DDPH ameliorated oxygen and glucose deprivation-induced injury in rat hippocampal neurons via interrupting Ca2+ overload and glutamate release

Our previous work has demonstrated that DDPH (1-(2, 6-dimethylphenoxy)-2-(3, 4-dimethoxyphenylethylamino) propane hydrochloride), a competitive α1-adrenoceptor antagonist, could improve cognitive deficits, reduce histopathological damage and facilitate synaptic plasticity in vivo possibly via increasing NR2B (NMDA receptor 2B) expression and antioxidation of DDPH itself. The present study further evaluated effects of DDPH on OGD (Oxygen and glucose deprivation)-induced neuronal damage in rat primary hippocampal cells. The addition of DDPH to the cultured cells 12 h before OGD for 4 h significantly reduced neuronal damage as determined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and LDH (lactate dehydrogenase) release experiments. The effects of DDPH on intracellular calcium concentration were explored by Fura-2 based calcium imaging techniques and results showed that DDPH at the dosages of 5 μM and 10 μM suppressed the increase of intracellular calcium ([Ca2+]i) stimulated by 50 mM KCl in Ca2+-containing extracellular solutions. However, DDPH couldn't suppress the increase of [Ca2+]i induced by both 50 μM glutamate in Ca2+-containing extracellular solutions and 20 μM ATP (Adenosine Triphosphate) in Ca2+-free solution. These results indicated that DDPH prevented [Ca2+]i overload in hippocampal neurons by blocking Ca2+ influx (voltage-dependent calcium channel) but not Ca2+ mobilization from the intracellular Ca2+ store in endoplasm reticulum (ER). We also demonstrated that DDPH could decrease glutamate release when hippocampal cells were subjected to OGD. These observations demonstrated that DDPH protected hippocampal neurons against OGD-induced damage by preventing the Ca2+ influx and decreasing glutamate release.