bibp-3226 and phenylalanyl-leucyl-phenylalanyl-glutaminyl-prolyl-glutaminyl-arginyl-phenylalaninamide

Neuropeptide FF, a member of the RFamide family of peptides, has demonstrated an interesting array of pharmacological effects. To date however, little information has been obtained as to the exact pharmacological roles of the individual NPFF1 and NPFF2 receptors. Through peptide analogs of NPFF and related peptides, the essential pharmacophore has emerged somewhat. Yet, the field is lacking small molecule ligands selective for each receptor. This review of the structure-activity relationships of the reported NPFF peptide analogs and some non-selective small molecule ligands highlights the current understanding of the pharmacophoric elements required for affinity and activity at the NPFF receptors. The lack of mutagenesis data on the receptor as well as a crystal structure has also hindered the understanding of ligand recognition at the receptor level. If the targets can be further investigated as to their requirements for ligand recognition, the successful development of highly selective ligands should follow.

Topics: Amino Acid Sequence; Animals; Arginine; CHO Cells; Cricetinae; Cricetulus; Humans; Oligopeptides; Peptide Fragments; Receptors, Neuropeptide; Structure-Activity Relationship

Functional defects in cilia are associated with various human diseases including congenital hydrocephalus. Previous studies suggested that defects in cilia not only disrupt the flow of cerebrospinal fluid (CSF) generated by motile cilia in ependyma lining the brain ventricles, but also cause increased CSF production at the choroid plexus. However, the molecular mechanisms of CSF overproduction by ciliary dysfunction remain elusive. To dissect the molecular mechanisms, choroid plexus epithelial cells (CPECs) were isolated from porcine brain. These cells expressed clusters of primary cilia on the apical surface. Deciliation of CPECs elevated the intracellular cyclic AMP (cAMP) levels and stimulated basolateral-to-apical fluid transcytosis, without detrimental effects on other morphological and physiological features. The primary cilia possessed neuropeptide FF (NPFF) receptor 2. In deciliated cells, the responsiveness to NPFF was reduced at nanomolar concentrations. Furthermore, CPECs expressed NPFF precursor along with NPFFR2. An NPFFR antagonist, BIBP3226, increased the fluid transcytosis, suggesting the presence of autocrine NPFF signaling in CPECs for a tonic inhibition of fluid transcytosis. These results suggest that the clusters of primary cilia in CPECs act as a sensitive chemosensor to regulate CSF production.

Topics: Animals; Anti-Anxiety Agents; Arginine; Autocrine Communication; Base Sequence; Caco-2 Cells; Cattle; Cell Line, Tumor; Cerebrospinal Fluid; Choroid Plexus; Cilia; Cyclic AMP; Epithelium; Humans; Mice; Models, Biological; Molecular Sequence Data; Oligopeptides; Protein Transport; Rats; Receptors, Neuropeptide; Swine

GPR103 is one of the orphan G protein-coupled receptors. Recently, an endogenous ligand for GPR103, 26RFa, was identified. Many 26RFa binding sites have been observed in various nuclei of the brain involved in the processing of pain such as the parafascicular thalamic nucleus, the locus coeruleus, the dorsal raphe nucleus, and the parabrachial nucleus. In the present study, the effects of intracerebroventricular injection of 26RFa were tested in the rat. Intracerebroventricular injection of 26RFa significantly decreased the number of both phase 1 and phase 2 agitation behaviors induced by paw formalin injection. This analgesic effect of 26RFa on the phase 1 response, but not phase 2 response, was antagonized by BIBP3226, a mixed antagonist of neuropeptide Y Y1 and neuropeptide FF receptors. Intracerebroventricular injection of 26RFa has no effect in the 52.5 degrees C hot plate test. Intracerebroventricular injection of 26RFa had no effect on the expression of Fos-like immunoreactivity induced by paw formalin injection in the superficial layers of the spinal dorsal horn. These data suggest that (1) 26RFa modulates nociceptive transmission at the supraspinal site during a formalin test, (2) the mechanism 26RFa uses to produce an analgesic effect on the phase 1 response is different from that on the phase 2 response, and (3) intracerebroventricularly injected 26RFa dose not directly inhibit the nociceptive input to the spinal cord.

