Nicotine is a component of tobacco products and is one of the most commonly abused substances that leads to addiction. Therefore, the present study was performed to investigate the behavioral pattern and toxicity by nicotine exposure in planarians. Basically, planarians were exposed to different concentration of nicotine for 5 min. To investigate detoxification effect, planarians were exposed to nicotine for 5 min, and treated glycyrrhizin for 5 min, then motility and seizure-like behavior were observed for 5 min. As a result, the motility of nicotine-exposed planarians decreased approximately more than 50% compared to freshwater control. However, the motility of glycyrrhizin-exposed planarians recovered than nicotineexposed planarians. In the assessment of seizure-like behavioral pattern, planarians exposed to nicotine showed head-bop or c-like type rather than screw-like or snake-like patterns. However, planarians exposed to glycyrrhizin showed no seizure-like behavior. To examine the oxidative stress response, planarians were cultured in fresh water containing 1 mM nicotine for 1 day. Planarians were homogenized and extracted to assay the contents of reactive oxygen species (ROS), lipid hydroperoxides (LH), glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD). The result showed that a significantly higher level of ROS, LH indicated in planarians exposed to nicotine, on the other hand, glycyrrhizin-exposed planarians were significantly decreased ROS, LH levels. In conclusion, the motility decreased when planarians were exposed to nicotine, in a dose-dependent manner, whereas seizurelike behavior increased. Nicotine induced behavioral disturbances and cell toxicity in planarians were recovered by glycyrrhizin, suggesting a candidate substance for nicotine addiction treatment.

Introduction
 Materials and Methods
  실험 동물과 시약
  플라나리아의 운동성과 발작 형태 측정
  플라나리아 세포의 산화적 스트레스(oxidative stress) 반응측정을 위한 샘플 처리
  Catalase assay(CAT)
  Superoxide dismutase assay(SOD)
  Lipid hydroperoxides assay(LH)
  Reactive oxygen species(ROS) 측정
  Glutathione assay
  통계분석 및 유의성 검정
 Results and Discussion
  니코틴이 플라나리아의 운동과 발작 행동에 미치는 영향
  글리시리진이 플라나리아의 운동과 발작에 미치는 영향
  니코틴에 노출된 플라나리아에 글리시리진 처리가 미치는영향
  니코틴에 노출된 플라나리아에 글리시리진 처리가 세포의산화적 스트레스 반응에 미치는 영향
 References

• Yong-Jin Kim(Division of Biotechnology Chonbuk National University)
• Juneno So(Department of Pharmaceutical Engineering, Woosuk University)
• Young-Joo Yi(Division of Biotechnology Chonbuk National University) Corresponding author
• Sang-Myeong Lee(Division of Biotechnology Chonbuk National University) Corresponding author