Effects Of Sesamol On Gamma Radiation-induced Damages In Whole-body Irradiated Wistar Rats

Objective：To investigate the radioprotective effects and mechanisms of sesamol（SM） onwhole-body irradiated Wistar rats.Methods：1. Free radical scavenging ability of SMThe system H2O2/Fe2+was used to produce hydroxy radical （OH·） through Fentonreaction, and1,1-Diphenyl-2-picrylhydrazyl was dissolved in dehydrated alcohol togenerate DPPH radical （DPPH·）. Spectrophotometry was performed to evaluate theclearing ability of SM against OH· and DPPH·.2. Antioxidative effect of SM on whole-body irradiated rats for3days’ gavageTwenty-four male Wistar rats were randomly divided into4groups: control group（CON）, radiation control group （6Gy）,（50mg/kg bw SM+6Gy） group and （100mg/kgbw SM+6Gy） group. SM, dissolved in double distilled water, was administeredintragastriclly at a volume of10ml/kg bw, once a day. After3days, all rats wereexposed to whole-body⁶⁰Co-γ irradiation, except CON group. The dose rate ofirradiation was2.0Gy/min and total absorbed dose was6.0Gy. After24hours, bloodwas collected by inferior vena cava and plasma SOD, GSH, MDA and T-AOC weremeasured.3. Radioprotective effect of SM on irradiated rats for8weeks’ intake60male Wistar rats were randomly divided into3groups and given distilled water,20mg/L SM,100mg/L SM, respectively. SM was dissolved in distilled water andrenewed every two days. Body weight, food and water intakes were recorded once aweek.8weeks later, half of rats from each group were extracted randomly and exposedto4.0Gy whole-body⁶⁰Co-γ irradiation at a dose rate of2.0Gy/min. Finally, animalswere divided into6groups: control group （CON）,20mg/L sesamol feeding group （20mg/L SM）,100mg/L sesamol feeding group （100mg/L SM）, irradiated group （4Gy）,20mg/L sesamol feeding and irradiated group （20mg/L SM+4Gy）,100mg/L sesamolfeeing and irradiated group （100mg/L SM+4Gy）. After24hours, blood from tail veinswas collected to analyze the DNA damage using single cell gel electrophoresis （SCGE）.After3days, rats were sacrificed and observed the following indexes:1) the liver,spleen, spermary indices;2) blood cell counts;3) plasma SOD, MDA, GSH and T-AOC;4) formation rate of micronuclei in marrow DNA using giemsa staining method;5)histopathological observation in jejunum, spleen and spermary;6) protein expression ofNF-κB and IκB.Results：1. SM showed obvious ability of free radical scavenging with dose-dependentmanner. The calculated IC50values of SM were2.1mM and239.5μM for OH· andDPPH·, respectively. Free radical scavenging ability was lower in SM than in Vitamin C.2. Compared with irradiated group, SM administration significantly increasedplasma SOD activity （P<0.05） and decreased MDA level （P<0.01） in irradiationexposed rats. The increase of GSH and T-AOC levels did not reach significantdifferences.3. There was no any adverse effect of SM intake on rats. Compared with theirradiation group，SM intake in irradiation exposed rats:1) significantly increasedactivity of SOD and the levels of GSH, T-AOC, and decreased MDA in plasma;2)significantly increased the number of RBC, HGB and LYM%;3) significantlydecreased the tail length,%tail DNA, tail moment and olive tail moment. For example,%tail DNA was3.30±2.36in only irradiation group and decreased to2.50±2.11and2.57±2.95in20mg/L and100mg/L SM intake rats exposed to irradiation （P<0.01）;4)significantly decreased the formation rate of micronuclei in marrow DNA. For example,rate of micronuclei was （37.30±9.62）‰in only irradiation group and decreased to（31.50±8.71）‰and （27.40±10.42）‰in20mg/L and100mg/L SM intake rats exposedto irradiation （P<0.01）;5) increased the jejunum villus height and alleviated radiationenterocolitis; protected the spermatogenic epithelial integrity and maintained thenumber of sperm; protected the structural integrity of spleen tissue and maintained thenumber of splenic corpuscle.6) had no effect on protein expression of NF-κB and IκB. Conclusions：Our findings suggested that SM was a potential radioprotector through free radicalscavenging and antioxidant ability. The lower ability of free radical scavenging in SMthan in Vitamin C was likely to be link with index selection. In addition, othermechanisms may be involved in the effects of SM on improvement of cell DNA damage,and function of intestine, spleen, seminiferous epithelium, which were sensitive toradiation.