Alexandre D, Vaudry H, Jégou S, Anouar Y
European Institute for Peptide Research (IFRMP 23), Laboratory of Cellular and Molecular Neuroendocrinology, INSERM U413, UA CNRS, University of Rouen, 76821 Mont-Saint-Aignan, France.
J Comp Neurol. 2000 May 29;421(2):234-46. doi: 10.1002/(sici)1096-9861(20000529)421:2<234::aid-cne8>3.0.co;2-s.
The structure of the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) has been characterized in several species including protochordates, fish, amphibians, birds, and mammals. Although PACAP has been shown to stimulate frog pituitary and adrenal cell activity, the structure of the PACAP precursor and the expression of its gene have not yet been reported in any amphibian species. In this study, we have characterized two cDNA variants encoding PACAP of the frog Rana ridibunda, one of which encodes a second peptide exhibiting strong homologies to growth hormone-releasing hormone (GHRH) of fish and mammals. Northern blot and reverse transcriptase-polymerase chain reaction (RT-PCR) analyses revealed that PACAP/GHRH-like peptide mRNAs are predominantly expressed in the brain and spinal cord and, to a lesser extent, in the neurointermediate lobe of the pituitary. Other tissues including the testis and the distal lobe of the pituitary do not express the PACAP precursor gene. The distribution of PACAP/GHRH-like peptide mRNAs in the frog brain has been determined by in situ hybridization histochemistry. High levels of expression were found in the accessory olfactory bulb, the distal pallium, the ventral part of the magnocellular preoptic nucleus, the ventral hypothalamic nucleus, the posterior tuberculum, and the ventral habenular nucleus. These data contribute to the understanding of the evolution of the PACAP and GHRH genes in vertebrates and provide the anatomical bases to elucidate the roles of PACAP and the GHRH-like peptide in amphibians.
神经肽垂体腺苷酸环化酶激活多肽（PACAP）的结构已在包括原索动物、鱼类、两栖动物、鸟类和哺乳动物在内的多个物种中得到表征。尽管PACAP已被证明能刺激青蛙垂体和肾上腺细胞的活性，但尚未有任何两栖动物物种报道过PACAP前体的结构及其基因的表达情况。在本研究中，我们表征了青蛙泽蛙编码PACAP的两个cDNA变体，其中一个编码的第二种肽与鱼类和哺乳动物的生长激素释放激素（GHRH）具有很强的同源性。Northern印迹和逆转录聚合酶链反应（RT-PCR）分析表明，PACAP/GHRH样肽mRNA主要在脑和脊髓中表达，在垂体神经中间叶中的表达程度较低。包括睾丸和垂体远侧叶在内的其他组织不表达PACAP前体基因。通过原位杂交组织化学确定了PACAP/GHRH样肽mRNA在青蛙脑中的分布。在副嗅球、远侧大脑皮层、大细胞视前核腹侧部分、下丘脑腹侧核、后结节和腹侧缰核中发现了高水平的表达。这些数据有助于理解脊椎动物中PACAP和GHRH基因的进化，并为阐明PACAP和GHRH样肽在两栖动物中的作用提供了解剖学基础。
