Aim:To evaluate the effect of tetramethylpyrazine(TMP)injection on retinaldamage induced by N-methyl-N-nitrosourea(MNU)in rats and on nuclear factor-kappa B(NF-κB)family members.Methods:Female Sprague-Dawley(SD)ratswere randomly divided into groups:(i),control group;(ii),model group;and(iii),TMP-injection groups,in which the rats were subdivided into 40 mg/kg,80 mg/kgand 160 mg/kg groups.Drugs were injected ip into 47-day-old SD rats once a day.At 50 days of age,all rats in the model group and drug groups also received asingle ip injection of 60 mg/kg MNU.Rats in group 1 received ip injection ofphysiological saline.All rats were killed at different times after MNU or physi-ological saline treatment.The apoptotic index of photoreceptor cells was calcu-lated by TUNEL labeling;retinal damage was evaluated based on retinal thicknessand the expression of NF-κB family members was detected by Western blot.Results:TMP injections,in a dose-dependent manner,suppressed photorecep-tor cell apoptosis and decreased its loss in the peripheral retina.As comparedwith the MNU-treated group,TMP injection at a dose of 160 mg/kg also time-dependently upregulated the NF-κB/p65 protein level in the nucleus anddownregulated the IκBα protein level in the cytoplasm.However,no protectiveeffect of TMP injection on MNU-induced central retinal damage was found.Conclusion:TMP injection partially protects against MNU-induced retinal dam-age by upregulating the nuclear translocation of p65 to inhibit photoreceptor cellsapoptosis. Aim: To evaluate the effect of tetramethylpyrazine (TMP) on retinal induced by N-methyl-N-nitrosourea (MNU) in rats and on nuclear factor-kappa B (NF-κB) family members. Methods: Female Sprague-Dawley (Ii), model group; and (iii), TMP-injection groups, in which the rats were subdivided into 40 mg / kg, 80 mg / kg and 160 mg / kg groups. Drugs injected ip into 47-day-old SD rats once a day. At 50 days of age, all rats in the model group and drug groups also received as single ip injection of 60 mg / kg MNU. Rats in group 1 received ip injection of physiologic saline. All rats were killed at different times after MNU or physi-ological saline treatment. Apoptotic index of photoreceptor cells was calcu-lated by TUNEL labeling; retinal damage was evaluated based on retinal thickness and the expression of NF- κB family members was detected by Western blot. Results: TMP injections, in a dose-dependent manner, suppressed photorecep-tor cell apoptotic osis and decreased its loss in the peripheral retina. As compared to the MNU-treated group, TMP injection at a dose of 160 mg / kg also time-dependently upregulated the NF-κB / p65 protein level in the nucleus and downregulated the IκBα protein level in No protective effect of TMP injection on MNU-induced central retinal damage was found. Conlusion: TMP injection partially protects against MNU-induced retinal dam-age by upregulating the nuclear translocation of p65 to inhibit photoreceptor cell apoptosis.