title: Nicotine behavioral pharmacology: clues from planarians.
abstract: BACKGROUND
  Nicotine is one of the world's most addictive substances and the primary reason that humans inhale tobacco smoke. The pharmacological effects of nicotine can be investigated in planarians, aquatic flatworms that possess an integrated neural network including cephalic ganglia that some consider the earliest 'brain' and spinal cord. Here, we tested the hypothesis that nicotine exposure elicits mammalian-like behaviors in planarians.
  
  
  METHODS
  Planarian motility and stereotypy (C-shape hyperkinesias) were quantified following acute nicotine exposure. During repeated nicotine exposure, we investigated the presence of withdrawal, tolerance, behavioral sensitization, and environmental place conditioning.
  
  
  RESULTS
  Acute nicotine exposure increased stereotypical activity and elicited biphasic effects on motility. A low concentration (0.01 mM) increased motility whereas higher concentrations (0.3-10mM) elicited the opposite effect. Planarians exposed to nicotine (0.03 mM) for 60 min and then tested in water displayed reduced motility that was not observed during exposure to water, acute nicotine, or continuous nicotine. Nicotine-treated planarians withdrawn from the drug for 3 days before being challenged with nicotine displayed behavioral sensitization at low concentrations (0.1, 0.3mM) but tolerance at higher concentrations (1, 3mM). Planarians conditioned with nicotine in the ambient light (non-preferred environment) displayed a reduction in their natural preference for a dark environment.
  
  
  CONCLUSIONS
  The present results suggest nicotine elicits mammalian-like effects in planarians, including decreased motility and increased stereotypy following acute administration and abstinence-induced withdrawal, behavioral sensitization, tolerance, and place conditioning during repeated exposure.
authors.affiliation: Department of Pharmaceutical Sciences, Temple University Health Sciences Center, Philadelphia, PA 19140, USA. scott.rawls@temple.edu
authors.forename: Scott M
authors.initials: SM
authors.lastname: Rawls
authors.forename: Tanvi
authors.initials: T
authors.lastname: Patil
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Tallarida
authors.forename: Steven
authors.initials: S
authors.lastname: Baron
authors.forename: Myongji
authors.initials: M
authors.lastname: Kim
authors.forename: Kevin
authors.initials: K
authors.lastname: Song
authors.forename: Sara
authors.initials: S
authors.lastname: Ward
authors.forename: Robert B
authors.initials: RB
authors.lastname: Raffa
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D009043:Motor Activity / Q000187:drug effects; D009068:Movement / Q000187:drug effects*; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D010932:Planarians / Q000187:drug effects*; D013239:Stereotyped Behavior / Q000187:drug effects*; D013375:Substance Withdrawal Syndrome
chemical_list: D018722:Nicotinic Agonists; D009538:Nicotine