EXERCISE AND NEUROGENESIS

Öz

Neurogenesis is a biological process characterized by the formation of new neurons. During embryogenesis, neural stem cells multiply, migrate, and differentiate into mature neurons that will eventually form the central nervous system. After proliferation, differentiation, and displacement, it has been proven that, during exercise, new neurons in the dentate gyrus settle in the neural circuits of the hippocampus and brain areas that are important for memory consolidation and learning. During and after exercise, the triggering factor for exercise-induced neurogenesis is a molecule called brain-derived neurotrophic factor, also known as BDNF in recent publications. Being a member of the neurotrophin family, BDNF is vital for many functions involved in neurogenesis, including proliferation, differentiation, maturation, and survival. Besides BDNF, signal pathways molecules, such as insulin-like growth factor-1, fibroblast growth factor 2, and vascular endothelial growth factor, have also proven to be effective in neuroplasticity and hippocampal neurogenesis. During physical activities, the most affected brain region is the hippocampus. Aerobic exercises have been found to significantly increase the size and function of the human hippocampus, especially when performed with moderate exercise; it is important to ensure that the exercise is not stressful. Stress suppresses neurogenesis by increasing the release of glucocorticoids in the hypothalamic–pituitary–adrenal axis and thus prevents the formation of new neurons. If voluntary exercise exceeds a certain threshold and become exhaustion, neurogenesis is prevented via the same mechanism. Therefore, it is important that exercise is done according to each person’s ability and should not cause exhaustion.

Anahtar Kelimeler

• Neurogenesis
• exercise
• brain ınduced neurotrophic factor (BDNF Protein)

EGZERSİZ VE NÖROGENEZ

Öz

Nörogenez, yeni nöronların oluştuğu biyolojik bir süreçtir. Nöral kök hücreler, embriyogenez sırasında, merkezi sinir sistemini oluşturacak olgun nöronlar halinde çoğalır, göç eder ve farklılaşır. Proliferasyonun, farklılaşmanın ve yer değiştirmenin ardından, egzersiz ile dentat girusda yeni doğan nöronların hipokampusun sinirsel devrelerine ve bellek konsolidasyonu ve öğrenme için önemli olan beyin bölgelerine yerleştiği kanıtlanmıştır. Egzersiz esnasında ve sonrasında “Egzersiz kaynaklı nörogenezi tetikleyen faktörün”, son yayınlarda beyin kaynaklı nörotrofik faktör (brain-derived neurotrophic factor-BDNF) adlı bir molekül olduğunun ön planda tutulduğu görülmektedir. Nörotrofin ailesinin bir üyesi olan BDNF, proliferasyon, farklılaşma, olgunlaşma ve hayatta kalma dahil olmak üzere nörogenezden sorumlu birçok fonksiyon için hayati öneme sahiptir. BDNF’nin yanı sıra nöroplastisite ve hipokampal nörogenezde İnsülin Benzeri Büyüme Faktörü-1 (IGF-1), Fibroblast Büyüme Faktörü-2 (FGF-2), Vasculer- Endotelyal Büyüme Faktörü (VEGF) gibi sinyal yolaklarının da etkili olduğu gösterilmiştir. Fiziksel aktivitelerde en fazla etkilenen beyin bölgesi hipokampus bölgesidir. Aerobik egzersizlerin, özellikle de aşırıya kaçmadan yapıldığında, insanların hipokampus boyutunda ve fonksiyonlarında anlamlı artışlara neden olduğu tespit edilmiştir. Egzersizin bir stres haline dönüştürülmemesi önemlidir. Stres Hipotalamo-hipofiz-adrenal korteks ekseninde glikokortikoid salınımını artırarak nörogenezi baskılamakta, yeni nöron oluşumuna engel olmaktadır. İstemli yapılan egzersizler bile belirli bir seviyenin üzerinde olursa, tüketici hale geldiğinde yine aynı mekanizma ile nörogenezi engellemektedir. Bu nedenle egzersizin kişiye özel olması ve tükenmeye neden olacak kadar olmaması önemlidir.

Anahtar Kelimeler

• Nörogenez
• egzersiz
• beyin kaynaklı nörotrofik faktör

Kaynakça

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