The hypothalamus (from Greek, "under" and , "room, chamber") is a or!ion of!he brain !ha! con!ains a number of sma"" nuc"ei #i!h a $arie!% of func!ions& 'ne of !he mos! imor!an! func!ions of !he h%o!ha"amus is !o "ink !he ner$ous s%s!em !o !heendocrine s%s!em $ia !he i!ui!ar% ("and (h%oh%sis)&The h%o!ha"amus is "oca!ed be"o# !he !ha"amus, )us! abo$e !he brains!em and is ar! of !he "imbic s%s!em&*+, -n !he !ermino"o(% ofneuroana!om%, i! forms !he $en!ra" ar! of !he dienceha"on& ."" $er!ebra!e brains con!ain a h%o!ha"amus& -n humans, i! is !he si/e of an a"mond&The h%o!ha"amus is resonsib"e for cer!ain me!abo"ic rocesses and o!her ac!i$i!ies of !he au!onomic ner$ous s%s!em& -! s%n!hesi/es and secre!es cer!ain neurohormones, of!en ca""ed re"easin( hormones or h%o!ha"amic hormones, and !hese in !urn s!imu"a!e or inhibi! !he secre!ion of i!ui!ar% hormones& The h%o!ha"amus con!ro"s bod% !emera!ure, hun(er, imor!an! asec!s of aren!in( and a!!achmen! beha$iors, !hirs!,*0, fa!i(ue, s"ee, and circadian rh%!hms&Contents*hide, +1!ruc!ureo +&+2uc"eio +&02eura" connec!ionso +&31e4ua" dimorhismo +&56e$e"omen! 07unc!iono 0&+8ormone re"easeo 0&01!imu"a!ion 0&0&+'"fac!or% s!imu"i 0&0&09"ood:borne s!imu"i 0&0&31!eroids 0&0&52eura"o 0&3;on!ro" of food in!akeo 0&57ear rocessin(o 0&8, differen!ia" de$e"omen! be!#een se4es is based uon in u!ero !es!os!erone "e$e"s1urao!ic nuc"eus Easoressin re"ease '4%!ocin re"easeDara$en!ricu"ar nuc"eus !h%ro!roin:re"easin( hormone re"ease cor!ico!roin:re"easin( hormone re"ease o4%!ocin re"ease $asoressin re"ease soma!os!a!in re"ease.n!erior h%o!ha"amic nuc"eus !hermore(u"a!ion an!in( s#ea!in( !h%ro!roin inhibi!ion1urachiasma!ic nuc"eus ;ircadian rh%!hmsFa!era"Fa!era" nuc"eus 1ee Fa!era" h%o!ha"amusG7unc!ion H rimar% source of ore4in neurons !hrou(hou! !he brain and sina" cordTubera"Bedia"6orsomedia" h%o!ha"amic nuc"eus 9"ood Dressure 8ear! >a!e G- s!imu"a!ionEen!romedia" nuc"eus sa!ie!% neuroendocrine con!ro".rcua!e nuc"eus Gro#!h hormone:re"easin( hormone (G8>8) feedin( 6oamine:media!ed ro"ac!in inhibi!ionFa!era"Fa!era" nuc"eus1ee Fa!era" h%o!ha"amusG7unc!ion H rimar% source of ore4in neurons !hrou(hou! !he brain and sina" cordFa!era" !ubera" nuc"eiDos!eriorBedia"Bammi""ar% nuc"ei (ar!ofmammi""ar% bodies) memor%Dos!erior nuc"eus -ncrease b"ood ressure ui""ar% di"a!ion shi$erin( $asoressin re"easeFa!era" Fa!era" nuc"eus 1ee Fa!era" h%o!ha"amusG7unc!ion H rimar% source of ore4in neurons !hrou(hou! !he brain and sina" cordTuberomammi""ar% nuc"eus *?, arousa" (#akefu"ness and a!!en!ion) feedin( and ener(% ba"ance "earnin( memor% s"eeSee also: $en!ro"a!era" reo!ic nuc"eus, eri$en!ricu"ar nuc"eus&. cross sec!ion of !he monke% h%o!ha"amus dis"a%s 0 of !he ma)or h%o!ha"amic nuc"ei on ei!her side of !he f"uid:fi""ed 