Effect of High Fat Diet on Hypothalamic Appetite Regulatory Peptides in Broiler Chickens

23 Pages·2016·1.64 MB·English

©2017.PublishedbyTheCompanyofBiologistsLtd|JournalofExperimentalBiology(2017)220,607-614doi:10.1242/jeb.143792
RESEARCHARTICLE
Dietary fat alters the response of hypothalamic neuropeptide Y to
subsequent energy intake in broiler chickens
XiaoJ.Wang,ShaoH.Xu,LeiLiu,ZhiG.Song,HongC.JiaoandHaiLin*
ABSTRACT Severalstudieshaveshownthatthesehypothalamicneuropeptides
are sensitive to body energy status and critical to whole-body
Dietaryfataffectsappetiteandappetite-relatedpeptidesinbirdsand
metabolic adjustment. NPY reduces energy expenditure by
mammals;however,theeffectofdietaryfatonappetiteisstillunclear
decreasing adipose tissue thermogenesis (Egawa et al., 1991; Patel
in chickens faced with different energy statuses. Two experiments
etal.,2006; Chaoet al., 2011; Zhangetal.,2014).The obesityof
wereconductedtoinvestigatetheeffectsofdietaryfatonfoodintake
ob/obmiceisattenuatedwhenNPYisknockedout(Ericksonetal.,
and hypothalamic neuropeptides in chickens subjected to two
1996; Segal-Lieberman et al., 2003). NPY deficiency attenuates
feeding states or two diets. In Experiment 1, chickens were fed a
responsestoapalatablehighfatdietinmice(Hollopeteretal.,1998;
high-fat(HF)orlow-fat(LF)dietfor35days,andthensubjectedtofed
Patel et al., 2006). Animals in which POMC neurons have been
(HF-fed,LF-fed)orfasted(HF-fasted,LF-fasted)conditionsfor24h.
knocked out are obese and hyperphagic (Butler and Cone, 2002;
InExperiment2,chickensthatwerefedaHForLFdietfor35days
Mencarelli et al., 2012; Diané et al., 2014; Raffan et al., 2016).
werefastedfor24handthenre-fedwithHF(HF-RHF,LF-RHF)orLF
Additionally,thereleaseoftheseneuropeptidesiscloselyassociated
(HF-RLF, LF-RLF) diet for 3h. The results showed that chickens
withdietaryfatlevel.MicefedahigherfatdiethadlowerNPYand
fedaHFdietfor35dayshadincreasedbodyfatdepositiondespite
AgRPmRNAlevels(Linetal.,2000;Wangetal.,2002)andhigher
decreasing food intake even when the diet was altered during the
POMC mRNA levels (Lukaszewski et al., 2013). Therefore, we
re-feedingperiod(P<0.05).LFdiet(35days)promotedagouti-related
hypothesized that the response of hypothalamic neuropeptides to
peptide (AgRP) expression compared with HF diet (P<0.05) under
energystatuscouldbechangedbythedietaryfatlevel.
both fed and fasted conditions. LF-RHF chickens had lower
Inthepresentstudy,twoexperimentswereconductedtoevaluate
neuropeptideY(NPY)expressioncomparedwithLF-RLFchickens;
the effect of dietary fat on the response of hypothalamic
conversely, HF-RHF chickens had higher NPY expression than
neuropeptides to different energy statuses in broiler chickens. The
HF-RLFchickens(P<0.05).Theseresultsdemonstrate:(1)thatHF
modernbroilerchickenhasafastgrowthrate,largefatdepositionrate
dietdecreasesfoodintakeevenwhenthesubsequentdietisaltered;
and highinsulin level,and thereforeisanexcellentmodelforafat
(2)theorexigeniceffectofhypothalamicAgRP;and(3)thatdietaryfat
metabolismstudy(Sundicketal.,1996;Tsietal.,2003).Twofeeding
alters the response of hypothalamic NPY to subsequent energy
states (fasted versus fed in Experiment 1) and two re-feeding diets
intake. These findings provide a novel view of the metabolic
withdifferentenergylevels(re-fedhighfatdietversusre-fedlowfat
perturbationsassociatedwithlong-termdietaryfatover-ingestionin
diet in Experiment 2) were employed to induce differential body
chickens.
