Relaxin-3 ⁄ insulin-like peptide 7, a neuropeptide involvedin the stress response and food intake Masaki Tanaka Department of Basic Geriatrics, Kyoto Prefectural University of Medicine,
Trang 1Relaxin-3 ⁄ insulin-like peptide 7, a neuropeptide involved
in the stress response and food intake
Masaki Tanaka
Department of Basic Geriatrics, Kyoto Prefectural University of Medicine, Japan
Introduction
Relaxin-3⁄ insulin-like peptide-7 (INSL7) has recently
been identified as a new member of the insulin⁄ relaxin
family using human genomic databases [1] The 142
amino acid human precursor polypeptide sequence is
well conserved among humans, pigs, rats and mice [2]
Structurally, this precursor polypeptide consists of
sig-nal peptides, and a B-chain, C-peptide and A-chain,
and contains the RXXXRXXI motif in the B chain
(B12–B19 in human) for binding to the relaxin
recep-tor [3] Similar to insulin, a mature two-chain peptide
is produced after removal of the C-peptide and the
for-mation of three disulfide bonds between respective
cys-teine residues of the A-chain and B-chain [4] An
evolutionary study showed that relaxin-3 orthologs are
present in fugu fish and zebrafish, but not in any
inver-tebrate or prokaryote, and that these orthologs show
high homology between different species in the mature peptide region When compared with other insu-lin⁄ relaxin superfamily members, relaxin-3 is con-strained by strong purifying selection, suggesting that this protein is an ancestral form and has a highly-con-served function [5]
In the present minireview, the expression of relaxin-3
in the brain, and particularly its functions, including the stress response and food intake, are described
Expression of relaxin-3 in the brain
Relaxin-3 neurons in the brain Examination of relaxin-3 mRNA expression by north-ern blotting and reverse transcriptase-PCR revealed
Keywords
food intake; gene expression;
hypothalamus; nucleus incertus; RXFP3;
stress
Correspondence
M Tanaka, Department of Basic Geriatrics,
Kyoto Prefectural University of Medicine,
Kawaramachi-Hirokoji, Kamikyo-ku, Kyoto
602-8566, Japan
Fax: +81 75 251 5797
Tel: +81 75 251 5797
E-mail: mtanaka@koto.kpu-m.ac.jp
(Received 13 June 2010, revised 26 August
2010, accepted 18 October 2010)
doi:10.1111/j.1742-4658.2010.07931.x
Relaxin-3, also known as insulin-like peptide-7, is a newly-identified peptide of the insulin superfamily All members of this superfamily have a similar structure, which consists of two subunits (A-chain and B-chain) linked by disulfide bonds Relaxin-3 is so named because it has a motif that can interact with the relaxin receptor By contrast to other relaxins, relaxin-3 is mainly expressed in the brain and testis In rodent brain, ana-tomical studies have revealed its predominant expression in neurons of the nucleus incertus of the dorsal pons, and a few other regions of the brain-stem On the other hand, relaxin-3-expressing nerve fibers and the relaxin-3 receptors, RXFP3 and RXFP1, are widely distributed in the forebrain, with the hypothalamus being one of the most densely-innervated regions Therefore, relaxin-3 is considered to exert various actions through its ligand-receptor system This minireview describes the expression of
relaxin-3 in the brain, as well as its functions in the hypothalamus, including the stress response and food intake
Abbreviations
ARC, arcuate nucleus; CRF, corticotropin-releasing factor; CRFR1, CRF type 1 receptor; GnRH, gonadotropin-releasing hormone;
HPA, hypothalamo-pituitary-adrenal; HPG, hypothalamo-pituitary-gonadal; INSL, insulin-like peptide; KO, knockout; LH, lateral hypothalamic area; NI, nucleus incertus; NPY, neuropeptide Y; PKA, protein kinase A; PVN, paraventricular hypothalamic nucleus; SON, supraoptic nucleus.