3rd $en!ric"e& 8%o!ha"amic nuc"ei 8%o!ha"amic nuc"ei on one side of !he h%o!ha"amus, sho#n in a 3:6 comu!er recons!ruc!ion*@,Neural connections*edi!,Further information: Lateral hypothalamus Orexinergic projection system and Tuberomammillary nucleus Histaminergic outputsThe h%o!ha"amus is hi(h"% in!erconnec!ed #i!h o!her ar!s of !he cen!ra" ner$ous s%s!em, in ar!icu"ar !he brains!em and i!s re!icu"ar forma!ion& .s ar! of !he "imbic s%s!em, i! has connec!ions !oo!her "imbic s!ruc!ures inc"udin( !he am%(da"a and se!um, and is a"so connec!ed #i!h areas of !he au!onomous ner$ous s%s!em&The h%o!ha"amus recei$es man% inu!s from !he brains!em, !he mos! no!ab"e from !he nuc"eus of !he so"i!ar% !rac!, !he "ocus coeru"eus, and !he $en!ro"a!era" medu""a&Bos! ner$e fibres #i!hin !he h%o!ha"amus run in !#o #a%s (bidirec!iona")& Dro)ec!ions !o areas cauda" !o !he h%o!ha"amus (o !hrou(h !he media" forebrain bund"e, !he mammi""o!e(men!a" !rac! and !he dorsa" "on(i!udina" fascicu"us& Dro)ec!ions !o areas ros!ra" !o !he h%o!ha"amus are carried b% !he mammi""o!ha"amic !rac!, !he forni4 and !ermina" s!ria& Dro)ec!ions !o areas of !he s%ma!he!ic mo!or s%s!em ("a!era" horn sina" se(men!s T+:F0IF3) are carried b% !he h%o!ha"amosina" !rac! and !he% ac!i$a!e !he s%ma!he!ic mo!or a!h#a%Sexual dimorphism*edi!,1e$era" h%o!ha"amic nuc"ei are se4ua""% dimorhicJ i&e&, !here are c"ear differences in bo!h s!ruc!ure and func!ion be!#een ma"es and fema"es&*citation needed,1ome differences are aaren! e$en in (ross neuroana!om%C mos! no!ab"e is !he se4ua""% dimorhic nuc"eus #i!hin !he reo!ic area& 8o#e$er mos! of !he differences are sub!"e chan(es in !he connec!i$i!% and chemica" sensi!i$i!% of ar!icu"ar se!s of neurons&*citation needed,The imor!ance of !hese chan(es can be reco(nised b% func!iona" differences be!#een ma"es and fema"es& 7or ins!ance, ma"es of mos! secies refer !he odor and aearance of fema"es o$er ma"es, #hich is ins!rumen!a" in s!imu"a!in( ma"e se4ua" beha$ior& -f !he se4ua""% dimorhic nuc"eus is"esioned, !his reference for fema"es b% ma"es diminishes& ."so, !he a!!ern of secre!ion of (ro#!h hormone is se4ua""% dimorhic, and !his is one reason #h% in man% secies, adu"! ma"es are much "ar(er !han fema"es&*citation needed,Responsiveness to ovarian steroids'!her s!rikin( func!iona" dimorhisms are in !he beha$iora" resonses !o o$arian s!eroids of !he adu"!& Ba"es and fema"es resond !o o$arian s!eroids in differen! #a%s, ar!"