Monoaminergic neuronal development is not affected in PACAP-gene-deficient mice Tetsuo Ogawa a , Tomoya Nakamachi a , Hirokazu Ohtaki a , Hitoshi Hashimoto b , Shintani N b , Akemichi Baba b , Jun Watanabe a,c , Sakae Kikuyama c , Seiji Shioda a, * a Department of Anatomy, Showa University School of Medicine, Tokyo 142-8555, Japan b Laboratory of Molecular Neuropharmacology, Graduate School of Pharmaceutical Sciences, Osaka University, Osaka 565-0871, Japan c Department of Biology, School of Education, Waseda University, Tokyo 169-8050, Japan Available online 2 October 2004 Abstract Pituitary adenylate cyclase-activating polypeptide (PACAP) has been implicated in several physiological functions. Several lines of evidence from in vitro studies have shown that PACAP plays some important roles in development of nervous system such as neural proliferation and differentiation. Recently, mice lacking PACAP have been reported to show a higher mortality shortly after birth, impaired thermal adaptation, and altered psychomotor behaviors. Inasmuch as monoaminergic nervous systems are implicated in these phenotypes and a quite few data have been reported on the role of this peptide in nervous development in vitro, we studied early development [embryonic days 10.5 (E10.5) and 12.5 (E12.5)] of monoaminergic nervous systems in mice lacking PACAP. The fetuses lacking PACAP showed immunoreactivities (IRs) for tyrosine hydroxylase (TH) and serotonin (5-HT) similarly to the wild type. We observed TH-IR in the forebrain [striatal differentiating zone (dz) and hypothalamic dz], midbrain, hindbrain, neural-crest-derived sympathetic ganglionic primordia, ventral spinal cord dz, and bowel at E10.5 in both PACAP null and wild type with no difference. At E12.5, in the wild-type- and PACAP-gene- deficient mice, no differences of 5-HT- and TH-IRs were observed in several brain regions, including brainstem (midbrain and pons). Thus, the depletion of PACAP does not affect monoaminergic nervous systems in the early development. D 2004 Elsevier B.V. All rights reserved. Keywords: PACAP; Catecholaminergic neuron; Serotonergic neuron; Neurodevelopment; Immunohistochemistry 1. Introduction Pituitary adenylate cyclase-activating polypeptide (PACAP) is a 38-amino acid peptide that is first isolated from ovine hypothalamic extracts on the basis of its activity to stimulate cAMP formation in the anterior pituitary cells [1]. PACAP is widely distributed in the brain and peripheral organs and is revealed to show plenty of biological and pharmacological effects in these tissues (review Refs. [2– 4]). Inasmuch as PACAP and its selective receptor, PAC1-R, are expressed at very high levels in the developing nervous system, PACAP has been focused in association with a role in events such as neuronal proliferation, differentiation, and survival in the field of developmental neuroscience [5–16]. It is reported that a functional PACAP ligand/receptor cAMP signaling system is present in the early embryonic mouse neural tube [10]. Expression of PACAP is observed in the newly differentiating cells appearing just outside the ventricular zone, and its receptor is present within the ventricular zone, most prominently in the dorsal region and floor plate [10,17]. PACAP is shown to down-regulate expression of the sonic-hedgehog (Shh)- and cAMP- dependent protein-kinase-A-dependent target gene gli-1 and induces a decrease in DNA synthesis in cultured neuroepithelial cells, suggesting a potential role in pattern- ing and neurogenesis during the early development of neural tube [10]. The gli-1 gene encodes a transcription factor which is believed to be critically involved in promoting the 0167-0115/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.regpep.2004.08.034 * Corresponding author. Tel.: +81 3 3784 8103; fax: +81 3 3784 6815. E-mail address: shioda@med.showa-u.ac.jp (S. Shioda). Regulatory Peptides 126 (2005) 103 – 108 www.elsevier.com/locate/regpep