{"id":9680,"date":"2021-01-26T19:18:17","date_gmt":"2021-01-26T16:18:17","guid":{"rendered":"http:\/\/blog.ulubat.org\/?p=9680"},"modified":"2021-01-26T19:18:19","modified_gmt":"2021-01-26T16:18:19","slug":"ghrelin-hormonu-ve-fizyolojik-etkileri","status":"publish","type":"post","link":"https:\/\/blog.ulubat.org\/index.php\/genel\/ghrelin-hormonu-ve-fizyolojik-etkileri\/","title":{"rendered":"GHREL\u0130N HORMONU VE F\u0130ZYOLOJ\u0130K ETK\u0130LER\u0130"},"content":{"rendered":"\n

Ghrelin hormonu, 28 aminoasitten olu\u015fan bir gastrointestinal peptittir. Ba\u015fl\u0131ca \u00fcretim yeri mide fundusu olmakla birlikte beyin, ba\u011f\u0131rsak, b\u00f6brek, kalp, yumurtal\u0131klar, pankreas gibi bir\u00e7ok organdan da salg\u0131lan\u0131r. Preproghrelin geni taraf\u0131ndan inaktif olarak \u00fcretilir. \u00dc\u00e7\u00fcnc\u00fc aminoasidi olan serine Ghrelin O-a\u00e7il transferaz (GOAT) enzimi arac\u0131l\u0131\u011f\u0131yla 8 ya da 10 karbonlu ya\u011f asidi ba\u011flanmas\u0131 ile aktif formu olan ghrelin olu\u015fur (\u015eekil 1) [1,3].<\/p>\n\n\n\n

\"\"
\u015eekil 1. Preproghrelin(mavi ve ye\u015fil) ve ghrelin (ye\u015fil) [4]<\/figcaption><\/figure><\/div>\n\n\n\n

Ghrelinin Fizyolojik Etkileri<\/strong><\/p>\n\n\n\n

\u0130lk olarak b\u00fcy\u00fcme hormonunun sal\u0131n\u0131m\u0131n\u0131 uyaran bir peptit olarak ke\u015ffedilen ghrelinin, bir\u00e7ok farkl\u0131 fizyolojik etkisi bulunur (\u015eekil 2.).<\/p>\n\n\n\n

1.Besin al\u0131m\u0131<\/strong><\/p>\n\n\n\n

Beslenme metabolizmas\u0131n\u0131n \u00f6nemli bir eleman\u0131d\u0131r. A\u00e7l\u0131k durumunda kandaki seviyeleri artarak hipotalamusta i\u015ftah a\u00e7\u0131c\u0131 merkez olan oreksijenik alan\u0131 uyar\u0131r ve yeme iste\u011fini artt\u0131r\u0131r. Ayr\u0131ca, hipotalamus, amigdala ve prefrontal korteks gibi \u00f6d\u00fcl merkezlerini de uyar\u0131r. Bu da yeme \u00fczerinde etkisinin \u00f6d\u00fcl odakl\u0131 olabilece\u011fini d\u00fc\u015f\u00fcnd\u00fcrmektedir. Anoreksiyal\u0131 kad\u0131nlarda santral sinir sistemi direnci nedeniyle bu merkezlerin uyar\u0131m\u0131 ger\u00e7ekle\u015fmemektedir [1,2].   <\/p>\n\n\n\n

2.Enerji ve ya\u011f metabolizmas\u0131<\/strong><\/p>\n\n\n\n

Enerji metabolizmas\u0131n\u0131 d\u00fczenler.  \u0130\u015ftah a\u00e7\u0131c\u0131 etkisiyle enerji al\u0131m\u0131n\u0131 artt\u0131r\u0131rken, di\u011fer taraftan enerji t\u00fcketimi artt\u0131r\u0131r. Ya\u011f metabolizmas\u0131nda ise, i\u015ftah a\u00e7\u0131c\u0131 etkisinden ba\u011f\u0131ms\u0131z olarak g\u00f6rev g\u00f6r\u00fcr. Lipogenez ve adipogenezi artt\u0131r\u0131r, lipolizi azalt\u0131r ve ya\u011f depolanmas\u0131na sebep olur [2].<\/p>\n\n\n\n

