Metoclopramide Restores the Sympathoadrenal Response to Hypoglycemia in a Novel Model of HAAF

We sought to develop a novel animal model of hypoglycemia-associated autonomic failure (HAAF) and investigate the pathological process involved. We previously noted that recurrent 2-deoxyglucose (R2DG) administration induced hypoglycemia unawareness (indicated by a blunted food intake response to hypoglycemia). We now evaluate whether R2DG also induces an impaired counterregulatory response and whether this pathological process is mediated by dopaminergic receptor activation. Sprague-Dawley rats were randomized to one of three, 3-day treatments: 1) recurrent saline (Control), 2) R2DG (200 mg/kg/d, SQ), or 3) R2DG and antecedent pretreatment with the dopaminergic antagonist metoclopramide (R2DG+Meto, 3 mg/kg/d, IP). On the fourth day, all rats underwent hyperinsulinemic (50 mU/kg/min) hypoglycemic (∼50 mg/dl) clamps. Notably, recurrent 2DG abrogated the epinephrine response to hypoglycemia as compared to controls. In addition to restoring hypoglycemia awareness (i.e., the food intake response to hypoglycemia), metoclopramide normalized the epinephrine response to hypoglycemia in 2DG treated rats. Glucagon showed a similar pattern of suppression with R2DG and restoration with R2DG+Meto. In this model of HAAF, our data identifies a novel role of dopaminergic receptor activation in the development of HAAF and a potential role for metoclopramide as a potential therapeutic agent to prevent HAAF.