Nobiletin attenuates neurotoxic mitochondrial calcium overload through K⁺ influx and ΔΨ(m) across mitochondrial inner membrane

Mitochondrial calcium overload is a crucial event in determining the fate of neuronal cell survival and death, implicated in pathogenesis of neurodegenerative diseases. One of the driving forces of calcium influx into mitochondria is mitochondria membrane potential (ΔΨ(m)). Therefore, pharmacological manipulation of ΔΨ(m) can be a promising strategy to prevent neuronal cell death against brain insults. Based on these issues, we investigated here whether nobiletin, a Citrus polymethoxylated flavone, prevents neurotoxic neuronal calcium overload and cell death via regulating basal ΔΨ(m) against neuronal insult in primary cortical neurons and pure brain mitochondria isolated from rat cortices. Results demonstrated that nobiletin treatment significantly increased cell viability against glutamate toxicity (100 µM, 20 min) in primary cortical neurons. Real-time imaging-based fluorometry data reveal that nobiletin evokes partial mitochondrial depolarization in these neurons. Nobiletin markedly attenuated mitochondrial calcium overload and reactive oxygen species (ROS) generation in glutamate (100 µM)-stimulated cortical neurons and isolated pure mitochondria exposed to high concentration of Ca²⁺ (5 µM). Nobiletin-induced partial mitochondrial depolarization in intact neurons was confirmed in isolated brain mitochondria using a fluorescence microplate reader. Nobiletin effects on basal ΔΨ(m) were completely abolished in K⁺-free medium on pure isolated mitochondria. Taken together, results demonstrate that K⁺ influx into mitochondria is critically involved in partial mitochondrial depolarization-related neuroprotective effect of nobiletin. Nobiletin-induced mitochondrial K⁺ influx is probably mediated, at least in part, by activation of mitochondrial K⁺ channels. However, further detailed studies should be conducted to determine exact molecular targets of nobiletin in mitochondria.

Effects of Nicotine on mineralization in human fetal osteoblasts / 대한치주과학회지

Nicotine is one of the major components of cigarette smoking which causes various systemic and local diseases to human body. The purpose of the present study was to investigate the effects of nicotine on bone mineralization in human fetal osteoblasts cell line(hFOB1). To compare the alkaline ph-osphatase(ALP) synthesis, hFOB1 were cultured with DMEM/F-12 1:1 Mixture and 100 pg/ml, 1 ng/ml, 10 ng/ml, 100 ng/ml, 1 microgram/ml, 10 microgram/ml, 100 microgram/ml of nicotine. And to compare the calcium accumulation, hFOB1 cultured for 23 days were quantified and photographed. ALP activity of hFOB1 exposed to nicotine was not significantly changed at a lower concentrations of nicotine, but was significantly decreased at a higher concentrations (10 microgram/ml, 100 microgram/ml) of nicotine (p<0.05). A quantified calcium acculation in hFOB1 was significantly decreased at 1, 10, and 100microgram/ml of nicotine (p<0.05). Significantly decreased calcium deposition was observed at 1, 10, and 100microgram/ml of nicotine. These results indicate that a higher concentration of nicotine show a negative effects on mineralization of hFOB1.

Effects of Olibanum Extracts on the Activity and Differentiation of MC3T3-E1 Cells / 대한치주과학회지

Recently, many natural medicines, which have advantage of less side effects and possibility of long-term use have been studied for their capacity of anti-bacterial, anti-inflammatory and regenerative potential of periodontal tissues. Olibanum has the effects to hemostasis, analgesic and anti-inflammatory, and it also has been traditionally used as a drug for the treatment of bone disease in oriental medicine. The purpose of the present study was to investigate the effects of Olibanum extracts on the activity and differentiation of MC3T3-E1 cells, alkaline phosphatase(ALP) synthesis, formation of bone nodules and expression of type I collagen of MC3T3-E1 cells. To examine the cellular activity, MC3T3-E1 cells were cultured with alpha-MEM(control) and each concentration of Olibanum for 2 days and 4 days. To compare the ALP synthesis, MC3T3-E1 cells were cultured with alpha-MEM(negative control), dexamethasone(positive control), and each concentration of Olibanum for 2 days and 4 days. To compare the bone nodule formation, MC3T3-E1 cells were cultured for 21 days, and to compare the type I collagen expression, MC3T3-E1 cells were cultured for 4 days. The cellular activity of MC3T3-E1 cells treated with 1 microgram/ml of Olibanum extracts was significantly increased at 4-day(p<0.05) to control. The activity of ALP in MC3T3-E1 cells treated with 1 microgram/ml Olibanum extracts was significantly increased at 4-day(p<0.05). All the experimental groups showed much more bone nodule formation than control groups. The group treated with 1 microgram/ml of Olibanum extracts was the highest bone nodule formation, and showed much more type I collagen expression than negative control. These results indicate that Olibanum extracts may be considered effective in the activity and differentiation of MC3T3-E1 cells.