ABSTRACT
BACKGROUND: Retinitis pigmentosa (RP) is a non-inflammatory, bilaterally progressive, retinal degeneration characterized by loss of photoreceptor cells via an apoptotic mechanism, and it eventually leads to blindness.Research shows that the traditional Chinese medicines of Astragalus has great prospect on blocking the progression of RP disease.OBJECTIVE: To observe the protective effect of Astragalus on N-methylN-nitrosourea (MNU)-induced retinal damage in Sprague-Dawley (SD) rats and provide the optimal treatment for RP in humans.DESIGN: Randomized controlled experiment.SETTING: School of Pharmaceutical Sciences, Xinxiang Medical College.MATERIALS :The experiment was completed in Pharmacological Laboratory of Zhongshan Ophthalmic Centre, Sun Yat-sen University between March to December 2004. Totally 114 female SD rats were purchased from the Animal Center of Zhongshan Medical College, Sun Yat-sen University.MNU was purchased from Sigma Company of America. Astragalus injection was purchased from Chengdu Diao Jiuhong Pharmaceutical Factory (Batch No. Z99060535, 2 mL/ampoule, main ingredient: Astragalus).METHODS: Among 114rats, 30 were for morphometric analysis of retinal layers, 30 were for detection of apoptosis and 54 were for detection of NF-κB p65 activity. All of them were randomly divided into different groups and each group had 6 rats. Astragalus at doses of 2.5, 5 and 10 g/kg were injected intraperitoneally into 47-day rats once a day. Meanwhile, a single intraperitoneal injection of 60 mg/kg MNU was given to 50-day rats in model and Astragalus groups. At different intervals after MNU treatment,the animals were sacrificed. Retinal damage was evaluated based on retinal thickness, the apoptotic index of the photoreceptor cells was detected by TUNEL labeling and the DNA-binding activity of NF-κB p65 was analyzed according to transcription factor assay kit.MAIN OUTCOME MEASURES: Comparison of retinal thickness, apoptotic index and the activity of nuclear NF-κB p65.RESULTS: Totally 114 rats entered the result analysis. Pretreatment with Astragalus could dose-dependently suppress MNU-induced photoreceptor cell loss and decreased the apoptotic index. Astragalus at dose of 10 g/kg also time-dependently up-regulated the activity of nuclear NF-κB p65.However, protective effect of Astragalus on MNU-induced central retinal damage was not found.CONCLUSION: Astragalus partially protects against MNU-induced retinal damage by up-modulating the activity of nuclear NF-κB p65 to inhibit apoptosis of photoreceptor cells in a dose-dependent manner.
ABSTRACT
Aim To study the molecular mechanism of retinal toxicity induced by N-methyl-N-nitrosourea (MNU) in SD rats. Methods A single intraperitoneal injection of 60 mg?kg~(-1) MNU was given to 50-day-old female SD rats. After MNU treatment for different times, the rats were sacrificed and both eyes were enucleated immediately and processed for histological examination. The apoptotic index of photoreceptor cells was calculated by TUNEL labeling and the expression of c-jun and c-fos genes was detected by RT-PCR technique. Results After the application of MNU for 24 h,the disorientation of photoreceptor outer segments was seen. The outer nuclear layer and photoreceptor layer were almost completely lost at 7 d. Apoptosis had already started at 12 h post-MNU and peaked at 24 h. MNU time-dependently up-regulated the expression of c-jun and c-fos genes. Conclusion MNU has a toxic effect on retina by up-modulating expression of c-jun and c-fos genes to promote photorecptor cells apoptosis.
ABSTRACT
Aim To explore the effects and its mechanisms of ginsenoside-Rg1 on level of t-PA and PAI-1.Methods Type 1 plasminogen activator inhibitor(PAI-1) and tissue type plasminogen activator(t-PA) activity in plasma were assayed using chromogenic substrate.Results The results showed that ginsenoside-Rg1 in vitro or in vivo significantly inhibited PAI-1activity,while increased t-PA activity.These effects were concentration-dependent.Intravenous Panax notoginsenoside Rg1 at 30,60,120 and 240 mg?kg~(-1) markedly suppressed PAI-1 level in plasma as well as platelet-released substances stimulated by thrombin,while increased plasma t-PA activity.And release level of PAI-1 owing to blood platelet was greatly decreased by ginsenoside-Rg1.Conclusion Ginsenoside-Rg1 showed potent antithrombosis due to the inhibition of PAI-1 and increase of t-PA.It might also be a advantagous mechanism to its antithrombsis.
ABSTRACT
Objective To investigate the mechanism of the toxic effect of N-methyl-N-nitrosourea (MNU) on photoreceptor cell apoptosis of rat′s retina. Methods Thirty 50-day-old female Sprague-Dawley ( SD ) rats were intraperitoneally injected with MNU (60 mg/kg) and were put to death by dislocation of cervical vertebra 12, 24, 48, and 72 hours and 7 days after the injection, respectively. The photoreceptor cell apoptosis was detected by terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) and transmission electron microscope. The expression of proliferating cell nuclear antigen (PCNA), vimentin and glial fibrillary acidic protein (GFAP) was detected at different time after injection by immunohistochemical methods. Results The apoptotic index of the retina in the posterior pole was (33.6?2.3)%, (46.5?5.7)%, (20.1?5.3)%, (8.2?3.6)% and (2.5?1.3% at the 12th, 24 th, 48 th, and 72nd hour and on the 7th day, respectively, after injection. Karyopyknosis was found in most photoreceptor cells 24 hours after injection. The expression of PCNA was found in internal granular layer and between internal granular layer and choroid 24 hours after injection, reached the peak after 72 hours, and reduced obviously after 7 days. The positive expression of GFAP and vimentin was found in internal and external granular layer 24 hours after injection, reached the peak after 72 hours, and reduced obviously after 7 days. Conclusion MNU may selectively lead the photoreceptor cell apoptosis and proliferation of M?ller cells.