Trang 2that relaxin-3 is abundant in the brain, but not in
female reproductive tissue such as the ovary and uterus
[1,6] By contrast, the expression of two other known
relaxin genes (i.e those encoding human relaxin-1 and
-2) was detected in the ovarian corpus luteum during
pregnancy, and in the deciduas trophoblast [7–9]
Thus, the physiological function of relaxin-3 is
consid-ered to be different from that of other relaxin proteins
involved in the growth and remodeling of reproductive
and other tissues during pregnancy [10]
In the mouse and rat brain, relaxin-3 expression was
reported to be localized to the central gray matter of
the median dorsal pons near the fourth ventricle,
termed the nucleus incertus (NI) [1,6,11] We
previ-ously reported details of relaxin-3 expression at the
cel-lular level using immunocytochemistry and in situ
hybridization [12] In addition to the primary site of
expression (i.e the NI), where, in the rat,
approxi-mately 2000 relaxin-3-positive neurons are found
(Fig 1A), a smaller number of these neurons are
scattered in the pontine raphe nucleus, the periaqu-eductal gray matter, and the area dorsal to the substantia nigra in the midbrain reticular formation
By immunostaining using monoclonal antibody against the N-terminus of the human relaxin-3 A-chain [2], relaxin-3-immunoreactive fibers were observed to project densely to the septum, hippocampus, lateral hypothalamic area (LH) and intergeniculate leaflet of the thalamus (Fig 1B) Ultrastructural examination revealed that relaxin-3 was localized to the dense-core vesicles in the perikarya, and it was also observed in the synaptic terminals of axons [12] The NI comprises
a distinct cell group in the caudoventral region of the pontine periventricular gray matter, adjacent to the ventromedial border of the caudal dorsal tegmental nucleus [13] Studies involving neuronal tracing with anterograde and retrograde tracers have shown that the NI, together with the median raphe and interpe-duncular nuclei, may form a midline behavior control network, and many targets of the NI, such as the med-ial septum, hippocampus, hypothalamus, mammillary complex and amygdala, are involved in arousal mecha-nisms, including the synchronization and desynchroni-zation of the theta rhythm [14,15] Recently, Ma et al [16] reported that relaxin-3 neurons in the NI can help modulate spatial memory and the underlying hippo-campal theta activity Using immunocytochemistry studies, relaxin-3-positive neurons in the NI have been shown to be GABAergic and to co-express corticotro-pin-releasing factor (CRF) type 1 receptors (CRFR1) [12,17]
Relaxin-3 receptor The cognate receptor for relaxin-3 is RXFP3, formally known as GPCR135 or SALPR [6,18] Although it can also bind and activate RXFP1 and RXFP4, relaxin-3 binds RXPF3 with higher affinity (0.31 nm) than RXFP1 (2.0 nm) or RXFP4 (1.1 nm) [6,19] RXFP3 mRNA is abundant in the olfactory bulb, paraventric-ular nucleus (PVN) and supraoptic nucleus (SON) in the hypothalamus amygdaloid–hippocampal area, as well as the bed nucleus stria terminalis, paraventricular thalamus, superior colliculus and interpeduncular nucleus in the brainstem The distribution of RXFP3 approximately overlaps with the autoradiography pattern, showing selective RXFP3 binding of the chi-meric peptide, relaxin-3 B-chain⁄ INSL5 A-chain [20]
In the brain, there is generally a close correlation between relaxin-3-positive nerve terminals and RXFP3 expression; however, the density of expression of ligand and receptor is not always equal For example, the olfactory bulb exhibits abundant RXFP3
expres-DTg
A
B
NIc 4V
IP
Hippocampus
PAG RSC
DB
Hypothalamus
LS
NI
DR
NId
MS
mlf
Fig 1 (A) Relaxin-3 immunoreactivity in the NI Relaxin-3 is
expressed in neurons of both the pars compacta (NIc) and pars
dissi-pata (NId) of the NI DTg, dorsal tegmental nucleus; 4V, fourth
ventri-cle; mlf, medial longitudinal fasciculus Scale bars = 100 lm (B) A
schematic representation of the major projection of relaxin-3 in the
forebrain DB, diagonal band; DR, dorsal raphe nucleus; IP,
interpe-duncular nucleus; LS, lateral septal nucleus; MS, medial septal
nucleus; PAG, periaqueductal gray matter; RSC, retrosplenial cortex.
