Hypoglycemia-associated autonomic failure is prevented by opioid receptor blockade.
BACKGROUND
Repeated hypoglycemia is associated with hypoglycemia-associated autonomic failure (HAAF), a syndrome of defective counterregulation.


OBJECTIVE
HAAF increases the risk of severe hypoglycemia in diabetes, although its mechanism remains unresolved. Because beta-endorphin influences the autonomic response to hypoglycemia via opioid receptor activation, we hypothesized that it is also involved in the pathogenesis of HAAF.


METHODS
We asked whether opioid receptor blockade during antecedent hypoglycemia (60 mg/dl) on d 1 would prevent development of HAAF on d 2 in eight nondiabetic subjects (five males, 3 females; age, 28 +/- 3.5 yr; body mass index, 24.2 +/- 2.1 kg/m(2)). On four occasions, d 1 was: 1) two 90-min hypoglycemic clamps (N-); 2) two 90-min hypoglycemic clamps plus naloxone (N+); 3) two euglycemic 90-min clamps (C); or 4) two euglycemic 90-min clamps plus naloxone (C+).


RESULTS
Day 1 hypoglycemia caused marked deterioration of d 2 hormonal responses to hypoglycemia, consistent with HAAF-i.e. decreased plasma epinephrine, norepinephrine, and glucagon compared to control (C) (374 +/- 71 vs. 810 +/- 94, 307 +/- 65 vs. 686 +/- 98, and 71 +/- 9 vs. 93 +/- 4 pg/ml, respectively, P < 0.01), as well as in endogenous glucose production (24 vs. 163%; P < 0.01). In contrast, naloxone on d 1 completely prevented the defective counterregulatory responses; epinephrine, norepinephrine, and glucagon (852 +/- 82, 769 +/- 77, and 98 +/- 7 pg/ml) and endogenous glucose production recovery (167%) were identical to those after d 1 euglycemia (P < NS for all). Infusion of naloxone alone during euglycemia on d 1 (C+) had no effect on d 2 responses.


CONCLUSIONS
These data suggest that the opioid signaling system is a promising target for further studies to prevent HAAF.
Leu
James
J
Department of Medicine, Division of Endocrinology and Metabolism, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.
Cui
Min-Hui
MH
Shamoon
Harry
H
Gabriely
Ilan
I
D000328:Adult; D001342:Autonomic Nervous System Diseases / Q000209:etiology / Q000517:prevention & control*; D001786:Blood Glucose / Q000032:analysis; D002096:C-Peptide / Q000032:analysis; D004837:Epinephrine / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D005943:Gluconeogenesis; D006801:Humans; D007003:Hypoglycemia / Q000150:complications* / Q000503:physiopathology; D007328:Insulin / Q000097:blood; D008297:Male; D009270:Naloxone / Q000627:therapeutic use*; D009292:Narcotic Antagonists; D009638:Norepinephrine / Q000097:blood; D011957:Receptors, Opioid / Q000502:physiology; D013577:Syndrome; D001615:beta-Endorphin / Q000097:blood
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D009270:Naloxone; D001615:beta-Endorphin; D005934:Glucagon; D009638:Norepinephrine; D004837:Epinephrine