT497 neither showed A3AR binding activity nor anti-platelet activity.LMT497 significantly reduced the ascending cellular level of reactive oxygen species under ischemic conditions by increasing the superoxide dismutase (SOD) levels.In rats subjected to middle cerebral artery occlusion (MCAO, 1.5 h) followed by reperfusion, LMT497 largely reduced brain infarction volume, and edema, and improved neurological score.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, School of Medicine, Korea University, Seoul 136-705, Korea.

ABSTRACT
Recently, we reported that the A3 adenosine receptor (A3AR) agonist LJ529 (2-chloro-N(6)-(3-iodobnzyl)-5'-N-methylcarbamoyl-4'-thioadenosine) reduces cerebral ischemic injury via inhibition of recruitment of peripheral inflammatory cells into ischemic brain lesion. A3AR agonists, however, are known to possess anti-platelet activity, which may deter the combination therapy with tissue plasminogen activator for the therapy of cerebral ischemic stroke. Thus, the present study investigates the neuroprotective/anti-ischemic effect of a synthetic seco-nucleoside, LMT497 ((S)-2-((R)-1-(2-chloro-6-(3-iodobenzylamino)-9H-purin-9-yl)-2-hydroxyethoxy)-3-hydroxy-N-methylpropanamide) with little anti-platelet activity. LMT497 neither showed A3AR binding activity nor anti-platelet activity. In our present study LMT497 significantly attenuated the injury/death of cortical neurons exposed to oxygen-glucose deprivation (OGD) followed by re-oxygenation (R). LMT497 significantly reduced the ascending cellular level of reactive oxygen species under ischemic conditions by increasing the superoxide dismutase (SOD) levels. LMT497 also inhibited the migration of microglia which mediates inflammatory responses in ischemia. In rats subjected to middle cerebral artery occlusion (MCAO, 1.5 h) followed by reperfusion, LMT497 largely reduced brain infarction volume, and edema, and improved neurological score. Therapeutic efficacy of LMT497 was obtained by twice treatments even at 10 h and 18 h after the onset of ischemia. Collectively, LMT497 could be a therapeutic drug candidate with a wide therapeutic time window for the treatment of cerebral ischemic stroke.

No MeSH data available.


Related in: MedlinePlus