Neuroprotective effects of tempol on retinal ganglion cells in a partial optic nerve crush rat model with and without iron load

TY - JOUR

T1 - Neuroprotective effects of tempol on retinal ganglion cells in a partial optic nerve crush rat model with and without iron load

AU - Thaler, Sebastian

AU - Fiedorowicz, Michal

AU - Rejdak, Robert

AU - Choragiewicz, Tomasz J

AU - Sulejczak, Dorota

AU - Stopa, Piotr

AU - Zarnowski, Tomasz

AU - Zrenner, Eberhart

AU - Grieb, Pawel

AU - Schuettauf, Frank

N1 - Copyright 2009 Elsevier Ltd. All rights reserved.

PY - 2010/2

Y1 - 2010/2

N2 - Iron overload can contribute to oxidative stress in many tissues. We studied the effects of pretreatment with iron dextran on RGC loss in a calibrated partial optic nerve crush (PONC) model in rats, along with the protection offered by tempol (4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl, a membrane-permeable superoxide dismutase mimetic and free-radical scavenger), in the same experimental paradigm. A total of 40 rats in 6 groups of 5-8 animals each underwent PONC in one eye and sham crush in the other. Animals were pretreated with a single iron dextran load 24 h prior to PONC, and treated with tempol 6 h before and then once daily after PONC. Control animals were treated with PBS. RGC were retrogradely labeled with a fluorescent marker; all data are expressed in percent of the RGC count in the respective sham-treated eye. Immunohistochemistry was performed to visualize 3-nitrotyrosine, a marker of nitroxidative stress. PONC without iron pretreatment resulted in the survival of only 31.4% of labeled RGC after 7 days. Even fewer RGC (12.7%) survived after PONC with iron pretreatment. However, tempol in doses of 20 mg/kg of body weight (BW) significantly attenuated this effect when given as described above; in the group without iron pretreatment the number of surviving RGC doubled from 31.4% to 62.1%. In the group with iron pretreatment the survival rate of RGC increased even more pronouncedly, from 12.7% without tempol to 46.2% with tempol. Tempol in doses of 1 mg/kg BW and 5 mg/kg BW showed no significant rescue of RGC. Immunostaining showed nitrotyrosine-positive RGCs in PONC but not in sham-treated eyes and an increase in positive cells after iron load. Tempol treatment reduced nitrotyrosine staining in both the iron and non-iron groups. Our results demonstrate that PONC results in significantly greater RGC damage when iron pretreatment is performed, and that the compound tempol may provide additional protection for RGC in cases of neuronal damage both with and without prior iron treatment.

AB - Iron overload can contribute to oxidative stress in many tissues. We studied the effects of pretreatment with iron dextran on RGC loss in a calibrated partial optic nerve crush (PONC) model in rats, along with the protection offered by tempol (4-hydroxy-2,2,6,6-tetramethylpiperidinyl-1-oxyl, a membrane-permeable superoxide dismutase mimetic and free-radical scavenger), in the same experimental paradigm. A total of 40 rats in 6 groups of 5-8 animals each underwent PONC in one eye and sham crush in the other. Animals were pretreated with a single iron dextran load 24 h prior to PONC, and treated with tempol 6 h before and then once daily after PONC. Control animals were treated with PBS. RGC were retrogradely labeled with a fluorescent marker; all data are expressed in percent of the RGC count in the respective sham-treated eye. Immunohistochemistry was performed to visualize 3-nitrotyrosine, a marker of nitroxidative stress. PONC without iron pretreatment resulted in the survival of only 31.4% of labeled RGC after 7 days. Even fewer RGC (12.7%) survived after PONC with iron pretreatment. However, tempol in doses of 20 mg/kg of body weight (BW) significantly attenuated this effect when given as described above; in the group without iron pretreatment the number of surviving RGC doubled from 31.4% to 62.1%. In the group with iron pretreatment the survival rate of RGC increased even more pronouncedly, from 12.7% without tempol to 46.2% with tempol. Tempol in doses of 1 mg/kg BW and 5 mg/kg BW showed no significant rescue of RGC. Immunostaining showed nitrotyrosine-positive RGCs in PONC but not in sham-treated eyes and an increase in positive cells after iron load. Tempol treatment reduced nitrotyrosine staining in both the iron and non-iron groups. Our results demonstrate that PONC results in significantly greater RGC damage when iron pretreatment is performed, and that the compound tempol may provide additional protection for RGC in cases of neuronal damage both with and without prior iron treatment.

KW - Animals

KW - Antioxidants/administration & dosage

KW - Cell Count

KW - Cell Survival

KW - Cyclic N-Oxides/administration & dosage

KW - Disease Models, Animal

KW - Dose-Response Relationship, Drug

KW - Hematinics/therapeutic use

KW - Immunoenzyme Techniques

KW - Iron Overload/metabolism

KW - Iron-Dextran Complex/therapeutic use

KW - Neuroprotective Agents/administration & dosage

KW - Optic Nerve Injuries/complications

KW - Oxidative Stress

KW - Rats

KW - Rats, Inbred BN

KW - Retinal Degeneration/etiology

KW - Retinal Ganglion Cells/drug effects

KW - Spin Labels

KW - Tyrosine/analogs & derivatives

U2 - 10.1016/j.exer.2009.10.013

DO - 10.1016/j.exer.2009.10.013

M3 - SCORING: Journal article

C2 - 19883642

VL - 90

SP - 254

EP - 260

JO - EXP EYE RES

JF - EXP EYE RES

SN - 0014-4835

IS - 2

ER -