Trang 3sion, whereas it has relatively low levels of
relaxin-3-immunoreactive fibers In the hypothalamus, relaxin-3
fibers densely innervate the lateral hypothalamic area,
although RXFP3 is strongly expressed in the PVN and
SON [12,17,21] The structure and function of the
relaxin family peptide receptors, including RXFP3 and
RXFP4, were recently reviewed by Kong et al [22]
Relaxin-3 expression in development and in other
species
During the development of the rat, relaxin-3 mRNA
expression appears at embryonic day 18 near the
fourth ventricle Relaxin-3 peptide can be detected
after birth by immunocytochemistry [23] This
develop-mental expression pattern is comparable with that of
relaxin, the rodent equivalent of human relaxin-2,
whose mRNA is not detectable in the rat brain at
embryonic day 15, although it is detectable at
postna-tal day 1 [24] As well as rodents, the distribution of
relaxin-3 in the brain has recently been reported for
fish, monkeys and humans In the zebrafish, the
relaxin-3 gene is expressed in two neuron clusters in
the brainstem: one is a midbrain cell cluster of the
periaqueductal gray matter and the other is in a
pos-terior region that could be homologous to the
mam-malian NI [25] Two groups have described the
distribution of relaxin-3 in the primate brain In the
brain of Macaca fascicularis, relaxin-3-positive cell
bodies were found to be distributed within a
ventrome-dial region of the central gray matter of the pons and
medulla, which appears to correspond to the NI in
lower species [26] In the rhesus macaque and humans,
relaxin-3 immunostaining was predominantly observed
in the ventral and dorsal tegmental nuclei of the
brain-stem [27] Thus, from fish to primates, this peptide is
expressed in the dorsal tegmentum of the brain stem,
corresponding to the NI in rodents
Regulation of relaxin-3 gene expression
Concerning the regulation of relaxin-3 gene expression,
relaxin-3 mRNA expression in the NI is enhanced by
restraint stress or forced swim stress (Fig 2A) [12,28]
This swim stress-induced increase in relaxin-3
tran-script levels is blunted by the systemic administration
of CRFR1 antagonist [28] Relaxin-3 transcript levels
are also increased after treatment with
p-chlorophenyl-alanine, a potent inhibitor of serotonin synthesis,
indi-cating that serotonin negatively regulates relaxin-3
gene expression [23] From these results, the expression
of relaxin-3 may be observed to be dynamically altered
under different physiological conditions We found
that relaxin-3 is expressed in a mouse neuroblastoma cell line, Neuro2a, and investigated the intracellular signaling that leads to activation of relaxin 3 gene transcription in vitro [29] Using a clone stably-trans-fected with a relaxin-3 promoter-enhanced green fluo-rescent protein gene, we observed that the increase in intracellular cAMP induced by dibutyryl cAMP and forskolin treatment increased relaxin-3 promoter activ-ity These increases were inhibited by pretreatment with the protein kinase A (PKA) inhibitors, H89 and KT5720 Moreover, the relaxin-3 promoter activity was enhanced by CRF treatment after the expression
CRFR1 CRF
cAMP
Gs
PKA
Relaxin-3 gene
P
Transcription factor
ATP
PKA
Plasma membrane
P
Promoter
Stress
Nucleus
0 100 200 300 400
A
B
Cont
Stress
*
Cont Stress
AC
Fig 2 (A) Relaxin-3 mRNA expression in the NI after 6 h of restrained stress The upper panel shows a representative image of
in situ hybridization using the [ 35 S]-labeled probe The graph below indicates the calculated signal intensity of relaxin-3 mRNA Data are shown as the mean ± SD of photostimulated luminescence (PSL) [12] (B) A schematic representation of the intracellular signaling that regulates relaxin-3 gene expression Downstream of CRFR1, the cAMP-PKA pathway is involved in the activation of relaxin-3 gene transcription.
