title: Microinjections of acetaldehyde or salsolinol into the posterior ventral tegmental area increase dopamine release in the nucleus accumbens shell.
abstract: BACKGROUND
  Published findings indicate that acetaldehyde (ACD; the first metabolite of ethanol [EtOH]) and salsolinol (SAL; formed through the nonenzymatic condensation of ACD and dopamine [DA]) can be formed following EtOH consumption. Both ACD and SAL exhibit reinforcing properties within the posterior ventral tegmental area (pVTA) and both exhibit an inverted "U-shaped" dose-response curve. The current study was undertaken to examine the dose-response effects of microinjections of ACD or SAL into the pVTA on DA efflux in the nucleus accumbens shell (AcbSh).
  
  
  METHODS
  For the first experiment, separate groups of male Wistar rats received pulse microinjections of artificial cerebrospinal fluid (aCSF) or 12-, 23-, or 90-μM ACD into the pVTA, while extracellular DA levels were concurrently measured in the AcbSh. The second experiment was similarly conducted, except rats were given microinjections of aCSF or 0.03-, 0.3-, 1.0-, or 3.0-μM SAL, while extracellular levels of DA were measured in the AcbSh.
  
  
  RESULTS
  Both ACD and SAL produced a dose-dependent inverted "U-shaped" response on DA release in the AcbSh, with 23-μM ACD (200% baseline) and 0.3-μM SAL (300% baseline) producing maximal peak responses with higher concentrations of ACD (90 μM) and SAL (3.0 μM) producing significantly lower DA efflux.
  
  
  CONCLUSIONS
  The findings from the current study indicate that local application of intermediate concentrations of ACD and SAL stimulated DA neurons in the pVTA, whereas higher concentrations may be having secondary effects within the pVTA that inhibit DA neuronal activity. The present results parallel the studies on the reinforcing effects of ACD and SAL in the pVTA and support the idea that the reinforcing effects of ACD and SAL within the pVTA are mediated by activating DA neurons.
authors.affiliation: Department of Psychiatry, Indiana University School of Medicine, Indianapolis, IN 46202, USA. gdeehan@iupui.edu
authors.forename: Gerald A
authors.initials: GA
authors.lastname: Deehan
authors.forename: Eric A
authors.initials: EA
authors.lastname: Engleman
authors.forename: Zheng-Ming
authors.initials: ZM
authors.lastname: Ding
authors.forename: William J
authors.initials: WJ
authors.lastname: McBride
authors.forename: Zachary A
authors.initials: ZA
authors.lastname: Rodd
mesh_terms: D000079:Acetaldehyde / Q000494:pharmacology*; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D059290:Dopaminergic Neurons / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D000431:Ethanol; D007546:Isoquinolines / Q000494:pharmacology*; D008297:Male; D017551:Microdialysis; D008845:Microinjections; D009714:Nucleus Accumbens / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D012054:Reinforcement, Psychology; D017557:Ventral Tegmental Area
chemical_list: D007546:Isoquinolines; D000431:Ethanol; C036617:salsolinol; D000079:Acetaldehyde; D004298:Dopamine