title: Nicotine infusion in the wake-promoting basal forebrain enhances alcohol-induced activation of nucleus accumbens.
abstract: BACKGROUND
  Nicotine and alcohol co-abuse is highly prevalent. Recently, we have shown that nicotine infusion in the basal forebrain (BF) increases alcohol consumption. As nucleus accumbens (NAc) is the terminal brain region associated with drug addiction, we hypothesize that nicotine infusion in the BF may enhance alcohol-induced activation of NAc.
  
  
  METHODS
  Adult male Sprague-Dawley rats were surgically implanted with bilateral guide cannulas in the BF. Following postoperative recovery, rats were divided into 4 groups: (i) ACSF + W group received artificial cerebrospinal fluid (ACSF; 500 nl/side) in the BF and systemic water (intragastric [ig]; 10 ml/kg; N = 5), (ii) ethanol (EtOH) group received ACSF in the BF (500 nl/side) and systemic alcohol (ig; 3 g/kg; N = 5), (iii) NiC group received nicotine in the BF (75 pmole/500 nl/side) and systemic water (ig; 10 ml/kg; N = 5), and (iv) NiC + EtOH group received nicotine in the BF (75 pmole/500 nl/side) and systemic alcohol (ig; 3 g/kg; N = 5). Rats were euthanized 2 hours after treatment to examine c-Fos expression in the NAc by immunohistochemistry.
  
  
  RESULTS
  All injections sites were localized in the BF. Two-way analysis of variance (ig vs. infusion) revealed significant main effects of both treatments (ig and infusion, p < 0.001) on c-Fos expression in the NAc shell, but not in the core. Subsequent post hoc test (Bonferroni's) revealed that as compared to ACSF + W group, c-Fos expression was significantly increased in the shell of NAc of rats in all 3 (EtOH, NiC, and NiC + EtOH) groups with maximal increase observed in NiC + EtOH group.
  
  
  CONCLUSIONS
  The results suggest the following: (i) BF nicotine infusion induced c-Fos in both core and the shell region of NAc at levels comparable to those observed after systemic alcohol administration; (ii) BF nicotine infusion with systemic alcohol induced a significant additive increase in c-Fos expression only in the NAc shell region. These findings implicate the BF in alcohol and nicotine co-use.
authors.affiliation: Department of Neurology, Harry S. Truman Memorial Veterans Hospital, University of Missouri, Columbia, Missouri.
authors.forename: Rishi
authors.initials: R
authors.lastname: Sharma
authors.forename: Samuel
authors.initials: S
authors.lastname: Dumontier
authors.forename: David
authors.initials: D
authors.lastname: DeRoode
authors.forename: Pradeep
authors.initials: P
authors.lastname: Sahota
authors.forename: Mahesh M
authors.initials: MM
authors.lastname: Thakkar
mesh_terms: D000284:Administration, Oral; D000428:Alcohol Drinking / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D066187:Basal Forebrain / Q000187:drug effects* / Q000502:physiology*; D000431:Ethanol / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D057967:Infusions, Intraventricular; D008297:Male; D023421:Models, Animal; D009538:Nicotine / Q000008:administration & dosage / Q000494:pharmacology*; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D019966:Substance-Related Disorders / Q000378:metabolism / Q000503:physiopathology; D014851:Wakefulness / Q000502:physiology*
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D000431:Ethanol; D009538:Nicotine
keywords: Alcohol; Basal Forebrain; Nicotine; Nucleus Accumbens; c-Fos