Window of opportunity for neuroprotection with an antioxidant, allene oxide synthase, after hypoxia-ischemia in adult male rats

Prevention of cell death by the zinc ion chelating agent TPEN in cultured PC12 cells exposed to Oxygen-Glucose Deprivation (OGD)

To elucidate the role of Zn(2+)-associated glutamate signaling pathway and voltage-dependent outward potassium ion currents in neuronal death induced by hypoxia-ischemia, PC12 cells were exposed to Oxygen-Glucose Deprivation (OGD) solution mimicking the hypoxic-ischemic condition in neuron, and the effect of N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN), a specific Zn(2+) chelating agent on OGD-induced neuronal death was assessed in the present study. The cell survival rate, apoptosis status, potassium channel currents, intracellular free glutamate concentration and GluR2 expression in PC12 cells exposed to OGD in the absence or presence of TPEN for different time were investigated. The results showed that OGD exposure increased apoptosis, reduced the cell viability (P < 0.01 at 3h, 6h and 24h, respectively compared to control), changed the voltage-dependent outward potassium ion current (increase at 1h, but decrease at 3h) and decreased the concentration of intracellular glutamate (P < 0.05 at 3h and 6h, P < 0.01 at 24h respectively compared to control) and GluR2 expression (P < 0.05 at 3h, 6h and 24h, respectively compared to control) in PC12 cells. TPEN partially reversed the influence resulted from OGD. These results suggest that OGD-induced cell apoptosis and/or death is mediated by the alteration in glutamate signaling pathway and the voltage-dependent outward potassium ion currents, while TPEN effectively prevent cell apoptosis and/or death under hypoxic-ischemic condition.

Overexpression of adiponectin improves neurobehavioral outcomes after focal cerebral ischemia in aged mice

AIMS

To study whether adiponectin (APN) could improve neurological outcomes in aged mice after ischemic stroke.

METHODS

Adeno-associated virus carrying APN gene was injected into aged and young adult mice 7 days before transient middle cerebral artery occlusion (tMCAO). Atrophic volumes and neurobehavioral deficiencies were determined up to 28 days after tMCAO. Focal angiogenesis was determined based on blood vessel number in the ischemic regions.

RESULTS

Increased atrophic volume and more sever neurobehavioral deficits were found in the aged mice compared with young adult mice (P < 0.05). AAV-APN gene transfer attenuated atrophic volume and improved neurobehavioral outcomes, along with increased focal angiogenesis in both aged and young adult mice, compared with control animals (P < 0.05). In addition, the attenuation of atrophic volume and the improvement in neurobehavioral outcomes were much more significant in aged mice than in young adult mice after AAV-APN administration (P < 0.05). The number of microvessels in aged AAV-APN mouse ischemic brain was higher than in young adult AAV-APN treated mouse brain (P < 0.05).

CONCLUSIONS

Our results demonstrate that APN overexpression reduces ischemic brain injury and improves neurobehavioral function recovery in aged mice than in young mice, suggesting APN is more beneficial in aged animals after ischemic stroke.