Immunohistochemical distribution and partial characterization of FLFQPQRFamidelike peptides in the central nervous system of rats

Abstract

Two peptides that are structurally related to the molluscan tetrapeptide Phe-Met-Arg-Phe-NH2 (FMRF-NH2) were recently isolated from bovine brain extract (Yang et al.: Proc. Natl. Acad. Sci. USA 82:7757-7761, '85). These peptides have an attenuating effect on morphine-induced analgesia when injected intracerebroventricularly in rats. Antisera against the two peptides--an octapeptide, Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2 (F8F-NH2), and an octadecapeptide, Ala-Gly-Glu-Gly-Leu-Ser-Ser-Pro-Phe-Trp-Ser-Leu-Ala-Ala-Pro-Gln-Arg-Phe- NH2 (A18F-NH2)--were raised in rabbits and characterized with standard radioimmunoassay and immunohistochemical blocking controls. This study was aimed at localizing neurons in the rat brain that contain immunoreactivity for these peptides. Cryostat sections of normal and colchicine-treated Sprague-Dawley rat brains were incubated with the specific antisera and the immunoreactivity was visualized by the PAP or the FITC method. Immunoreactive neurons were detected in the hypothalamus and nucleus of the solitary tract. Relatively dense networks of fibers and terminals were observed in the lateral parabrachial nucleus and in the nucleus of the solitary tract. Fibers and terminals were also seen in the lateral septum, amygdala, hypothalamus, neurohypophysis, thalamus, periaqueductal gray, and several medullary nuclei. In these areas the immunoreactivity was abolished when the antisera were incubated with the corresponding synthetic peptides F8F-NH2 and A18F-NH2. Preincubation of the antisera with neuropeptide Y (NPY) did not affect the staining. The results suggest that there are neurons in the rat brain that contain F8F-NH2- and A18F-NH2-like peptides. The neuronal system described here may have a role in the regulation of autonomic functions, such as hypothalamic control and respiratory functions. The neuronal connections of the cells containing F8F-NH2- and A18F-NH2-like peptides remain to be studied.

Identification and Characterization of Two G Protein-coupled Receptors for Neuropeptide FF

“…The localization of mRNA and binding sites for NPFF1 and NPFF2 in various components of the basal ganglia, such as the nucleus accumbens, substantia nigra, and the caudate putamen, suggests that NPFF receptors might play an in the regulation of the central dopaminergic system, albeit and indirect one, because previous studies have shown that NPFF binding sites are not found in dopaminergic cell bodies (36). Some of the highest levels of NPFF-like immunoreactivity have been observed in the rat hypothalamus (3,37). The localization of NPFF2 receptor binding sites and NPFF2 mRNA in the hypothalamus, a region involved in catecholaminergic and serotonergic feeding systems, circadian feeding, and spontaneous activity, suggests that NPFF2 may be involved in the regulation of ingestive behavior.…”

The role of RFamide peptides in feeding

“…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.…”

Relevance of the C‐terminal Arg‐Phe sequence in γ2‐melanocyte‐stimulating hormone (γ2‐MSH) for inducing cardiovascular effects in conscious rats

“…The chemical structural resemblance (ArgPhe-amide) between FMRFa-like peptides and g-MSHs, their comparable haemodynamic pro®le (increase in MAP and HR) (Allard et al, 1995;Barnard & Dockray, 1984a;De Wildt et al, 1993;Mues et al, 1982;Thiemermann et al, 1991;Wong et al, 1985) and correspondent anatomical location of these peptides and their receptors within the brain (hypothalamus and nucleus tractus solitarius) (Fodor et al, 1996;Kivipelto et al, 1989;Majane et al, 1989;O'Donohue et al, 1984;Pittius et al, 1984), makes the FMRFa/NPFFa/MERFa receptor a very important candidate for mediating the cardiovascular e ects of g-MSHs. Therefore, in the present study various peptides with a Cterminal Arg-Phe structure are tested for their haemodynamic pro®le in conscious rats.…”