% because !he e4ression of es!ro(en:sensi!i$e neurons in !he h%o!ha"amus is se4ua""% dimorhicJ i&e&, es!ro(en rece!ors are e4ressed in differen! se!s of neurons&*citation needed,As!ro(en and ro(es!erone can inf"uence (ene e4ression in ar!icu"ar neurons or induce chan(es in ce"" membrane o!en!ia" and kinase ac!i$a!ion, "eadin( !o di$erse non:(enomic ce""u"ar func!ions& As!ro(en and ro(es!erone bind !o !heir co(na!e nuc"ear hormone rece!ors, #hich !rans"oca!e !o !he ce"" nuc"eus and in!erac! #i!h re(ions of 62. kno#n as hormone resonse e"emen!s (8>As) or (e! !e!hered !o ano!her !ranscri!ion fac!orKs bindin( si!e& As!ro(en rece!or (A>) has been sho#n !o !ransac!i$a!e o!her !ranscri!ion fac!ors in !his manner, desi!e !he absence of an es!ro(en resonsee"emen! (A>A) in !he ro4ima" romo!er re(ion of !he (ene& -n (enera", A>s and ro(es!erone rece!ors (D>s) are (ene ac!i$a!ors, #i!h increased m>2. and subseLuen! ro!ein s%n!hesis fo""o#in( hormone e4osure&*citation needed,Ba"e and fema"e brains differ in !he dis!ribu!ion of es!ro(en rece!ors, and !his difference is an irre$ersib"e conseLuence of neona!a" s!eroid e4osure& As!ro(en rece!ors (and ro(es!erone rece!ors) are found main"% in neurons in !he an!erior and mediobasa" h%o!ha"amus, no!ab"%C*citation needed, !he reo!ic area (#here F8>8 neurons are "oca!ed) !he eri$en!ricu"ar nuc"eus (#here soma!os!a!in neurons are "oca!ed) !he $en!romedia" h%o!ha"amus (#hich is imor!an! for se4ua" beha$ior)&Development*edi!,Bedian sa(i!!a" sec!ion of brain of human embr%o of !hree mon!hs-n neona!a" "ife, (onada" s!eroids inf"uence !he de$e"omen! of !he neuroendocrine h%o!ha"amus& 7or ins!ance, !he% de!ermine !he abi"i!% of fema"es !o e4hibi! a norma" reroduc!i$e c%c"e, and of ma"es and fema"es !o dis"a% aroria!e reroduc!i$e beha$iors in adu"! "ife&*citation needed, -f a female rat is in)ec!ed once #i!h !es!os!erone in !he firs! fe# da%s of os!na!a" "ife (durin( !he "cri!ica" eriod" of se4:s!eroid inf"uence), !he h%o!ha"amus is irre$ersib"% mascu"ini/edJ !he adu"! ra! #i"" be incaab"e of (enera!in( an F8 sur(e in resonse !o es!ro(en (a charac!eris!ic of fema"es), bu! #i"" be caab"e of e4hibi!in( male se4ua" beha$iors (moun!in( a se4ua""% rece!i$e fema"e)&*citation needed, 9% con!ras!, a male rat cas!ra!ed )us! af!er bir!h #i"" be feminized, and !he adu"! #i"" sho# female se4ua" beha$ior in resonse !o es!ro(en (se4ua" rece!i$i!%, "ordosis beha$ior)&*citation needed,-n rima!es, !he de$e"omen!a" inf"uence of andro(ens is "ess c"ear, and !he conseLuences are "ess unders!ood& Mi!hin !he brain, !es!os!erone is aroma!i/ed !o (es!radio"), #hich is !he rincia" ac!i$e hormone for de$e"omen!a" inf"uences& The human !es!is secre!es hi(h "e$e"s of !es!os!erone from abou! #eek @ of fe!a" "ife un!i" 7 s%n!hesis and secre!ion, bu! e"se#here !heir ro"e is no! #e"" unders!ood&Function*edi!,Hormone release*edi!,Andocrine ("ands in !he human head and neck and !heir hormonesThe h%o!ha"amus has a cen!ra" neuroendocrine func!ion, mos! no!ab"% b% i!s con!ro" of !he an!erior i!ui!ar%, #hich in !urn re(u"a!es $arious endocrine ("ands