energystatuses.Ourresultsindicatethatdietaryfatalterstheresponse
KEYWORDS:Poultry,Appetite,Energystatus,Hypothalamus, ofhypothalamicNPYtosubsequentenergyintake.NPY-basedself-
Energybalance adjustingmechanismscandevelopinleanchickensbutdonotreadily
occurinobesityinducedbyahighfatdiet.Thesefindingsprovidea
INTRODUCTION novelviewofthemetabolicperturbationsassociatedwithlong-term
Thehypothalamusisaprocessingcentrethatintegratessignalsfrom dietaryfatover-ingestioninchickens.
thebrain,peripheralcirculationandgastrointestinaltracttoregulate
energy intake and expenditure. Two neuron populations in the MATERIALSANDMETHODS
arcuatenucleus(ARC)ofthehypothalamusexertpotenteffectson Ethicsstatement
y
foodintake,energybalanceandglucosehomeostasis:agouti-related All of the animal experiments were reviewed and approved by the g
o
peptide/neuropeptide Y (AgRP/NPY) neurons are orexigenic Institutional Animal Care and Use Committee of Shandong
l
o
(promote feeding and inhibit energy expenditure), while Agricultural University and performed in accordance with the i
proopiomelanocortin (POMC) and corticotropin-releasing ‘Guidelines for Experimental Animals’ of the Ministry of Science B
l
hormone (CRH) neurons promote anorexia (reduce food intake andTechnology(Beijing,China).Alleffortsweremadetominimize a
t
andincreasecatabolicprocesses)intheARCofavianspeciesand suffering. n
e
mammals(Boswelletal.,2002;Richards,2003). m
Birdsandhusbandry i
r
Male broiler chicks [Arbor Acres, Gallus gallus domesticus e
p
DepartmentofAnimalScience,ShandongAgriculturalUniversity,ShandongKey (Linnaeus 1758); 1day old] were obtained from a local hatchery x
LabforAnimalBiotechnologyandDiseaseControl,Taian,Shandong271018, E
and were reared in an environmentally controlled room. In both
China. f
Experiment1andExperiment2,128chickswererearedin16floor o
*Authorforcorrespondence([email protected]) pens each containing eight chicks (1m2 per pen). Each pen was al
equipped with a feeder and a nipple water line. The brooding n
H.L.,0000-0002-0878-137X r
temperaturewasmaintainedat35°C(65%relativehumidity)forthe u
o
Received2June2016;Accepted23November2016 first 2 days, then decreased gradually to 21°C (45% relative J
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RESEARCHARTICLE JournalofExperimentalBiology(2017)220,607-614doi:10.1242/jeb.143792
and body mass gain (BMG) of one chicken were calculated. At
Listofsymbolsandabbreviations 36daysold,halfoftheexperimentalchickensineachdiettreatment
AgRP agouti-relatedpeptide were sampled during the fasted state after 24h of food withdrawal
ARC arcuatenucleus (HF-fasted,LF-fasted),andtheotherhalfweresampledinafedstate
BMG bodymassgain (HF-fed,LF-fed).Attheendoftheexperiment,eightchickenswitha
CRH corticotropin-releasinghormone
similarbodymasswere randomlyselected from each treatment for
GAPDH glyceraldehyde3-phosphatedehydrogenase
sampling. A blood sample was drawn from a wing vein using a
HF highfat
heparinizedsyringe.Plasmawasobtainedfollowingcentrifugationat
INSR insulinreceptor
LF lowfat 400gfor10minat4°Candstoredat−20°C.Immediatelyafterthe
NPY neuropeptideY blood samples were obtained, the chickens were killed by
POMC proopiomelanocortin exsanguination. The abdominal, cervical and subcutaneous thigh
PVH paraventricularnucleus fatswereharvestedandweighedusinganelectronicbalancewithan
RHF re-fedwithHFdiet
accuracy of 0.01g (A&D, Tokyo, Japan). Hypothalamus samples
RLF re-fedwithLFdiet
werecollectedaccordingtoYuanetal.(2009),snap-frozeninliquid
18S 18SribosomalRNA
nitrogenandstoredat−80°CuntilRNAextraction.
