Immunocytochemical localization of neuropeptide FF (FMRF amide‐like peptide) in the hypothalamo‐neurohypophyseal system of Wistar and Brattleboro rats by light and electron microscopy

Abstract

Neuropeptide FF (F8Famide, FMRFamide-like, or morphine modulating peptide) immunoreactivity was localized by light and electron microscopy in the hypothalamo-neurohypophyseal system of Wistar and Brattleboro rats. In Wistar rats neuropeptide FF was present in part of the magnocellular neurones of the paraventricular and supraoptic nuclei in which it was coexpressed with vasopressin. Neuropeptide FF containing fibres were present in the paraventricular and the supraoptic nuclei, and in the central part of the neural lobe. At the electron microscopic level, neuropeptide FF containing nerve terminals in the neural lobe formed synaptoid contacts exclusively with pituicytes. No neuropeptide FF containing neurovascular contacts or contacts with other neuronal structures were observed. In contrast with Wistar rats, neuropeptide FF was almost completely absent in cell bodies of the paraventricular and supraoptic nuclei, and in fibres of the neural lobe in Brattleboro rats. Only a few solitary cells could be observed in these structures. The present results demonstrate that neuropeptide FF coexists with vasopressin within the hypothalamo-neurohypophyseal system. As we did not observe neuropeptide FF containing neurovascular contacts, neuropeptide FF containing nerve terminals probably have a local function within the neural lobe. Neuropeptide FF may be involved in the modulation of oxytocin and vasopressin release, with the pituicyte as an intermediate cell.

The role of RFamide peptides in feeding

“…In line with its role in nociception, NPFF and NPFF2 are expressed in dorsal horn of the spinal cord (Panula et al 1996, Vilim et al 1999, Gouarderes et al 2002. It is important to point out that pronounced inter-species and inter-strain differences have been reported for the localisation of NPFF and its receptors (Boersma et al 1993, Gouarderes et al 2002, 2004b.…”

“…The major population of NPFF-expressing neurons in the rat brain lies within the nucleus of the tractus solitarius (NTS; Kivipelto et al 1989, Boersma et al 1993, Lee et al 1993, Vilim et al 1999) and projects to the ventral lateral medulla (VLM), lateral parabrachial nucleus (lPBN) and paraventricular nucleus of the hypothalamus (PVN; Jhamandas et al 2001, Goncharuk et al 2006. NPFF-expressing neurons have also been reported in the vicinity of the ventromedial (VMN) and dorsomedial (DMN) nuclei of the hypothalamus.…”

“…However, the lack of mRNA expression in this region (Vilim et al 1999) suggests that the immunostaining may be due to cross-reactivity of antibodies with other related RFamide peptides (such as RFRP) which have been reported in the region . While NPFF immunoreactive fibres have a fairly wide distribution in the rat brain, major targets include the PVN, the lPBN and the VLM, as all the three areas exhibit dense NPFF-containing nerve fibres, NPFF receptor expression and NPFF-binding activity (Kivipelto et al 1989, Boersma et al 1993, Vilim et al 1999, Liu et al 2001, Gouarderes et al 2002, 2004a, Goncharuk et al 2006. PVN neurons have also been shown to be electrically responsive to NPFF and express the immediate early gene, c-fos, following intracerebroventricular (ICV) injection of the peptide (Jhamandas & MacTavish 2003).…”

Localization of FMRFamide-Like Immunoreactivity in the Brain of the Viviparous Skink <i>(Chalcides chalcides)</i>

“…It recognizes the RFamide terminal and should, therefore, recognize tissue peptides belonging to the FMRFamide family. Nevertheless, it has previously been observed that antibodies against FaRPs can crossreact with some members of the pancreatic polypeptide family, in particular with NPY Hokfelt et al, 1983;O'Donohue et al, 1984;Triepel and Grimmelikhuijzen, 1984a;Majane and Yang, 1987;Muske and Moore, 1987;Bonn and Konig, 1988;Chen et al, 1989;Kivipelto et al, 1989;Shen and Cheng, 1989;Vallarino et al, 1991Vallarino et al, , 1993Fujii and Kobayashi, 1992a;Boersma et al, 1993;Fischer et al, 1996;Yamamoto et al, 1996]. In this study, we consistently observed that preabsorption of anti-FMRFamide (diluted 1:10,000) with 5 µM of synthetic NPY totally eliminated the immunostaining in the dorsal cortex and preoptic nucleus, and the intensity of immunoreaction in other brain nuclei was reduced.…”

“…Peptides belonging to FMRFamide family are easily visualized in the nervous system by using antibodies raised against the tetrapeptide. Indeed, there are numerous studies on the immunohistochemical localization of FMRFamide-like peptides in the central nervous system of vertebrates from cyclostomes to mammals [see Dockray et al, 1986;Wicht and Northcutt, 1992;Vallarino et al, 1991Vallarino et al, , 1994Vallarino et al, , 1995Boersma et al, 1993;Eisthen and Northcutt, 1996;Pestarino and Vallarino, 1996;D'Aniello et al, 1996;Wright and Demski, 1996;Oelschläger et al, 1998;Pinelli et al, 1999, 2000, andreferences therein]. Based on the functions shown in mammals and the widespread distribution of FMRFamide-like immunoreactivity in the brain, it has hitherto been speculated that FMRFamide and related peptides are involved in neuromodulation, neurotransmission and neuroendocrine regulation.…”