A possible central opiate mechanism involved in the inhibition of food intake and reticular motility by duodenal DL-lactic acid infusion in sheep.
Intraduodenal infusion of DL-lactic acid was performed in sheep fitted with a permanent cannula into the lateral cerebral ventricle and nichrome electrodes on the reticulum in order to record its electrical activity during periods of controlled food intake in a series of experiments subsequently repeated in animals fasted for 12 hours. A solution of 0.2M DL-lactic acid was infused at a rate of 1 ml/min during the 1st hour of a 3-hour period of feeding with or without previous intracerebroventricular (ICV) or IV administration of naloxone (2.4 and 10 micrograms/kg). During lactic acid infusion, the food intake and the frequency of reticular contraction (measured during eating) were reduced by 48% and 19%, respectively--these effects being prolonged for the 1st hour after infusion. Previous ICV administration of naloxone (2.4 micrograms/kg) partially blocked the effects of lactic acid on food intake (63%) and frequency of reticulum contractions (58%). These effects were abolished for the largest dose of naloxone (10 micrograms/kg) administered ICV, whereas its IV administration did not affect significantly the effects of lactic acid. It is concluded that the duodenal lactic acid concentration may have a role in the control of food intake by a mechanism involving central opiate mediation.
D000818:Animals; D001067:Appetite Depressants / Q000494:pharmacology; D004386:Duodenum / Q000187:drug effects*; D004435:Eating / Q000187:drug effects*; D005769:Gastrointestinal Motility / Q000187:drug effects*; D007773:Lactates / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D019344:Lactic Acid; D051379:Mice; D009270:Naloxone / Q000008:administration & dosage; D011957:Receptors, Opioid / Q000187:drug effects / Q000502:physiology*; D012159:Reticulum / Q000187:drug effects / Q000502:physiology*; D012417:Rumen / Q000502:physiology; D012756:Sheep / Q000502:physiology*
D001067:Appetite Depressants; D007773:Lactates; D011957:Receptors, Opioid; D019344:Lactic Acid; D009270:Naloxone