Pituitary adenylate cyclase activating peptide (PACAP) immunoreactivity and mRNA expression in the duck gastrointestinal tract

Abstract

The presence and distribution of pituitary adenylate cyclase activating peptide (PACAP) immunoreactivity were studied in the duck gastrointestinal tract using immunohistochemistry and radioimmunoassays. Expression and distribution of PACAP mRNA were also studied using reverse transcriptase polymerase chain reaction (RT-PCR) and hybridization techniques. In addition, a partial coding sequence (cds) of the duck growth hormone-releasing hormone (GRF)/PACAP gene was identified. The presence of both PACAP-38 and PACAP-27 was demonstrated, the former being the predominant form. PACAP immunoreactivity was found in neurons and fibers of the enteric nervous system (ENS), in endocrine cells and in the gut associated lymphoid tissue (GALT). Double immunostaining showed that PACAP is almost completely colocalized with vasoactive intestinal peptide (VIP) in the ENS. Moreover, PACAP was also found in nitric oxide synthase (NOS)-containing neurons and nerve fibers. Radioimmunoassay (RIA) performed on denervated gut showed that more than one-half of the duodenal PACAP is extrinsic in origin. RT-PCR, Northern blot analysis and in situ hybridization confirmed the immunohistochemical data. The findings of the present study suggest that, in birds, PACAP may have multiple roles in regulating gastrointestinal functions.

Duck Pancreatic Acinar Cell as a Unique Model for Independent Cholinergic Stimulation–Secretion Coupling

“…The amino acid sequence of PACAP has been known to be highly conserved during evolution (Mirabella et al 2001(Mirabella et al , 2002Arimura 2007), with the PACAP sequence being identical in mammals, but shows one amino acid difference in birds (chick, turkey; Vaudry et al 2000;Nowak and Zawilska 2003). The Ser 2 to Ile 2 substitution in birds does not seem to affect the PACAP efficacy; similar concentration ranges are used in ducks and geese (Nowak et al 2000), and mammalian PACAP-27 and -38 have been used for works done in birds (Zawilska et al 2004).…”

Distribution and Molecular Evolution of the Neuropeptide Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) and its Receptors in the Lizard Podarcis sicula (Squamata, Lacertidae)

“…It is well accepted that PACAP can be detected not only in the central and peripheral nervous systems but also in a variety of non-neuronal tissues of vertebrates, probably because of its paracrine/autocrine role in essential biological functions (Vincze et al 1999;Kantor et al 2002;Mirabella et al 2002;Valiante et al 2006). In the gastrointestinal tract, PACAP has been shown to stimulate histamine and pancreastatin secretion from enterochromaffin-like cells with a greater potency than gastrin (Lindstrom et al 1997) and this stimulation is carried out through the PAC 1 activation (Zeng et al 1999); further, PACAP immunoreactive endocrine cells are present in the chicken gut (Sundler et al 1991).…”

“…The presence of PACAP occurs in the myenteric ganglia throughout the gastrointestinal tract and in the nerve fibers innervating smooth muscle and blood vessels of the lung (Vaudry et al 2000). In birds, PACAP has been extensively found in neurons, fibers of the enteric nervous system, in endocrine cells, in immune cells (Mirabella et al 2002;Squillacioti et al 2006), and in a number of other tissues (McRory et al 1997;Yoo et al 2000). In lower vertebrates, PACAP has been found in several tissues of fishes (McRory et al 1995;Matsuda et al 1998;Small and Nonneman, 2001;Valiante et al 2006) and amphibians (Gobbetti et al 1997;Yon et al 2001).…”

Presence and Effects of Pituitary Adenylate Cyclase Activating Polypeptide Under Physiological and Pathological Conditions in the Stomach

“…After the pharyngeal appearance at E4, PACAP elements formed a weak network in the marginal mesenchymal zone of the stomach bud, followed by gradual appearance in myenteric and submucous plexuses ( 31 ). PACAP immunoreactivity has also been studied in another avian species by Mirabella et al ( 32 – 34 ). The presence of both PACAP1–38 and PACAP1–27 was demonstrated, the former being the predominant form, in the gastrointestinal tract of the duck ( 32 ).…”

“…PACAP immunoreactivity has also been studied in another avian species by Mirabella et al ( 32 – 34 ). The presence of both PACAP1–38 and PACAP1–27 was demonstrated, the former being the predominant form, in the gastrointestinal tract of the duck ( 32 ). They found PACAP immunoreactivity in neurons and fibers of the ENS, in endocrine cells and in the gut-associated lymphoid tissue, suggesting multiple roles of the peptide in the duck gastrointestinal system.…”