Trang 4of CRFR1 receptor in the cells These results suggest
that relaxin-3 transcription in vivo is activated via the
cAMP-PKA pathway, which is downstream of CRFR1
[29] (Fig 2B)
The function of relaxin-3 in the brain
Because relaxin-3-producing cells showed a relatively
limited distribution, predominantly in neurons of the
NI, the function of this peptide has been assessed based
upon anatomical studies of the NI at the neuronal level
[14,15] The NI is composed of two subdivisions, the
pars compacta and pars dissipata, and
relaxin-3-positive neurons are found in both regions (Fig 1A)
With reference to the distribution of relaxin-3-positive
nerve fibers and RXFP3 and RXFP1 expression,
several functions of relaxin-3 in the brain have been
demonstrated, including those related to
neuroendo-crine processes, stress response, water intake and spatial
memory [12,16,28,30–35] Particularly, this peptide also
regulates food intake, as well as other hypothalamic
peptides described in this minireview series [36,37]
Stress response
The NI is a region showing abundant expression of
CRFR1, and strong c-Fos induction was observed in
the NI in response to an intracerebroventricular
injec-tion of CRF [38,39] It is well known that CRF is
expressed in parvocellular neurons of the PVN and,
during the stress response, CRF activates the
hypotha-lamic-pituitary-adrenal (HPA) axis, acting at CRFR1
on anterior pituitary corticotropes to stimulate the
release of adrenocorticotropic hormone There are also
extrahypothalamic CRF-expressing neurons distributed
through the brain in areas such as the neocortex and
limbic regions, including the central amygdala and
hippocampus [40,41] The regulation of CRF expression
may be involved in setting the ‘tone’ of stress-related
behavior, including anxiety, as well as learning and
memory [42,43] CRF exerts its actions via two major
receptors: CRFR1 and CRFR2 Both receptors belong
to the class B subtype of G protein-coupled receptors,
although they have a different distribution, suggesting
that the two receptors have different functions CRFR1
is considered to be involved in the acute phase of the
stress response, whereas CRFR2 contributes to the
maintenance and recovery phase that involves a gradual
reduction of HPA axis activation [43,44]
In the rat NI, almost all relaxin-3-positive neurons
coexpress CRFR1 and respond to CRF
intracerebro-ventricular administration Moreover, application of a
water-restraint stress for 2–4 h induces c-Fos
expres-sion and leads to an increase in relaxin-3 mRNA levels
in the NI [12] On the other hand, relaxin-3-positive neurons project fibers to the hypothalamus, and RXFP3 is intensely expressed in the PVN where hypo-thalamic CRF neurons exist These results suggest that relaxin-3-expressing neurons respond immediately to stress and modulate the HPA axis Recently, Banerjee
et al [28] reported that exposure of rats to a repeated forced swim for 10 min each time leads to a marked increase in relaxin-3 mRNA levels in the NI at 30–60 min after the second swim Systemic treatment with the CRFR1 antagonist alarmin 30 min before the second swim blunted the stress-induced effect on relaxin-3 transcripts in the NI [28] This supports the idea that relaxin-3-expressing neurons in the NI (and therefore relaxin-3) play a role in the central stress regulating system by mutual interaction with CRF-expressing neurons
Food intake Relaxin-3 was first reported to stimulate food intake when administered into the third ventricle or PVN of male Wistar rats Administration of human relaxin-3, but not human relaxin-2, either intracerebroventricu-larly (180 pmol) or intra-PVN (18 pmol) increased 1-h food intake both in the early light and early dark phase (Fig 3) [31] The doses of relaxin-3 required to elicit a significant feeding response are in the picomo-lar range and are simipicomo-lar to the effective doses of other orexigenic peptides such as ghrelin (30 pmol; PVN) and neuropeptide Y (NPY) (78 pmol; intra-PVN) [45,46] Although RXFP3 and RXFP1 are expressed in the PVN, relaxin (specifically, human relaxin-2) binds RXFP1 but not RXFP3, suggesting that this feeding-promoting action of relaxin-3 is exerted through RXFP3 because the actions of relaxin have not been reported to include hyperphagia, but do include hemodynamic effects such as increasing arterial blood pressure and vasopressin release [47], or dipso-genesis [48] In reverse, relaxin-3 was recently reported
