Necrostatin-1 protection of dopaminergic neurons.

Necroptosis is characterized by programmed necrotic cell death and autophagic activation and might be involved in the death process of dopaminergic neurons in Parkinson's disease. We hypothesized that necrostatin-1 could block necroptosis and give protection to dopaminergic neurons. There is likely to be crosstalk between necroptosis and other cell death pathways, such as apoptosis and autophagy. PC12 cells were pretreated with necroststin-1 1 hour before exposure to 6-hydroxydopamine. We examined cell viability, mitochondrial membrane potential and expression patterns of apoptotic and necroptotic death signaling proteins. The results showed that the autophagy/lysosomal pathway is involved in the 6-hydroxydopamine-induced death process of PC12 cells. Mitochondrial disability induced overactive autophagy, increased cathepsin B expression, and diminished Bcl-2 expression. Necrostatin-1 within a certain concentration range (5-30 µM) elevated the viability of PC12 cells, stabilized mitochondrial membrane potential, inhibited excessive autophagy, reduced the expression of LC3-II and cathepsin B, and increased Bcl-2 expression. These findings suggest that necrostatin-1 exerted a protective effect against injury on dopaminergic neurons. Necrostatin-1 interacts with the apoptosis signaling pathway during this process. This pathway could be a new neuroprotective and therapeutic target in Parkinson's disease.

Up-regulation of glyoxalase 1 by mangiferin prevents diabetic nephropathy progression in streptozotocin-induced diabetic rats.

Advanced glycation endproducts (AGEs) and its precursor methylglyoxal are associated with diabetic nephropathy (DN). Mangiferin has many beneficial biological activities, including anti-inflammatory, anti-oxidative and anti-diabetic effects. We investigated the effect of mangiferin on DN and its potential mechanism associated with glyoxalase 1 (Glo-1), a detoxifying enzyme of methylglyoxal, in streptozotocin-induced rat model of DN. Diabetic rats were treated orally with mangiferin (15, 30, and 60 mg/kg) or distilled water for 9 weeks. Kidney tissues were collected for morphologic observation and the determination of associated biochemical parameters. The cultured mesangial cells were used to measure the activity of Glo-1 in vitro. Chronic treatment with mangiferin significantly ameliorated renal dysfunction in diabetic rats, as evidenced by decreases in albuminuria, blood urea nitrogen, kidney weight index, periodic acid-schiff stain positive mesangial matrix area, glomerular extracellular matrix expansion and accumulation, and glomerular basement membrane thickness. Meanwhile, mangiferin treatment caused substantial increases in the enzymatic activity of Glo-1 in vivo and in vitro, and protein and mRNA expression of Glo-1, reduced levels of AGEs and the protein and mRNA expression of their receptor (RAGE) in the renal cortex of diabetic rats. Moreover, mangiferin significantly attenuated oxidative stress damage as reflected by the lowered malondialdehyde and the increased glutathione levels in the kidney of diabetic rats. However, mangiferin did not affect the blood glucose and body weight of diabetic rats. Therefore, mangiferin can remarkably ameliorate DN in rats through inhibiting the AGEs/RAGE aix and oxidative stress damage, and Glo-1 may be a target for mangiferin action.

Suppression of methylglyoxal hyperactivity by mangiferin can prevent diabetes-associated cognitive decline in rats.

RATIONALE: Evidences indicate that methylglyoxal, a highly reactive metabolite of hyperglycemia, can enhance protein glycation, oxidative stress, or inflammation. Mangiferin, a polyphenol compound of C-glucoside, has many beneficial biological activities, including anti-inflammation, anti-oxidation, neuroprotection, cognitive enhancement, etc. Whether mangiferin alleviates diabetes-associated cognitive impairment is still unclear. OBJECTIVES: The present study was designed to investigate the effects of mangiferin on the behavioral deficits of diabetic rats induced by streptozotocin; the mechanisms associated with methylglyoxal toxicity are especially investigated. METHODS: Diabetic rats were treated with mangiferin (15, 30, and 60 mg/kg, p.o.) for 9 weeks. Cognitive performances were evaluated with the Morris water maze. Hippocampus and blood were obtained for evaluation of the effects of mangiferin on protein glycation, oxidative stress, and inflammation in diabetic state. RESULTS: Mangiferin significantly improved the behavioral performances of diabetic rats, evidenced by a decrease in escape latency as well as increases in numbers of crossing the platform and percentage of time spent in the target quadrant, which were accompanied by decreases in the levels of advanced glycation end-products and their receptor (RAGE), interleukin-1ß, TNF-α, and malondialdehyde and increases in the activity and expression of glyoxalase 1 as well as glutathione level in the hippocampus of diabetic rats. Furthermore, mangiferin produced a significant decrease in malondialdehyde level and increased glutathione level and superoxide dismutase activity in the serum of diabetic rats. CONCLUSIONS: This study demonstrates that mangiferin can markedly ameliorate diabetes-associated cognitive decline in rats, which is done likely through suppressing methylglyoxal hyperactivity (promoting protein glycation, oxidative stress, and inflammation) mediated noxious effects.

[Effect of C21 steroidal glycoside from root of Cynanchum auriculatum on D-galactose induced aging model mice].

OBJECTIVE: To study the effect of C21 steroidal glycoside (CSG) from the root of Cynanchum auriculatum from Jiangsu on D-galactose (D-gal) induced aging model mice. METHOD: D-gal aging mouse model was established by cervicodorsal region subcutaneous injection with D-gal once a day for eight successive weeks. The mice in the normal control group (NCG, non-modeled) and the model control group (MCG, modeled but untreated) were treated with 1% CMC-Na. The model mice in the low, middle and high-dose CSG and Vitamin E treated groups were treated with a dose of (10, 20, 40, 100 mg x kg(-1) per day, respectively. The SOD activity, MDA content and telomerase activity in serum, heart, liver and brain tissues of mice were measured. RESULT: CSG could obviously increase the SOD activity and decrease the MDA level in serum, heart, liver and brain tissues in D-gal aging mice (P < 0.01). There was no significant difference between three CSG treated groups and Vitamin E treated groups. In comparison of telomerase activity between MCG and the treated groups, it was shown that there was a significant increase in serum in middle and high dose group, and in heart tissues in CSG and Vit E treated groups, but was not in liver and brain tissue. CONCLUSION: This study demonstrates that CSG can antagonize free radical injury, increase the SOD activity and decrease the MDA content of serum, heart, liver and brain in D-gal aging mice, and increase the telomerase activity in serum and heart tissues but not in liver and brain tissue.