Protopanaxtriol protects against 3-nitropropionic acid-induced oxidative stress in a rat model of Huntington's disease.

AIM: Protopanaxtriol (Ppt) is extracted from Panax ginseng Mayer. In the present study, we investigated whether Ppt could protect against 3-nitropropionic acid (3-NP)-induced oxidative stress in a rat model of Huntington's disease (HD) and explored the mechanisms of action. METHODS: Male SD rats were treated with 3-NP (20 mg/kg on d 1, and 15 mg/kg on d 2-5, ip). The rats received Ppt (5, 10, and 20 mg/kg, po) daily prior to 3-NP administration. Nimodipine (12 mg/kg, po) or N-acetyl cysteine (NAC, 100 mg/kg, po) was used as positive control drugs. The body weight and behavior were monitored within 5 d. Then the animals were sacrificed, neuronal damage in striatum was estimated using Nissl staining. Hsp70 expression was detected with immunohistochemistry. Reactive oxygen species (ROS) generation was measured using dihydroethidium (DHE) staining. The levels of components in the Nrf2 pathway were measured with immunohistochemistry and Western blotting. RESULTS: 3-NP resulted in a marked reduction in the body weight and locomotion activity accompanied by progressive striatal dysfunction. In striatum, 3-NP caused ROS generation mainly in neurons rather than in astrocytes and induced Hsp70 expression. Administration of Ppt significantly alleviated 3-NP-induced changes of body weight and behavior, decreased ROS production and restored antioxidant enzymes activities in striatum. Moreover, Ppt directly scavenged free radicals, increased Nrf2 entering nucleus, and the expression of its downstream products heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidase 1 (NQO1) in striatum. Similar effects were obtained with the positive control drugs nimodipine or NAC. CONCLUSION: Ppt exerts a protective action against 3-NP-induced oxidative stress in the rat model of HD, which is associated with its anti-oxidant activity.

[Morphology of soil iron oxides and its correlation with soil-forming process and forming conditions in a karst mountain].

The quantity and morphology of iron oxides are indicators of soil forming-process and forming conditions. In order to analyze the connection between soil iron oxides and soil forming conditions and degenerative process of karst ecosystem, we have chosen 14 soil profiles on the top and middle section of Jinfo Mountain, a typical karst slope in Chongqing, China. Morphology and contents of soil iron oxides were studied by using chemical selective extraction techniques. We draw conclusions: 1) total iron (Fe(t)) is mainly controlled by parent material and lithology. Significant difference of Fe(t) content exists between soils in Top Mountain (51.49 g x kg(-1), mean value from 5 profiles) and soils at the middle sector of North Slope (86.29 g x kg(-1), mean value of 9 profiles); 2) the results show low concentration of F(d) (29.16 g x kg(-1)) and low ratio of Fe(d) to Fe(t)(35.40%) in soil clay under conditions of high elevation and low temperature on Top Mountain. In contrast, the results indicate advanced weathering and soil-forming process at middle slope sites due to high temperature; this is supported by high mean values of Fe(d) (43.92 g x kg(-1)) and ratio of Fe(d)/Fe(t) in clay (60.41%); 3) long humid climatic setting and large numbers of soil organic matter on top of the mountain result in high activation degrees (F(o)/Fe(d)) and high complexation degrees (Fe(p)/Fe(d)); mean values of them are 73.51%, 17.21% respectively, which are higher than that of soils at middle slope sites (13.06%, 0.41%); 4) after degradation or deforestation of secondary forestland (pines massoniana among bushes) at middle section of the hillslope, soil free iron oxides (Fe(d)) and total iron oxides (Fe(t)) decrease as well as soil organic carbon and clay, because of progressively increasing of soil erosion. Average contents of Fe(t) and Fe(d) in clay from 2 shrub profiles are 98.25 g x kg(-1), 50.81 g x kg(-1) respectively. However, the four tillage soils we have studied reveal lower values of Fe(t) (84.52 g x kg(-1)) and Fe(d) in clay (47.86 g x kg(-1)). Soil iron oxides are reliable indicators to estimate degeneration of karst ecosystem and karst rock desertification.