title: [µ-opioid receptors in the central nucleus of the amygdala regulate food rather than water intake in rats].
abstract: OBJECTIVE
  To investigate the effect of µ-opioid receptors (µ-ORs) in the central nucleus of the amygdala (CeA) on feeding and drinking behaviors in rats and evaluate the role of glutamate signaling in opioid-mediated ingestive behaviors.
  
  
  METHODS
  Stainless steel cannulas were implanted in the unilateral CeA for microinjection of different doses of the selective µ-OR agonist DAMGO in satiated or water-deprived male SD rats. The subsequent food intake or water intake of the rats was measured at 60, 120, and 240 min after the injection. The rats receiving microinjections of naloxone (NTX, a nonselective opioid antagonist) or D-AP-5 (a selective N-methyl-D-aspartic acid-type glutamate receptor antagonist) prior to DAMGO microinjection were tested for food intake at 60, 120, and 240 min after the injections.
  
  
  RESULTS
  Injections of DAMGO (1-4 nmol in 0.5 µl) into the CeA significantly increased food intake in satiated rats, but did not affect water intake in rats with water deprivation. NTX (26.5 nmol in 0.5 µl) injected into the CeA antagonized DAMGO-induced feeding but D-AP-5 (6.3-25.4 nmol in 0.5 µl) injections did not produce such an effect.
  
  
  CONCLUSIONS
  µ-ORs in the CeA regulate food intake rather than water intake in rats, and the orexigenic role of µ-ORs is not dependent on the activation of the NMDA receptors in the CeA.
authors.affiliation: Department of Physiology, Medical College of Henan University of Science and Technology, Luoyang 471003, China.E-mail: hkdyxyyjb@haust.edu.cn.
authors.forename: Junbao
authors.initials: J
authors.lastname: Yan
authors.forename: Jianqun
authors.initials: J
authors.lastname: Yan
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D066274:Central Amygdaloid Nucleus / Q000502:physiology*; D004326:Drinking / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000502:physiology*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D009292:Narcotic Antagonists; D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D009270:Naloxone; D015763:2-Amino-5-phosphonovalerate