Korean Mistletoe (Viscum album var. coloratum) Inhibits Amyloid beta Protein (25-35)-induced Cultured Neuronal Cell Damage and Memory Impairment

The present study aims to investigate the effect of methanol extract of Korean mistletoe (KM; Viscum album var. coloratum), on amyloid beta protein (Abeta) (25-35), a synthetic 25-35 amyloid peptide, -induced neurotoxicity in cultured rat cerebral cortical neurons and memory impairment in mice. Exposure of cultured neurons to 10 microM Abeta (25-35) for 24 h induced a neuronal cell death, which was measured by a 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT) assay and Hoechst 33342 staining. KM (10, 30 and 50 microg/ml) significantly inhibited the Abeta (25-35)-induced apoptotic neuronal death. KM (50 microg/ml) inhibited 10 microM Abeta (25-35)-induced elevation of intracellular calcium concentration ([Ca2+]i), which was measured by a fluorescent dye, Fluo-4 AM. Glutamate release into medium and generation of reactive oxygen species (ROS) induced by 10 microM Abeta (25-35) were also inhibited by KM (10, 30 and 50 microg/ml). These results suggest that KM may mitigate the Abeta (25-35)-induced neurotoxicity by interfering with the increase of [Ca2+]i and then inhibiting glutamate release and generation of ROS in cultured neurons. In addition, orally administered KM (25 and 50 mg/kg, 7 days) significantly prevented memory impairment induced by intracerebroventricular injection of Abeta (25-35) (8 nmol). Taken together, it is suggested that anti-dementia effect of KM is due to its neuroprotective effect against Abeta (25-35)-induced neurotoxicity and that KM may have therapeutic role in prevention of the progression of Alzheimer's disease.

Roles of PKA and PKC in the process of anoxic apoptosis of cultured rat cortical neurons / 第三军医大学学报

Objective To detect the percentage of cultured neuron apoptosis after the neurons were treated with anoxia and specific inhibitors of protein kinase A (PKA) and protein kinase C (PKC). Methods After establishment of the model of neurons cultured under hypoxic condition, the neurons were cocultured with different concentrations of Rp-cAMP and Calphostin C, specific inhibitors of protein kinase A and C, respectively. Then neurons were cultured under an ischemic condition until the number of survived neurons, the activity of mPKA,and mPKC, and the apoptotic neurons stained by TUNEL in each group were observed. Results The activity of mPKA and mPKC significantly increased after the onset of hypoxia. With the increases in concentrations of Rp-cAMP or Calphostin C, the percentage of apoptotic neurons obviously decreased or increased, respectively. Conclusion The pathways of PKA and PKC signal transduction may participate in the hypoxic neuron injury. The functions of these two kinases are opposite for apoptotic regulation. It suggests that the signal transduction of PKA and PKC in hypoxic neurons belongs to a monophasic controlling system and the ratio of PKA to PKC in cells may determine the survival of hypoxic neurons.