Chinese Journal of Physiology

: 2019  |  Volume : 62  |  Issue : 2  |  Page : 47--52

Neuropeptide FF modulates neuroendocrine and energy homeostasis through hypothalamic signaling

Ya-Tin Lin1, Jin-Chung Chen2,  
1 Department of Physiology and Pharmacology, Graduate Institute of Biomedical Sciences, School of Medicine; Healthy Aging Research Center, Chang Gung University, Taoyuan, Taiwan
2 Department of Physiology and Pharmacology, Graduate Institute of Biomedical Sciences, School of Medicine; Healthy Aging Research Center, Chang Gung University; Neuroscience Research Center, Chang Gung Memorial Hospital, Taoyuan, Taiwan

Correspondence Address:
Dr. Jin-Chung Chen
259 Wenhua 1st Road, Guishan Dist., Taoyuan 33302


Neuropeptide FF (NPFF) is known as a morphine-modulating peptide and was first isolated in 1985. It has been characterized as an RF-amide peptide. The traditional role of NPFF is mediation of the pain response, and it displays both anti-opioid and pro-opioid actions through central nervous system. In the recent decade, additional evidence has revealed some untraditional features of NPFF, such as regulation of the neuroendocrine system, energy homeostasis, anti-inflammation, pain transmission, and peripheral modulation of adipose tissue macrophages. Neuropeptide FF receptor 2 (NPFFR2) is a physiological receptor of NPFF, and the actions of NPFF may occur through downstream NPFFR2 signaling. NPFF and NPFFR2 increase the neuronal activity in various areas of the hypothalamus to modulate the hypothalamic–pituitary–adrenal axis, the autonomic nervous system, food intake, and energy balance. These underlying cellular mechanisms have been explored in the past few years. Here, we review the impact of NPFF and related RF-amide peptides on hypothalamic function. The interaction of NPFF with NPFFR2 in the hypothalamus is emphasized, and NPFF-NPFFR2 system may represent an important therapeutic target in hypothalamic-related disorders in the future.

How to cite this article:
Lin YT, Chen JC. Neuropeptide FF modulates neuroendocrine and energy homeostasis through hypothalamic signaling.Chin J Physiol 2019;62:47-52

How to cite this URL:
Lin YT, Chen JC. Neuropeptide FF modulates neuroendocrine and energy homeostasis through hypothalamic signaling. Chin J Physiol [serial online] 2019 [cited 2019 Jun 20 ];62:47-52
Available from:

Full Text


The Phe-Met-Arg-Phe-NH2 (FMRF-amide) peptide is characterized as a cardioexcitatory peptide and has been originally isolated from the ganglia of Macrocallista nimbosa in 1977.[1] Two of the FMRF-amide-like peptides have been identified by cross-reaction with FMRF-amide antiserum from the bovine central nervous system (CNS). Their sequences are Ala-Gly-Glu-Gly-Leu-Ser-Ser-Pro-Phe-Trp-Ser-Leu-Ala-Ala-Pro-Gln-Arg-Phe-NH2 (neuropeptide AF [NPAF]) and Phe-Leu-Phe-Gln-Pro-Gln-Arg-Phe-NH2 (neuropeptide FF [NPFF]).[2] NPFF and NPAF are known as mammalian RF-amide peptides. RMFR-amide peptides are identified as pain modulation peptides and show anti-opioid profiles.[3] Intraventricular (ICV) injection of NPFF (5 μg) and NPAF (20 μg) increases the pain response in rats. NPFF further reverses the analgesic effect of morphine.[2] NPFF and NPAF are encoded by a common precursor and are expressed as a splicing mRNA, which is also characterized as the gene for proNPFFA-related peptides.[4],[5] ProNPFFB-related peptides are encoded by a distinct gene, which generates RF-amide-related peptide-1 (RFRP-1, also known as NPSF) and RFRP-3 (also known as NPVF).[6]

NPFF is referred to as an F8F-amide or morphine-modulating peptide. It plays a role in multiple neural and pathological functions, such as pain sensation, morphine tolerance, feeding behavior, and acts in the cardiovascular system.[3],[7],[8] However, different functions of NPFF have been reported including involvement in the inflammatory pathway and the neuroendocrine system, and it modulates stress-induced analgesia, pain transmission, and the peripheral activation of M2 macrophages.[9],[10],[11],[12],[13]

NPFF is abundant in the hypothalamic area. There is growing evidence supporting the modulatory role of the NPFF and NPFF receptor systems in the hypothalamus to maintain physiological homeostasis.[8] The atypical function of NPFF may be beneficial in developing a therapeutic strategy for stress-related disorders and obesity. This review focuses on the characterization of NPFF and its receptor type 2 (NPFFR2) for their involvement in the neuroendocrine regulation, energy homeostasis and the cardiovascular system.

