Kedi ve Köpeklerde GnRH’nın Reprodüktif Endikasyonları

Gonadotropin salıcı hormon (GnRH), ön hipofizden folikül uyarıcı hormon (FSH) ve lüteinleştirici hormon (LH) salınımını uyararak, ovaryum fonksiyonlarını kontrol eder. Doğal GnRH molekülünde bulunan aminoasit yapılarının değiştirilmesi sonucu geliştirilen GnRH analogları, endojen GnRH'ya göre daha güçlü ve etkilidir. Genellikle östrüsün uyarılması veya baskılanması amacıyla güvenle kullanılan GnRH analogları diğer yöntemlere karşı bir avantaj sağlamaktadır. Agonistler, doğal GnRH'yı taklit ederek farklı güçlerle ön hipofizden gonadotropinlerin salınımını uyarır, bunu takiben gonadotropin salgısının artışı ve piki sebebiyle başlangıçta alevlenme etkisi ortaya çıkar. Ancak, uygulamadan yaklaşık 10-15 gün sonra hipogonadotropik hipogonad durumu oluşur. Bu amaçla, son yıllarda sıklıkla tercih edilen GnRH agonistleri, östrüsun uyarılması veya baskılanması, gebeliğin sonlandırılması, endokrinolojik tanı, idrar tutamama ve meme tümörü tedavisi amacıyla güvenle kullanılmaktadır. Antagonist moleküller gonadotroplarda yer alan GnRH almaçlarına endojen GnRH molekülü ile başarılı bir şekilde yarışarak bağlanır. Böylece almacın işgali sonucu blokaj sağlanarak gonadotropinlerin salınımı baskılanır. Antagonistlerin uygulanması sonrası gerçekleşen bu hızlı baskılama ilk uyarım etkisi görülmeden oluştuğu için agonistlere karşı avantaj sağlar. Son yıllarda GnRH antagonistlerinin dişi kedi ve köpeklerin reprodüktif olguları üzerine yapılan çalışmaları artmış olsa da, daha fazla araştırmaya gerek duyulmaktadır. Sunulan derlemede, GnRH analoglarının yapısı ile dişi kedi ve köpeklerde kullanım alanları hakkında genel bilgi verilecektir

Reproductive Use of the GnRH in Cats and Dogs

Gonadotropin-releasing hormone (GnRH) stimulates the pituitary secretion of both follicle-stimulating hormone (FSH) and luteinising hormone (LH), and thus controls the hormonal functions of the ovarium. GnRH analogues have been produced by amino acid substitutions within the native GnRH molecule resulting in a greater potency and a longer duration of effectiveness. Generally, GnRH analogues are used safely for oestrus induction or suppression and provide an advantage over other methods. The GnRH agonists mimic the native GnRH and stimulate the release of gonadotropin with different power from adenohypophysis. Upon the GnRH agonist administration, it causes initially a flare-up effect due to gonadotropin secretion. However, hypogonadotropic hypogonadism occurs about 10-15 days after the administration of agonist. For this purpose, in recent years, GnRH agonist, as often preferred, is safely used for irreversible oestrus induction or suppression, termination of pregnancy, endocrinological diagnosis, urinary incontinence and the treatment of mammary tumour. Antagonists compete successfully with the endogenous GnRH and bind to gonadotrope GnRH receptors. Thus, upon the occupancy of the receptor, they provide blockade and suppress the secretion of gonadotropins. Upon the administration of GnRH antagonists, they rapidly down-regulate the gonadotropin level without flare-up effect and this feature provides an advantage against the agonists. In recent years, although studies on reproduction in female cats and dogs have increased, more research is needed. In the present review, the structure of the GnRH analogues and their current use in cats and dogs are given

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