Aim: Glucose homeostasis is maintained under strict physiological control in which the central nervous system is very important. Ketamine/xylazine mixture induces hyperglycemia, although the mechanism involved is unknown. We aimed to study the role of sympathoadrenal axis on glycemia and insulinemia in adult rats.
Methods: NInety-day-old male Wistar rats were used. Half of the rats underwent removal of the adrenal gland medullae (adrenodemedullation, ADM). After overnight fasting, all rats were given the intravenous glucose tolerance test (ivGTT), which was performed in six groups: awake, ketamine/xylazine (KX) and thiopental (Thiop) anesthetized intact rats, and the same groups of ADM rats. The intraperitoneal insulin tolerance test (1U/kg BW) was performed in an additional animal group to record the rate constant of plasma glucose disappearance (Kitt). Tissue insulin sensitivity was also evaluated by the homeostasis model assessment (HOMA).
Results: Ketamine/xylazine increased basal glycemia by 110.6% (P<0.001) in intact rats. In the ADM group, KX rats had a reduction of 36.6% (P<0.05) basal glycemia. Thiop caused a decrease of 70.3% (P<0.05) in basal insulinemia in intact rats. ADM reduced fasting insulin in all groups. Insulin sensitivity was elevated in intact Thiop rats, while insulin resistance was observed in intact KX rats. Both anesthetics induced glucose intolerance during ivGTT in the intact group, but not in ADM rats. Insulin secretion was reduced for both anesthetics in intact and ADM rats.
Conclusion: Sympathoadrenal axis activity is not involved with the hyperglycemia induced by thiopental or ketamine/xylazine.