Measurement of plasma chromogranin A concentrations for assessment of stress responses in dogs with insulin-induced hypoglycemia

OBJECTIVE: To determine whether cross-reactivity exists between canine chromogranin A (CgA) and anti-human CgA antibody and investigate the usefulness of plasma CgA concentration measurements as an index of acute stress responses in dogs. ANIMALS: 12 healthy Beagles. PROCEDURE: Canine CgA was extracted and purified from canine adrenal glands of cadaver dogs for studying cross-reactivity with anti-human CgA antibody. Western blotting with anti-human CgA antibody was performed. Blood samples were collected from dogs at 0, 10, 20, 30, 40, 60, 120, and 180 minutes after IV administration of saline (0.9% NaCl) solution or insulin. Canine plasma CgA concentrations were determined by use of a CgA ELISA kit with rabbit antiserum against the carboxy-terminal fragment of human CgA. Plasma cortisol and catecholamine (ie, norepinephrine and epinephrine) concentrations were measured by use of an ELISA and a high-performance liquid chromatography method, respectively. RESULTS: Purified canine CgA was specifically detected by use of western blot analysis and an ELISA with anti-human CgA antibody. An increase in plasma CgA concentrations was observed in insulin-induced hypoglycemic dogs. Changes in plasma CgA concentration were correlated with changes in plasma cortisol or catecholamine concentrations of hypoglycemic dogs. CONCLUSIONS AND CLINICAL RELEVANCE: Use of the CgA ELISA kit for determination of human plasma CgA concentrations is applicable to the measurement of canine plasma CgA concentrations. Canine plasma CgA concentrations, along with measurements of plasma cortisol and catecholamine concentrations, correctly reflect insulin-induced hypoglycemic stressed conditions in dogs. Measurement of canine plasma CgA concentrations may provide a useful index for evaluation of an acute stress response.