Oxytocin is an essential hormone for mammalian labor and lactation. Here, we show a new function of oxytocin in causing plastic changes in hippocampal synapses during motherhood. In oxytocin-perfused hippocampal slices, one-train tetanus stimulation induced long-lasting, long-term potentiation (L-LTP) and phosphorylation of cyclic AMP-responsive element binding protein (CREB), and MAP kinase inhibitors blocked these inductions. An increase in CREB phosphorylation and L-LTP induced by one-train tetanus were observed in the multiparous mouse hippocampus without oxytocin application. Furthermore, intracerebroventricular injection of oxytocin in virgin mice improved long-term spatial learning in vivo, whereas an injection of oxytocin antagonist in multiparous mice significantly inhibited the improved spatial memory, L-LTP and CREB phosphorylation. These findings indicate that oxytocin is critically involved in improving hippocampus-dependent learning and memory during motherhood in mice.

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Background and Purpose-Our previous studies have demonstrated that oxidative DNA injury occurs in the brain after intracerebral hemorrhage (ICH). We therefore examined whether edaravone, a free-radical scavenger, could reduce ICH-induced brain injury. Methods-These experiments used pentobarbital-anesthetized, male Sprague-Dawley rats that received an infusion of either 100 L autologous whole blood (ICH), FeCl 2 , or thrombin into the right basal ganglia. The rats were humanely killed 24 hours later. There were 4 sets of experiments. In the first, the dose-dependent effects of edaravone on ICH-induced brain injury were examined by measuring brain edema and neurologic deficits. In the second set, apurinic/apyrimidinic abasic sites and 8-hydroxyl-2Ј-deoxyguanosine, which are hallmarks of DNA oxidation, were investigated after treatment for ICH. In the third, the effect of delayed treatment with edaravone on ICH-induced injury was determined, whereas the fourth examined the effects of edaravone on iron-and thrombin-induced brain injury. Results-Systemic administration of edaravone immediately or 2 hours after ICH reduced brain water content 24 hours after ICH compared with vehicle (PϽ0.05). Edaravone treatment immediately or 2 hours after ICH also ameliorated neurologic deficits (PϽ0.05). Edaravone also attenuated ICH-induced changes in apurinic/apyrimidinic abasic sites and 8-hydroxyl-2Ј-deoxyguanosine and reduced iron-and thrombin-induced brain injury. Conclusions-Edaravone attenuates ICH-induced brain edema, neurologic deficits, and oxidative injury. It also reduces iron-and thrombin-induced brain injury. These results suggest that edaravone is a potential therapeutic agent for ICH.