Merkezi siklooksijenaz ve lipooksijenaz yolaklarının nesfatin-1'in oluşturduğu kardiyovasküler etkilerdeki rolünün araştırılması
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Date
2020-01-10
Authors
Bayram, Gökçen Güvenç
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Publisher
Bursa Uludağ Üniversitesi
Abstract
Bu çalışmada, serebral yan ventriküle ekzojen olarak uygulanan nesfatin-1'in kardiyovasküler parametreler üzerindeki etkilerini göstermek ve nesfatin-1 kaynaklı kardiyovasküler parametre değişimlerinde merkezi siklooksijenaz (COX) tromboksan A2 (TXA2), prostaglandin (PG) E, D, F2α sinyal yolağı ve lipooksijenaz (LOX) yolağının aracılığını hemodinami ve mikrodiyaliz çalışmaları ile ortaya koymak amaçlandı. Çalışma, 91 adet Sprague Dawley ırkı erkek sıçanlar üzerinde gerçekleştirildi. Tüm cerrahi işlemler sevofluran anestezisi (%2-4/%100 O2) altında yapıldı. Kardiyovasküler parametre takibi için sıçanların sol femoral arterlerine heparinli tuzlu su (%0,9 tuzlu suda 100 Ü/ml heparin) içeren PE 50 kateter yerleştirildi. Serebral yan ventriküle (s.y.v.) ilaç enjeksiyonlarının yapılabilmesi için laboratuvarımızda hazırlanmış kılavuz kanül belirlenen koordinatlara göre kafatasına sabitlendi. Enjeksiyonlar Hamilton enjektöre bağlantılı olarak bulunan ve laboratuvarımızda hazırlanmış olan enjeksiyon kanülünün kılavuz kanül içine yerleştirilmesini takiben uygulandı. Posterior hipotalamustan (PH) ekstraselüler total PG seviyelerini belirlemek için PH'ye elde hazırlanmış mikrodiyaliz probları yerleştirildi ve PH'den diyalizat örnekleri toplandı. İlk deney setinde, s.y.v. yolla uygulanan farklı dozlardaki (100, 200 ve 400 pmol) nesfatin-1'in ortalama kan basıncı ve kalp atım sayısı üzerindeki etkileri araştırıldı. Nesfatin-1 doza bağlı olarak, sıçanlarda kan basıncı üzerinde pressör, kalp atım sayısı üzerinde ise bradikardik ve taşikardik fazları içeren bir yanıta neden oldu. Çalışmanın ikinci aşamasında 200 pmol dozda uygulanan nesfatin-1'in, PH'de ekstraselüler total PG seviyelerinde bir artış yarattığı, yapılan mikrodiyaliz çalışması ile ortaya koyuldu. Son deney setinde ise nesfatin-1 kaynaklı kardiyovasküler etkilerde merkezi COX, TXA2, PGE, PGD, PGF2α ve LOX'un aracılığını göstermek amacıyla seçici olmayan COX inhibitörü ibuprofen (250 µg), TXA2 sentez inhibitörü furegrelate (250 µg), PGE ve PGD'nin reseptör antagonisti AH6809 (10 µg), PGF2α reseptör antagonisti PGF2α dimetil amin (10 µg), seçici olmayan LOX inhibitörü NDGA (250 µg) veya kontrol amaçlı tuzlu su ve DMSO ön tedavileri nesfatin-1 (200 pmol) tedavisinden 5 dakika önce uygulandı. İbuprofen tamamen; furegrelate, AH6809, PGF2α dimetil amin ve NDGA ise kısmen nesfatin-1'in yaratmış olduğu kardiyovasküler etkileri bloke etti. Sonuçta bulgular, s.y.v. yolla uygulanan nesfatin-1'in normotansif sıçanlarda PH'de ekstraselüler total PG seviyesinde bir artışa neden olarak kan basıncında bir yükselmeye ve bradikardik/taşikardik fazları içeren kardiyovasküler bir yanıta neden olduğunu göstermektedir. Nesfatin-1'in yarattığı kardiyovasküler etkilere merkezi COX enzim yolağının tamamen; COX ürünlerinden TXA2, -PGE, -PGD ve -PGF2α ve ayrıca LOX enzim yolağının da kısmen aracılık ettiğini de ortaya koymaktadır.
