Background & Aims: Sympathetic nervous system thorough α-2 adrenoceptors and insulin have principal roles in blood glucose regulation. On the other hand, vitamin B12 participates in sympathetic system and insulin functions. In this study, the effect of vitamin B12 on acute hyperglycemia induced by ketamine-xylazine was investigated. In order to clarify the possible mechanism of the effect of vitamin B12, we used yohimbine (an α2-adrenergic receptor antagonist) and insulin.
Materials & Methods: Sixty-six rats were divided into 11 experimental groups and were injected intraperitoneally with normal saline, vitamin B12, yohimbine and insulin 15 min. after acute hyperglycemia induction. Acute hyperglycemia was induced with intraperitoneal injection of a mixture of ketamine (100 mg/kg) and xylazine (10 mg/kg). The tail blood glucose levels were measured at 30, 60, and 120 min. after hyperglycemia induction. Data were analyzed using two-way ANOVA followed by Tukeyʼs test.
Results: Blood glucose levels were significantly (P<0.05) increased at 30, 60, and 120 minutes after ketamine-xylazine injection. Vitamin B12 (0.5 and 2 mg/kg), yohimbine (1 mg/kg) and insulin (2 IU/kg) decreased the acute hyperglycemia induced by ketamine-xylazine. Furthermore, co-administration of ineffective doses of vitamin B12 (0.125 mg/kg), yohimbine (0.5 mg/kg), and insulin (0.5 IU/kg) significantly reduced the hyperglycemia.
Conclusion: The results of the present study showed that vitamin B12, yohimbine and insulin decreased acute hyperglycemia. Synergistic effects were observed between vitamin B12 with yohimbine and insulin in reducing the hyperglycemia.