title: Toxic cocaine- and convulsant-induced modification of forced swimming behaviors and their interaction with ethanol: comparison with immobilization stress.
abstract: BACKGROUND
  Swimming behaviors in the forced swimming test have been reported to be depressed by stressors. Since toxic convulsion-inducing drugs related to dopamine [cocaine (COC)], benzodiazepine [methyl 6,7-dimethoxy-4-ethyl-beta-carboline-carboxylate (DMCM)], gamma-aminobutyric acid (GABA) [bicuculline (BIC)], and glutamate [N-methyl-D-aspartate (NMDA)] receptors can function as stressors, the present study compared their effects on the forced swimming behaviors with the effects of immobilization stress (IM) in rats. Their interactions with ethanol (EtOH), the most frequently coabused drug with COC which also induces convulsions as withdrawal symptoms but interferes with the convulsions caused by other drugs, were also investigated.
  
  
  RESULTS
  Similar to the IM (10 min) group, depressed swimming behaviors (attenuated time until immobility and activity counts) were observed in the BIC (5 mg/kg IP) and DMCM (10 mg/kg IP) groups at the 5 h time point, after which no toxic behavioral symptoms were observed. However, they were normalized to the control levels at the 12 h point, with or without EtOH (1.5 g/kg IP). In the COC (60 mg/kg IP) and NMDA (200 mg/kg IP) groups, the depression occurred late (12 h point), and was normalized by the EtOH cotreatment. At the 5 h point, the COC treatment enhanced the swimming behaviors above the control level.
  
  
  CONCLUSIONS
  Although the physiological stress (IM), BIC, and DMCM also depressed the swimming behaviors, a delayed occurrence and EtOH-induced recovery of depressed swimming were observed only in the COC and NMDA groups. This might be correlated with the previously-reported delayed responses of DA and NMDA neurons rather than direct effects of the drugs, which could be suppressed by EtOH. Furthermore, the characteristic psychostimulant effects of COC seemed to be correlated with an early enhancement of swimming behaviors.
authors.affiliation: Department of Legal Medicine, Kyoto University Graduate School of Medicine, Faculty of Medicine, Yoshidakonoe-cho, Sakyo-ku, Kyoto 606-8501, Japan. hayaselab@jweb.co.jp
authors.forename: Tamaki
authors.initials: T
authors.lastname: Hayase
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Yamamoto
authors.forename: Keiichi
authors.initials: K
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects*; D003042:Cocaine / Q000633:toxicity*; D003292:Convulsants / Q000633:toxicity*; D018765:Dopamine Uptake Inhibitors / Q000633:toxicity; D004347:Drug Interactions; D000431:Ethanol / Q000494:pharmacology*; D007103:Immobilization / Q000009:adverse effects*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013312:Stress, Physiological / Q000523:psychology*; D013550:Swimming
chemical_list: D003292:Convulsants; D018765:Dopamine Uptake Inhibitors; D000431:Ethanol; D003042:Cocaine