Akademik Veri Yönetim Sistemi
Yeni Symposium, cilt.45, sa.3, ss.99-106, 2007 (Scopus)
This article reviews the effects of antenatal exposure to high levels of endogenous or exogenous steroids on fetal brain regions and the long-term outcome in terms of psychiatric morbidity. It is known that glucocorticoids are essential for maturation in the developing central nervous system, where they play a pivotal role in the remodeling of axons and dendrites, and in cell survival. However, both human and animal studies show that either excess or the deficiency of these hormones during brain development may affect corticosteroid receptor programming and cause structural and functional changes. Several studies in fetal rats have shown that antenatal steroid exposure causes persistent decreases in brain weight and volume. These changes in brain weight are accompanied by a significant reduction in DNA content, suggesting that fewer cells are present in the brains of exposed animals. High maternal steroid levels, exposure to high dosage of exogenous steroid, particularly used for prophylaxis in preterm infants and traumatic experiences in very early childhood may have harmful effects on developing brain. The nature and magnitude of the effects of administered corticosteroids depend on the dose and regimen and on the species' receptor sensitivity and complement at the time of treatment. Hippocampal neurons are known to contain the highest concentration of corticosteroid receptors, and several studies have documented the vulnerability of this region to glucocorticoid induced damage. Besides, amygdala, cerebellar vermis and cerebral cortex are also vulnerable to high levels of steroids. Early damage to these regions may have persistent outcome later in lifetime, such as succeptibility to depression, attention and learning disorders, impulse control disorders and substance abuse. The research studies had not yet clarified the differential affects of early exposure to high levels of enogenous or exogenous steroids and long-term outcome. Longitudinally designed follow-up studies are necessary to resolve these issues.