Neuropeptide FF receptors and downstream signaling

Neuropeptide FF receptors

Two receptors of NPFF have been cloned, the NPFF receptor type 1 (NPFFR1, also known as GPR147 and OT7T022) and the NPFF receptor type 2 (NPFFR2, also known as GPR74 and HLWAR77).[6],[14],[15] Both are seven transmembrane G-protein-coupled receptors that are coupled to Gi/o proteins.[3] The stimulation of NPFF receptors inhibits the activity of adenylyl cyclase on membranes and reduces cyclic AMP production. ProNPFFA-related peptides can bind to either receptor but show higher affinity toward NPFFR2 than NPFFR1.[16] ProNPFFB-related peptides display higher affinity toward NPFFR1 and show poor agonist activity to NPFFR2.[16],[17] In this context, NPFFR2 is considered to be the physiological receptor for NPFF, and NPFFR1 is the physiological receptor for NPVF.[3]

Downstream signaling of neuropeptide FF-neuropeptide FF receptor 2

NPFF mediates the action of opiates which includes analgesia, tolerance, dependence, locomotor activity, food intake, and opioid-dependent reward.[18] However, NPFF and other FMRP-amide-related peptides show no binding affinity to mu, delta, and kappa opiate receptors.[19] The signaling regulation of NPFF on mu opioid receptor (MOR) is largely reported. An analogue of NPFF reverses the MOR-inhibited calcium conductance in cultured rat spinal ganglion neurons.[20] NPFFR2 forms a heteromeric receptor complex with MOR. The activation of NPFFR2 induces heterologous desensitization of MOR through the G protein receptor kinase, i.e. GRK2, and this receptor complex is transphosphorylated in SH-SY5Y cells.[21] Different phosphorylation sites of NPFFR2 have been identified in SH-SY5Y cell lines, including412 TNST415 s,372 TS373, and Ser395.[22] NPFFR2 activates MAP kinase 1/2 and NF kappa B signaling pathways in SH-SY5Y cell lines.[22],[23]

The mammalian RF-amide peptide superfamily

Five groups of the RF-amide peptide family that share an Arg-Phe-NH2 sequence include NPFF, prolactin-releasing peptide (PrRP), RFRP, kisspeptin, and pyroglutamylated RFamide peptide.[24] The corresponding peptides in the different subgroups are NPFF and NPAF for the NPFF group, PrRP-20 and PrRP-31 for the PrRP group, RFRP-1 (NPSF) and RFRP-3 (NPVF) for the RFRP group, kisspeptin and metastin for the kisspeptins group, and 43RFa and 26RFa for the QRPF group.[24],[25] NPFF, NPAF, and NPVF share the N-terminal sequence homology (PQRF) and contain a different number of amino acids. The sequences of mammalian RF-amide and the corresponding receptors in humans, rats, and mice are documented by Ayachi and Simonin.[26] These RF-amide peptides are involved in the modulation of nociception[26] and hypothalamic function, including energy homeostasis, reproduction, food intake, and the stress response.[8],[24]

Although GRP10 is the endogenous receptor for PrRP, PrRP shows high-binding affinity toward NPFFR2.[8],[27] NPFF and RFRP bind to both NPFFR1 and NPFFR2, but RFRP binds to NPFFR1 with higher binding affinity than NPFFR2, while NPFF binds to NPFFR2 with higher binding affinity than NPFFR1.[25] Most endogenous mammalian RF-amide peptides modulate nociception and morphine analgesia. These peptides all bind with human NPFF receptors (Ki between 0.2 and 84 nM for NPFFR1; Ki between 0.1 and 131 nM for NPFFR2).[28] For this reason, it is difficult to distinguish the effects between ligands and receptors, particularly because of lack of selective agonists or antagonists.

