LEPTİN VE NÖROENDOKRİN DÜZENLEME

İnsan ob gen kromozomu tarafından yağ dokusunda sentezlenen bir hormon olan leptin iştahı ve enerji harcamasını düzenler. Obez kişilerde serum leptin düzeyleri belirgin olarak yüksektir. Ob gen defekti olan ob/ob tipi farelerde, leptinin yeterince üretilememesi nedeniyle yağ depolanması fazladır. Obez kadın ve erkeklerde leptin düzeyi ile vücut kitle indeksi arasında pozitif bir ilişki gösterilmiştir. Leptin reprodüktif fonksiyonlarda da görevlidir. İnfertil ve gonadotropin seviyesi düşük ob/ob farelere leptin enjekte edildiğinde, uterus ve overlerinin ağırlıkları ve overlerdeki folikül sayısı artarak fertilitenin korunması sağlanmıştır. Normal dişi farelere leptin uygulandığında ise pubertenin hızlandığı gözlenmiştir. Diğer yandan leptin osteoblastik hücre büyümesinde ve kemik mineralizasyonunda rol oynayabilir. Leptin ayrıca nöropetid Y'yi inhibe edip gonadotropinlerin ve seks steroidlerinin sentezini stimüle eder. Uterin miyomlarda leptin geninin ekspresyonu gösterilirken sağlıklı insanlardan alınan miyometriumda gösterilememiştir, bu nedenle uterin miyom etyopatogenezinde leptinin rolü olabileceği savunulmaktadır. Sonuç olarak iştahı ve enerji harcanmasını regüle eden leptin reprodüktif ve nöroendokrin sistemde de önemli rol oynamaktadır

Anahtar Kelimeler:

leptin, bazal metabolizma hızı, osteoporoz, uterin miyom

Leptin and Neuroendocrine Regulation

Leptin, the product of the ob gene, is produced exclusively by the adipose tissue and regulates energy intake and expenditure. Obese individuals have considerably higher serum leptin concentrations. In ob/ob mice, the fat deposition is increased as a result of insufficient production of leptin. In obese women and men, there is correlation between serum leptin concentrations and body mass index. Leptin appears to influence various reproductive functions. Injecting leptin into ob/ob mice that are infertile and with low levels of gonadotropin increases the weight of the uterus and ovaries and the number of follicles, resulting in restoration of fertility. Administering leptin treatment to normal female mice accelerates puberty. Leptin may be of importance for osteoblastic cell growth and bone mineralization. Leptin may also be expected to stimulate gonadotropin and sex- steroid synthesis and secretion through inhibition of Neuropeptide Y. It has been reported that leptin was expressed in several uterine myomas but not in normal myometrium, so leptin may have a role in the etiopathogenesis in uterine leiomyoma. In conclusion, leptin, regulating energy intake and expenditure also has regulatory effects on reproductive and neuro-endocrine systems.

Keywords:

leptin, basal metabolic rate, osteoporosis, uterine leiomyoma,

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