Immunoreactive neuropeptide systems in avian embryos (domestic mallard, domestic fowl, Japanese quail)

Abstract

In embryos of the domestic mallard, domestic fowl, and Japanese quail vasotocin-, mesotocin-, luliberin (LHRH)-, met-enkephalin-, corticotropin-, and somatostatin-immunoreactive perikarya and fiber formations were visualized at different incubation stages by means of the PAP technique (Sternberger 1979). The most striking results were: (1) Vasotocin-, mesotocin-, and luliberin-immunoreactive systems display, up to the late embryonic period, morphological features most probably related to a neurohormonal function. (2) Met-enkephalin immunoreactivity appears very late during embryonic life; it is restricted to fiber networks and not found in perikarya. (3) Corticotropin immunoreactivity is observed in the tuberal region temporarily at the end of the second and the beginning of the last third of the incubation period. (4) Somatostatin-immunoreactive material is present (i) at the end of the first third of incubation, in association with the olfactory system; (ii) during the same period, adjacent to thin-layered portions of the roof of the brain; (iii) shortly thereafter, in cells of both pancreatic primordia and thyroid gland; and (iv) onward from the middle of the incubation period, in a mesencephalic cell group. The striking difference, in the early embryo, between the mature somatostatin plays a role in the development of the brain, as well as the pancreas, and the thyroid gland.

Embryonal Development of Arginine Vasotocin/Mesotocin Gene Expression in the Chicken Brain

“…Immunostaining with antibodies against AVT and M T failed to show clearly identifiable immunostainable perikarya before embryonal day (E) 8 (7). Earlier studies (8) were unable to visualize AVT immunoreactive cell bodies before E 14 though investigations using chromalum-haematoxylin staining d o indicate neurosecretory material as early as E4 (9), E l l (10) and E l 3 (11,12). The differences may be due to various methods of fixation and staining.…”

“…The differences may be due to various methods of fixation and staining. It is also unclear which hypothalamic nuclei first express the nonapeptides: staining has been reported first either in the median eminence (8), or in the cells of the SON (9, 1 I ) or the PVN (7,10).…”

Pre- and posthatch developmental changes in hypothalamic thyrotropin-releasing hormone and somatostatin concentrations and in circulating growth hormone and thyrotropin levels in the chicken

“…The GH-releasing activity of TRH is, however, only established around E18 (Kühn et al 1988a, Darras et al 1994. The SRIH neuronal system is already fully developed in the hypothalamus before hatching (Blahser & Heinrichs 1982). Both GH and TSH secretion are inhibited by SRIH at the end of the incubation .…”

Effects of Increased Levels of Prenatal Mesotocin on Postnatal Individual Recognition and Stress Responsiveness in Northern bobwhite quail (Colinus Virginianus)

“…The brains of 40 quail embryos were collected to determine the average endogenous levels of mesotocin present throughout the 23 days of prenatal development in Northern bobwhite quail eggs. Eggs were weighed prior to incubation and brain tissue was collected and weighed on embryonic days 8, 12, 16, and 20 (Charvet & Striedter, 2010;Milewski et al, 1989;Tennyson et al, 1986;Blähser & Heinrichs, 1982). An additional 13 embryos were used to verify the efficacy of the injection procedure once the baseline levels of MT were determined.…”

“…Similarly, MT which differs from OT by only one amino acid (Jonaidi, Oloumi, & Denbow, 2003;Gimpl & Fahrenholz, 2001;Bons, 1980) has been shown to be produced and stored in the same relative brain structures as OT in humans and other mammal species (Ross & Young 2009;Tennyson, Nilaver, Hou-Yu, Valiquette, & Zimmerman, 1986). Research has also provided support for MT serving similar functional purposes as those of OT (Jonaidi et al, 2003;Milewski, Ivell, Grossman, & Ellendorff, 1989;Tennyson et al, 1986;Blähser & Heinrichs, 1982; discussed in further detail below).…”