The distribution of neuropeptide FF-neuropeptide FF receptor 2 in the nervous system

NPFF and its receptors are ubiquitously expressed in the CNS with prevalence in the spinal cord, posterior pituitary, and hypothalamus, of which NPFFR2 is more dominant in the CNS than NPFFR1.[29],[30],[31],[32] There are high levels of NPFF and NPFFR2 expression in the superficial laminae of the dorsal spinal cord in most mammals.[30],[33] Among the receptors of the RF-amide peptides, only NPFFR2 is expressed in the spinal cord.[25] This indicates that most of the RF-amide peptides mediate the pain response, but actin in spinal cord is only through the interaction of NPFFR2 and not other endogenous receptors.[26],[28],[34] NPFF and NPFFR2 are also expressed in the dorsal root ganglia (DRG).[35],[36] NPFFR2 is synthesized in the DRG and translocates to the nerve terminals of primary sensory neurons in the spinal dorsal horn.[36]

NPFF and NPFFR2 immunoreactivities have been detected in different areas of the hypothalamus, including the paraventricular nucleus (PVN), the perifornical nucleus (PFA), the posterior hypothalamic area, ventromedial hypothalamic nucleus and dorsomedial hypothalamic nucleus (VMH and DMH), the arcuate nucleus (ARC), and the lateral hypothalamic area (LHA) of human and rodents.[29],[37] These brain areas are involved in the central control of energy homeostasis, neuroendocrine regulation, and the stress response.

The modulation of neuropeptide FF on the hypothalamic–pituitary–adrenal axis

The action of the neuropeptide FF-neuropeptide FF receptor system in the hypothalamus

The hypothalamic–pituitary–adrenal (HPA) axis is viewed as key neural circuitry in maintaining homeostasis and adaptive reactions in response to stress status. Within the hypothalamic nuclei, PVN, which contains magnocellular and parvocellular subdivisions, is the primary regulator of the HPA axis and mediates physiological responses when individuals face environmental or homeostatic challenges.[38],[39] The magnocellular PVN contains neurosecretory cells which synthesize and secrete vasopressin or oxytocin into posterior pituitary.[40] Parvocellular PVN consists of both neurosecretory and non-neurosecretory cells. The neurosecretory cells synthesize and secrete corticotropin-releasing factor (CRF) into the anterior pituitary to regulate the secretion of adrenocorticotrophic hormone (ACTH). ACTH is further released into the circulation and triggers the secretion of cortisol (corticosteroid [CORT] in rodents) from the adrenal cortex. The parvocellular non-neurosecretory neurons are known as autonomic neurons, whose axons project into the brain stem and spinal cord.[39],[41] The HPA axis can be modulated by the hippocampus (inhibition) and the amygdala (excitation) through the action of γ-aminobutyric acid (GABA) originating in the bed nucleus of the stria terminals to parvocellular PVN.[39],[42] The HPA axis not only controls the stress response but also regulates metabolism, food intake, and function of the immune, cardiovascular, and reproductive systems.[39],[43]

NPFF is an important neuromodulator that controls the neuroendocrine and autonomic stress systems. Central injection (ICV) of NPFF causes the activation of PVN neurons, which are mainly located in the parvocellular compartments, including VMH, DMH, and the dorsal subdivisions.[44] The CRF is predominantly expressed in the DMH neurons and regulates the downstream HPA axis. Both NPFF and NPVF activate the PVN parvocellular neurons through disinhibiting the GABA-ergic (GABAergic) terminals in PVN. The NPFF-induced reduction of inhibitory postsynaptic currents is further inhibited by the nonselective NPFF receptor antagonist RF9.[45] PrRP also disinhibits GABA signaling and activates the CRF-containing neurons in the parvocellular PVN. Due to the high-binding affinity of PrRP toward NPFFR2, the effect may be mediated through NPFFR2.[27],[46],[47] On the other hand, central administration of NPFF inhibits the release of vasopressin, a peptide hormone secreted from the magnocellular subdivision of PVN.[48] This effect is most likely mediated by NPFF-augmented GABAergic neurotransmission in the magnocellular neurons.[49]

Central administration of the NPFFR2-specific agonist (dNPA or AC-263093) increases the neural activity of hypothalamic PVN and the amount of circulating CORT. These actions can be counteracted by either NPFF or CRF antagonists.[11] The NPFFR1 agonist, i.e. RFRP-3 stimulates the release of CORT through the activation of PVN CRF-expressing neurons.[50] Other RF-amide peptides activate the HPA axis and increase the circulation of CORT, including PrRP, NPSF, NPAF, and kisspeptin-13.[51],[52],[53],[54] Distinguishing the action of these receptors is difficult because all of these peptides show binding affinity to NPFFR1 and NPFFR2.[28]

