The Effects of L-Arginine on Transforming Growth Factor Beta 1 (TGF-β1) Expression and Early Renal Alterations in Streptozotocin-Induced Diabetic Rats

Abstract

Diabetic nephropathy (DN) is a prevalent microvascular complication of diabetes mellitus, occurring in more than 40% of affected individuals, with reactive oxygen species–induced endothelial dysfunction playing a central role in its development. L-arginine may exert protective effects by interacting with these oxygen metabolites. This study investigated the effects of L-arginine on early renal changes in streptozotocin-induced diabetic rats. Additionally, renal levels and localization of transforming growth factor beta 1 (TGF-β1), an important fibrogenic factor involved in DN and endothelial-mesenchymal transition, were evaluated by ELISA and immunohistochemistry. Forty-eight male Wistar albino rats (250-300 g) were divided into four groups (n=12); control (0.1 mol/L sodium citrate buffer i.p.); L-arginine (100 mg/kg by gavage); STZ (50 mg/kg, i.p.); STZ+L-arginine (50 mg/kg STZ i.p.+ 100 mg/kg L-arginine by gavage). STZ was administered as a single dose, and L-arginine was given for twenty-one days. Histopathological examination of diabetic kidneys revealed glomerular enlargement, erythrocyte congestion in glomerular and interstitial vessels, cytoplasmic vacuolization in tubular epithelium, and hyaline deposition in glomeruli and tubules. TGF-β1 expression was detected in proximal and distal tubular epithelial cells and in the vascular media of all groups. However, TGF-β1 immunoreactivity was very mild in the control and L-arginine groups compared with the diabetes-induced groups. ELISA results confirmed significantly elevated renal TGF-β1 levels in diabetic rats, while L-arginine administration markedly reduced these increases. In conclusion, diabetes induced notable morphologic kidney alterations accompanied by increased TGF-β1 levels. L-arginine treatment attenuated TGF-β1 elevation, suggesting potential protective effects against diabetes-related renal vascular damage.

Keywords

• Diabetes mellitus
• kidney
• L-arginine
• rat
• TGF-β1

Supporting Institution

This research was supported within the scope of the project numbered TYL-2018-8378 by the Erciyes University Scientific Research Projects Coordination Unit.

Project Number

TYL-2018-8378

Ethical Statement

This study was carried out after the animal experiment was approved Erciyes University Animal Experiments Local Ethics Committee (Decision date and number: 11.01.2018 and 18/017).

Thanks

We would like to thank the Erciyes University Scientific Research Projects Unit for their support of this thesis study under the project code TYL-2018-8378.

Streptozotosin ile Diyabet Oluşturulmuş Ratlarda L-Arjinin’in Dönüştürücü Büyüme Faktör Beta 1 (TGF-β1) Ekspresyonu ve Erken Böbrek Değişiklikleri Üzerine Etkileri

Abstract

Diyabetik nefropati (DN), diabetes mellitusun yaygın bir mikrovasküler komplikasyonudur ve etkilenen bireylerin %40'ından fazlasında görülür; gelişiminde reaktif oksijen türlerinin neden olduğu endotel disfonksiyonu merkezi bir rol oynar. L-arjinin, bu oksijen metabolitleri ile etkileşime girerek koruyucu etkiler gösterebilir. Bu çalışmada, streptozotosin (STZ) ile indüklenen tip 1 diyabetli sıçanlarda L-arjininin böbrek histopatolojisi üzerindeki etkileri araştırılmıştır. Ayrıca, DN ve endotel-mezenkimal geçişte rol oynayan önemli bir faktör olan transformasyon büyüme faktörü beta 1'in (TGF-β1) böbrek düzeyleri ve lokalizasyonu ELISA ve immünohistokimyasal yöntemlerle değerlendirilmiştir. Kırk sekiz erkek Wistar albino sıçan (250-300 g) dört gruba ayrılmıştır (n:12); kontrol (0,1 mol/L sodyum sitrat tamponu i.p.); L-arjinin (100 mg/kg gavaj yoluyla); STZ (50 mg/kg, i.p.); STZ+L-arjinin (50 mg/kg STZ i.p.+ 100 mg/kg L-arjinin gavaj yoluyla). STZ tek doz olarak, L-arjinin ise yirmi bir gün boyunca verildi. Diyabetik böbreklerin histopatolojik incelemesinde, glomerüler genişleme, glomerüler ve interstisyel damarlarda eritrosit birikimi, tübüler epitelde sitoplazmik vakuolizasyon ve glomerüllerde ve tübüllerde hiyalin birikimi görüldü. TGF-β1 ekspresyonu, tüm grupların proksimal ve distal tübüler epitel hücrelerinde ve vasküler medialarında tespit edildi. Bununla birlikte, TGF-β1 immünoreaktivitesi, diyabetli gruplara kıyasla kontrol ve L-arjinin gruplarında çok hafifti. ELISA ile diyabetik sıçanlarda böbrek TGF-β1 düzeylerinin önemli ölçüde yükseldiği, L-arjinin uygulamasının ise bu artışları belirgin şekilde azalttığı gözlendi. Sonuç olarak, STZ uygulaması, TGF-β1 düzeylerini arttırarak belirgin morfolojik böbrek değişikliklerine neden oldu. L-arjinin tedavisi, artmış olan TGF-β1 düzeylerini azaltarak diyabetle ilişkili böbrek damar hasarına karşı olası koruyucu etkilerini düşündürdü.

Keywords

• Böbrek
• diabetes mellitus
• L-arjinin
• rat
• TGF-β1

Supporting Institution

Bu araştırma, Erciyes Üniversitesi Bilimsel Araştırma Projeleri Koordinasyon Birimi tarafından TYL-2018-8378 numaralı proje kapsamında desteklenmiştir.

Project Number

TYL-2018-8378

Ethical Statement

Çalışma için Erciyes Üniversitesi Hayvan Deneyleri Yerel Etik Kurulundan onay alındı ve çalışma etik kurul yönergesine uygun bir şekilde yapıldı (Karar Tarih ve No: 11.01.2018 ve 18/017).

Thanks

TYL-2018-8378 kodlu proje ile bu tez çalışmasının yapılmasındaki katkılarından dolayı Erciyes Üniversitesi Bilimsel Araştırma Projeleri Birimi’ne teşekkür ederiz.

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