Oreksinler (hipokretinler), 1998 yılında keşfedilmesinden itibaren farklı patolojik mekanizmalarda bilim camiasının ilgisini çekmiştir. Oreksin peptitleri, hipokretin nöropeptit öncü geni tarafından kodlanan ve daha sonra aynı öncü olan prepro-oreksin'den üretilen oreksin A ve B olmak üzere iki türden oluşur. Oreksin üreten nöronlar hipotalamusun lateral, dorsomedial, posterior ve perifornikal bölgelerinde bulunur. Oreksin A ve B sinyalizasyonu, oreksin1 ve oreksin2 reseptörleri olarak adlandırılan iki G proteinine bağlı reseptör aracılığıyla gerçekleşmektedir. Oreksin peptitlerinin sinyalizasyonu, endojen olarak oreksin reseptörü ifade eden nöronlar gibi çeşitli hücrelerde araştırılmıştır. Oreksin1 reseptörü genellikle beslenme, öğrenme ve hafıza ile ilgili bölgelerde yoğun dağılım gösterirken, oreksin2 reseptörü ise esas olarak uyanıklık mekanizmasını kontrol eden bölgelerde bulunur. Oreksin ilk olarak gıda alımını artırarak beslenme davranışını düzenleyen bir hipotalamik nöropeptit olarak tanımlanmıştır. Oreksin nöronlarının ve reseptörlerinin dağılımından, oreksin sisteminin fizyolojik mekanizmalarda çok sayıda işleve sahip olduğu düşünülmektedir. Son kanıtlar, merkezi oreksin sisteminin, hayvan ve insan modellerinde besin alımının düzenlenmesi ve uyku için önemli bir düzenleyici role sahip olduğunu göstermektedir. Oreksinin, beslenme davranışındaki etkinliğinin yanında enerji düzenlenmesinde de etkin rolü bulunmaktadır. Uyanıklığın korunmasında etkin olan hipotalamik bir nöropeptid olan oreksin, uyku-uyanıklık döngüsünün düzenlenmesinde önemli rol oynamaktadır. Oreksin; öğrenme, hafıza gibi bilişsel süreçleri ve beynin ödül mekanizmalarını etkilediği gibi nöbetler ve epilepsi üzerinde de fonksiyonları vardır. Oreksinin, stres etkeni altındaki hayvanlarda gözlenen kaygılı ve depresif bulgular üzerinde düzenleyici etkilerinin farkedilmesinden dolayı bu reseptörün depresyon üzerinde de etkili olabileceği düşünülmüştür. Oreksin sisteminin etkilerinin detaylı şekilde incelenebileceği insan ve hayvan modelleri ile yapılacak deneysel çalışmalar oreksinle ilgili terapotik yaklaşımlara yön verebilecektir. Bu derlemede oreksinin beslenme bozukluğu, uyku bozuklukları, bağımlılık, şizofreni, epilepsi, depresyon ve anksiyete gibi nöropsikiyatrik hastalıkların fizyopatolojik mekanizmalarındaki rolü açıklanmaktadır.
Atıf yapmak için : Özen Koca R, Solak Görmüş ZI, Ekenler Ş, Yıldırım B, Akalın M, Simsar B.
Nöropsikiyatrik Hastalıkların Fizyopatolojisinde Oreksin’in Rolü. Mev Med Sci. 2025; 5(1): 22-29
Çıkar İlişkisi : Yazarlar çıkar çatışması olmadığını beyan etmiştir.
Mevlana Tıp Bilimleri 2025, Cilt5, Sayı1 E-ISSN: 2757-976X
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