Effect of neuropeptide FF on hypothalamic-dependent behaviors

The HPA axis serves as a stress response pathway in dealing with environmental challenges. Hyperactivity of the HPA axis triggers behavioral changes, including depressive- and anxiety-like behaviors. The chronic stress increases the risk of mood disorders through disruption of neuroplasticity at the structural and functional level.[55] The biochemical changes include the impairment of hippocampal-negative feedback, high circulating CORT, downregulation of glucocorticoid receptor, and reduced neurogenesis.[56],[57],[58] NPFF regulates the stress response, i.e. activation of the HPA axis and consequent behavioral changes.[10] Central administration of the NPFF antagonist, dansyl-PQR-amide, or RF9 restores ethanol or amphetamine withdrawal-induced anxiety behavior.[59],[60] NPFF-related RF-amide neuropeptides induce anxiety behavior through the stimulation of the HPA axis.[50],[51],[52],[53] Chronic stimulation of NPFFR2 signaling by systemic injection of the NPFFR2 agonist or in NPFFR2 overexpressed transgenic mice induces depressive- and anxiety-like behaviors.[10] These mice display depressive-like behavior, hyperactivity of the HPA axis, impairment of hippocampal negative feedback and neurogenesis, of which similar to chronic mild stress-induced phenotypes. The depressive-like behavior is ameliorated by bilateral intra-PVN injection of NPFFR2-shRNA.[10] Impact of RF-amide peptides in the hypothalamus on HPA axis activity and animal behavior is summarized in [Table 1]. The findings pinpoint the importance of NPFFR2 on the HPA axis and the stress response through upstream PVN.{Table 1}

Of importance, NPFF regulates the cardiovascular system through its cellular effects on PVN neurons.[46],[48] The NPFF immunopositive cells of the hypothalamus are increased in hypertensive patients compared to healthy controls.[61] These events may be mediated through the autonomic nervous system and the neuroendocrine system.

Food consumption and energy homeostasis

The hypothalamus serves as an important brain area in regulating food intake and energy homeostasis, including ARC, PVN, VMH, DMH, LHA, and PFA, of which, all contain NPFF and NPFFR2 proteins.

Various hormones, transmitters, and peptides function in the modulation of appetite. These include noradrenaline, serotonin, dopamine, neuropeptide Y (NPY), pro-opiomelanocortin and its posttranslational product, α-melanocyte-stimulating hormone, agouti-related protein, cocaine- and amphetamine-regulated transcript, insulin, leptin, ghrelin, and cholecystokinin (CCK).[62],[63],[64] The hypothalamus receives the peripheral adiposity and satiety signals such as insulin, leptin, ghrelin, and CCK to stimulate the catabolic or anabolic pathways and further responds to signals from the nucleus of the solitary tract (NTS) to maintain energy balance.[65]

Neuropeptide FF and food consumption

NPFF regulates food consumption through modulation of hypothalamic function. The ICV injection of NPFF reduces food intake with no influence on water consumption in chicks. The NPFF-treated chicks show higher hypothalamic activity in PVN, DMH, and VMH as identified by c-ios expression.[66] Similar result was reported that ICV injection of NPFF reduces food intake but also causes a large increase of water consumption in rats.[67] These findings suggest that NPFF exhibits a direct action on hypothalamic neurons to modulate feeding behavior. NPFF has numerous interactions with the central opioid system, including the modulation of food intake. NPFF modulates feeding behavior through pro- and anti-opioid actions in the parabrachial nucleus (PBN), which receives NPFF projections from the NTS.[68] PBN infusion of NPFF increases food intake in rats and this effect is further inhibited by co-injection with the MOR antagonist, i.e., naloxone. Pretreatment of NPFF in PBN diminishes DAMGO (a μ-opioid agonist)-induced food intake.[68]

Neuropeptide FF receptor 2 signaling and energy homeostasis

The NPFF-NPFFR2 system participates in the modulation of energy metabolism. NPFF exhibits metabolic benefit in mice through NPFFR2 signaling. Mice chronically treated with NPFF exhibit lower blood glucose, increased glucose metabolism, and higher sensitivity to insulin.[12] The treatment of NPFF in mice on a high-fat diet (HFD) provokes the M2 activation of adipose tissue macrophages, which supports the health of adipocytes.[12] NPFFR2 signaling also mediates diet-induced thermogenesis. HFD-fed NPFFR2 knockout mice exhibit an impaired thermogenic response of brown adipose tissue, which results in obesity when compared to control mice.[69] ARC NPFFR2 signaling is required for the expression of NPY, which has an important role in directing energy homeostasis from the central to the peripheral systems.