humidity) until day 28 and was thereafter maintained at 21°C Experiment2
through to the end of the experiment. The light regime was 23 h At1dayold,128chickswithsimilarbodymassweredividedintotwo
light:1 h dark. All of the birds had free access to food and water groups with eight replicates/pens per group and eight chickens per
duringtherearingperiod. replicate.AsshowninFig.1B,thechickswererandomlyfedtheHFor
theLFdietfor35days.At36daysold,allofthechickenswerefasted
Experimentalprotocolandsamplecollection for 24h, then half of the experimental chickens in each group were
Experiment1 randomlyre-fedwithHFdietfor3h(HF-RHF,LF-RHF)orLFdiet
At1dayold,128chickswithsimilarbodymassweredividedinto for3h(LF-RLF,HF-RLF).Foodintakewasrecordedafterre-feeding.
twogroupswitheightreplicates/penspergroupandeightchickens Attheendoftheexperiment,eightchickenswithasimilarbodymass
per replicate. As shown in Fig. 1A, the chicks were randomly wererandomlyselectedfromeachtreatmentforsampling.Plasmaand
subjectedtooneofthefollowingtwotreatmentsfor35days:(1)high- hypothalamussampleswerecollectedasabove.
fat(HF)diet(15.06MJkg−1,13.5%soyoil)or(2)low-fat(LF)diet
(10.90MJkg−1,0%soyoil).Thecompositionandnutrientlevelsof Measurementofplasmainsulinlevels
theexperimentaldietsareshowninTable1.Foodintakeandbody Plasma insulin was measured using a radioimmunoassay with
massoftheeightchickensrearedinonepenwereweighedweekly guinea pig anti-porcine insulin serum (3V, Weifang, China). A
using an electronic balance with an accuracy of 1g (Senssun, largecross-reactionhasbeenobservedbetweenchickeninsulinand
Guangdong,China),andthedailyaveragefoodintake,energyintake theguineapiganti-porcinesera(Simonetal.,1974).Theinsulinin
A Fig.1.Schematicdiagramofthe
Fasted for 24 h experimentaldesign.Experiments
(N=32) weredesignedtoassesstheeffectof
Fed HF for 35 days dietaryfatonchickensunderdifferent
(N=64) feedingconditions[A,Experiment1;
Fed ad libitum
highfat(HF)andlowfat(LF)diet]or
(N=32)
1 day old chickens re-feedingconditions(B,Experiment2).
(N=128)
Fasted for 24 h
(N=32)
Fed LF for 35 days
(N=64)
Fed ad libitum
y
(N=32) g
o
l
o
B
i
B
Fasted for 24 h and then re-fed with HF for 3 h
l
(N=32) a
Fed HF for 35 days t
n
(N=64) e
Fasted for 24 h and then re-fed with LF for 3 h m
(N=32) i
r
e
1 day old chickens p
(N=128) x
E
f
Fasted for 24 h and then re-fed with HF for 3 h o
(N=32) l
Fed LF for 35 days a
n
(N=64)
r
Fasted for 24 h and then re-fed with LF for 3 h u
(N=32) o
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RESEARCHARTICLE JournalofExperimentalBiology(2017)220,607-614doi:10.1242/jeb.143792
Table1.Thecompositionandnutrientlevelsoftheexperimentaldiets (ΔCt). On the basis of the Ct values, 18S and GAPDH mRNA
(airdrybasis) expressionwerestableacrossthetreatmentsinthisstudy(P>0.1).
LF HF
Statisticalanalysis
Ingredients(%)
Dataarepresentedasmeans±s.e.m.Allofthedataweresubjected
Maize 46.622 44.859 to one-way ANOVA to test the effect of energy status under pre-
Soybeanmeal 30.676 36.984 feedingHForLFconditionsusingtheStatisticalAnalysisSystems
Cholinechloride 0.260 0.260
statistical software package (Version 8e, SAS Institute, Cary, NC,
Dicalciumphosphate 1.424 1.643
USA).Homogeneityofvariancesamongthegroupswasconfirmed
Limestone 1.893 1.742
DL-Methionine 0.255 0.294 using Bartlett’s test (SAS Institute). When the main effect of the
Lysine 0.271 0.246 treatmentwassignificant,thedifferencesbetweenthemeanswere
NaCl 0.255 0.255 assessed by Duncan’s multiple range analysis. The mean was
Soyoil 0 13.468 consideredsignificantlydifferentatP<0.05.
