Ghrelin, an endogenous
ligand for the
growth hormone secretagogue receptor, is synthesized as a preprohormone and then proteolytically processed to yield a 28-amino
acid peptide. This
peptide was originally reported to induce
growth hormone release; large evidence, however, has indicated many other physiological activities of
ghrelin, including regulation of food intake and energy balance, as well as of
lipid and
glucose metabolism.
Ghrelin receptors have been detected in the hypothalamus and the pituitary, but also in the cardiovascular system, where
ghrelin exerts beneficial hemodynamic activities.
Ghrelin administration acutely improves endothelial dysfunction by increasing
nitric oxide bioavailability and normalizes the altered balance between
endothelin-1 and
nitric oxide within the vasculature of patients with
metabolic syndrome. Other cardiovascular effects of
ghrelin include improvement of left ventricular contractility and cardiac output, as well as reduction of arterial pressure and systemic vascular resistance. In addition, antinflammatory and antiapoptotic actions of
ghrelin have been reported both in vivo and in vitro. This review summarizes the most recent findings on the metabolic and cardiovascular effects of
ghrelin through GH-dependent and -independent mechanisms and the possible role of
ghrelin as a therapeutic molecule for treating
cardiovascular diseases.