Studies on screening methods for evaluation of novel nootropics and development of the drugs

我们已经研究了第二信使系统在大脑记忆功能中的作用。我们发现新的腺苷类似物强烈和选择性地作用于腺苷受体和黄酮类化合物纯化的东方harbs作用于α_2受体。本研究对黄酮类化合物的药理作用进行了研究，特别是对NG 108 -15细胞腺苷酸环化酶抑制作用最强的优帕福林。Eupafolin抑制NG 108 -15细胞和原代培养的大鼠海马神经元腺苷酸环化酶活性，但不影响NG 108 -15细胞磷酸肌醇的形成和cGMP含量，也不影响培养神经元花生四烯酸的释放。向小鼠施用优帕福林（i.（第30页）诱导镇静和抑制自发性震颤活动。这些作用被育亨宾阻断。优帕福林还延长硫喷妥钠引起的翻正反射丧失。此外，优帕福林选择性地抑制大鼠脑突触膜上[ ^3H]可乐定的高亲和力结合位点。这些结果表明，优帕福林选择性地刺激α_2受体。α_2受体激动剂可乐定具有改善记忆功能的作用，优帕福林有望成为一种促智药物，我们还发现加速衰老小鼠（SAM）的谷氨酸含量和释放、NMDA受体/离子通道和蛋白激酶C的异常变化。提示SAM似乎是1）加速老化以及记忆障碍的优良动物模型和2）可用于筛选作用于脑老化和记忆的药物。

We have been investigated the involvement of the second messenger systems in memory function in the brain. We found novel adenosine analogs strongly and selectively acting on adenosine receptors and flavonoids purified from oriental harbs acting on alpha_2-receptors. In this year, we studied on pharmacological actions of flavonoids, specially of eupafolin which most strongly inhibited the adenylate cyclase in NG108-15 cells. Eupafolin inhibited adenylate cyclase activity in both NG108-15 cells and primary cultured neurons form rat hipocampus, although it did not influence inositol phosphates formation and the cGMP content in NG108-15 and arachidonic acid release in cultured neurons. Administration of eupafolin into mice (i. p.) induced sedation and inhibition of spontaneous locomoter activities. These effects were blocked by yohimbine. Eupafolin also prolonged thiopental-induced loss of righting reflex. Furthermore, eupafolin selectively inhibited the high affinity binding site of [ ^3H]clonidine in rat brain synaptic membranes. These results suggest that eupafolin selectively stimulated alpha_2-receptors. Scince clonidine, and alpha_2-receptor agonist, has been shown to ameliorate memory function, eupafolin could be expected as a nootropic drug.We also found abnormal age-related changes in 1) the content and release of glutamic acid, 2) NMDA-receptor/ion channels and 3) protein kinase C in senescence accelerated mice (SAM), suggesting that SAM seems to be 1) an excellent animal model of accelerating aging as well as of memory disfunction and 2) useful for screening of drugs acting on brain aging and memory.