Bran 18.094 0
Vitaminpremix* 0.050 0.050
Mineralpremix‡ 0.200 0.200 RESULTS
Effectsofdietaryfatonproductionperformance,fat
Calculatedchemicalcomposition
depositionandplasmainsulin
Metabolizableenergy(MJkg−1) 10.900 15.060 After35daysoffeeding,thefoodintakeofthechickensfedtheHF
Crudeprotein(%) 20.000 20.000 diet was significantly lower than that of the LF diet-fed chickens
Met(%) 0.551 0.556
(P<0.05; Fig. 2A), but the energy intake and BMG showed the
Lys(%) 1.064 1.073
opposite result (P<0.05; Fig. 2B,C, Table 3). HF chickens had
Ca(%) 1.000 1.000
significantlyenhancedbodymassandfatdepositionintheabdomen
P(%) 0.450 0.450
and cervical subcutaneous tissues (P<0.05, Fig. 3) than chickens
HF,highfat;LF,lowfat.
fed the LF diet. Compared with the LF diet, the HF diet did not
*Vitaminpremixprovided(perkgofdiet):vitaminA,8000IU;vitaminD3,
3000IU;vitaminE,33mg;vitaminK3,2.3mg;thiamine,1.75mg;riboflavin, significantlyaffectinsulincontentintheplasmaofeitherfastedor
6.9mg;niacin,28.45mg;pantothenicacid,6.7mg;biotin,2.75mg;folicacid, adlibitumfedchickens(P>0.05,Fig.4A).
0.6mg;vitaminB12,2.2mg;choline(50%),840mg;cobalamin,2.2mg;and During the re-feeding period, the chickens fed the HF diet for
pyridoxine,3.35mg. 35daysmaintainedalowerfoodintakethanthechickensontheLF
‡Mineralpremixprovided(perkgofdiet):ferroussulphateheptahydrate,
diet (P<0.05), even when they were re-fed a different diet after
183.4mg;heptahydratezincsulphate,255mg;monohydrousmanganese
fasting (Fig. 2D); that is, the HF groups maintained a lower food
sulphate,276.8mg;coppersulphate,22mg;calciumiodide,2.2mg;and
intakethantheLFgroups,independentofthedietthechickenswere
pentahydratesodiumselenite,0.6mg.
re-fed.Theplasmainsulinlevelwasnotaffectedbytheleveloffat
thisstudyisreferredtoasimmunoreactiveinsulin.Thesensitivityof inthere-feedingdiet (P>0.05,Fig.4B).
theassaywas1μIUml−1,andallofthesampleswereincludedin
the same assay to avoid inter-assay variability. The intra-assay EffectsofdietaryfatonmRNAexpressionofhypothalamic
coefficientofvariationwas1.99%. appetite-relatedgenesinchickenswithdifferentenergy
statuses
RNAisolationandanalysis In Experiment 1, 24h fasting reduced the mRNA expression of
Total RNA extraction and real-time PCR were performed as NPY,AgRP,POMC,CRHandinsulinreceptor(INSR)compared
described previously (Liu et al., 2014). The primer sequences are with the fed condition (P<0.05; Figs 4C and 5A,C,E,G),
shown in Table 2. The PCR data were analysed with the 2−ΔΔCt independent of the diet the chickens ate before fasting. Under
method(LivakandSchmittgen,2001).ThemRNAlevelsoftarget both fed and fasted conditions, HF diet-fed chickens had a lower
genes were normalized to glyceraldehyde 3-phosphate AgRP mRNA level compared with the LF diet-fed chickens
dehydrogenase (GAPDH) mRNA and 18S ribosomal RNA (18S) (P<0.05,Fig.5C).
