The role of urocortin-2 in pulmonary arterial hypertension

• Autor(a) principal: Ribeiro, Diana Raquel Santos
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/15381
• topic: Biologia molecular; Hipertensão pulmonar; Doenças cardiovasculares; Insuficiência cardíaca - Terapêutica; Péptidos - Efeitos terapêuticos

Pulmonary arterial hypertension (PAH) is a syndrome based on diverse aetiologies, characterized by a persistent increase in pulmonary vascular resistance and overload of the right ventricle (RV), leading to heart failure (HF) and death. Urocortin (UCN)-2 is a peptide highly expressed in the cardiovascular system that has shown promising therapeutic effects in several studies both in humans and animal models of HF. Thus, this study aims to explore the effects of UCN-2 treatment in an animal model of RV HF secondary to PAH and its impact on myocardial function. Male Wistar rats (180-200g) randomly received monocrotaline (MCT, 60mg/kg) or vehicle. After 14 days, animals were randomly assigned to receive UCN-2 treatment (5μg/kg/day) or vehicle. The study resulted in 4 groups: CTRL (n=9), CTRL+UCN-2 (n=9), MCT (n=7) and MCT+UCN-2 (n=10). Echocardiographic, hemodynamic studies and sample collection were performed 24-25 days after MCT administration. Only significant results (mean±SEM, p<0.05) are given. MCT animals developed PAH, demonstrated by impaired pulmonary flow, RV dilation and increased RV pressures, as well as decreased cardiac output. MCT administration also resulted in RV hypertrophy. UCN-2 treatment was able to restore PAH-induced severe abnormalities in cardiac function and structure. Moreover, Kaplan-Meier analysis showed increased survival rate for MCT+UCN-2 rats when compared with the MCT group. The molecular studies revealed an altered genetic expression of the UCN-2/CRHR2 system components in the MCT animals, as shown by the increase in molecular markers of hypertrophy, overload, hypoxia and apoptosis that were reversed with UCN-2 treatment. As well as an impaired protein activation/phosphorylation seen in peptides pertaining to different signaling pathways. In conclusion, we show that UCN-2 chronic treatment is able to restore PAHinduced severe abnormalities in cardiac function and structure, as well as to reverse the changes in the expression of markers of cardiac overload, hypertrophy, hypoxia and apoptosis induced by the disease. The beneficial effects of UCN-2 seem to be associated with the modulation of numerous signaling pathways, such as survival and proliferation. These findings suggest that the UCN-2/CRHR2 pathway has a relevant role on the pathophysiology of PAH and progression to RV failure, representing a potential therapeutic target.