Potential Radioprotective Effect of AT1 Receptor Antagonists Against Morphological and Ultrastructural Changes in the Testes Induced by Ionizing Radiation

Author(s)

Franciele Cristina Schwarz ^[1] ; Naira da Silva Mansano ^[2] ; Agnaldo Bruno Chies ^[3] ; Gustavo Arruda Viani ^[4] ; Maria Angélica Spadella ^[5]

Affiliation

^[1] Faculdade de Medicina de Marília - Brasil

^[2] Faculdade de Medicina de Marília - Brasil

^[3] Faculdade de Medicina de Marília - Brasil

^[4] Universidade de São Paulo. Radioterapia e Oncologia - Brasil

^[5] Faculdade de Medicina de Marília - Brasil

• Document type: Journal article
• Source: INTERNATIONAL JOURNAL OF MORPHOLOGY; v. 35, n. 3, p. 820-830, 2017-09-00.

Abstract

Radiotherapy is a source of human exposure to ionizing radiation. This pure energy causes deleterious effects on tissues, which result from oxidative stress, a phenomenon in which there is the participation of the Renin-Angiotensin System (RAS). The male genital organs are extremely radiosensitive and the action of radiation in the testes can significantly affect spermatogenesis. In search of potential radioprotective for male genital system, this study investigated whether the AT1 receptor antagonists minimize radiation-induced damage to reproductive tissues, by decreasing oxidative stress. Male Wistar rats were divided into six groups: 0 Gray (Gy) (control), 5 Gy (single dose in the scrotal area), telmisartan, losartan, 5Gy+telmisartan and 5Gy+losartan. The treatment started the day after irradiation with losartan 34 mg/kg (two times/day) and telmisartan 12 mg/kg (one time/day) during 60 days. For ultrastructural analysis, the testis fragments were fixed in 2 % glutaraldehyde and 4 % paraformaldehyde in 0.1 M phosphate buffer, pH 7.3. The material was postfixed for 2 h in 1 % osmium tetroxide. For collagen evaluation, the sections were stained with Picrosirius-red method. Serum testosterone was determined. The date showed the deleterious effects of gamma radiation on testicular ultrastructure. Rich accumulation of collagen fibers in the interstitium was observed in the irradiated groups, especially the irradiated and nontreated testes. No significant difference was detected in serum testosterone concentration among the studied experimental groups. Treatments with telmisartan and losartan influenced the onset of attenuation on ultrastructural damages arising from ionizing radiation. Although the data strongly suggest that AT1 receptor antagonists may promote radioprotection to the testes, further studies with a longer duration of treatment are required for these potentially positive effects to be maximized and, therefore, to better characterize radioprotection to reproductive parameters. (AU)

• FAPESP's process: 15/20740-4 - Action of AT1 receptor antagonists in the mitigation of structural and functional damage in reproductive tissue of rats exposed to ionizing radiation
• Grantee: Maria Angélica Spadella Santos
• Support Opportunities: Regular Research Grants