垂体腺苷酸环化酶激活多肽对鲤鱼脑垂体细胞内cAMP和Ca^(2+)的影响  

Effects of Pituitary Adenylate Cyclase Activating Polypeptide (PACAP) on Intracellular cAMP and Ca ^( 2+) Levels in Common Carp (Cyprinus carpio) Pituitary Cellsin vitro

作　　者：肖东[1] 朱美诗[2] 李继仁 黄安林[2] 林浩然[1] 

机构地区：[1]中山大学生命科学学院水生经济动物研究所,广州510275 [2]香港大学动物学系

出　　处：《生物化学与生物物理学报》2002年第6期790-795,共6页

基　　金：香港RGC(Research Grand Council)研究基金资助项目 (No .HKU 72 3 2 /98M );国家自然科学基金资助项目 (No .3 93 70 0 99);广东省自然科学基金资助项目 (No .980 3 0 8)~~

摘　　要：采用环腺苷酸 (cAMP)放射免疫测定法和活细胞内Ca2 + 荧光探针Indo 1,研究绵羊垂体腺苷酸环化酶激活多肽 (oPACAP)对原代培养的鲤鱼脑垂体细胞内cAMP和游离Ca2 + ([Ca2 + ]i)的影响 ,以期探讨PACAP调节脑垂体生长激素 (GH)分泌的机制受体后。oPACAP 38和oPACAP 2 7以剂量依存方式促进脑垂体细胞内cAMP释放和合成。oPACAP 38和oPACAP 2 7也能升高脑垂体细胞内 [Ca2 + ]i 水平 ,该作用会因用EGTA消竭细胞外Ca2 +([Ca2 + ]e)而迅速消失 ;L型电位敏感性Ca2 + 通道 (VSCC)阻断剂硝苯吡啶可抑制oPACAP 38诱导的 [Ca2 + ]i 水平的升高 ,而当用硝苯吡啶预处理脑垂体细胞 ,oPACAP 38诱导 [Ca2 + ]i 水平升高作用完全被抑制。可见 ,PACAP刺激鲤鱼脑垂体GH分泌机制包括依赖于cAMP和依赖于通过L型VSCC内流的 [Ca2 + ]e 的机制。In order to study signal transduction in PACAP-stimulated GH release, effects of ovine PACAPs (oPACAPs) on cAMP synthesis and intracellular free Ca 2+([Ca 2+] i) levels in primarily cultured common carp (Cyprinus carpio) pituitary cells were investigated using radioimmunoassay (RIA) for cAMP and [Ca 2+] i Indo-I/AM loading techniques. The main results obtained could be briefly summarized as follows: parallel with their GH-releasing effects, oPACAP-38 (0.01 nmol/L to 1 μmol/L) and oPACAP-27 (0.01 nmol/L to 1 μmol/L) were also effective in increasing cAMP release, cellular cAMP content, and total cAMP production in a dose- dependent manner in common carp pituitary cells. In addition to their cAMP synthesis, 0.5 μmol/L oPACAP-38 and 0.5 μmol/L oPACAP-27 were also effective in elevating [Ca 2+] i levels in common carp pituitary cells preloaded with the Ca 2+-sensitive dye Indo-1; the stimulatory actions were dependent on the presence of extracellular Ca 2+([Ca 2+] e), as removal of [Ca 2+] e by adding the Ca 2+ chelator 4 mmol/L EGTA blocked the rise of [Ca 2+] i induced by oPACAP-38 and oPACAP-27, respectively. Besides, the rise in [Ca 2+] i induced by 0.5 μmol/L oPACAP-38 was blocked by treatment with 10 μmol/L nifedipine, an inhibitor of 'L-type' voltage- sensitive Ca 2+ channels (VSCC); but 0.5 μmol/L oPACAP-38 was not effective in elevating [Ca 2+] i levels after the cells treated with Ca 2+-sensitive dye Indo-1 were challenged with 10 μmol/L nifedipine. These results, taken as a whole, strongly suggest the involvement of the cAMP- and Ca 2+-dependent pathways in PACAP-stimulated GH release in common carp.

关 键 词：垂体腺苷酸环化酶激活多肽 鲤鱼 脑垂体细胞 CAMP CA^2+ 钙 信号传导 

分 类 号：Q575[生物学—生物化学] Q959.4