Biosynthesis and metabolism of native and oxidized neuropeptide Y in the hippocampal mossy fiber system.
Biosynthesis and metabolism of native and oxidized neuropeptide Y in the hippocampal mossy fiber system.
复制标题
海马苔藓纤维系统中天然和氧化神经肽 Y 的生物合成和代谢。
DOI：
10.1046/j.1471-4159.1998.70051950.x
复制
发表时间：
1998
影响因子：
4.7
通讯作者：
White,JD
中科院分区：
文献类型：
--
作者：
McCarthy,JB;Walker,M;Pierce,J;Camp,P;White,JD
神经肽Y（NPY）基因的表达是已知的调制苔藓纤维投射海马颗粒细胞癫痫发作后。我们研究了NPY的生物合成和代谢，试图以生物化学的方式表征NPY作为颗粒细胞苔藓纤维投射中的神经递质。在正常对照动物和经历过单次戊四唑诱导癫痫发作的动物中比较了NPY生物合成。原位杂交分析建立了癫痫发作后海马结构中前神经肽原mRNA表达的时间过程，定位于齿状回门部的大部分前神经肽原mRNA含量增加。CA 3/苔藓纤维末端子区域的放射免疫分析证实了随后的NPY肽含量增加。通过在体内放射性标记输注到齿状回/门，随后通过连续HPLC纯化从CA 3/苔藓纤维末端子区域鉴定的放射性标记肽，证明了颗粒细胞的NPY肽生物合成和运输到CA 3/苔藓纤维子区域。其他体内放射性标记研究显示，癫痫发作后未识别的NPY样免疫反应性（NPY-LI）物质增加。比较正常对照动物和戊四唑处理动物的CA 3分区组织提取物的HPLC/放射免疫分析证实了总NPY-LI增加，并证明增加的NPY-LI包括天然NPY的轻微增加和未知NPY-LI的主要增加。来自后续和单独分析的数据，包括免疫沉淀与NPY的抗C末端侧翼肽，进一步HPLC纯化和基质辅助激光解吸/电离质谱，支持未知的NPY-LI是蛋氨酸亚砜NPY的结论。NPY和NPY-亚砜对苔藓纤维突触体释放的钙敏感性不同。与NPY类似，NPY亚砜显示出与克隆的Y1、Y2、Y 4和Y 5受体亚型的高亲和力结合。在苔藓纤维突触体制备中证明了NPY的释放后失活。因此，本研究结合先前报道的电生理活性的NPY在CA 3子字段表明，NPY满足经典标准的神经递质在海马颗粒细胞苔藓纤维投射，并揭示了存在两种分子形式的NPY，显示不同的释放机制，同时保持类似的受体效力。
Neuropeptide Y (NPY) gene expression is known to be modulated in the mossy fiber projection of hippocampal granule cells following seizure. We investigated NPY biosynthesis and metabolism in an attempt to characterize NPY biochemically as a neurotransmitter in the granule cell mossy fiber projection. NPY biosynthesis was compared in normal control animals and in animals that had experienced a single pentylenetetrazole‐induced seizure. In situ hybridization analysis established the postseizure time course of preproNPY mRNA expression in the hippocampal formation, localizing the majority of increased preproNPY mRNA content to the hilus of the dentate gyrus. Radioimmunoassay analysis of the CA3/mossy fiber terminal subfield confirmed a subsequent increase in NPY peptide content. Biosynthesis of NPY peptide by granule cells and transport to the CA3/mossy fiber subfield was demonstrated by in vivo radiolabel infusion to the dentate gyrus/hilus followed by sequential HPLC purification of identified radiolabeled peptide from the CA3/mossy fiber terminal subfield. Additional in vivo radiolabeling studies revealed a postseizure increase in an unidentified NPY‐like immunoreactive (NPY‐LI) species. HPLC/radioimmunoassay analyses of CA3 subfield tissue extracts comparing normal control animals and pentylenetetrazole‐treated animals confirmed the increased total NPY‐LI, and demonstrated that the increased NPY‐LI was comprised of a minor increase in native NPY and a major increase in the unknown NPY‐LI. Data from subsequent and separate analyses incorporating immunoprecipitation with anti‐C‐terminal flanking peptide of NPY, further HPLC purification, and matrix‐assisted laser desorption/ionization mass spectrometry support the conclusion that the unknown NPY‐LI is methionine sulfoxide NPY. NPY and NPY‐sulfoxide displayed differential calcium sensitivity for release from mossy fiber synaptosomes. Similar to NPY, NPY sulfoxide displayed high‐affinity binding to each of the cloned Y1, Y2, Y4, and Y5 receptor subtypes. Postrelease inactivation of NPY was demonstrated in a mossy fiber synaptosomal preparation. Thus, the present study in combination with previously reported electrophysiological activity of NPY in the CA3 subfield demonstrates that NPY fulfills the classical criteria for a neurotransmitter in the hippocampal granule cell mossy fiber projection, and reveals the presence of two molecular forms of NPY that display differential mechanisms of release while maintaining similar receptor potencies.