Red Ginseng Attenuates Aß-Induced Mitochondrial Dysfunction and Aß-mediated Pathology in an Animal Model of Alzheimer's Disease.

Alzheimer's disease (AD) is the most common neurodegenerative disease and is characterized by neurodegeneration and cognitive deficits. Amyloid beta (Aß) peptide is known to be a major cause of AD pathogenesis. However, recent studies have clarified that mitochondrial deficiency is also a mediator or trigger for AD development. Interestingly, red ginseng (RG) has been demonstrated to have beneficial effects on AD pathology. However, there is no evidence showing whether RG extract (RGE) can inhibit the mitochondrial deficit-mediated pathology in the experimental models of AD. The effects of RGE on Aß-mediated mitochondrial deficiency were investigated in both HT22 mouse hippocampal neuronal cells and the brains of 5XFAD Aß-overexpressing transgenic mice. To examine whether RGE can affect mitochondria-related pathology, we used immunohistostaining to study the effects of RGE on Aß accumulation, neuroinflammation, neurodegeneration, and impaired adult hippocampal neurogenesis in hippocampal formation of 5XFAD mice. In vitro and in vivo findings indicated that RGE significantly improves Aß-induced mitochondrial pathology. In addition, RGE significantly ameliorated AD-related pathology, such as Aß deposition, gliosis, and neuronal loss, and deficits in adult hippocampal neurogenesis in brains with AD. Our results suggest that RGE may be a mitochondria-targeting agent for the treatment of AD.

Protective Effects of Curcumin on Renal Oxidative Stress and Lipid Metabolism in a Rat Model of Type 2 Diabetic Nephropathy.

PURPOSE: Diabetic nephropathy is a serious complication of type 2 diabetes mellitus, and delaying the development of diabetic nephropathy in patients with diabetes mellitus is very important. In this study, we investigated inflammation, oxidative stress, and lipid metabolism to assess whether curcumin ameliorates diabetic nephropathy. MATERIALS AND METHODS: Animals were divided into three groups: Long-Evans-Tokushima-Otsuka rats for normal controls, Otsuka-Long-Evans-Tokushima Fatty (OLETF) rats for the diabetic group, and curcumin-treated (100 mg/kg/day) OLETF rats. We measured body and epididymal fat weights, and examined plasma glucose, adiponectin, and lipid profiles at 45 weeks. To confirm renal damage, we measured albumin-creatinine ratio, superoxide dismutase (SOD), and malondialdehyde (MDA) in urine samples. Glomerular basement membrane thickness and slit pore density were evaluated in the renal cortex tissue of rats. Furthermore, we conducted adenosine monophosphate-activated protein kinase (AMPK) signaling and oxidative stress-related nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling to investigate mechanisms of lipotoxicity in kidneys. RESULTS: Curcumin ameliorated albuminuria, pathophysiologic changes on the glomerulus, urinary MDA, and urinary SOD related with elevated Nrf2 signaling, as well as serum lipid-related index and ectopic lipid accumulation through activation of AMPK signaling. CONCLUSION: Collectively, these findings indicate that curcumin exerts renoprotective effects by inhibiting renal lipid accumulation and oxidative stress through AMPK and Nrf2 signaling pathway.

Dibenzoylmethane exerts metabolic activity through regulation of AMP-activated protein kinase (AMPK)-mediated glucose uptake and adipogenesis pathways.

Dibenzoylmethane (DBM) has been shown to exert a variety of beneficial effects on human health. However, the mechanism of action is poorly understood. In this study, DBM increased phosphorylation of AMP-activated protein kinase (AMPK) and stimulated glucose uptake in a skeletal muscle cell line. Both knockdown of AMPK with siRNA and inhibition with AMPK inhibitor blocked DBM-induced glucose uptake. DBM increased the concentration of intracellular calcium and glucose uptake due to DBM was abolished by STO-609 (a calcium/calmodulin-dependent protein kinase inhibitor). DBM stimulated phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), which was blocked by pretreatment with compound C, an AMPK inhibitor. The expression of glucose transporter type 4 (GLUT4) was increased by DBM. The translocation of GLUT4 to the plasma membrane was also increased by DBM in AMPK dependently. In addition, DBM suppressed weight gain and prevented fat accumulation in the liver and abdomen in mice fed a high-fat diet. In pre-adipocyte cells, DBM decreased the activity of acetyl-CoA carboxylase (ACC), the rate-limiting enzyme of fatty acid synthesis. Expression of the adipogenic gene, fatty acid synthase (FAS), was suppressed by DBM in an AMPK-dependent manner. These results showed that the beneficial metabolic effects of DBM might be due to regulation of glucose uptake via AMPK in skeletal muscle and inhibition of adipogenesis in pre-adipocytes.