and or(ans& >e"easin( hormones (a"so ca""ed re"easin( fac!ors) are roduced in h%o!ha"amic nuc"ei !hen !ransor!ed a"on( a4ons !o ei!her !he median eminence or !he os!erior i!ui!ar%, #here !he% are s!ored and re"eased as needed&*+P,Anterior pituitary-n !he h%o!ha"amicHadenoh%oh%sea" a4is, re"easin( hormones, a"so kno#n as h%oh%sio!roic or h%o!ha"amic hormones, are re"eased from !he median eminence, a ro"on(a!ion of !he h%o!ha"amus, in!o !he h%oh%sea" or!a" s%s!em, #hich carries !hem !o !he an!erior i!ui!ar% #here!he% e4er! !heir re(u"a!or% func!ions on !he secre!ion of adenoh%o%sea" hormones&*++,Secreted hormoneAbbreviationProduced by Eect!hyrotropin"releasing hormone#Prolactin"releasinghormone$T>8, T>7, orD>8Dar$oce""u"ar neurosecre!or% ce""s of !heara$en!ricu"ar nuc"eus1!imu"a!e !h%roid:s!imu"a!in( hormone (T18) re"ease from an!erior i!ui!ar% (rimari"%)1!imu"a!e ro"ac!in re"ease from an!erior i!ui!ar%Corticotropin"releasing hormone;>8 or ;>7Dar$oce""u"ar neurosecre!or% ce""s of !he ara$en!ricu"ar nuc"eus1!imu"a!e adrenocor!ico!roic hormone (.;T8) re"ease from an!erior i!ui!ar%Dopamine#Prolactin"inhibitinghormone$6. or D-86oamine neurons of !he arcua!e nuc"eus-nhibi! ro"ac!in re"ease from an!erior i!ui!ar%%ro&th"hormone"releasing hormoneG8>82euroendocrine neurons of !he .rcua!e nuc"eus1!imu"a!e (ro#!h:hormone (G8) re"ease from an!erior i!ui!ar%%onadotropin"releasing hormoneGn>8 or F8>82euroendocrine ce""s of!heDreo!ic area1!imu"a!e fo""ic"e:s!imu"a!in( hormone (718) re"ease from an!erior i!ui!ar%1!imu"a!e "u!eini/in( hormone (F8) re"ease from an!erior i!ui!ar%Somatostatin *+0,#gro&th"hormone"inhibiting hormone$11, G8-8, or1>-72euroendocrine ce""s of!heDeri$en!ricu"ar nuc"eus-nhibi! (ro#!h:hormone (G8) re"ease from an!erior i!ui!ar%-nhibi! (modera!e"%) !h%roid:s!imu"a!in( hormone (T18) re"ease from an!erior i!ui!ar%'!her hormones secre!ed from !he median eminence inc"ude $asoressin, o4%!ocin, and neuro!ensin&*+3,*+5,*+8 is inhibi!ed&The h%o!ha"amus is resonsi$e !oC Fi(h!C da%"en(!h and ho!oeriod for re(u"a!in( circadian and seasona" rh%!hms '"fac!or% s!imu"i, inc"udin( heromones 1!eroids, inc"udin( (onada" s!eroids and cor!icos!eroids 2eura""% !ransmi!!ed informa!ion arisin( in ar!icu"ar from !he hear!, !he s!omach, and !he reroduc!i$e !rac! .u!onomic inu!s 9"ood:borne s!imu"i, inc"udin( "e!in, (hre"in, an(io!ensin, insu"in, i!ui!ar% hormones, c%!okines, "asma concen!ra!ions of ("ucose and osmo"ari!% e!c& 1!ress -n$adin( microor(anisms b% increasin( bod% !emera!ure, rese!!in( !he bod%Ks !hermos!a! u#ard&'lactory stimuli*edi!,'"fac!or% s!imu"i are imor!an! for se4ua" reroduc!ion and neuroendocrine func!ion in man% secies&7or ins!ance if a re(nan! mouse is e4osed !o !he urine of a Ks!ran(eK ma"e durin( a cri!ica" eriod af!er coi!us !hen !he re(nanc% fai"s (!he 9ruce effec!)