RF-amide peptides on feeding and energy metabolism

RF-amide peptides, in addition to NPFF, have a role in feeding behavior and energy homeostasis.[7] ICV injection of PrRP inhibits food intake in fasting rats and rats with free access to food, which is mediated through central satiating actions of CCK.[70],[71] Leptin receptors in PrRP-containing DMN neurons are required for the thermogenic response of PrRP to leptin. PrRP knockout mice exhibit the obese phenotype with a reduced response to leptin and CCK.[72] Kisspeptin also reduces energy metabolism and impairs glucose tolerance.[73] Since PrRP and kisspeptin can bind to NPFFR2,[27],[28] it is likely that their influence on energy homeostasis is through NPFFR2 signaling. These overall findings support the role of NPFF and NPFFR2 signaling on energy metabolism that is controlled in the hypothalamus, and the action is manifested peripherally.


NPFF mediates the pain response by interaction with the NPFFR2. NPFF and its related RF-amide peptides in their interactions with NPFFR2 can also increase the neuronal activity of various areas of the hypothalamus to modulate the HPA axis, the autonomic nervous system, food intake, and energy homeostasis. The underlying cellular mechanisms of these actions can now be explored because of the recent development of genomic and pharmacological tools. NPFFR2 signaling in part of the stress-modulation pathway induces depressive- and anxiety-like behaviors. NPFFR2 also regulates the energy homeostasis cascade to increase brown adipose tissue-mediated thermogenesis. This leads to benefiting body health and reduces the obese phenotypes. NPFFR2 signaling might be a potential therapeutic target of stress- and obese-related disorders. Specific NPFF receptor agonists and antagonists have not been identified. Once this has occurred, it will lead to a better understanding of the function and signaling of the RF-amide peptides on specific receptors.


We thank Prof. Arnold Stern for providing English editing.

Financial support and sponsorship

This work was supported by the Chang Gung Memorial Hospital (CMRPD1H0431) and Healthy Aging Research Center, Chang Gung University (EMRPD1H0551).

Conflicts of interest

There are no conflicts of interest.


