Evaluation of different central nervous system depressors combined with ketamine for anaesthesia in mice

Abstract

ABSTRACT:The aim of this study was to compare some depressors of the central nervous system combined with ketamine in order to find an adequate scombination for anaesthesia in mice, coupled with a simple, easy to use and reliable method. Forty Swiss OF-1 mice (Mus musculus), 20 females and 20 males with a body weight from 35 to 45 g aged from 12 to 16 weeks, were used to evaluate one of the following central nervous system depressors (CNSD): acepromazine (5 mg/kg), diazepam (5 mg/kg), medetomidine (1 mg/kg), midazolam (5 mg/kg) and xylazine (10 mg/kg) combined with the dissociative anaesthetic ketamine (100 mg/kg) by the intraperitoneal route. Different parameters were evaluated at regular intervals to assess the depth of anaesthesia (time of induction, time of loss and recovery of pedal withdrawal reflex, time of recovery from the anaesthesia), and respiratory and heart rate and oxygen saturation. Most of the assessment times and physiological parameters were exhibited earlier in females than in males but, in most cases, these differences were not significant. The diazepam combination resulted in death in half of the male group. Significant differences for the combination comparison were found for induction, pedal withdrawal reflex and recovery from anaesthesia, as well as for respiratory and heart rate and oxygen saturation. The best results for mice of both genders, i.e. induction, maintenance and recovery from anaesthesia were more stable with α 2 -agonists than with other combinations (benzodiazepines or acepromazine), which did not reach a good anaesthetic level, that is, an adequate anaesthetic plane with an absence of the pedal withdrawal reflex and the maintenance of stable vital constants.

Analyses of anaesthesia with ketamine combined with different sedatives in rats

“…These observations are in contrast to data obtained in mice by Serrano et al (2013) who reported that female mice lost PWR earlier than males in response to treatment with α 2 -agonists. However, the rats did not lose the pedal reflex after treatment with the acepromazine and midazolam combinations.…”

“…Consequently, only the combination of α 2 -agonists and ketamine seems to be adequate at these doses for use as an anaesthetic because it reduces pain perception, as previously reported by other authors (Cruz et al 1998;Arras et al 2001). Similar to other authors, we did not observe an increase of diuresis (side-effect of α 2 -agonists), nor salivary secretion (Cruz et al 1998;Serrano-Caballero et al 2013). …”

Anesthetic effects and body weight changes associated with ketamine-xylazine-lidocaine administered to CD-1 mice

“…Anesthesia for small rodents is commonly performed through the injection of one, or a mixture of parenteral agents [ 1 – 3 ]. The intraperitoneal (IP) route of administration is often utilized for laboratory mice when there is an inability to use inhalant anesthesia for research-specific requirements, lack of inhalational anesthesia equipment, or due to technical limitations of intravenous or intramuscular injections in small species [ 4 ].…”