y
g
Table2.Gene-specificprimersusedfortheanalysisofchickengeneexpression o
l
o
Gene GenBankaccessionno. Primersequences(5′–3′) Productsize(bp) i
B
AgRP NM_001031457 F:GGAACCGCAGGCATTGTC 163 l
a
R:GTAGCAGAAGGCGTTGAAGAA t
n
CRH NM_001123031 F:CTCCCTGGACCTGACTTTCC 86 e
R:TGTTGCTGTGGGCTTGCT m
GAPDH NM_204305 F:ACATGGCATCCAAGGAGTGAG 266 i
r
R:GGGGAGACAGAAGGGAACAGA e
p
INSR AF111857 F:CAAACGGTGACCAAGCCTCA 186
x
R:CATCCTGCCCATCAAACTCCG E
NPY M87294 F:GAGGCACTACATCAACCTCATCAC 101 f
o
R:TGTTTTCTGTGCTTTCCCTCAA
l
POMC NM_001031098 F:CGCTACGGCGGCTTCA 88 a
R:TCTTGTAGGCGCTTTTGACGAT n
r
18S AF173612 F:ATAACGAACGAGACTCTGGCA 136 u
R:CGGACATCTAAGGGCATCACA o
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RESEARCHARTICLE JournalofExperimentalBiology(2017)220,607-614doi:10.1242/jeb.143792
A B
90 * 1250
*
1) –1) 1000
– y
y a
g da 60 kJ d 750
e ( e (
k k
a a
nt nt 500
d i 30 y i
o g
Fo ner 250
E
0 0
HF LF HF LF
C D
*
50
100 RHF
* RLF
40
–1day) 30 –1g 3 h) 6800
G (g 20 ake ( 40
M nt
B d i
o
10 o 20
F
0 0
HF LF HF LF
Fig.2.EffectsoftheHFdietonfoodintakeandbodymassgainofchickensafter35daysoffeedingand3hofre-feeding.(A–C)Foodintake,energy
intakeandbodymassgain(BMG)perbird,measuredduring35daysoffeeding.(D)Foodintakeperbird,measuredafter3hofre-feedingwiththeHF(RHF)orLF
(RLF)diet.Allofthedataweresubjectedtoone-wayANOVA.Valuesaremeans±s.e.m.(N=8forA–C,N=4forD).*Significantdifference(P<0.05).
InExperiment2,geneexpressioninresponsetore-feedingdiet demonstratethatchickensfedahighfatdietshowdecreasedfood
was compared between HF and LF groups. Among five appetite- intakeevenwhenthesubsequentdiettypeischanged.Inaddition,
related genes measured in the present study, NPY expression in dietaryfatalterstheresponseofhypothalamicNPYtosubsequent
response to re-feeding dietary fat was altered depending upon the energyintake.
feeding experience: in the HF group, re-feeding with the HF diet
(RHF)increasedNPYexpressioncomparedwithre-feedingwiththe HFdietdecreasesfoodintakeevenwhenthesubsequent
LF diet (RLF; P<0.05), while the LF group showed the opposite diettypeischanged
result,inwhichRHFdecreasedNPYexpressioncomparedwithRLF Chickensfedfor35dayswiththeHFdietdisplayeddecreasedfood
(P<0.05; Fig. 5B). For AgRP (Fig. 5D), RHF decreased AgRP intake,inlinewithourpreviousresultsdemonstratingthatchickens
expression compared with RLF in the LF group (statistically adjusted their food intake according to the dietary metabolizable
significant,P<0.05)andshowedatendencytodosointheHFgroup energy concentration (Yuan et al., 2008). The HF effect on food
(−51%,notstatisticallysignificant,P>0.05).ThemRNAexpression intakeislikelytobedrivenmainlybyenergyneeds,becauseseveral
ofPOMC,CRHandINSRwasnotsignificantlyaffectedbythelevel reports have shown that taste or palatability was relatively less
offatinthere-feedingdiet(P>0.05;Figs4Dand5F,H). important (Blundell et al., 1993, 1996; Berridge, 1996). The
viewpointthataHFdietinducesanincreaseinbodymasshasbeen
y
DISCUSSION widelyverifiedinhumanandanimalstudies(WestandYork,1998; g
o
Inthepresentstudy,weinvestigatedwhetherdietaryfatinfluenced Murtaughetal.,2007)andwasalsoshowninthepresentstudy.The l
o
theresponseofhypothalamicappetite-relatedpeptidestodifferent increaseinbodymassresultedfromahigherproportionofadipose i
B
energy statuses (fed versus fasted; RHF versus RLF). The results tissueratherthanskeletalmuscle(WestandYork,1998;Murtaugh
l
a
etal.,2007).Weobservedthattheadiposemassintheabdomenand
t
Table3.EffectofHFdietonbodymassofchickensover35days cervical subcutaneoustissues relative to body mass was higher in en
HF diet-fed chickens than in LF diet-fed chickens, in line with m
BMG(gday−1) HF LF P-value
previous work showing that high dietary energy promotes lipid ri
Week1 7.5±0.1 7.8±0.2 0.1993 deposition(Eitsetal.,2002).ThefavourableeffectoftheHFdiet e
p
Week2 32.1±0.6 33.3±0.2 0.0876 on body mass and fat deposition can be ascribed to the higher x
Week3 27.6±1.2 27.2±1.6 0.8376 E
energy ingestion, despite the lower food intake. In addition, fat
Week4 51.4±2.7a 40.7±2.1b 0.0199 f
accumulation isgreater whenmoreenergy comes from dietary fat o
Week5 70.3±4.2a 51.4±2.4b 0.0077
thanfromcarbohydratesorproteins(Hortonetal.,1995;Leanand al
Bodymasswasrecordedweekly,andbodymassgain(BMG)perbirdwas n
James,1988).