1Price DA, Greenberg MJ. Structure of a molluscan cardioexcitatory neuropeptide. Science 1977;197:670-1.
2Yang HY, Fratta W, Majane EA, Costa E. Isolation, sequencing, synthesis, and pharmacological characterization of two brain neuropeptides that modulate the action of morphine. Proc Natl Acad Sci U S A 1985;82:7757-61.
3Yang HY, Tao T, Iadarola MJ. Modulatory role of neuropeptide FF system in nociception and opiate analgesia. Neuropeptides 2008;42:1-18.
4Perry SJ, Yi-Kung Huang E, Cronk D, Bagust J, Sharma R, Walker RJ, et al. A human gene encoding morphine modulating peptides related to NPFF and FMRFamide. FEBS Lett 1997;409:426-30.
5Vilim FS, Aarnisalo AA, Nieminen ML, Lintunen M, Karlstedt K, Kontinen VK, et al. Gene for pain modulatory neuropeptide NPFF: Induction in spinal cord by noxious stimuli. Mol Pharmacol 1999;55:804-11.
6Hinuma S, Shintani Y, Fukusumi S, Iijima N, Matsumoto Y, Hosoya M, et al. New neuropeptides containing carboxy-terminal RFamide and their receptor in mammals. Nat Cell Biol 2000;2:703-8.
7Bechtold DA, Luckman SM. The role of RFamide peptides in feeding. J Endocrinol 2007;192:3-15.
8Jhamandas JH, Goncharuk V. Role of neuropeptide FF in central cardiovascular and neuroendocrine regulation. Front Endocrinol (Lausanne) 2013;4:8.
9Sun YL, Zhang XY, Sun T, He N, Li JY, Zhuang Y, et al. The anti-inflammatory potential of neuropeptide FF in vitro and in vivo. Peptides 2013;47:124-32.
10Lin YT, Liu TY, Yang CY, Yu YL, Chen TC, Day YJ, et al. Chronic activation of NPFFR2 stimulates the stress-related depressive behaviors through HPA axis modulation. Psychoneuroendocrinology 2016;71:73-85.
11Lin YT, Yu YL, Hong WC, Yeh TS, Chen TC, Chen JC, et al. NPFFR2 activates the HPA axis and induces anxiogenic effects in rodents. Int J Mol Sci 2017;18. pii: E1810.
12Waqas SF, Hoang AC, Lin YT, Ampem G, Azegrouz H, Balogh L, et al. Neuropeptide FF increases M2 activation and self-renewal of adipose tissue macrophages. J Clin Invest 2017;127:2842-54.
13Li N, Han ZL, Fang Q, Wang ZL, Tang HZ, Ren H, et al. Neuropeptide FF and related peptides attenuates warm-, but not cold-water swim stress-induced analgesia in mice. Behav Brain Res 2012;233:428-33.
14Bonini JA, Jones KA, Adham N, Forray C, Artymyshyn R, Durkin MM, et al. Identification and characterization of two G protein-coupled receptors for neuropeptide FF. J Biol Chem 2000;275:39324-31.
15Elshourbagy NA, Ames RS, Fitzgerald LR, Foley JJ, Chambers JK, Szekeres PG, et al. Receptor for the pain modulatory neuropeptides FF and AF is an orphan G protein-coupled receptor. J Biol Chem 2000;275:25965-71.
16Liu Q, Guan XM, Martin WJ, McDonald TP, Clements MK, Jiang Q, et al. Identification and characterization of novel mammalian neuropeptide FF-like peptides that attenuate morphine-induced antinociception. J Biol Chem 2001;276:36961-9.
17Mollereau C, Mazarguil H, Marcus D, Quelven I, Kotani M, Lannoy V, et al. Pharmacological characterization of human NPFF (1) and NPFF (2) receptors expressed in CHO cells by using NPY Y (1) receptor antagonists. Eur J Pharmacol 2002;451:245-56.
18Moulédous L, Mollereau C, Zajac JM. Opioid-modulating properties of the neuropeptide FF system. Biofactors 2010;36:423-9.
19Raffa RB, Kim A, Rice KC, de Costa BR, Codd EE, Rothman RB, et al. Low affinity of FMRFamide and four faRPs (FMRFamide-related peptides), including the mammalian-derived faRPs F-8-famide (NPFF) and A-18-famide, for opioid mu, delta, kappa 1, kappa 2a, or kappa 2b receptors. Peptides 1994;15:401-4.
20Rebeyrolles S, Zajac JM, Roumy M. Neuropeptide FF reverses the effect of mu-opioid on ca2+channels in rat spinal ganglion neurones. Neuroreport 1996;7:2979-81.
21Moulédous L, Froment C, Dauvillier S, Burlet-Schiltz O, Zajac JM, Mollereau C, et al. GRK2 protein-mediated transphosphorylation contributes to loss of function of μ-opioid receptors induced by neuropeptide FF (NPFF2) receptors. J Biol Chem 2012;287:12736-49.
22Bray L, Froment C, Pardo P, Candotto C, Burlet-Schiltz O, Zajac JM, et al. Identification and functional characterization of the phosphorylation sites of the neuropeptide FF2 receptor. J Biol Chem 2014;289:33754-66.
23Sun YL, Zhang XY, He N, Sun T, Zhuang Y, Fang Q, et al. Neuropeptide FF activates ERK and NF kappa B signal pathways in differentiated SH-SY5Y cells. Peptides 2012;38:110-7.
24Findeisen M, Rathmann D, Beck-sickinger AG. Rfamide peptides: Structure, function, mechanisms and pharmaceutical potential. Pharmaceuticals 2011;4:1248-80.