to facilitate water intake as well as relaxin, suggesting that RXFP1 was involved in this action [35] Concern-ing the chronic administration of relaxin-3, intracere-broventricular injection for 14 days (600 pmolÆday)1) using osmotic minipumps led to a significant increase
in food consumption and weight compared to vehicle infusion There was no difference in locomotor activity between two groups either in the light phase or dark phase, suggesting that this effect of relaxin-3 is not a result of increased locomotor or arousal activity [34] Chronic intra-PVN administration of human relaxin-3 (180 pmol twice a day for 7 days) also increased the
Trang 5cumulative food intake in ad libitum-fed rats [32] After
such chronic administration, the plasma concentration
of leptin and insulin was significantly increased [32] In
addition to the PVN, relaxin-3-administration into the
SON or arcuate nucleus (ARC), but not into the LH,
stimulated 1-h food intake [32] The ARC and LH are
well known as feeding centers where orexigenic
peptides such as NPY, melanin-concentrating
hor-mone and orexin are distributed Although
relaxin-3-immunoreactive fibers are densely distributed, the
RXFP3 level is relatively low in the ARC and LH
An electrophysiological study of neurons in these
hypothalamic nuclei may help to resolve this disparity and clarify the hyperphagic mechanisms
Recently, relaxin-3 gene knockout (KO) mice of mixed background (129S5:B6) were examined in two studies One group reported that KO mice are smaller and leaner than congenic controls [21], although the results obtained by the second group indicated that there was no genotypic difference in body weight or motor coordination [49] Further studies using
relaxin-3 KO mice backcrossed to C57⁄ B6 should help to clar-ify the role of relaxin-3 in regulating body weight and metabolism
Actions of relaxin-3 at the hypothalamo-pituitary-gonadal (HPG) axis
Recently, a role of relaxin-3 in regulation of the HPG axis was reported in that intracerebroventricular (5 nmol) and intra-PVN (540–1620 pmol) administra-tion of relaxin-3 in adult male rats significantly increased plasma luteinizing hormone levels This effect was inhibited by pretreatment with a peripheral gona-dotropin-releasing hormone (GnRH) antagonist By contrast, the central administration of human relaxin-2 was not found to influence the plasma luteinizing hor-mone concentration Using hypothalamic explants and GT1-7 cells that express RXFP1 and RXFP3,
relaxin-3 was shown to dose-dependently stimulate GnRH release GnRH neuronal cell bodies are found in sev-eral forebrain regions, including the medial septum, diagonal band, preoptic area and LH, where relaxin-3-positive fibers and RXFP3 are moderately-to-densely distributed [12,17,50] These results suggest that relaxin-3 regulates the HPG axis via hypothalamic GnRH neurons Thus, relaxin-3 is seen to belong to the group of neuropeptides that regulate energy homeostasis and reproduction (i.e modulate both appetite and the HPG axis) This group includes NPY, orexin and galanin-like peptides [51–54]
Conclusions
In this minireview, relaxin-3, which is the latest mem-ber of the insulin⁄ relaxin family, is described in terms
of its gene transcript and peptide expression in the brain, as well as its functional aspects that have thus far been reported Although relaxin-3-expressing neu-rons show a confined distribution in the brainstem, being particularly dense in the NI of the dorsal tegmen-tal pons, their fibers and receptors (i.e RXFP3 and RXFP1) are widely distributed in the forebrain One of the target areas of relaxin-3 is the hypothalamus Relaxin-3 is considered to have various actions
medi-Fig 3 Effect of intracerebroventricular administration of relaxin-3
in satiated male Wistar rats (A) Effect of human relaxin-3 (H3) (18–
180 pmol) on 1-h food intake *P < 0.05 versus vehicle in the early
light phase (B) Effect of H3 (18–180 pmol) on cumulative food
intake over 4 h in the early light phase. &P < 0.05 at 18 pmol
versus vehicle; *P < 0.05 at 54 pmol versus vehicle; #P < 0.05
at 180 pmol versus vehicle Reproduced with permission [31];
ª 2005, The Endocrine Society).