Topics: Analgesics, Non-Narcotic; Animals; Anti-Anxiety Agents; Arginine; Formaldehyde; Hot Temperature; Injections, Intraventricular; Male; Narcotic Antagonists; Neuropeptide Y; Neuropeptides; Oligopeptides; Pain; Pain Measurement; Proto-Oncogene Proteins c-fos; Rats; Rats, Sprague-Dawley; Reaction Time; Receptors, G-Protein-Coupled; Spinal Cord

BIBP3226 {(R)-N2-(diphenylacetyl)-N-[(4-hydroxyphenyl)-methyl]-argininamide} was recently shown to display relatively high affinities for neuropeptide FF (NPFF) receptors and exhibit antagonist activities towards NPFF receptors in vitro. The present study was undertaken to investigate the antagonistic effects of BIBP3226 on several in vivo pharmacologic profiles induced by exogenous NPFF and NPVF. (1) BIBP3226 (5 nmol) injected into the third ventricle completely antagonized the hypothermic effects of NPFF (30 nmol) and NPVF (30 nmol) after cerebral administration in mice; (2) BIBP3226 (5 nmol, i.c.v.) prevented the anti-morphine actions of NPFF (10 nmol, i.c.v.) in the mouse tail-flick assay; (3) in urethane-anaesthetized rats, both NPFF (200 nmol/kg, i.v.) and NPVF (200 nmol/kg, i.v.) increased the mean arterial blood pressure, which were significantly reduced by pretreatment with BIBP3226 (500 nmol/kg, i.v.). Collectively, these data suggest that BIBP3226, a mixed antagonist of NPY Y1 and NPFF receptors, shows in vivo antagonistic effects on NPFF receptors. In addition, it seems to be clear that the in vivo pharmacological profiles of NPFF are mediated directly by NPFF receptors.

Topics: Animals; Anti-Anxiety Agents; Arginine; Hypothermia; Male; Mice; Oligopeptides; Rats; Rats, Wistar; Receptors, Neuropeptide; Receptors, Neuropeptide Y; Tachycardia; Time Factors

Neuropeptide FF (NPFF) and NPVF, two closely NPFF related peptides, have different affinities for the two NPFF receptors (NPFF1 and NPFF2). To assess the peripheral effects of NPFF receptors in the gastrointestinal tract motility, NPFF and NPVF were tested in the mouse isolated distal colon. Both NPFF (1-15 microM) and NPVF (1-15 microM) dose-dependently caused significant colonic contractions. Pre-treatment with the putative NPFF antagonist, BIBP3226 (30 microM) abolished the contractile responses to the two neuropeptides (3 microM). They had no additional contractile activities in colonic preparations contracted by Nomega-nitro-L-arginine (30 microM). Moreover, the contractions of these two neuropeptides were weakened by L-arginine (2 mM). The responses to NPFF (5 microM) and NPVF (5 microM) were not modified by atropine or naloxone (1 microM). Furthermore, NPFF (1 microM) and NPVF (1 microM) did not influence the contractive responses to acetylcholine (0.1-10 microM), morphine (1 microM) or nociceptin (0.1 microM). These data suggest that NPFF and NPVF cause contractions of the mouse distal colon via their NPFF receptors and this effect is mediated by NO but not by cholinergic pathways, independently from opioid system. In addition, the isolated bioassay may be applied as a simple parameter to characterize the potential NPFF agonists and antagonists.

Topics: Acetylcholine; Animals; Arginine; Biological Assay; Colon, Sigmoid; Enzyme Inhibitors; In Vitro Techniques; Mice; Muscle Contraction; Neuropeptides; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Oligopeptides; Receptors, Neuropeptide

The central nervous system octapeptide, neuropeptide FF (NPFF), is believed to play a role in pain modulation and opiate tolerance. Two G protein-coupled receptors, NPFF1 and NPFF2, were isolated from human and rat central nervous system tissues. NPFF specifically bound to NPFF1 (K(d) = 1.13 nm) and NPFF2 (K(d) = 0.37 nm), and both receptors were activated by NPFF in a variety of heterologous expression systems. The localization of mRNA and binding sites of these receptors in the dorsal horn of the spinal cord, the lateral hypothalamus, the spinal trigeminal nuclei, and the thalamic nuclei supports a role for NPFF in pain modulation. Among the receptors with the highest amino acid sequence homology to NPFF1 and NPFF2 are members of the orexin, NPY, and cholecystokinin families, which have been implicated in feeding. These similarities together with the finding that BIBP3226, an anorexigenic Y1 receptor ligand, also binds to NPFF1 suggest a potential role for NPFF1 in feeding. The identification of NPFF1 and NPFF2 will help delineate their roles in these and other physiological functions.

Topics: Amino Acid Sequence; Animals; Arginine; Binding Sites; Brain; Calcium; Chromosome Mapping; Cloning, Molecular; COS Cells; Cyclic AMP; DNA, Complementary; Electrophysiology; Gene Library; Humans; Kinetics; Ligands; Molecular Sequence Data; Oligopeptides; Oocytes; Phosphatidylinositols; Protein Binding; Protein Structure, Tertiary; Rats; Receptors, Cell Surface; Receptors, Neuropeptide; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sequence Homology, Amino Acid; Tissue Distribution; Xenopus