25Fukusumi S, Fujii R, Hinuma S. Recent advances in mammalian RFamide peptides: The discovery and functional analyses of PrRP, RFRPs and QRFP. Peptides 2006;27:1073-86.
26Ayachi S, Simonin F. Involvement of mammalian RF-amide peptides and their receptors in the modulation of nociception in rodents. Front Endocrinol (Lausanne) 2014;5:158.
27Engström M, Brandt A, Wurster S, Savola JM, Panula P. Prolactin releasing peptide has high affinity and efficacy at neuropeptide FF2 receptors. J Pharmacol Exp Ther 2003;305:825-32.
28Elhabazi K, Humbert JP, Bertin I, Schmitt M, Bihel F, Bourguignon JJ, et al. Endogenous mammalian RF-amide peptides, including prRP, kisspeptin and 26RFa, modulate nociception and morphine analgesia via NPFF receptors. Neuropharmacology 2013;75:164-71.
29Gouardères C, Puget A, Zajac JM. Detailed distribution of neuropeptide FF receptors (NPFF1 and NPFF2) in the rat, mouse, octodon, rabbit, guinea pig, and marmoset monkey brains: A comparative autoradiographic study. Synapse 2004;51:249-69.
30Gouardères C, Faura CC, Zajac JM. Rodent strain differences in the NPFF1 and NPFF2 receptor distribution and density in the central nervous system. Brain Res 2004;1014:61-70.
31Kivipelto L. Ultrastructural localization of neuropeptide FF, a new neuropeptide in the brain and pituitary of rats. Regul Pept 1991;34:211-24.
32Majane EA, Panula P, Yang HY. Rat brain regional distribution and spinal cord neuronal pathway of FLFQPQRF-NH2, a mammalian FMRF-NH2-like peptide. Brain Res 1989;494:1-12.
33Zeng Z, McDonald TP, Wang R, Liu Q, Austin CP. Neuropeptide FF receptor 2 (NPFF2) is localized to pain-processing regions in the primate spinal cord and the lower level of the medulla oblongata. J Chem Neuroanat 2003;25:269-78.
34Lin YT, Liu HL, Day YJ, Chang CC, Hsu PH, Chen JC, et al. Activation of NPFFR2 leads to hyperalgesia through the spinal inflammatory mediator CGRP in mice. Exp Neurol 2017;291:62-73.
35Allard M, Rousselot P, Lombard MC, Theodosis DT. Evidence for neuropeptide FF (FLFQRFamide) in rat dorsal root ganglia. Peptides 1999;20:327-33.
36Gouardères C, Roumy M, Advokat C, Jhamandas K, Zajac JM. Dual localization of neuropeptide FF receptors in the rat dorsal horn. Synapse 2000;35:45-52.
37Goncharuk VD, Buijs RM, Mactavish D, Jhamandas JH. Neuropeptide FF distribution in the human and rat forebrain: A comparative immunohistochemical study. J Comp Neurol 2006;496:572-93.
38Herman JP, Cullinan WE, Ziegler DR, Tasker JG. Role of the paraventricular nucleus microenvironment in stress integration. Eur J Neurosci 2002;16:381-5.
39Ulrich-Lai YM, Herman JP. Neural regulation of endocrine and autonomic stress responses. Nat Rev Neurosci 2009;10:397-409.
40Gainer H, Yamashita M, Fields RL, House SB, Rusnak M. The magnocellular neuronal phenotype: Cell-specific gene expression in the hypothalamo-neurohypophysial system. Prog Brain Res 2002;139:1-14.
41Bonfiglio JJ, Inda C, Refojo D, Holsboer F, Arzt E, Silberstein S, et al. The corticotropin-releasing hormone network and the hypothalamic-pituitary-adrenal axis: Molecular and cellular mechanisms involved. Neuroendocrinology 2011;94:12-20.
42Riedemann T, Patchev AV, Cho K, Almeida OF. Corticosteroids: Way upstream. Mol Brain 2010;3:2.
43Carrasco GA, Van de Kar LD. Neuroendocrine pharmacology of stress. Eur J Pharmacol 2003;463:235-72.
44Jhamandas JH, MacTavish D. Central administration of neuropeptide FF causes activation of oxytocin paraventricular hypothalamic neurones that project to the brainstem. J Neuroendocrinol 2003;15:24-32.
45Jhamandas JH, Simonin F, Bourguignon JJ, Harris KH. Neuropeptide FF and neuropeptide VF inhibit GABAergic neurotransmission in parvocellular neurons of the rat hypothalamic paraventricular nucleus. Am J Physiol Regul Integr Comp Physiol 2007;292:R1872-80.
46Ma L, MacTavish D, Simonin F, Bourguignon JJ, Watanabe T, Jhamandas JH, et al. Prolactin-releasing peptide effects in the rat brain are mediated through the neuropeptide FF receptor. Eur J Neurosci 2009;30:1585-93.
47Yamada T, Mochiduki A, Sugimoto Y, Suzuki Y, Itoi K, Inoue K, et al. Prolactin-releasing peptide regulates the cardiovascular system via corticotrophin-releasing hormone. J Neuroendocrinol 2009;21:586-93.
48Arima H, Murase T, Kondo K, Iwasaki Y, Oiso Y. Centrally administered neuropeptide FF inhibits arginine vasopressin release in conscious rats. Endocrinology 1996;137:1523-9.
