Alpha-lipoic acid activates AMPK to protect against oxidative stress and apoptosis in rats with diabetic peripheral neuropathy.

PURPOSE: To investigate the AMPK pathway-mediated effect of alpha-lipoic acid (ALA) on the dorsal root ganglia (DRGs) of rats with diabetic peripheral neuropathy (DPN) and to attempt to elucidate the underlying mechanism. METHODS: Sprague-Dawley rats (n = 15) were randomly divided into three groups. The control group was fed a standard diet, and the other groups were fed a high-carbohydrate/high-fat diet. Diabetes was established by a single streptozotocin (STZ) (30 mg/kg) injection, and control rats were injected with an equal volume of citrate buffer. ALA (60 mg/kg/day) was administered for 12 weeks. The nerve conduction velocity (NCV) of the sciatic nerve was measured. Glutathione (GSH) and malondialdehyde (MDA) concentrations in serum were measured with the thiobarbituric acid method and biochemistry. Pathological changes in the rat DRGs were observed. AMPK, phospho-AMPK (p-AMPK), nuclear factor erythroid-2-related factor 2 (Nrf2), phospho-nuclear factor erythroid-2-related factor 2 (p-Nrf2), heme oxygenase 1 (HO-1), quinone oxidoreductase 1 (NQO1), Forkhead box O3 (FoxO3a), phospho-Forkhead box O3 (p-FoxO3a), and Bcl-2 interacting mediator of cell death (Bim) expression levels were assessed by immunohistochemistry and western blotting. RESULTS: ALA improved the motor NCV (MNCV) and sensory NCV (SNCV) of rats with DPN and reduced their mechanical pain threshold. ALA increased serum GSH concentrations and decreased serum MDA concentrations. Additionally, AMPK was activated by ALA. Nrf2, p-Nrf2, HO-1, and NQO1 expression was upregulated, while FoxO3a, p-FoxO3a, and Bim expression was downregulated. ALA reduced oxidative stress and apoptosis in DRG. CONCLUSION: ALA alleviates DPN and improves peripheral nerve function. ALA reduces oxidative stress by activating Nrf2 through AMPK and inhibits FoxO3a and Bim thereby reducing neuronal apoptosis.

[Response of chloroplast ultrastructure of ear leaves of spring maize to field managements].

Spring maize was selected as research object, and the characteristics of chloroplast ultrastructure of ear leaves were evaluated with scanning electron microscopy (SEM) as affected by irrigation, organic manure fertilization and nitrogen application. The results showed that with increasing irrigation amount, organic manure fertilization amount and nitrogen application amount, the chloroplast ultrastructure gradually became integrated, the membrane envelope of chloroplast became clear, the stroma lamellae increased and arranged regularly, the grana were clear and stacked increasingly, the starch particles increased and the osmiophilic grains decreased. Compared with other treatments, irrigation, organic manure fertilization and nitrogen application at a rate of 1200 milliliter per pot and per day, 4000 kilogram per mu and 23 kilogram N per mu could make the chloroplast ultrastructure show greater predominance. Compared with one topdressing, two topdressing and one deep application with control fertilizer made chloroplast become a more integrated membrane system. It was indicated that whether the chloroplast ultrastructure was normal was considered as an important index judging activities of plant cells, and reasonable field managements could make chloroplast ultrastructure of spring maize more stable, which was advantaged for high-efficiency production of spring maize.