Santral sinir sisteminde kolesterol metabolizması

Amaç: Bu derlemede normal ve patolojik durumlardaki santral sinir sistemi kolesterol metabolizması gözden geçirilmiş ve diğer dokulardaki kolesterol metabolizması ile karşılaştırılmıştır. Ana bulgular: Santral sinir sistemi vücut ağırlığının % 2’sini oluşturmasına rağmen vücutta bulunan serbest kolesterolün yaklaşık % 25’ini içerir. Santral sinir sistemi ile ekstrahepatik dokuların kolesterol metabolizması arasında büyük farklılıklar vardır. Beyin dışındaki dokular ihtiyaçları olan kolesterolü kendileri sentezlerler veya dolaşımdan sağlarlar. Beyinde ise kan beyin bariyeri dolaşımdan beyne kolesterol geçişini engellemekte ve beyindeki bütün kolesterol de novo sentezlenmektedir. Dolaşımdan santral sinir sistemine kolesterol geçişi olmamasına rağmen beyinden dolaşıma kolesterol, 24S-hidroksikolesterol olarak geçmekte ve bunun miktarı da vücutta hareket eden kolesterolün yaklaşık % 0,9’unu oluşturmaktadır. Bu oran Alzheimer ve Nieman Pick tip C gibi nörodejeneratif hastalıklarda değişmektedir. Sonuç: Vücut kolesterol metabolizmasındaki değişiklikler santral sinir sisteminde ApoE yapımı ve sterol resirkülasyonunda değişikliklere sebep olarak nöron ve miyelinin yapısına etki eder. Bundan dolayı, kolesterol turnoveri ve bu olaylardaki kontrol mekanizmalarının açığa çıkarılması nörodejeneratif hastalıkların etyolojisinin en azından bir kısmını anlamamızı sağlayacaktır.

Cholesterol metabolism in the central nervous system

Objective: In this review, cholesterol metabolism of the central nervous system at healthy and pathologic conditions was reviewed and compared with cholesterol metabolism of the other tissues. Main findings: The central nervous system accounts for about 2% of the whole body mass but contains almost 25% of unesterified cholesterol present in the body. The cholesterol metabolism in the central nervous system is significantly different from that in most other extrahepatic tissues. The cellular cholesterol content of tissues other than brain is regulated by de novo synthesis and by cellular uptake of lipoprotein cholesterol from the circulation. Although, the blood-brain barrier effectively prevents uptake of cholesterol from the circulation and de novo synthesis is responsible for practically all cholesterol present in this organ, cholesterol diffuses to circulation as 24S-hydroxycholesterol and this represents about0.9% of cholesterol movement in the whole body. This ratio changes in neurodegenerative disorders such as Alzheimer’s and Niemann-Pick type C disease. Conclusion: Disturbances in cholesterol metabolism, transport, storage and balance in the whole body may effect brain structure and function. Alterations in sterol recycling and ApoE expression within the central nervous system may effect neuron and myelin integrity. Therefore, further evaluation of cholesterol metabolism either in the whole body or in the central nervous system is very important to understand and event prevent a variety of neurodegenerative diseases.

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Kaynak Göster

  • ISSN: 2602-3741
  • Yayın Aralığı: Yılda 4 Sayı
  • Başlangıç: 1997

3.1b 2.2b