EN
Healthy, and insulin-deficient (streptozotocin-induced diabetic, STZ) Sprague-Dawley rats were used to investigate the effects of different doses of ß-endorphin (25 and 50 µg/kg) on plasma ß-endorphin, insulin, glucagon, and glucose levels at 15- and 30-min time points. In experimental groups, plasma ß-endorphin levels were higher at the 15-min than at the 30-min time point in healthy rats; however, in STZ-diabetic rats, ß-endorphin levels were lower at 15 min than at 30 min, indicating that intraperitoneal absorption of ß-endorphin differed between healthy and insulin-deficient rats, ß-endorphin did not affect plasma glucose, insulin, or glucagon at either dose in the healthy group. In the insulin-deficient rats, ß-endorphin at 50 µg/kg reduced plasma glucose levels at the 30-min time point compared to the 25 µg/kg dose, without affecting plasma insulin. Moreover, ß-endorphin at 50 µg/kg decreased plasma glucagon levels at the 15-min time point in comparison to the 25 µg/kg dose in insulin-deficient rats. Plasma glucose levels may be reduced in insulin-deficient rats at high ß-endorphin levels regardless of insulin status.