Vitamin A Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin A, including details on retinol, benefits, dosage, supplements, deficiency, information.

Effects of all-trans retinoic acid on orphan receptor APJ signaling in spontaneously hypertensive rats.

Zhong JC, Huang DY, Liu GF, Jin HY, Yang YM, Li YF, Song XH, Du K

Center for Molecular Biology, Shantou University Medical College, Shantou, Guangdong 515041, China. g_jczhong@stu.edu.cn

OBJECTIVE: Studies show general agreement that all-trans retinoic acid (atRA) has been linked to the regulation of G protein-coupled receptor (GPCRs) signaling. To further validate effects of atRA on the cardiovascular GPCRs, the present study was designed to assess whether atRA will modulate orphan receptor APJ, a homologue of angiotensin II type 1 (AT(1)) receptor. METHODS: Real-time polymerase chain reaction and Western blot methods were performed to examine the expression of APJ and its endogenous ligand apelin in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats after chronic atRA treatment. RESULTS: APJ and apelin expression were markedly depressed in placebo-treated SHR, compared with WKY rats (p<0.01). However, in atRA-treated SHR, a significant upregulation of APJ and apelin expression was observed in both heart and aorta (p<0.05), accompanied by a reduction of AT(1) expression, an elevation of serum nitric oxide levels and a subsequent decrease of blood pressure. CONCLUSIONS: Chronic atRA treatment activates gene and protein expression of APJ and apelin and reduces blood pressure in SHR, suggesting that atRA may regulate the balance between apelin-APJ and angiotensin II-AT(1) signaling and have potential clinical value in the prevention and treatment of human hypertension.

Published 24 January 2005 in Cardiovasc Res, 65(3): 743-50.
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