Ontogeny of galanin-immunoreactive elements in the intrinsic nervous system of the chicken gut

Abstract

Galanin is a brain-gut peptide that is present in the central and peripheral nervous systems. In the gut, it is contained exclusively in intrinsic and extrinsic nerve supplies, and it is involved overall in the regulation of gut motility. To obtain information about the ontogeny of galanin, we undertook an immunohistochemical study of chicken embryos.The time of first appearance and the distribution patterns of galanin were investigated with fluorescence and streptavidin-biotin-peroxidase (ABC) immunohistochemical protocols by using a galanin polyclonal antiserum. The various regions of the gut and the pancreas were obtained from chicken embryos aged from 3 days of incubation to hatching. All specimens were fixed in buffered picric acid-paraformaldehyde, frozen, and cut with a cryostat.Galanin-immunoreactive neuroblasts were first detected at 4 days in the mesenchyme of the proventriculus/gizzard primordium and within the Remak ganglion. They then extended cranially and caudally, reaching all of the other gut regions at 6.5 days. Galanin-immunoreactive nerve elements mainly occupied the sites of myenteric and submucous plexuses. From day 15, galanin-immunoreactive nerve fibers tended to invade the circular muscular layer and part of the lamina propria of the mucosa. In the pancreas, weak galanin-immunoreactive nerve elements were detected at 5.5 days. They tended to be distributed among the glandular lobules according to the organ differentiation.The widespread distribution during the earlier embryonic stages represents evidence indicating that the neuropeptide galanin may have a role as a differentiating or growth factor. From late embryonic life, its predominant presence in sympathetic nerves and in muscular layers fits with the functions demonstrated previously in adults of other vertebrates for galanin as a modulator of intestinal motility. Anat Rec 254: 28-38, 1999. 1999 Wiley-Liss, Inc.

Nervous system development in normal and atresic chick embryo intestine: an immunohistochemical study

“…The presence of VIP-IR neuroblasts on E12 accords with our previous finding on the presence of peptide immunoreactivity at an early embryonic age (Salvi et al 1999;Parisi Salvi et al 2000, 2003. This could be related to the functional activity of VIP; VIP stimulates neuronal growth, differentiation, and survival (Gozes and Brenneman 1993) and inhibits enteric smooth muscle cell proliferation (Van Assche et al 1999).…”

Changes in expression of neuropeptides and their receptors in the hypothalamus and gastrointestinal tract of calorie restricted hens

“…Galanin immunoreactive signal appears at day 4 during embryonic life in chicken gut and acts as a growth or differentiating factor and later the appearance in muscular layers indicates its regulatory role in intestinal motility [38]. Intracerebro-ventricular Acta Biologica Hungarica 68, 2017 injection of galanin stimulated feeding behavior, but it did not affect water intake of layer and broiler chicks.…”

Biology of the Gastrointestinal Tract in Poultry

“…The function of GMAP is not known. Galanin is found in sympathetic neurons in the muscular layer of the intestine (Salvi et al, 1999). There are at least four galanin receptors in birds 2012): galanin type I receptor (GalR1); a novel GalR1-like receptor; galanin type 2 receptor (GalR1); and a novel GalR2-like receptor.…”