Trang 6ated through receptors in the hypothalamus, including
effects on the stress response, feeding and
neuroendo-crine function
Acknowledgements
The present work was supported by a grant (no
21500329) to M.T from the Ministry of Education,
Culture, Sports, Science and Technology, Japan
References
1 Bathgate RA, Samuel CS, Burazin TC, Layfield S,
Claasz AA, Reytomas IG, Dawson NF, Zhao C, Bond
C, Summers RJ et al (2002) Human relaxin gene 3
(H3) and the equivalent mouse relaxin (M3) gene
Novel members of the relaxin peptide family J Biol
Chem 277, 1148–1157
2 Kizawa H, Nishi K, Ishibashi Y, Harada M, Asano T,
Ito Y, Suzuki N, Hinuma S, Fujisawa Y, Onda H et al
(2003) Production of recombinant human relaxin 3 in
AtT20 cells Regul Pept 113, 79–84
3 Bullesbach EE, Yang S & Schwabe C (1992) The
receptor-binding site of human relaxin II A dual
prong-binding mechanism J Biol Chem 267, 22957–22960
4 James R, Niall H, Kwok S & Bryand-Greenwood G
(1977) Primary structure of porcine relaxin: homology
with insulin and related growth factors Nature 267,
544–546
5 Wilkinson TN, Speed TP, Tregear GW & Bathgate RA
(2005) Evolution of the relaxin-like peptide family
BMC Evol Biol 5, 14
6 Liu C, Chen J, Sutton S, Roland B, Kuei C, Farmer N,
Sillard R & Lovenberg TW (2003) Identification of
relaxin-3⁄ INSL7 as a ligand for GPCR142 J Biol Chem
278, 50765–50770
7 Hudson P, Haley J, Cronk M, Shine J & Niall H
(1981) Molecular cloning and characterization of
cDNA sequences coding for rat relaxin Nature 291,
127–131
8 Hudson P, John M, Crawford R, Haralambidis J,
Scanlon D, Gorman J, Tregear G, Shine J & Niall H
(1984) Relaxin gene expression in human ovaries
and the predicted structure of a human preprorelaxin
by analysis of cDNA clones EMBO J 3, 2333–2339
9 Hansell DJ, Bryant-Greenwood GD & Greenwood FC
(1991) Expression of the human relaxin H1 gene in the
decidua, trophoblast, and prostate J Clin Endocrinol
Metab 72, 899–904
10 Sherwood OD (1994) Relaxin In The Phsiology of
Reproduction, 2nd edn (Knobil E & Neill J eds), pp
861–1009 Raven Press, Ltd, New York
11 Burazin TC, Bathgate RA, Macris M, Layfield S,
Gundlach AL & Tregear GW (2002) Restricted, but
abundant, expression of the novel rat gene-3 (R3) relaxin in the dorsal tegmental region of brain J Neuro-chem 82, 1553–1557
12 Tanaka M, Iijima N, Miyamoto Y, Fukusumi S, Itoh
Y, Ozawa H & Ibata Y (2005) Neurons expressing relaxin 3⁄ INSL 7 in the nucleus incertus respond to stress Eur J Neurosci 21, 1659–1670
13 Berman AL (1968) The brain stem of the cat: a cytoar-chitectonic atlas with stereotaxic coordinates University
of Wisconsin Press, Madison
14 Goto M, Swanson LW & Canteras NS (2001) Connec-tions of the nucleus incertus J Comp Neurol 438, 86– 122
15 Olucha-Bordonau FE, Teruel V, Barcia-Gonzalez J, Ruiz-Torner A, Valverde-Navarro AA & Martinez-Soriano F (2003) Cytoarchitecture and efferent projections of the nucleus incertus of the rat J Comp Neurol 464, 62–97
16 Ma S, Olucha-Bordonau FE, Hossain MA, Lin F, Kuei C, Liu C, Wade JD, Sutton SW, Nunez A & Gundlach AL (2009) Modulation of hippocampal theta oscillations and spatial memory by relaxin-3 neurons of the nucleus incertus Learn Mem 16, 730–742
17 Ma S, Bonaventure P, Ferraro T, Shen PJ, Burazin TC, Bathgate RA, Liu C, Tregear GW, Sutton SW & Gundlach AL (2007) Relaxin-3 in GABA projection neurons of nucleus incertus suggests widespread influence on forebrain circuits via G-protein-coupled receptor-135 in the rat Neuroscience 144, 165–190
18 Matsumoto M, Kamohara M, Sugimoto T, Hidaka K, Takasaki J, Saito T, Okada M, Yamaguchi T & Furui-chi K (2000) The novel G-protein coupled receptor SALPR shares sequence similarity with somatostatin and angiotensin receptors Gene 248, 183–189