calculatedweekbyweekfor5weeks(35days).Allofthedataweresubjected r
Chickens fed for 35days with the HF diet maintained a lower u
toone-wayANOVA.Valuesaremeans±s.e.m.(N=8).Differentsuperscript o
lettersindicateasignificantdifference(P<0.05). food intake than those fed the LF diet, even when the diet was J
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RESEARCHARTICLE JournalofExperimentalBiology(2017)220,607-614doi:10.1242/jeb.143792
A B Fig.3.EffectsoftheHFdietonfat
*
1.5 1.5 depositionandbodymassinchickens
s
as after35days.(A)Abdominalfat,
m
at massmass) 1.0 eous fat mass) 01..92 ((mBCa))scsseu.rbBvciocudataylnsmeuaobsucssutwtahanigsehomufeasatfsaaunt,rded(Da)ttbhoedeynd
ominal f% body 0.5 ubcutan% body 0.6 * ommfaathsssse.iesAxelplxdeparritmeaseswneetdraeanssduaibspjegecirvcteeednnttpaoegorenboeirf-dwb.oaFdyayt
Abd( al s( 0.3 ANOVA.Valuesaremeans±s.e.m.(N=8).
vic *Significantdifference(P<0.05).
er
0 C 0
HF LF HF LF
C D
1.5 2000
s
s *
a
m 1.2
utaneous thigh fat (% body mass) 000...963 Body mass (g)11505000000
c
b
u
S
0 0
HF LF HF LF
altered during the re-feeding period. These results could be meal-induced satiety, thereby reducing food intake (Marx, 2003;
explained by the following. (1) Chickens have a short-term Mortonetal.,2014).
memory function regarding food intake; according to studies in In mammals, circulating insulin signals the hypothalamus to
humans(Higgs,2002),arecenteatingepisodemaybefactoredinto effect long-term changes in energy balance by activating and/or
decisions about howmuch to consume atthe next meal.(2) Food inhibiting specific anabolic and catabolic pathways (Woods et al.,
intake is adjusted in response to changes in body fat content; the 2006). Insulin receptors have been identified in the brains of
increased leptin activity following body fat deposition decreases chickens (Simon and Leroith, 1986), and intracerebroventricular
foodintakebyincreasingthehindbrainresponsetosatietysignals insulininjectioninhibitedfoodconsumptioninlayerhens(Shiraishi
(Schwartz et al., 2000). The positive energy balance induced by et al., 2011). Obrosova et al. (2007) found that a HF diet was
HF inhibits the rewarding properties of food while enhancing accompanied by an increase in insulin; however, in the present
A Fed B RHF Fig.4.EffectsoftheHFdieton
30 Fasted 30 RLF plasmainsulinlevelsand
* hypothalamicinsulinreceptor
*
24 24 (INSR)mRNAexpressionin
1) chickensunderdifferentfeeding
–
ml andre-feedingconditions.
U 18 18 (A,C)Insulin(A)andINSRexpression
µI
ulin ( 12 12 (thCe;ffoelddainncdrefaassteedofsLtaFt-efa.stedlevels)in
ns (B,D)Insulin(B)andINSRexpression
I 6 6 (D;foldincreaseofLF-RLFlevels) y
g
followingre-feedingwiththeHFdiet o
0 0 (RHF)orLFdiet(LFR).Valuesare ol
HF LF HF LF means±s.e.m.(N=8).*Significant Bi
difference(P<0.05).
