title: Effects of acute ethanol on beta-endorphin release in the nucleus accumbens of selectively bred lines of alcohol-preferring AA and alcohol-avoiding ANA rats.
abstract: BACKGROUND
  The selectively bred lines of alcohol-preferring alko alcohol (AA) and alcohol-avoiding alko nonalcohol (ANA) rats have been used to demonstrate differences in relevant neurotransmitters which could account for their difference in alcohol consumption. Studies have demonstrated differences in distinct components of the endogenous opioid system in various brain regions associated with the process of reinforcement between the AA and ANA lines of rats.
  
  
  OBJECTIVE
  The goal of this current study was to investigate the hypotheses that the AA and ANA rats will show differences in the release of beta-endorphin at the level of nucleus accumbens (NAC) and in locomotor activity in response to acute systemic administration of ethanol.
  
  
  METHODS
  AA and ANA rats were unilaterally implanted with a guide cannula to aim microdialysis probes at the level of NAC. Intraperitoneal injections of 0.0, 1.5, 2.0, and 2.5 g ethanol/kg body weight were administered. Dialysate samples were collected at 30-min intervals prior to and following the injection. Radioimmunoassay specific for beta-endorphin was used to determine the dialysate beta-endorphin content.
  
  
  RESULTS
  The 2.5-g/kg ethanol dose induced a transient increase in extracellular beta-endorphin at the level of NAC of AA but not of ANA rats. The 2.5-g/kg ethanol dose also attenuated locomotor activity in the AA but not in the ANA rats.
  
  
  CONCLUSIONS
  The lack of an increase in the beta-endorphin concentration in the NAC of ANA rats in response to ethanol may partially account for their lower alcohol consumption and lower alcohol-induced attenuation of locomotor activity compared to AA rats.
authors: Department of Physiology, McGill University, Montreal, QC, Canada.
authors: Minh P
authors: MP
authors: Lam
authors: Harri
authors: H
authors: Nurmi
authors: Noora
authors: N
authors: Rouvinen
authors: Kalervo
authors: K
authors: Kiianmaa
authors: Christina
authors: C
authors: Gianoulakis
mesh_terms: D000428:Alcohol Drinking; D000818:Animals; D002492:Central Nervous System Depressants / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000008:administration & dosage / Q000494:pharmacology*; D007274:Injections, Intraperitoneal; D008297:Male; D017551:Microdialysis; D009043:Motor Activity / Q000187:drug effects; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D001615:beta-Endorphin / Q000187:drug effects* / Q000378:metabolism
chemical_list: D002492:Central Nervous System Depressants; D000431:Ethanol; D001615:beta-Endorphin