19 Liu C, Chen J, Kuei C, Sutton S, Nepomuceno D, Bon-aventure P & Lovenberg TW (2005) Relaxin-3⁄ insulin-like peptide 5 chimeric peptide, a selective ligand for G protein-coupled receptor (GPCR)135 and GPCR142 over leucine-rich repeat-containing G protein-coupled receptor 7 Mol Pharmacol 67, 231–240
20 Sutton SW, Bonaventure P, Kuei C, Roland B, Chen J, Nepomuceno D, Lovenberg TW & Liu C (2004) Distri-bution of G-protein-coupled receptor (GPCR)135 bind-ing sites and receptor mRNA in the rat brain suggests a role for relaxin-3 in neuroendocrine and sensory pro-cessing Neuroendocrinology 80, 298–307
21 Sutton SW, Shelton J, Smith C, Williams J, Yun S, Motley T, Kuei C, Bonaventure P, Gundlach A, Liu C
et al.(2009) Metabolic and neuroendocrine responses to RXFP3 modulation in the central nervous system Ann
N Y Acad Sci 1160, 242–249
22 Kong RC, Shilling PJ, Lobb DK, Gooley PR & Bathgate RA (2010) Membrane receptors: structure and function of the relaxin family peptide receptors Mol Cell Endocrinol 320, 1–15
Trang 723 Miyamoto Y, Watanabe Y & Tanaka M (2008)
Devel-opmental expression and serotonergic regulation of
relaxin 3⁄ INSL7 in the nucleus incertus of rat brain
Regul Pept 145, 54–59
24 Osheroff PL & Ho WH (1993) Expression of relaxin
mRNA and relaxin receptors in postnatal and adult rat
brains and hearts Localization and developmental
pat-terns J Biol Chem 268, 15193–15199
25 Donizetti A, Grossi M, Pariante P, D’Aniello E,
Izzo G, Minucci S & Aniello F (2008) Two neuron
clusters in the stem of postembryonic zebrafish brain
specifically express relaxin-3 gene: first evidence of
nucleus incertus in fish Dev Dyn 237, 3864–3869
26 Ma S, Sang Q, Lanciego JL & Gundlach AL (2009)
Localization of relaxin-3 in brain of Macaca
fascicular-is: identification of a nucleus incertus in primate
J Comp Neurol 517, 856–872
27 Silvertown JD, Neschadim A, Liu HN, Shannon P,
Walia JS, Kao JC, Robertson J, Summerlee AJ &
Medin JA (2010) Relaxin-3 and receptors in the human
and rhesus brain and reproductive tissues Regul Pept
159, 44–53
28 Banerjee A, Shen PJ, Ma S, Bathgate RA & Gundlach
AL (2010) Swim stress excitation of nucleus incertus
and rapid induction of relaxin-3 expression via CRF1
activation Neuropharmacology 58, 145–155
29 Tanaka M, Watanabe Y & Yoshimoto K (2009)
Regulation of relaxin 3 gene expression via cAMP-PKA
in a neuroblastoma cell line J Neurosci Res 87, 820–
829
30 McGowan BM, Stanley SA, Donovan J, Thompson
EL, Patterson M, Semjonous NM, Gardiner JV,
Mur-phy KG, Ghatei MA & Bloom SR (2008) Relaxin-3
stimulates the hypothalamic-pituitary-gonadal axis Am
J Physiol Endocrinol Metab 295, E278–E286
31 McGowan BM, Stanley SA, Smith KL, White NE,
Connolly MM, Thompson EL, Gardiner JV, Murphy
KG, Ghatei MA & Bloom SR (2005) Central relaxin-3
administration causes hyperphagia in male Wistar rats
Endocrinology 146, 3295–3300
32 McGowan BM, Stanley SA, Smith KL, Minnion JS,
Donovan J, Thompson EL, Patterson M, Connolly
MM, Abbott CR, Small CJ et al (2006) Effects of
acute and chronic relaxin-3 on food intake and energy
expenditure in rats Regul Pept 136, 72–77
33 McGowan BM, Stanley SA, White NE, Spangeus A,
Patterson M, Thompson EL, Smith KL, Donovan J,
Gardiner JV, Ghatei MA et al (2007) Hypothalamic
mapping of orexigenic action and Fos-like
immunore-activity following relaxin-3 administration in male
Wistar rats Am J Physiol Endocrinol Metab 292,
E913–E919
34 Hida T, Takahashi E, Shikata K, Hirohashi T, Sawai
T, Seiki T, Tanaka H, Kawai T, Ito O, Arai T et al
(2006) Chronic intracerebroventricular administration
of relaxin-3 increases body weight in rats J Recept Signal Transduct Res 26, 147–158
