Nielsen H S, Hannibal J, Fahrenkrug J
Department of Clinical Biochemistry, Bispebjerg Hospital, University of Copenhagen, Denmark.
J Comp Neurol. 1998 May 18;394(4):403-15. doi: 10.1002/(sici)1096-9861(19980518)394:4<403::aid-cne1>3.0.co;2-5.
Pituitary adenylate cyclase-activating polypeptide (PACAP), a neuropeptide that is related structurally to vasoactive intestinal polypeptide (VIP), has been shown to stimulate neuronal growth and differentiation, indicating a possible function in the development of the nervous system. Studies have indicated that the PACAP receptor is expressed during development, but data on PACAP expression are limited mainly to postnatal development. In the present study, we used immunohistochemistry and in situ hybridization histochemistry to examine the expression of PACAP in autonomic and sensory ganglia and spinal cord of rat fetuses at embryonic days 12-21 (E12-E21). PACAP immunoreactivity was visualized by using a specific monoclonal anti-PACAP antibody to detect both PACAP-38 and PACAP-27, and PACAP mRNA was visualized by using a [33P]-labeled cRNA-probe. PACAP- nerve fibers were observed in the spinal cord as early as E13. At E14, PACAP-immunoreactive nerve fibers projected to the sympathetic trunk, where few PACAP- nerve cell bodies were seen from E15. On the same embryonic day, PACAP-immunoreactive nerve cell bodies appeared in the intermediolateral column of the spinal cord. From E15 to E16, PACAP-immunoreactive nerve cell bodies were visible within sensory and autonomic ganglia, such as the dorsal root, the trigeminal, the sphenopalatine, the otic, the submandibular, and the nodose ganglia. At E16, PACAP+ nerve fibers were innervating the adrenal medulla, and immunoreactive fibers could also be observed in the superior cervical ganglion, in which PACAP-immunoreactive cell bodies were detected occasionally from E18. The synthesis of PACAP in neuronal cell bodies was confirmed by the demonstration of PACAP mRNA with in situ hybridization histochemistry. Thus, in all of the structures examined, PACAP appeared at roughly the same embryonic stage and, thereafter, increased to the adult level before birth. Because PACAP occurred with the same distribution pattern as that described in the adult rat, there is no evidence for transient expression. The early expression of PACAP suggests a possible role for the peptide in the developing nervous system.
垂体腺苷酸环化酶激活多肽（PACAP）是一种神经肽，其结构与血管活性肠肽（VIP）相关，已被证明能刺激神经元生长和分化，表明其在神经系统发育中可能具有某种功能。研究表明，PACAP受体在发育过程中表达，但关于PACAP表达的数据主要限于出生后发育阶段。在本研究中，我们使用免疫组织化学和原位杂交组织化学方法，检测了胚胎第12至21天（E12 - E21）大鼠胎儿的自主神经节、感觉神经节和脊髓中PACAP的表达情况。通过使用特异性单克隆抗PACAP抗体来检测PACAP - 38和PACAP - 27，从而观察到PACAP免疫反应性，通过使用[33P]标记的cRNA探针来观察PACAP mRNA。早在E13时就在脊髓中观察到了PACAP阳性神经纤维。在E14时，PACAP免疫反应性神经纤维投射到交感干，从E15开始在交感干中很少见到PACAP阳性神经细胞体。在同一胚胎日，PACAP免疫反应性神经细胞体出现在脊髓的中间外侧柱。从E15到E16，在感觉神经节和自主神经节内可见PACAP免疫反应性神经细胞体，如背根神经节、三叉神经节、蝶腭神经节、耳神经节、下颌下神经节和结状神经节。在E16时，PACAP阳性神经纤维支配肾上腺髓质，并且在上颈神经节中也可观察到免疫反应性纤维，从E18开始偶尔能检测到PACAP免疫反应性细胞体。通过原位杂交组织化学证明PACAP mRNA，证实了神经元细胞体中PACAP的合成。因此，在所有检测的结构中，PACAP大约在相同的胚胎阶段出现，此后在出生前增加到成年水平。由于PACAP的分布模式与成年大鼠中描述的相同，没有证据表明其有短暂表达。PACAP的早期表达表明该肽在发育中的神经系统中可能发挥作用。
