Chromogranin A plays a crucial role in the age-related development of insulin resistance and hypertension

Abstract

Aging is associated with the development of metabolic disorders, including insulin resistance and hypertension. Young mice that are negative for the neuroendocrine prohormone Chromogranin A (CgA knockout, CgA-KO) display two opposite aging phenotypes: hypertension but heightened insulin sensitivity. We determined these phenotypes in aging CgA mice. In comparison, aging wild-type (WT) mice gradually lost glucose tolerance and insulin sensitivity. Moreover, while aging WT mice had increased inflammation with higher plasma TNF-, IFN-{gamma} and CCL2 and increased mitochondrial fission, these phenotypes were the opposite in aging CgA-KO mice. CgA-KO mice also showed increased expression of mitochondrial and nuclear-encoded complex I genes, implying that they were healthier than WT mice. Most intriguingly, the hypertension in CgA-KO mice was spontaneously reversed with aging. Supplementation of CgA-KO mice with pancreastatin, a hyperglycemic peptide produced from CgA by proteolysis, increased both blood glucose levels and blood pressure, implicating hyperglycemia, and hypertension. We conclude that age-related insulin resistance and hypertension are caused by CgA.