title: Continuous evaluation of drug withdrawal in the rat using telemetry: effects of morphine and chlordiazepoxide.
abstract: BACKGROUND
  The procedures used to assess withdrawal must be sensitive and widely applicable, i.e. not specific to any particular drug class. Furthermore, the measurements should not be affected by repeat testing.
  
  
  METHODS
  We have used implanted telemetry devices to continuously follow body temperature, locomotor activity (LMA), heart rate (HR) and mean arterial blood pressure (mean ABP) in addition to food intake and body weight gain over 20days of treatment and 8days of withdrawal. The effects of morphine (32 and 64mg/kg p.o., b.i.d.) and chlordiazepoxide (16, 32 and 64mg/kg p.o., b.i.d.) were studied in rats.
  
  
  RESULTS
  The results show that during the treatment phase chronic morphine reduced food intake and body weight gain, increased body temperature, HR, mean ABP and LMA. These effects continued over the 20days of treatment. In contrast, chlordiazepoxide slightly increased food intake and body weight gain throughout the treatment period. It also decreased body temperature and LMA but increased HR and mean ABP after the first few administrations but these effects disappeared over the 20days of treatment. Following discontinuation, both morphine- and chlordiazepoxide-treated rats showed a dose-related decrease in food intake and loss of weight on days 2 and 3 of discontinuation. Morphine discontinuation also induced a nocturnal hypothermia and a diurnal hypertension (i.e. during the light phase) which lasted for 4-5days and also moderate diurnal increases in locomotor activity and heart rate over the first 3days of discontinuation. Chlordiazepoxide discontinuation induced small increases in telemetry parameters some of which, such as the effect on locomotor activity, lasted for more than 5days. The intensity and duration of effects for both substances were broadly dose-related.
  
  
  CONCLUSIONS
  These data show that telemetry can increase the sensitivity of withdrawal experiments to changes that might otherwise be missed and allows a better definition of the time-course of withdrawal effects. This technique is therefore useful as part of safety pharmacology abuse liability evaluation of novel test substances across a broad range of pharmacological and therapeutic classes.
authors.affiliation: Porsolt, 9bis rue Henri Martin, 92100 Boulogne-Billancourt, France.
authors.forename: Christelle
authors.initials: C
authors.lastname: Froger-Colléaux
authors.forename: Sonia
authors.initials: S
authors.lastname: Rompion
authors.forename: Philippe
authors.initials: P
authors.lastname: Guillaume
authors.forename: Roger D
authors.initials: RD
authors.lastname: Porsolt
authors.forename: Vincent
authors.initials: V
authors.lastname: Castagné
authors.forename: Paul
authors.initials: P
authors.lastname: Moser
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D002707:Chlordiazepoxide / Q000494:pharmacology*; D004435:Eating / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D012680:Sensitivity and Specificity; D013375:Substance Withdrawal Syndrome / Q000175:diagnosis* / Q000503:physiopathology; D013686:Telemetry / Q000379:methods*
chemical_list: D002707:Chlordiazepoxide; D009020:Morphine