Effect of β-amyloid on calcium homeostasis and mitochondrial permeability transition pore proteins in primary cultured rat hippocampal neurons

Abstract

Objective To study the effects of β-amyloid (Aβ25-35) on calcium homeostasis and mitochondrial permeability transition pore (MPTP) in primary cultured rat hippocampal neurons, and explore the mechanism of neurotoxicity of Aβ25-35. Methods After 8 days of primary culture, hippocampal neurons were exposure with different doses( 1 μmol/L, 10 μmol/L, and 20 μmol/L, respectively) of Aβ25-35, and 0 μmol/L dose as control group.After cultured 24 h and 48 h, observed hippocampal neuronal morphology, intracellular free calcium concentration, activity of Ca2+ -ATPase, mitochondrial membrane potential, and MPTP protein expression by Western Blotting method. Results With the increase of Aβ25-35 dose and exposure time, morphological changes of hippocampal neurons in primary culture were observed, showing a diffuse swelling, deformation, vacuoles, and cell edge fuzzy; The concentration of free calciumions of Aβ25-3520 μmol/L group were (31.04±4.16) and (32.80±0.43)compared the control group with the (20.95±4.04)and(22.23±0.49)24 h and 48h after the exposure of Aβ25-35, the concentration showed a gradual upward trend (P<0.05). The activity of Ca2+ -ATPase Aβ25-3520 μmol/L group were (2.14±0.01) and (1.10±0.05)U/mgprol, compared the control group with the (5.17±0.08) and (4.57±0.06)(P<0.05)24 h and 48 h after the exposure of Aβ25-35.The membrane potential of mitochondrial decreased significantly in the ap groups compared with the control group.(P<0.05), The membrane potential of mitochondrial Aβ25-35 20 μmol/L group were (20.34±7.05) and (19.05±6.15), compared the control group with the (38.47±0.72) and (40.07±1.26) (P<0.05) 24 h and 48h after the exposure of Aβ25-35.With the increase of exposure dose and time, the activity of Ca2+ -ATPase and mitochondrial, and there was a significant dose-response relationship.The results of WB of MPTP showed that the protein expression was increased with the increase of dose. Conclusion Aβ25-35 exhibits a neurotoxicity effect by disturbing the calcium homeostasis, and affecting mitochondrial function by means of activating of MPTP channels. Key words: Aβ25-35; Calcium homeostasis; Mitochondrion; MPTP