Loss of secretin results in systemic and pulmonary hypertension with cardiopulmonary pathologies in mice.

More than 1 billion people globally are suffering from hypertension, which is a long-term incurable medical condition that can further lead to dangerous complications and death if left untreated. In earlier studies, the brain-gut peptide secretin (SCT) was found to be able to control blood pressure by its cardiovascular and pulmonary effects. For example, serum SCT in patients with congestive heart failure was one-third of the normal level. These observations strongly suggest that SCT has a causal role in blood pressure control, and in this report, we used constitutive SCT knockout (SCT^-/-) mice and control C57BL/6N mice to investigate differences in the morphology, function, underlying mechanisms and response to SCT treatment. We found that SCT^-/- mice suffer from systemic and pulmonary hypertension with increased fibrosis in the lungs and heart. Small airway remodelling and pulmonary inflammation were also found in SCT^-/- mice. Serum NO and VEGF levels were reduced and plasma aldosterone levels were increased in SCT^-/- mice. Elevated cardiac aldosterone and decreased VEGF in the lungs were observed in the SCT^-/- mice. More interestingly, SCT replacement in SCT^-/- mice could prevent the development of heart and lung pathologies compared to the untreated group. Taken together, we comprehensively demonstrated the critical role of SCT in the cardiovascular and pulmonary systems and provide new insight into the potential role of SCT in the pathological development of cardiopulmonary and cardiovascular diseases.