Rhus verniciflua extract modulates survival of MCF-7 breast cancer cells through the modulation of AMPK-pathway.

Rhus verniciflua STOKES (RVS) is used as an anti-cancer agent in traditional herbal medicine. However, the underlying molecular mechanism of its action is poorly understood. Here, we elucidated the mechanism of the anti-cancer mechanism of RVS in MCF-7 human breast cancer cells. We found that RVS increased the phosphorylation of AMP-activated protein kinase (AMPK) and downstream acetyl-CoA carboxylase (ACC) and suppressed cell viability in an AMPK-dependent fashion. RVS also induced an increase in reactive oxygen species (ROS) levels. RVS-induced AMPK phosphorylation was not observed in the presence of N-acetyl-cysteine (NAC), which indicated that ROS is associated with RVS-induced AMPK phosphorylation. In addition, fluorescent staining (Annexin V/propidium iodide) revealed that RVS increased the expression of Annexin V, which indicates that RVS leads to cancer-induced apoptosis. Moreover, RVS increased the phosphorylation of p53 and the expression of Bax. The inhibition of AMPK blocked RVS-induced p53 phosphorylation and Bax expression, which suggests that AMPK is involved in RVS-induced cancer apoptosis. Taken together, these results demonstrate that RVS has anti-tumor effects on MCF-7 cells through an AMPK-signaling pathway.

Regulation of AHI1 expression in adult rat brain: Implication in hypothalamic feeding control.

Recent studies revealed that Abelson helper integration site 1 (AHI1) plays a role in brain development. However, little is known about the role of AHI1 in adult brain. To directly assess the role of AHI1 in the adult brain, we cloned full-length cDNA of rat AHI1 and observed prominent expression of AHI1 in the hypothalamus, which contributes mainly to the control of energy homeostasis. Furthermore, we demonstrated that food deprivation caused induction of AHI1 in the hypothalamus and subsequent re-feeding down-regulated AHI1 expression, suggesting the involvement of AHI1 in feeding control. Moreover, the expression of AHI1 was increased in serum-depleted Neuro2A cells and restored by subsequent insulin treatment. Furthermore, treatment in food-deprived rat with intraperitoneal glucose also reduced the increased AHI1 expression. These results demonstrate that AHI1 expression can be regulated through diet and suggest the novel role of AHI1 in feeding behavior.

Serotonin stimulates GnRH secretion through the c-Src-PLC gamma1 pathway in GT1-7 hypothalamic cells.

Serotonin is a neurotransmitter that alters the hypothalamic-pituitary-adrenal axis. To date, however, the molecular mechanisms underlying the role of serotonin in hormone secretion have remained largely unclear. In this study, we report that serotonin activates phospholipase C (PLC) gamma1 in an Src-dependent manner in hypothalamic GT1-7 cells, and that pretreatment with either 4-amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazole [3, 4-d] pyrimidine, an Src-kinase inhibitor, or U73122, a PLC inhibitor, attenuates the serotonin-induced increase in calcium levels. Also, PLC gamma1 binds to c-Src through the Src-homology (SH) 223 domain upon serotonin treatment. Moreover, calcium increase is alleviated in the cells transientlyexpressing SH223 domain-deleted PLC gamma1 or lipase inactive mutant PLC gamma1, as compared with cells transfected with wild-type PLC gamma1. Furthermore, the inhibition of the activities of either PLC or Src results in a significant diminution of the serotonin-induced release of gonadotropin-releasing hormone (GnRH). In addition, the results of our small-interfering RNA experiment confirm that endogenous PLC gamma1 is a prerequisite for serotonin-mediated signaling pathways. Taken together, our findings demonstrate that serotonin stimulates the release of GnRH through the Src-PLC gamma1 pathway, via the modulation of intracellular calcium levels.