C D al
3 1.5 t
n
e
n * m
o
essie) 2 * 1.0 eri
e exprchang Exp
R gen(fold 1 0.5 of
S l
N a
I n
r
u
0 0
o
HF LF HF LF J
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RESEARCHARTICLE JournalofExperimentalBiology(2017)220,607-614doi:10.1242/jeb.143792
Fed RHF Fig.5.EffectsoftheHFdietonthe
1.5 A * * Fasted 1.5 B RLF mapRpNetAitee-xrperlaetsesdiognenoefshyinpocthhiaclkaemnisc
underdifferentfeedingandre-
*
on * feedingconditions.(A,C,E,G)
e expressincrease) 1.0 1.0 cpNreoreolrautotircepoodipotrepmopepetpiilndati-ednreoeYcle(oA(aNrgstiPRinnYPg(,P,hAOCo))M,r,maCgo,onEue)ti-and
genold i 0.5 0.5 (CRH,G)geneexpression(fold
Y (f increaseofLF-fastedlevels)inthefed
P
N andfastedstate.(B,D,F,H)NPY(B),
AgRP(D),POMC(F)andCRH(H)
0 0 geneexpression(foldincreaseofLF-
HF LF HF LF RLFlevels)followingre-feedingwith
theHFdiet(RHF)orLFdiet(LFR).
C
* D Dataweresubjectedtoone-way
18 * * 2.0 ANOVA.Valuesaremeans±s.e.m.
(N=8).*Significantdifference
n (P<0.05).
sio 1.5 *
ese) 12
pras
ene exd incre 1.0
RP g(fol 6 0.5
g
A
0 0
HF LF HF LF
E
* F
6 2.0
*
n
o
si 1.5
ese) 4
MC gene expr(fold increas 2 10..05
O
P
0 0
HF LF HF LF
G H
4 1.5
*
n *
pressioase) 3 1.0
xe
ene ed incr 2 gy
RH g(fol 1 0.5 olo
C
i
B
0 0 al
HF LF HF LF t
n
e
study, the plasma insulin and hypothalamic INSR mRNA levels InvolvementofAgRPintheHF-induceddecreaseinfood m
werenotaffectedbydietaryfat.Theseresultsareinconsistentwith intake ri
e
the previous report that HF induces an increase in insulin Multiple neuronal populations distributed throughout the brain
p
concentration compared with a control diet in mice (Obrosova influencethedecisiontoseekandconsumefood.AgRPneurons x
E
et al., 2007) and rats (Sinitskaya et al., 2007). Our results suggest are thought to positively regulate feeding behaviour. AgRP
f
that insulin secretion is not sensitive to dietary fat. Accordingly, increased food intake when injected into the brain (Hahn et al., o
Shiraishi et al. (2011) found that intracerebroventricular insulin 1998).Previousstudieshaveshownthatmiceonahighsaturated al
n
treatment did not affect food consumption in chicks under fasted fat diet for 1, 4 and 7weeks had decreased ARC AgRP mRNA
r
andadlibitumconditions.Theroleofinsulinasanafferentsignal levels (Wang et al., 2002). Similarly, our study showed that the u
o
forenergystoresinpoultryremainstobedetermined. HFdiet-fedchickenshadalowerAgRPmRNAlevelthantheLF J
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RESEARCHARTICLE JournalofExperimentalBiology(2017)220,607-614doi:10.1242/jeb.143792
diet-fed chickens under both fed and fasted conditions. Authorcontributions
HypothalamicAgRPneuronactivationmightbeassociatedwith H.L.conceivedanddesignedtheexperiments,X.J.W.performedtheexperiments,
S.H.X.andL.L.collectedandanalyzedthedata,X.J.W.interpretedthedataand
the higher food intake in LF diet-fed chickens, confirming the
wrotethearticle,H.C.J.andZ.G.S.revisedthearticle.Allauthorsreadandapproved
previousfindingontheorexigeniceffectofhypothalamicAgRP.
thefinalmanuscript.
IncontrasttoAgRP,wefoundthatNPY,POMCandCRHwere
not affected by 35days of HF diet in the present study. These Funding
results are inconsistent with studies in mammals which showed ThisworkwassupportedbytheNationalNaturalScienceFoundationofChina
that NPY, POMC and CRH levels were affected by a HF diet [31301993,31472114];andtheNaturalScienceFoundationofShandongProvince
[ZR2014CP028].
(Guan et al., 1998; Chavez et al., 1998; Lin et al., 2000;
Lukaszewski et al., 2013), implying a genetic bluntness in the
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