& Thus, durin( coi!us, a fema"e mouse forms a recise Ko"fac!or% memor%K of her ar!ner !ha! ersis!s for se$era" da%s& Dheromona" cues aid s%nchronisa!ion of oes!rus in man% seciesJ in #omen, s%nchronised mens!rua!ion ma% a"so arise from heromona" cues, a"!hou(h !he ro"e of heromones in humans is disu!ed&)lood"borne stimuli*edi!,De!ide hormones ha$e imor!an! inf"uences uon !he h%o!ha"amus, and !o do so !he% mus! ass !hrou(h !he b"oodHbrain barrier& The h%o!ha"amus is bounded in ar! b% secia"i/ed brain re(ions !ha! "ack an effec!i$e b"oodHbrain barrierJ !he cai""ar% endo!he"ium a! !hese si!es is fenes!ra!ed !o a""o# free assa(e of e$en "ar(e ro!eins and o!her mo"ecu"es& 1ome of !hese si!es are !he si!es of neurosecre!ion : !he neuroh%oh%sis and !he median eminence& 8o#e$er, o!hers are si!es a! #hich!he brain sam"es !he comosi!ion of !he b"ood& T#o of !hese si!es, !he 17' (subfornica" or(an) and !he 'EFT (or(anum $ascu"osum of !he "amina !ermina"is) are so:ca""ed circum$en!ricu"ar or(ans, #here neurons are in in!ima!e con!ac! #i!h bo!h b"ood and ;17& These s!ruc!ures are dense"% $ascu"ari/ed, and con!ain osmorece!i$e and sodium:rece!i$e neurons !ha! con!ro"drinkin(, $asoressin re"ease, sodium e4cre!ion, and sodium ae!i!e& The% a"so con!ain neurons #i!h rece!ors for an(io!ensin, a!ria" na!riure!ic fac!or, endo!he"in and re"a4in, each of #hich imor!an! in !he re(u"a!ion of f"uid and e"ec!ro"%!e ba"ance& 2eurons in !he 'EFT and 17' ro)ec! !o !he surao!ic nuc"eus and ara$en!ricu"ar nuc"eus, and a"so !o reo!ic h%o!ha"amic areas& The circum$en!ricu"ar or(ans ma% a"so be !he si!e of ac!ion of in!er"eukins !o e"ici! bo!h fe$er and .;T8 secre!ion, $ia effec!s on ara$en!ricu"ar neurons&*citation needed,-! is no! c"ear ho# a"" e!ides !ha! inf"uence h%o!ha"amic ac!i$i!% (ain !he necessar% access& -n !he case of ro"ac!in and "e!in, !here is e$idence of ac!i$e u!ake a! !he choroid "e4us from !he b"ood in!o !he cerebrosina" f"uid (;17)& 1ome i!ui!ar% hormones ha$e a ne(a!i$e feedback inf"uence uon h%o!ha"amic secre!ionJ for e4am"e, (ro#!h hormonefeeds back on !he h%o!ha"amus, bu! ho# i! en!ers !he brain is no! c"ear& There is a"so e$idence for cen!ra" ac!ions of ro"ac!in&*citation needed,7indin(s ha$e su((es!ed !ha! !h%roid hormone (T5) is !aken u b% !he h%o!ha"amic ("ia" ce""s in !he infundibu"ar nuc"eusI median eminence, and !ha! i! is here con$er!ed in!o T3b% !he !%e 0 deiodinase (60)& 1ubseLuen! !o !his, T3 is !ransor!ed in!o !he !h%ro!roin:re"easin( hormone (T>8):roducin( neurons in !he ara$en!ricu"ar nuc"eus& Th%roid hormone rece!ors ha$e been found in !hese neurons, indica!in( !ha! !he% are indeed sensi!i$e !o T3 s!imu"i& -n addi!ion, !hese neurons e4ressed B;T@, a !h%roid hormone!ransor!er, suor!in( !he !heor% !ha! T3 is !ransor!ed in!o !hem& T3 cou"d !hen bind !o !he !h%roid hormone rece!or in !hese neurons and affec! !he roduc!ion of !h%ro!roin:re"easin( hormone, !hereb% re(u"a!in( !h%roid hormone roduc!ion&*+@,The h%o!ha"amus func!ions as a !