Sensitivity to beta-endorphin as a cause of human obesity.
Naloxone, an opiate antagonist, was given as an intravenous bolus (5 mg) in both lean and obese healthy subjects. In lean people, there was a slight trend for insulin and C-peptide concentrations to decrease below baseline values with no glucose change. Obese subjects showed an exaggerated suppression of insulin and C-peptide and a slight decrease of glucose. Glucagon was suppressed in both groups. An infusion of human beta-endorphin (0.05 mg/h) produced only minor changes in plasma glucose, insulin, glucagon, and C-peptide concentrations in lean subjects, but caused marked increments in obese. Glucagon rose in both groups, but its response was greater in obese subjects. A ten-day treatment with naloxone (1.2 mg twice a day) did not change the metabolic and hormonal responses to an oral glucose load (75 g) in lean but significantly inhibited the insulin and C-peptide responses to glucose in obese people. These results suggest that an increased opiate drive to the pancreatic beta-cell and an increased responsiveness of insulin to beta-endorphin are present in human obesity.
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002096:C-Peptide / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D005951:Glucose Tolerance Test; D006801:Humans; D007328:Insulin / Q000097:blood; D007515:Islets of Langerhans / Q000187:drug effects / Q000503:physiopathology*; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D001615:beta-Endorphin / Q000494:pharmacology / Q000502:physiology*
D001786:Blood Glucose; D002096:C-Peptide; D007328:Insulin; D009270:Naloxone; D001615:beta-Endorphin; D005934:Glucagon