3.Beyin aktiviteleri<\/strong><\/p>\n\n\n\n

\u00d6\u011frenmede ve bellekte \u00f6nemli rol oynar. Dola\u015f\u0131mdaki ghrelin, hipokampustaki n\u00f6ronlara ba\u011flanarak uzaysal \u00f6\u011frenme ve belle\u011fi uyar\u0131r. Ghrelini kodlayan genin bozulmas\u0131, CA1 b\u00f6lgesinde omurga sinapslar\u0131n\u0131n azalmas\u0131na ve davran\u0131\u015fsal bellek testinde farelerin performans\u0131n\u0131n bozulmas\u0131na neden olurken, d\u0131\u015far\u0131dan ghrelin uygulanmas\u0131 bu etkileri h\u0131zla tersine d\u00f6nd\u00fcrm\u00fc\u015ft\u00fcr. Ayr\u0131ca iskemi vb. patolojilerden hipokampal n\u00f6ronlar\u0131 korur.  Ventral tegmental alan ve n\u00fckleus accumbensi de uyararak madde ba\u011f\u0131ml\u0131l\u0131\u011f\u0131nda rol oynar. \u00d6zellikle alkol, nikotin ve kokain ba\u011f\u0131ml\u0131l\u0131\u011f\u0131nda merkezi ghrelin sinyalinin \u00f6d\u00fcllendirici etkisi \u00f6nemlidir [1,5].<\/p>\n\n\n\n

4.Kalp sa\u011fl\u0131\u011f\u0131<\/strong><\/p>\n\n\n\n

Kardiyak h\u00fccrelerinin fonksiyonlar\u0131n\u0131n d\u00fczenlenmesinde rol oynar. Kalp krizinden sonra tedaviye ghrelin eklenmesi, sempatik aktivasyonu \u00f6nleyerek, kalbin \u00e7al\u0131\u015fma fonksiyonlar\u0131n\u0131 iyile\u015ftirir ve insidans\u0131 azalt\u0131r. Ayr\u0131ca, kronik iskemiye maruz kalan kalpte vask\u00fcler endotelyal b\u00fcy\u00fcme fakt\u00f6r\u00fcn\u00fc (VEGF) artt\u0131rarak anjiyogenezi artt\u0131r\u0131r, b\u00f6ylece kalbin beslenmesini sa\u011flar. Hayvanlarda kardiyopulmoner bypass sonucu artan inflamasyonu, apoptozu ve oksidatif stresi azaltt\u0131\u011f\u0131 da g\u00f6zlemlenmi\u015ftir [2].<\/p>\n\n\n\n

5.Hareket sistemi<\/strong><\/p>\n\n\n\n

Kas ve iskelet sistemi i\u00e7in \u00f6nemli bir elemand\u0131r. Miyositlerin farkl\u0131la\u015fmas\u0131n\u0131 engelleyerek, kaslar\u0131n atrofiye u\u011framas\u0131n\u0131 engeller. Kemik olu\u015fumunu destekler ve kemik k\u00fctlesini artt\u0131r\u0131r. Leptinle beraber kemik metabolizmas\u0131n\u0131 ya\u015fa ba\u011fl\u0131 olarak d\u00fczenler [2].<\/p>\n\n\n\n

6.Kanser etyolojisi<\/strong><\/p>\n\n\n\n

Kanser h\u00fccrelerinin olu\u015fumunda ve metastaz\u0131nda rol oynar. D\u00fc\u015f\u00fck doz ghrelin, apoptozu inhibe eder ve kanser h\u00fccrelerinin proliferasyonunu uyar\u0131r. Bir\u00e7ok t\u00fcm\u00f6r dokusunda y\u00fcksek miktarda bulunmakla birlikte, k\u00f6pek meme karsinomlar\u0131 \u00fczerine yap\u0131lan bir \u00e7al\u0131\u015fmada, metastatik t\u00fcm\u00f6rlerde de y\u00fcksek seviyeleri g\u00f6r\u00fclm\u00fc\u015ft\u00fcr [2].<\/p>\n\n\n\n

\"\"
\u015eekil 2. Ghrelinin fizyolojik etkileri [1]<\/figcaption><\/figure><\/div>\n\n\n\n

Salg\u0131s\u0131n\u0131n D\u00fczenlenmesi<\/strong><\/p>\n\n\n\n

\u0130nsanlarda dola\u015f\u0131mdaki ghrelin seviyesi genellikle kilo al\u0131m\u0131, ins\u00fclin direnci ile ters orant\u0131l\u0131d\u0131r. Obezitede de ghrelin seviyeleri d\u00fc\u015f\u00fckt\u00fcr. Fakat egzersiz, d\u00fc\u015f\u00fck kalorili diyet, gastrik bypass veya anoreksiya nevroza ile ind\u00fcklenen kilo kayb\u0131 gibi durumlarda bu de\u011fer y\u00fckselir. Akut veya kronik streste ghrelin d\u00fczeyi artar \u00e7\u00fcnk\u00fc sempatik aktivasyon ghrelin salg\u0131lanmas\u0131n\u0131 artt\u0131r\u0131r. Hem in vitro<\/em> hem de in vivo<\/em> \u00e7al\u0131\u015fmalar, ghrelin h\u00fccresinde bulunan b1-adrenerjik resept\u00f6rlerinin arac\u0131l\u0131\u011f\u0131yla bunun ger\u00e7ekle\u015fti\u011fini g\u00f6stermi\u015ftir. Epinefrin, norepinefrin, endotelin ve sekretin gibi hormonlar ghrelin sal\u0131n\u0131m\u0131n\u0131 uyar\u0131r. Ghrelin salg\u0131lanmas\u0131 sinir sistemi ile gastrointestinal sistem aras\u0131nda karma\u015f\u0131k bir etkile\u015fime ba\u011fl\u0131d\u0131r. Bu etkile\u015fim enerji dengesinden ba\u011f\u0131ms\u0131z \u00e7al\u0131\u015fan bir mekanizmaya sahiptir [1].<\/p>\n\n\n\n

