Opioid and non-opioid components of insulin-induced feeding.
The present study was initiated to clarify the involvement of endogenous opioids in insulin-induced feeding. Naloxone (3 mg/kg) was injected in male Sprague Dawley rats every hour for 2 hours after insulin injection (10 U/kg). Only the first hour food intake was depressed (68% reduction). When naloxone was given only 1 hour after insulin administration, depression of food intake was not noted. When food was withheld for 2 hours after insulin injection, both naloxone and its long acting congener, naltrexone (3 mg/kg) were able to depress only the first hour feeding subsequent to food presentation. These data suggest that insulin-induced feeding can be divided into two pharmacologically distinct phases: the early phase being naloxone-sensitive while the late phase is naloxone-insensitive. Furthermore, the early phase begins with the presentation of food and not with the administration of insulin.
D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001921:Brain / Q000502:physiology; D004347:Drug Interactions; D004723:Endorphins / Q000502:physiology; D005247:Feeding Behavior / Q000187:drug effects* / Q000502:physiology; D007328:Insulin / Q000008:administration & dosage*; D008297:Male; D051379:Mice; D009270:Naloxone / Q000008:administration & dosage*; D009271:Naltrexone / Q000008:administration & dosage*
D001786:Blood Glucose; D004723:Endorphins; D007328:Insulin; D009270:Naloxone; D009271:Naltrexone