The effects of different anaesthetic treatments on the adreno-cortical functions and glucose levels in NZW rabbits

The effects of five anaesthetics on the corticosterone, cortisol and glucose concentrations were investigated in the NZW rabbit. Sixty animals were assigned to 6 treatment groups (n= 10 per group): control ( iv saline solution injection), ketamine (10 mg/kg iv) with either xylazine (3 mg/kg iv) or diazepam (2 mg/kg iv), pentobarbitone (30 mg/kg iv), thiopentone (20 mg/kg iv) and fentanyl/droperidol (1 mg/kg sc). Plasma glucocorticoids were measured by competitive enzymeimmunoassay EIA and glucose by an autoanalyzer, previously validated for this species in both cases. Blood samples were obtained at 6 time-points: before injection, at 10, 30, 60, 120 min and 24 h after injection of the anaesthetics/saline. A significant decrease of plasma glucocorticoids at 10-60 min was observed in the pentobarbitone and fentanyl/ droperidol groups, whereas the administration of ketamine/diazepam or thiopentone stimulated plasma glucocorticoid release, principally in the recovery period. However, in the ketamine/xylazine group no changes were observed in the glucocorticoid levels, except for a significative increase of cortisol at 60-120 min. Glucose levels significantly increased after ketamine/diazepam administration and principally, after ketamine/xylazine treatment. The present data suggest that ketamine/xylazine has little effect on glucocorticoid levels and provides an adequate level of surgical anaesthesia, hence it would be the anaesthetic of choice, although the hyperglycaemic effect after injection has to be considered for any experimental procedures in rabbits.