Middendorff R, Maronde E, Paust H J, Muller D, Davidoff M, Olcese J
Institute of Anatomy, University of Hamburg, Germany.
J Neurochem. 1996 Aug;67(2):517-24. doi: 10.1046/j.1471-4159.1996.67020517.x.
Recent studies have pointed to membrane-bound guanylyl cyclases (GCs) type A and type B in the rat pineal gland, which augment levels of cyclic GMP (cGMP) in response to atrial natriuretic peptide (ANP), brain-type natriuretic peptide (BNP), and C-type natriuretic peptide (CNP). The present report demonstrates for the first time the expression of CNP in the bovine pineal gland. The CNP prohormone transcript (unlike pre-pro-ANP) was found by reverse transcriptase (RT)-PCR in bovine pineal extracts. CNP immunoreactivity (ir) was revealed in a subpopulation of pinealocytes in situ and in nearly all pinealocytes in culture. Electron microscopic immunohistochemical investigations showed the presence of CNP-ir in cytoplasmic vesicles, providing evidence for the potential secretion of this peptide by pineal cells. Furthermore, the CNP receptor (GC-B) and GC-A (receptor for ANP and BNP) were identified by RT-PCR. Although melatonin secretion was unaffected, natriuretic peptides were able to elevate markedly cGMP production in cultured bovine pinealocytes with a rank order of potency of CNP > BNP = ANP. These findings describe a tissue CNP system in the bovine pineal gland and suggest that CNP may be a local auto- or paracrine modulator of pineal function.
近期研究表明，大鼠松果体中存在A 型和B 型膜结合鸟苷酸环化酶（GCs），它们可响应心钠素（ANP）、脑钠素（BNP）和C 型钠尿肽（CNP），提高环磷酸鸟苷（cGMP）水平。本报告首次证明了C 型钠尿肽（CNP）在牛松果体中的表达。通过逆转录酶（RT）-PCR 在牛松果体提取物中发现了CNP 前激素转录本（与前心钠素原不同）。原位松果体细胞亚群以及几乎所有培养的松果体细胞中均显示出CNP 免疫反应性（ir）。电子显微镜免疫组织化学研究表明，细胞质囊泡中存在CNP-ir，这为松果体细胞潜在分泌该肽提供了证据。此外，通过RT-PCR 鉴定出了CNP 受体（GC-B）和GC-A（ANP 和BNP 的受体）。尽管褪黑素分泌未受影响，但钠尿肽能够显著提高培养的牛松果体细胞中cGMP 的生成，其效力顺序为CNP > BNP = ANP。这些发现描述了牛松果体中的一种组织CNP 系统，并表明CNP 可能是松果体功能的局部自分泌或旁分泌调节因子。