49Jhamandas JH, MacTavish D, Harris KH. Neuropeptide FF (NPFF) control of magnocellular neurosecretory cells of the rat hypothalamic paraventricular nucleus (PVN). Peptides 2006;27:973-9.
50Kim JS, Brownjohn PW, Dyer BS, Beltramo M, Walker CS, Hay DL, et al. Anxiogenic and stressor effects of the hypothalamic neuropeptide RFRP-3 are overcome by the NPFFR antagonist GJ14. Endocrinology 2015;156:4152-62.
51Jászberényi M, Bagosi Z, Thurzó B, Földesi I, Szabó G, Telegdy G, et al. Endocrine, behavioral and autonomic effects of neuropeptide AF. Horm Behav 2009;56:24-34.
52Csabafi K, Jászberényi M, Bagosi Z, Lipták N, Telegdy G. Effects of kisspeptin-13 on the hypothalamic-pituitary-adrenal axis, thermoregulation, anxiety and locomotor activity in rats. Behav Brain Res 2013;241:56-61.
53Jászberényi M, Bagosi Z, Csabafi K, Palotai M, Telegdy G. The actions of neuropeptide SF on the hypothalamic-pituitary-adrenal axis and behavior in rats. Regul Pept 2014;188:46-51.
54Samson WK, Keown C, Samson CK, Samson HW, Lane B, Baker JR, et al. Prolactin-releasing peptide and its homolog RFRP-1 act in hypothalamus but not in anterior pituitary gland to stimulate stress hormone secretion. Endocrine 2003;20:59-66.
55Pittenger C, Duman RS. Stress, depression, and neuroplasticity: A convergence of mechanisms. Neuropsychopharmacology 2008;33:88-109.
56Holsboer F. The corticosteroid receptor hypothesis of depression. Neuropsychopharmacology 2000;23:477-501.
57Nestler EJ, Barrot M, DiLeone RJ, Eisch AJ, Gold SJ, Monteggia LM, et al. Neurobiology of depression. Neuron 2002;34:13-25.
58Mahar I, Bambico FR, Mechawar N, Nobrega JN. Stress, serotonin, and hippocampal neurogenesis in relation to depression and antidepressant effects. Neurosci Biobehav Rev 2014;38:173-92.
59Kotlinska J, Pachuta A, Bochenski M, Silberring J. Dansyl-PQRamide, a putative antagonist of NPFF receptors, reduces anxiety-like behavior of ethanol withdrawal in a plus-maze test in rats. Peptides 2009;30:1165-72.
60Kotlinska JH, Gibula-Bruzda E, Koltunowska D, Raoof H, Suder P, Silberring J, et al. Modulation of neuropeptide FF (NPFF) receptors influences the expression of amphetamine-induced conditioned place preference and amphetamine withdrawal anxiety-like behavior in rats. Peptides 2012;33:156-63.
61Goncharuk VD, Buijs RM, Jhamandas JH, Swaab DF. The hypothalamic neuropeptide FF network is impaired in hypertensive patients. Brain Behav 2014;4:453-67.
62Woods SC, Seeley RJ, Porte D Jr., Schwartz MW. Signals that regulate food intake and energy homeostasis. Science 1998;280:1378-83.
63Kandel ER, Schwartz JH, Jessell TM. Principles of Neural Science. 3rd ed. New York: McGraw-Hill, Health Professions Division; 2000.
64Yeo GS, Heisler LK. Unraveling the brain regulation of appetite: Lessons from genetics. Nat Neurosci 2012;15:1343-9.
65Schwartz MW, Woods SC, Porte D Jr., Seeley RJ, Baskin DG. Central nervous system control of food intake. Nature 2000;404:661-71.
66Cline MA, Nandar W, Rogers JO. Central neuropeptide FF reduces feed consumption and affects hypothalamic chemistry in chicks. Neuropeptides 2007;41:433-9.
67Sunter D, Hewson AK, Lynam S, Dickson SL. Intracerebroventricular injection of neuropeptide FF, an opioid modulating neuropeptide, acutely reduces food intake and stimulates water intake in the rat. Neurosci Lett 2001;313:145-8.
68Nicklous DM, Simansky KJ. Neuropeptide FF exerts pro- and anti-opioid actions in the parabrachial nucleus to modulate food intake. Am J Physiol Regul Integr Comp Physiol 2003;285:R1046-54.
69Zhang L, Ip CK, Lee IJ, Qi Y, Reed F, Karl T, et al. Diet-induced adaptive thermogenesis requires neuropeptide FF receptor-2 signalling. Nat Commun 2018;9:4722.
70Lawrence CB, Celsi F, Brennand J, Luckman SM. Alternative role for prolactin-releasing peptide in the regulation of food intake. Nat Neurosci 2000;3:645-6.
71Bechtold DA, Luckman SM. Prolactin-releasing peptide mediates cholecystokinin-induced satiety in mice. Endocrinology 2006;147:4723-9.
72Dodd GT, Worth AA, Nunn N, Korpal AK, Bechtold DA, Allison MB, et al. The thermogenic effect of leptin is dependent on a distinct population of prolactin-releasing peptide neurons in the dorsomedial hypothalamus. Cell Metab 2014;20:639-49.
73Tolson KP, Garcia C, Yen S, Simonds S, Stefanidis A, Lawrence A, et al. Impaired kisspeptin signaling decreases metabolism and promotes glucose intolerance and obesity. J Clin Invest 2014;124:3075-9.