Etgen A M, Browning E T
J Neurosci. 1983 Dec;3(12):2487-93. doi: 10.1523/JNEUROSCI.03-12-02487.1983.
The present experiments tested the ability of putative neurotransmitters and neuromodulators to regulate cyclic adenosine 3':5'-monophosphate (cAMP) levels in rat hippocampal slices. Slices from ovariectomized adult female rats were equilibrated for 1 hr and incubated for 20 min with various test compounds, and cAMP was extracted and quantified using a competitive protein-binding assay. Norepinephrine, adenosine, histamine, and prostaglandins E1 and E2 alpha, induced moderate (1.5- to 5-fold) increases in cellular cAMP, whereas dopamine, serotonin, prostaglandin F2 alpha, and glutamate were relatively ineffective. Most striking was the observation that vasoactive intestinal peptide (VIP) produced marked elevation (approximately 80-fold at 6 microM) of hippocampal slice cAMP content. In contrast, other peptides produced only 2-fold increased (glucagon, somatostatin) or no change in cellular cAMP levels (enkephalins, LHRH, ACTH analogue, arginine vasopressin). Significant elevations in cAMP were seen with VIP concentrations as low as 20 nM; the cAMP response was half-maximal at 1 microM VIP and maximized between 10 and 20 microM. At maximally effective concentrations, VIP was 86% as effective in increasing cAMP as maximal concentrations of forskolin, a compound which activates adenylate cyclase in most cell types. The cAMP response to 10 microM VIP was pronounced after a 1-min incubation (16-fold elevations) and was maximal at 30 min (140-fold elevation). When slices from other brain areas were compared, it was found that regions known to contain high levels of VIP (cerebral cortex) also responded to VIP treatment with 30- to 50-fold elevations in cAMP.(ABSTRACT TRUNCATED AT 400 WORDS)
本实验测试了假定的神经递质和神经调质调节大鼠海马切片中环磷酸腺苷（cAMP）水平的能力。将去卵巢成年雌性大鼠的切片平衡1小时，然后与各种测试化合物一起孵育20分钟，使用竞争性蛋白结合测定法提取并定量cAMP。去甲肾上腺素、腺苷、组胺以及前列腺素E1和E2α可使细胞内cAMP适度增加（1.5至5倍），而多巴胺、5-羟色胺、前列腺素F2α和谷氨酸则相对无效。最引人注目的是观察到血管活性肠肽（VIP）可使海马切片中的cAMP含量显著升高（在6微摩尔时约为80倍）。相比之下，其他肽仅使细胞内cAMP水平增加2倍（胰高血糖素、生长抑素）或无变化（脑啡肽、促黄体生成素释放激素、促肾上腺皮质激素类似物、精氨酸加压素）。当VIP浓度低至20纳摩尔时，cAMP就会出现显著升高；在1微摩尔VIP时，cAMP反应达到最大值的一半，在10至20微摩尔时达到最大值。在最大有效浓度下，VIP增加cAMP的效果是最大浓度的毛喉素的86%，毛喉素是一种在大多数细胞类型中激活腺苷酸环化酶的化合物。在孵育1分钟后，对10微摩尔VIP的cAMP反应就很明显（升高16倍），在30分钟时达到最大值（升高140倍）。当比较来自其他脑区的切片时，发现已知含有高水平VIP的区域（大脑皮层）对VIP处理的反应也是cAMP升高30至50倍。（摘要截选至400字）