%e of !hermos!a! for !he bod%&*+N, -! se!s a desired bod% !emera!ure, and s!imu"a!es ei!her hea! roduc!ion and re!en!ion !o raise !he b"ood !emera!ure !o a hi(her se!!in( or s#ea!in( and $asodi"a!ion !o coo" !he b"ood !o a "o#er !emera!ure& ."" fe$ers resu"! from a raised se!!in( in !he h%o!ha"amusJ e"e$a!ed bod% !emera!ures due !o an% o!her cause are c"assified as h%er!hermia&*+N, >are"%, direc! dama(e !o !he h%o!ha"amus, such as from a s!roke, #i"" cause a fe$erJ !his is some!imes ca""ed a hypothalamic feer& 8o#e$er, i! is more common for such dama(e !o cause abnorma""% "o# bod% !emera!ures&*+N,Steroids*edi!,The h%o!ha"amus con!ains neurons !ha! reac! s!ron("% !o s!eroids and ("ucocor!icoids H (!he s!eroid hormones of !he adrena" ("and, re"eased in resonse !o .;T8)& -! a"so con!ains secia"i/ed ("ucose:sensi!i$e neurons (in !he arcua!e nuc"eus and $en!romedia" h%o!ha"amus), #hich are imor!an! for ae!i!e& The reo!ic area con!ains !hermosensi!i$e neuronsJ !hese are imor!an! for T>8 secre!ion&Neural*edi!,'4%!ocin secre!ion in resonse !o suck"in( or $a(ino:cer$ica" s!imu"a!ion is media!ed b% some of !hese a!h#a%sJ $asoressin secre!ion in resonse !o cardio$ascu"ar s!imu"i arisin( from chemorece!ors in !he caro!id bod% and aor!ic arch, and from "o#:ressure a!ria" $o"ume rece!ors, is media!ed b% o!hers& -n !he ra!, s!imu"a!ion of !he $a(ina a"so causes ro"ac!in secre!ion, and !his resu"!s in seudo:re(nanc% fo""o#in( an infer!i"e ma!in(& -n !he rabbi!, coi!us e"ici!s ref"e4 o$u"a!ion& -n !he shee, cer$ica" s!imu"a!ion in !he resence of hi(h "e$e"s of es!ro(en can induce ma!erna" beha$ior in a $ir(in e#e& These effec!s are a"" media!ed b% !he h%o!ha"amus, and !he informa!ion is carried main"% b% sina" a!h#a%s !ha! re"a% in !he brains!em& 1!imu"a!ion of !he ni"es s!imu"a!es re"ease of o4%!ocin and ro"ac!in and suresses !he re"ease of F8 and 718&;ardio$ascu"ar s!imu"i are carried b% !he $a(us ner$e& The $a(us a"so con$e%s a $arie!% of $iscera" informa!ion, inc"udin( for ins!ance si(na"s arisin( from (as!ric dis!ension or em!%in(, !o suress or romo!e feedin(, b% si(na""in( !he re"ease of "e!in or (as!rin, resec!i$e"%& .(ain !his informa!ion reaches !he h%o!ha"amus $ia re"a%s in !he brains!em&-n addi!ion h%o!ha"amic func!ion is resonsi$e !oSand re(u"a!ed b%S"e$e"s of a"" !hree c"assica" monoamine neuro!ransmi!!ers, noradrena"ine, doamine, and sero!onin (& "'$er$ie# of 8%o!ha"amic and Di!ui!ar% 8ormones"& >e!rie$ed < 'c!ober0P+5&++& +ump up , Be"med 1, Wameson WF (0PP