Ghrelinin kandaki miktar\u0131n\u0131n azalmas\u0131 al\u0131nan kalori y\u00fck\u00fc ve besin t\u00fcr\u00fcne ba\u011fl\u0131d\u0131r. Ghrelin seviyesinin d\u00fc\u015fmesinde lipitler en az etkili besin grubudur. Karbonhidratlar en b\u00fcy\u00fck bir d\u00fc\u015f\u00fc\u015fe neden olmakla birlikte, zamanda ge\u00e7tik\u00e7e ghrelin seviyesinin a\u00e7l\u0131k seviyesinden daha y\u00fcksek d\u00fczeylere \u00e7\u0131kmas\u0131na sebep olur. Ghrelin d\u00fczeyini azalt\u0131lmas\u0131nda en etkin besin grubu ise proteinlerdir.<\/p>\n\n\n\n

\"\"
\u015eekil 3. Aral\u0131k 2014’e kadar ABD Ulusal T\u0131p K\u00fct\u00fcphanesi Ulusal Sa\u011fl\u0131k Enstit\u00fcs\u00fc’nde (PubMed) listelenen “ghrelin” kelimesini i\u00e7eren yay\u0131nlar [1]<\/figcaption><\/figure><\/div>\n\n\n\n

1999 y\u0131l\u0131ndan itibaren ghrelin hakk\u0131nda yap\u0131lan \u00e7al\u0131\u015fmalar h\u0131zla artm\u0131\u015ft\u0131r. Bu art\u0131\u015f\u0131n bir sonucu olarak, ghrelin, sadece yemek yeme\u011fi sa\u011flayan bir hormon olmaktan \u00e7\u0131karak daha geni\u015f fizyolojik etkileri olan bir hormona d\u00f6n\u00fc\u015fm\u00fc\u015ft\u00fcr. \u00d6zellikle kanser ve kemik metabolizmas\u0131 \u00fczerine etkisi terap\u00f6tik olarak kullan\u0131lmas\u0131 i\u00e7in bir potansiyel olu\u015fturmaktad\u0131r [2].<\/p>\n\n\n\n

KAYNAKLAR<\/strong><\/p>\n\n\n\n

1.        M\u00fcller TD, Nogueiras R, Andermann ML, Andrews ZB, Anker SD, Argente J, et al. Ghrelin. Molecular Metabolism. 2015.<\/p>\n\n\n\n

2.        Pradhan G, Samson SL, Sun Y. Ghrelin: Much more than a hunger hormone. Current Opinion in Clinical Nutrition and Metabolic Care. 2013.<\/p>\n\n\n\n

3.        \u0130LHAN, T., & ERDOST, H. (2009). . Uluda\u011f \u00dcniversitesi Veteriner Fak\u00fcltesi Dergisi, 28(1), 67-74.<\/p>\n\n\n\n

4.      https:\/\/commons.wikimedia.org\/wiki\/File:Preproghrelin_1P7X.png <\/p>\n\n\n\n

5.        Diano S, Farr SA, Benoit SC, McNay EC, Da Silva I, Horvath B, et al. Ghrelin controls hippocampal spine synapse density and memory performance. Nat Neurosci. 2006;<\/p>\n","protected":false},"excerpt":{"rendered":"

Ghrelin hormonu, 28 aminoasitten olu\u015fan bir gastrointestinal peptittir. Ba\u015fl\u0131ca \u00fcretim yeri mide fundusu olmakla birlikte beyin, ba\u011f\u0131rsak, b\u00f6brek, kalp, yumurtal\u0131klar,<\/p>\n","protected":false},"author":265,"featured_media":9683,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[1805,415,250,1806,572,1804,1807,91,55,120,1546],"acf":[],"views":1135,"_links":{"self":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts\/9680"}],"collection":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/users\/265"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/comments?post=9680"}],"version-history":[{"count":16,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts\/9680\/revisions"}],"predecessor-version":[{"id":9700,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts\/9680\/revisions\/9700"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/media\/9683"}],"wp:attachment":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/media?parent=9680"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/categories?post=9680"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/tags?post=9680"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}