Evidence for the involvement of docosahexaenoic acid in cholinergic stimulated signal transduction at the synapse
Evidence for the involvement of docosahexaenoic acid in cholinergic stimulated signal transduction at the synapse
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DOI：
10.1023/a:1027341707837
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发表时间：
1997-06-01
影响因子：
4.4
通讯作者：
Rapoport, SI
中科院分区：
文献类型：
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作者：
Jones, CR;Arai, T;Rapoport, SI
[4，5-H-3]二十二碳六烯酸([H-3]DHA)或[9，10-H-3]棕榈酸([H-3]PAM)静脉滴注5min使成年雄性大鼠清醒，给药前后给予胆碱能激动剂槟榔碱15 mg/kg。输液15min后处死动物，快速取出脑组织，蔗糖密度离心法分离亚细胞。在对照动物中，[H-3]DHA和[H-3]PAM被掺入突触体组分，占膜标记总量的50%-60%。大部分残留的膜标记(30%-40%)在微体部分。这两个组分都含有突触标记突触体素。其余10%的放射性存在于髓鞘和线粒体部分。槟榔碱显著增加[H-3]DHA进入突触体组分的100%和进入微体组分的50%。在这些组分中，60%-65%的[H-3]DHA以磷脂形式存在，其余的对应于游离脂肪酸和二酰甘油。相反，槟榔碱不改变[~3H]PAM掺入脑内的任何部分。这些结果表明，胆碱能激活后，血浆[~3H]DHA掺入选择性地增加到大鼠脑突触膜磷脂中。胆碱能刺激增加DHA而不是PAM进入突触膜，提示DHA在磷脂介导的突触信号转导中起主要作用，涉及磷脂酶A(2)和/或C的激活。
[4,5-H-3]Docosahexaenoic acid ([H-3]DHA) or [9,10-H-3]palmitic acid ([H-3]PAM) was infused intravenously for 5 min to awake, adult male rats before and after treatment with arecoline (15 mg/kg, i.p.), a cholinergic agonist. Animals were killed 15 min post-infusion, the brains were rapidly removed and subcellular fractions were obtained after sucrose density centrifugation. In control animals, [H-3]DHA and [H-3]PAM were incorporated into the synaptosomal fractions, representing 50%-60% of total membrane label. Most remaining membrane label (30%-40%) was in the microsomal fraction. Both fractions contained the synaptic marker synaptophysin. The remaining 10% of radioactivity was in the myelin and mitochondrial fractions. Arecoline significantly increased [H-3]DHA entry into the synaptosomal fractions by 100% and into the microsomal fraction by 50%. In these fractions 60%-65% of the [H-3]DHA was in phospholipid, the rest corresponding to free fatty acid and diacylglycerol. In contrast, arecoline did not change [3H]PAM incorporation into any brain fraction. These results demonstrate that plasma [3H]DHA incorporation is selectively increased into synaptic membrane phospholipids of the rat brain in response to cholinergic activation. The increased incorporation of DHA but not of PAM into synaptic membranes in response to cholinergic stimulation indicates a primary role for DHA in phospholipid mediated signal transduction at the synapse involving activation of phospholipase A(2) and/or C.