35 Otsubo H, Onaka T, Suzuki H, Katoh A, Ohbuchi T, Todoroki M, Kobayashi M, Fujihara H, Yokoyama T, Matsumoto T et al (2010) Centrally administered relaxin-3 induces Fos expression in the osmosensitive areas in rat brain and facilitates water intake Peptides
31, 1124–1130
36 Shiba K, Kageyama H, Takenoya F & Shioda S (2010) Galanin-like peptide and the regulation of feeding behavior and energy metabolism FEBS J 277, 5006– 5013
37 Takayanagi Y & Onaka T (2010) Roles of prolactin-releasing peptide and RFamide related peptides in the control of stress and food intake FEBS J 277, 4998– 5005
38 Potter E, Sutton S, Donaldson C, Chen R, Perrin M, Lewis K, Sawchenko PE & Vale W (1994) Distribution
of corticotropin-releasing factor receptor mRNA expression in the rat brain and pituitary Proc Natl Acad Sci USA 91, 8777–8781
39 Bittencourt JC & Sawchenko PE (2000) Do centrally administered neuropeptides access cognate receptors? an analysis in the central corticotropin-releasing factor system J Neurosci 20, 1142–1156
40 Merchenthaler I, Vigh S, Petrusz P & Schally AV (1982) Immunocytochemical localization of corticotro-pin-releasing factor (CRF) in the rat brain Am J Anat
165, 385–396
41 Swanson LW, Sawchenko PE, Rivier J & Vale WW (1983) Organization of ovine corticotropin-releasing factor immunoreactive cells and fibers in the rat brain: an immu-nohistochemical study Neuroendocrinology 36, 165–186
42 Bale TL & Vale WW (2004) CRF and CRF receptors: role in stress responsivity and other behaviors Annu Rev Pharmacol Toxicol 44, 525–557
43 Korosi A & Baram TZ (2008) The central corticotropin releasing factor system during development and adult-hood Eur J Pharmacol 583, 204–214
44 Coste SC, Murray SE & Stenzel-Poore MP (2001) Animal models of CRH excess and CRH receptor deficiency display altered adaptations to stress Peptides
22, 733–741
45 Wren AM, Small CJ, Abbott CR, Dhillo WS, Seal LJ, Cohen MA, Batterham RL, Taheri S, Stanley SA, Gha-tei MA et al (2001) Ghrelin causes hyperphagia and obesity in rats Diabetes 50, 2540–2547
46 Stanley BG, Daniel DR, Chin AS & Leibowitz SF (1985) Paraventricular nucleus injections of peptide YY and neuropeptide Y preferentially enhance carbohydrate ingestion Peptides 6, 1205–1211
47 Mumford AD, Parry LJ & Summerlee AJ (1989) Lesion
of the subfornical organ affects the haemotensive response to centrally administered relaxin in anaesthe-tized rats J Endocrinol 122, 747–755
Trang 848 Summerlee AJ, Hornsby DJ & Ramsey DG (1998) The
dipsogenic effects of rat relaxin: The effect of
photope-riod and the potential role of relaxin on drinking in
pregnancy Endocrinology 139, 2322–2328
49 Smith CM, Lawrence AJ, Sutton SW & Gundlach AL
(2009) Behavioral phenotyping of mixed background
(129S5:B6) relaxin-3 knockout mice Ann N Y Acad Sci
1160, 236–241
50 King JC, Tobet SA, Snavely FL & Arimura AA (1982)
LHRH immunopositive cells and their projections to
the median eminence and organum vasculosum of the
lamina terminalis J Comp Neurol 209, 287–300
51 Kageyama H, Takenoya F, Kita T, Hori T, Guan JL &
Shioda S (2005) Galanin-like peptide in the brain:
effects on feeding, energy metabolism and reproduction Regul Pept 126, 21–26
52 Kalra SP & Kalra PS (2004) NPY and cohorts in regulat-ing appetite, obesity and metabolic syndrome: beneficial effects of gene therapy Neuropeptides 38, 201–211
53 Pu S, Jain MR, Kalra PS & Kalra SP (1998) Orexins, a novel family of hypothalamic neuropeptides, modulate pituitary luteinizing hormone secretion in an ovarian steroid-dependent manner Regul Pept 78, 133–136
54 Seth A, Stanley S, Jethwa P, Gardiner J, Ghatei M & Bloom S (2004) Galanin-like peptide stimulates the release of gonadotropin-releasing hormone in vitro and may mediate the effects of leptin on the hypothalamo-pituitary-gonadal axis Endocrinology 145, 743–750