| ObjectiveTo investigate the preventive and therapeutical effects of agent N-acetylcysteine (NAC) on the selenite-induced cataract of rats, and to discuss the possible mechanism.Methods1. Preventive effect:30 SD rats at the age of 10 days were divided into three groups:normol-1,selenite,NAC protective group. The normol-1 group received the normal saline (0.1ml/lOg b.w) by intraperitoneal injection daily for 6 days. The selenite group was subcutaneous injected of sodium selenite by 3.46mg/kg body weight (20μmol/kg), tertian, injections three times. While NAC protective group was received sodium selenite (20μmol/kg) subcutaneous injection and then received agent NAC (0.1ml/10g) intraperitoneal injection within 30 minutes in the first day and then received NAC for 5 consecutive days.2. Therapeutical effect:30 SD rats (day 10 post partum) received subcutaneous injection sodium selenite (20μmol/kg b.w.). The rats with selenite induced cataract were divided into two groups:control, NAC therapeutical group. The control group received the normal saline (0.1ml/10g b.w) by intraperitoneal injection daily for 30 days.The NAC therapeutical group received NAC (0.1ml/10g) by intraperitoneal injection daily for 30 days.The degree of lens opacity was observed by slit-lamp. ON day 7,30, the pathological changes of lens were observed by light microscopy and scanning electron microscopy; The level of caspase-3 expression was detected by immunohistorychemistry; At the same time, the levels of Superoxide dismutase (SOD),Malonaldehyde (MDA) were measured respectively.ResultsAll rats were success induced cataract by selenite.1. Slit lamp:In the selenite group and control group, the lens opacity continuously aggravated, dust opacity and cri co-opacity were formed d3 after injecting and typical nuclear cataract was formed at d7 after injecting. The lens opacity of NAC protective group was more slight than that of selenite group but severe than that of normal group. There was no difference between the control group and the NAC therapeutical group.2. Light microscopy and scanning electron microscopy:No obvious changes canbe found in the normal group. Compared with the normal group, there was significant chage in other groups.3. Immunohistory:The expression of caspase-3 in normal group was negative. the opatical density value was 250.319±2.347; the expression of caspase-3 in NAC protective group was positive, the opatical density value was 180.942±4.379; while the expression of caspase-3 in selenite group was hard-positive, the opatical density value was 70.312±14.216, The difference in the three group was significant (P<0.05). the expression of caspase-3 in control group and the NAC therapeutical group were hard-positive, the opatical density value were 100.467±4.477,71.437±11.329, there was no significant difference between the two groups(P>0.05).4. Biochemical indicators:The level of SOD in protective group was increased than that for the selenite group but lower than that for the normal group (P<0.05). The level of MDA in protective group was lower than that for the selenite group but higher than that for the normal group-1 (P<0.05). There was no significant difference between the control group and the NAC therapeutical group about the levels of SOD and MDA (P>0.05).Conclusion1. The model of cataract could be made successgully by selenite in rats.2. The apoptosis of LECs could be induced by selenite.3. NAC can evidently inhibit the rats cataract information by increasing the activity of SOD,decreasing the level of MDA and the expression of caspase-3.4. Agent NAC could protect lens of rats against selenite damage.5. NAC could not reverse the damaged lenses which induced by selenite.
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