Sasaki Tsutomu, Kitagawa Kazuo, Omura-Matsuoka Emi, Todo Kenichi, Terasaki Yasukazu, Sugiura Shiro, Hatazawa Jun, Yagita Yoshiki, Hori Masatsugu
Department of Cardiovascular Medicine, Division of Stroke Research, Osaka University Graduate School of Medicine, Yamadaoka, Suita City, Osaka, Japan.
Stroke. 2007 May;38(5):1597-605. doi: 10.1161/STROKEAHA.106.476754. Epub 2007 Mar 22.
Brain ischemia stimulates neurogenesis. However, newborn neurons show a progressive decrease in number over time. Under normal conditions, the cAMP-cAMP responsive element binding protein (CREB) pathway regulates the survival of newborn neurons. Constitutive activation of CREB after brain ischemia also stimulates hippocampal neurogenesis. Thus, activation of cAMP-CREB signaling may provide a promising strategy for enhancing the survival of newborn neurons. We examined whether treatment of mice with the phosphodiesterase-4 inhibitor rolipram enhances hippocampal neurogenesis after ischemia.
Both common carotid arteries in mice were occluded for 12 minutes. Bromodeoxyuridine (BrdU) was used to label proliferating cells. Mice were perfused transcardially with 4% paraformaldehyde, and immunohistochemistry was performed. To evaluate the role of CREB in the survival of newborn neurons after ischemia, intrahippocampal injection of a CRE-decoy oligonucleotide was delivered for 1 week. We examined whether the activation of cAMP-CREB signaling by rolipram enhanced the proliferation and survival of newborn neurons.
Phospho-CREB immunostaining was markedly upregulated in immature neurons, decreasing to low levels in mature neurons. The number of BrdU-positive cells 30 days after ischemia was significantly less in the CRE-decoy treatment group than in the vehicle group. Rolipram enhanced the proliferation of newborn cells under physiologic conditions but not under ischemic conditions. Rolipram significantly increased the survival of nascent BrdU-positive neurons, accompanied by an enhancement of phospho-CREB staining and decreased newborn cell death after ischemia.
CREB phosphorylation regulates the survival of newborn neurons after ischemia. Chronic pharmacological activation of cAMP-CREB signaling may be therapeutically useful for the enhancement of neurogenesis after ischemia.
脑缺血可刺激神经发生。然而,新生神经元的数量会随着时间的推移逐渐减少。在正常情况下,环磷酸腺苷-环磷酸腺苷反应元件结合蛋白(CREB)通路调节新生神经元的存活。脑缺血后CREB的组成性激活也可刺激海马神经发生。因此,激活环磷酸腺苷-CREB信号可能为提高新生神经元的存活率提供一种有前景的策略。我们研究了用磷酸二酯酶-4抑制剂咯利普兰治疗小鼠是否能增强缺血后的海马神经发生。
将小鼠双侧颈总动脉闭塞12分钟。用溴脱氧尿苷(BrdU)标记增殖细胞。小鼠经心脏灌注4%多聚甲醛后进行免疫组织化学检测。为评估CREB在缺血后新生神经元存活中的作用,在海马内注射CRE诱饵寡核苷酸,持续1周。我们研究了咯利普兰激活环磷酸腺苷-CREB信号是否能增强新生神经元的增殖和存活。
磷酸化CREB免疫染色在未成熟神经元中明显上调,在成熟神经元中降至低水平。缺血后30天,CRE诱饵治疗组的BrdU阳性细胞数量明显少于载体组。咯利普兰在生理条件下可增强新生细胞的增殖,但在缺血条件下则不能。咯利普兰显著提高了新生BrdU阳性神经元的存活率,同时伴有磷酸化CREB染色增强和缺血后新生细胞死亡减少。
CREB磷酸化调节缺血后新生神经元的存活。环磷酸腺苷-CREB信号的慢性药理激活可能对增强缺血后的神经发生具有治疗作用。