In this study, it was aimed to demonstrate the effects of exogenously intracerebroventricular (ICV) injected nesfatin-1 on cardiovascular parameters, and in this effect, the mediation of central cyclooxygenase (COX) thromboxane A2 (TXA2), prostaglandin (PG) E, D, F2α signaling pathways and lipoxygenase (LOX) pathway by using hemodynamic and microdialysis studies. The experiments were performed on male Sprague Dawley rats (n=91). All of the surgical operations were done under sevoflurane anaesthesia (%2-4 / %100 O2). Left femoral arteries of the rats were catheterized with PE 50 catheters containing heparinized saline (100U/ml heparin in 0.9% saline) to monitored cardiovascular parameters. Hand-made guide cannulas were fixed to the skulls of the rats according to the predetermined coordinates to inject the drugs ICV. The drugs were injected ICV by hand-made injection cannulas connected with Hamilton injectors inserted in the guide cannulas. Microdialysis probes were placed in posterior hypothalamus (PH) to determine extracellular total PG levels, and dialysate samples were collected from PH. In the first experimental group, it was investigated the effects of different doses of nesfatin-1 (100, 200 and 400 pmol) on the mean blood pressure and heart rate. Nesfatin-1, dose-dependently, caused pressor effects on the blood pressure, also bradycardic and tachycardic phases on the heart rate responses in the rats. On the second step of the experiment, it was revealed that 200 pmol dose of nesfatin-1 increased extracellular total PG levels in PH, in accordance with the results of the microdialysis study. To the determination of the central COX, TXA2, PGE, PGD, PGF2α and LOX mediation in nesfatin-1-induced cardiovascular effects, non-selective COX inhibitor ibuprofen (250 µg), TXA2 synthase inhibitor furegrelate (250 µg), PGE and PGD receptors antagonist AH6809 (10 µg), PGF2α receptor antagonist PGF2α dimethylamine (10 µg), non-selective LOX inhibitor NDGA (250 µg), in addition saline and DMSO (as control) pretreatments were administrated 5 min before nesfatin-1 (200 pmol) treatment, in the last experimental group. Ibuprofen completely, whereas furegrelate, AH6809, PGF2α dimethylamine and NDGA partially blocked nesfatin-1-induced cardiovascular effects. In conclusion, the data showed that ICV injected nesfatin-1 caused a rise in the blood pressure and cardiovascular responses including bradycardic/tachycardic phases because of an increase in extracellular total PG levels in PH, in normotensive rats. In the present study, it was also revealed that nesfatin-1-induced cardiovascular effects were mediated by COX enzyme pathway completely, TXA2, -PGE, -PGD and -PGF2α and also LOX enzyme pathway partially.
In this study, it was aimed to demonstrate the effects of exogenously intracerebroventricular (ICV) injected nesfatin-1 on cardiovascular parameters, and in this effect, the mediation of central cyclooxygenase (COX) thromboxane A2 (TXA2), prostaglandin (PG) E, D, F2α signaling pathways and lipoxygenase (LOX) pathway by using hemodynamic and microdialysis studies. The experiments were performed on male Sprague Dawley rats (n=91). All of the surgical operations were done under sevoflurane anaesthesia (%2-4 / %100 O2). Left femoral arteries of the rats were catheterized with PE 50 catheters containing heparinized saline (100U/ml heparin in 0.9% saline) to monitored cardiovascular parameters. Hand-made guide cannulas were fixed to the skulls of the rats according to the predetermined coordinates to inject the drugs ICV. The drugs were injected ICV by hand-made injection cannulas connected with Hamilton injectors inserted in the guide cannulas. Microdialysis probes were placed in posterior hypothalamus (PH) to determine extracellular total PG levels, and dialysate samples were collected from PH. In the first experimental group, it was investigated the effects of different doses of nesfatin-1 (100, 200 and 400 pmol) on the mean blood pressure and heart rate. Nesfatin-1, dose-dependently, caused pressor effects on the blood pressure, also bradycardic and tachycardic phases on the heart rate responses in the rats. On the second step of the experiment, it was revealed that 200 pmol dose of nesfatin-1 increased extracellular total PG levels in PH, in accordance with the results of the microdialysis study. To the determination of the central COX, TXA2, PGE, PGD, PGF2α and LOX mediation in nesfatin-1-induced cardiovascular effects, non-selective COX inhibitor ibuprofen (250 µg), TXA2 synthase inhibitor furegrelate (250 µg), PGE and PGD receptors antagonist AH6809 (10 µg), PGF2α receptor antagonist PGF2α dimethylamine (10 µg), non-selective LOX inhibitor NDGA (250 µg), in addition saline and DMSO (as control) pretreatments were administrated 5 min before nesfatin-1 (200 pmol) treatment, in the last experimental group. Ibuprofen completely, whereas furegrelate, AH6809, PGF2α dimethylamine and NDGA partially blocked nesfatin-1-induced cardiovascular effects. In conclusion, the data showed that ICV injected nesfatin-1 caused a rise in the blood pressure and cardiovascular responses including bradycardic/tachycardic phases because of an increase in extracellular total PG levels in PH, in normotensive rats. In the present study, it was also revealed that nesfatin-1-induced cardiovascular effects were mediated by COX enzyme pathway completely, TXA2, -PGE, -PGD and -PGF2α and also LOX enzyme pathway partially.
Description
Keywords
Nesfatin-1, Kan basıncı, Kalp atım sayısı, Serebral yan ventrikül, Hipotalamus, Siklooksijenaz, Lipooksijenaz, Mikrodiyaliz, Blood pressure, Heart rate, Lateral cerebral ventricle, Hypothalamus, Cyclooxygenase, Lipoxygenase, Microdialysis
Citation
Bayram, G. G. (2020). Merkezi siklooksijenaz ve lipooksijenaz yolaklarının nesfatin-1'in oluşturduğu kardiyovasküler etkilerdeki rolünün araştırılması. Yayınlanmamış doktora tezi. Bursa Uludağ Üniversitesi Sağlık Bilimleri Enstitüsü.