Effects of naloxone on glucose and insulin regulation during endotoxicosis in fed and fasted rats.

This study examined the effects of naloxone on glucose and insulin dyshomeostasis during endotoxicosis in ad libitum fed and overnight-fasted rats. Plasma glucose levels were measured in vivo to assess the effects of naloxone on glucose regulation during endotoxicosis. Naloxone's effects on endotoxin-induced portal and systemic hyperinsulinemia were evaluated in vivo. In addition, the ability of naloxone to alter the insulin hypersecretory state of the endotoxic pancreas was evaluated using the in vitro perfused rat pancreas preparation. Naloxone did not alter endotoxin-induced glucose dyshomeostasis in fasted rats, but potentiated hypoglycemia in fed, endotoxic rats. Naloxone potentiated endotoxin-induced hyperinsulinemia and insulin hypersecretion from the endotoxic pancreas in fed, but not fasted, rats. Thus the results indicated that naloxone had no apparent beneficial effects on glucose and insulin dyshomeostasis during endotoxicosis in either fed or fasted rats, and potentiated glucose and insulin dyshomeostasis in fed, endotoxic rats. Since naloxone is a specific opiate antagonist, these results suggested that endogenous opiate systems do not play a significant deleterious role in the glucose and insulin dyshomeostasis of endotoxic shock. In addition, this study identified prior feeding history of rats (ad libitum feeding vs. overnight fasting) as an important variable relative to the study of naloxone's effects on glucose and insulin regulation during endotoxicosis.